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Rice 121

Lemma Palea

Pericarp Starchy endosperm
Seed coat

Aleurone layer Embryo
Subaleurone layer Rachilla
Sterile lemmas

Pedicel
Fig. 3.2 A rice kernel in longitudinal cross-section.

bodies, while the rectangular aleurone cells, surrounding the embryo, are
characterized by fewer and smaller lipid bodies which lack aleurone grains
(Champagne et al., 2004). The starchy endosperm is characterized by two
distinct regions – the subaleurone layer and the central region. The sub-
aleurone region is typified by a limited number of small, oval-shaped starch
granules surrounded by three different types of membrane-bound protein
bodies. The starch granule takes a number of forms: a large spherical body
with a dense centre surrounded by concentric rings measuring 1–2 μm in
diameter; a small spherical body characterized by concentric rings and
measuring 0.5–0.75 μm in diameter; and crystalline protein bodies (2–3.5 μm
in diameter) that appear to be a composite of small, angular components,
each of which displays crystal lattice fringes (Bechtel and Pomeranz, 1978).
The central endosperm is primarily composed of large starch granules (with
diameter 3–9 μm), with a polygonal (hexagonal) shape resembling those of
oats (Kent and Evers, 1994; Delcour and Hoseney, 2010). They are highly
compact and surrounded by dense proteinaceous material. In this region of
the endosperm, the main protein bodies resemble the large spherical protein
bodies detected in the subaleurone zone (Bechtel and Pomeranz, 1978).

The embryo (germ) is situated on one side of the endosperm towards
the base of the caryopsis. Unusually, the embryo is not firmly attached to
the endosperm and consists of a short axis with the plumbe at its apex
and the primary root at its base (Tateoka, 1964). The embryonic axis is
bound on the inner side by the scutellum (cotyledon), which lies next to the
endosperm.

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122 Cereal grains for the food and beverage industries

3.2 Rice carbohydrate composition and properties

As reviewed by Champagne et al. (2004), the variety, environmental condi-
tions and processing all influence the gross composition of rice and its
fractions. Polysaccharides, proteins and lipids represent the three major
constituents of the rice kernel. Generally, rice has the lowest protein content
(7 %) (Table 3.4) amongst the cereals, even though rice protein has one of
the highest lysine contents (Juliano, 2003). From a chemical compositional
viewpoint, the hull is low in starch, protein and fat while it is particularly
rich in cellulose, lignin, arabinoxylans and minerals (mostly silica). Nutri-
tionally, the rice bran is a particularly interesting because of its balanced
content of protein (13.2–17.3 % dry basis), fat (17.0–22.9 % dry basis),
carbohydrate (16.1 % dry basis) and dietary fibre (27.6–33.3 % dry basis)
(Pomeranz and Ory, 1982), as well as vitamins and minerals presents in
amounts which are beneficial to humans (Champagne et al., 2004). Among
the structural components of the rice kernel, the starchy endosperm has the
highest and the lowest carbohydrate and lipid contents, respectively. Addi-
tionally, protein levels are low when compared to levels in the bran but
higher than levels in the hull. The embryo is particularly rich in lipids
(19.3–23.8 % dry weight basis) and protein (17.7–23.9 % dry weight basis)
(Pomeranz and Ory, 1982). The composition of brown rice is shown in Table
3.4. Vitamins are generally present in higher levels in brown rice than in
milled rice, particularly the B vitamins which are mainly concentrated in
the scutellum (Hinton, 1948b). Rice has no detectable levels of vitamins A,

Table 3.4 Brown rice composition

Constituent Content (per 100 g)

Moisture (g) 14.0
Energy content (Kcal) 363–385
Crude protein (g) 7.1–8.3
Crude fat (g) 1.6–2.8
Crude fibre (g) 0.6–1.0
Crude ash (g) 1.0–1.5
10–50
Calcium (mg) 0.17–0.43
Phosphorus (mg) 0.2–5.2
Iron (mg) 0.6–2.8
Zinc (mg) 73–87
Carbohydrates (g) 2.9–4.0
Total dietary fibre (g)
Water-insoluble fibre (g) 2.0
Sugar (g) 1.9
Othersa (mg) 6.5–10.4

aRice also contains small quantities of B-complex vitamins,
including thiamine (B1), riboflavin (B2), niacin, pyridoxine (B6),
pantothenic acid, biotin, folic acid and vitamin E.
Source: Adapted from Champagne et al. (2004).

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C or D. Minerals are mainly concentrated in the hull and in the bran;
however, the bran phytic acid, and also probably dietary fibre, in the aleu-
rone layer forms complexes with minerals and proteins, thus reducing their
bioavailability (Juliano, 2003).

3.2.1 Starch
Starch is concentrated in the endosperm fraction of the rice kernel (Table
3.5), and accounts for approximately 90 % of the total milled rice dry
weight. As observed in other cereal grains, starch granules are mainly com-
posed of a branched fraction, amylopectin, and a linear fraction, amylose.
Amylose is an essentially linear polymer of α-(1→4)-linked d-glucopyranosyl
units with few (<0.1 %) α-(1→6) linkages (Ball et al., 1996). Typical amylose
levels in starches are 15–25 % (Manners, 1997). In rice, amylose contents
have five classifications: waxy (0–2 % amylose), very low (5–12 %), low
(12–20 %), intermediate (20–25 %) or high (25–33 %) starch contents
(Juliano et al., 1981; Sano, 1984). The eating quality of rice is remarkably
influenced by gelatinization temperature of starch and its amylose content
(Juliano, 2003). Indeed, the latter is directly correlated with volume expan-
sion and water absorption during cooking and with final hardness, whiteness
and dullness of cooked rice (Bergman et al., 2004). In particular, rice with
a high amylose content exhibits high volume expansion and tends to cook
firm and dry and become hard upon cooling. In contrast, rice with a low
amylose content tends to cook moist and sticky and is often referred to as
sticky rice (Mutters and Thompson, 2009).

Amylopectin consists of α-(1→4) linked d-glucosyl chains and is highly
branched with 5–6 % α-(1→6)-bonds (Buléon et al., 1998). The individual
chains may vary between 10 and 100 glucose units (Manners, 1979). Since
milled rice is 85 % starch, starch gelatinization is one of the most important
factors affecting the texture and cooking time of the cooked products
(Juliano and Perez, 1983). The gelatinization behaviour is remarkably influ-
enced by the structure of the rice starch. In particular, very short (degree
of polymerization DP < 12) amylopectin chains were negatively correlated

Table 3.5 Carbohydrate content in rice kernel

Carbohydrate Amount References
(%, dry weight)
Yanai, 1979
Starch 90.68 Yanai, 1979
Amylose 29.46 Chrastil, 1990
Reducing sugar (g maltose/100 g rice) 0.12 Chrastil, 1990
Non-reducing sugar (g sucrose/100 g rice) 0.26 Chrastil, 1990
Total sugars 0.38 Moritaka, 1972
Fibre 0.28

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124 Cereal grains for the food and beverage industries

with gelatinization onset (To), peak (Tp) and conclusion (Tc) temperatures
of rice starches as measured by differential scanning calorimetry (DSC),
whilst longer (12 < DP < 24) amylopectin chains had a positive correlation
(Nakamura, 2002; Noda et al., 2003; Vandeputte et al., 2003). Additionally,
short amylopectin chains have a reduced tendency to form double helices,
a feature which may reduce the packing order within the crystalline struc-
ture (Gidley and Bulpin, 1987). Thus, starches with higher amounts of very
short amylopectin chains will have lower molecular weight, a crystalline
order and non-optimized packing within the crystalline lamellae. As a
result, they will most likely have a lower gelatinization temperature
(Vandeputte and Delcour, 2004). On the other hand, amylopectin, with the
chain length of 18–21 DP, is able to form double helices, adequately filling
the crystalline lamellae and thus increasing the gelatinization temperatures
(Vandeputte et al., 2003).

In addition to amylose and amylopectin, starch granules contain small
quantities of other minor components, such as proteins, lipids and minerals
(phosphorus) which are either at the surface or inside the granules. The
lipid content ranges from 0.9–1.3 % (Azudin and Morrison, 1986) in non-
waxy rice starches (12.2–28.6 % amylose), while its content is negligible in
waxy rice starches (1.0–2.3 % amylose) (Azudin and Morrison, 1986). Starch
proteins are generally either storage proteins that exist mainly as protein
bodies (i.e. prolamin or gluteline) (Resurreccion et al., 1993) or biosynthetic
or hydrolytic enzymes (Baldwin, 2001). The latter are probably entrapped
within the starch granules during starch synthesis (Denyer et al., 1995). In
addition to lipids and proteins,phosphorus is an important non-carbohydrate
component of rice starch. It is mainly 6-phosphoglucose phosphorus
(0.003 % on dry basis) in the waxy rice starch granule, whereas it is mainly
phospholipid phosphorus (0.048 % on dry basis) in the non-waxy rice
starches (Hizukuri et al., 1983; Jane et al., 1996). Other mineral components
of starch include Ca, K, Mg and Na in their ionic form. Rice starch is widely
used as a thickening, stabilizing or filling agent in many food applications;
however, it is primarily consumed as part of cooked, whole-grain rice
(James, 1983).

3.2.2 Dietary fibre
Studies on comparative chemical composition of several cereal grains have
shown that rice has the lowest fibre content (0.8 %), followed by wheat
(1 %), millet (1.5 %), corn (2.0 %), rye (2.2 %), barley (3.7 %), sorghum
(4.1 %) and oats (5.6 %) (Champagne et al., 2004). Moreover, the fibre
content also varied within the rice varieties. Savitha and Singh (2011) esti-
mated the fibre content of five different varieties of paddy (four pigmented
and one non-pigmented) which had been shelled and milled in pre- and
post-parboiled form. They observed that the dietary fibre contents were
high in pigmented varieties compared to non-pigmented rice with a

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Rice 125

concentration of 9–10 g/100 g and, ∼6 g/100 g, respectively. The distribution
of fibre throughout the rice kernel is uneven, with the bran containing 70 %
of the total dietary fibre followed by polish with 19 %, and the endosperm
with 11 % (Resurrection et al., 1979). Polish is a by-product obtained by
abrasive milling of rice. It is distinguished from the bran, since polish con-
tains relatively more starchy endosperm (Resurrection et al., 1979) than the
bran, which contains more of the pericarp, seed coat, nucellus, aleurone
layer and germ. Dietary fibre represent almost 17–29 % (Abdul-Hamid and
Luan, 2000) of the rice bran (Champagne et al., 2004).

Rice dietary fibre has been reported to have positive effects on human
health (Abdul-Hamid and Luan, 2000). In this regard, Abdul-Hamid and
Luan (2000) studied the use of a dietary fibre preparation, derived from
defatted rice bran, as a functional ingredient for bakery products. They
found that dietary fibre from defatted rice bran had comparable water-
binding, a higher fat-binding and an increased emulsifying capacity, when
compared to the commercial fibre from sugar beet which was used as
control. Additionally, sensory evaluations revealed that the incorporation
of 5 and 10 % of rice bran into the bread was acceptable to the sensory
panellists.

3.3 Other constituents of the rice kernel

After starch, protein is quantitatively the major rice component. In addi-
tion, rice also contains a whole array of minor constituents, and some of
these, such as vitamins, minerals and phytochemicals, have a great impact
on the functional properties of rice-based products.

3.3.1 Protein
Protein is the second most abundant component in rice, following starch. It
ranges between 4.3 and 18.2 % with a mean of 9 % (Gomez, 1979; Kennedy
and Burlingame, 2003). Its content (Gomez, 1979) was found to differ sig-
nificantly from one variety to another (Chandrasekhar and Mulk, 1970;
Gomez, 1979; Juliano and Villareal, 1993) ranging from 4.5 to 15.9 % in O.
sativa varieties and 10.2–15.9 % in O. glaberrima varieties (Kennedy and
Burlingame, 2003). Environmental conditions (radiation, temperature) and
cultural practices (water management, weed control, time of harvest) have
also been shown to greatly influence the protein content of the rice grain.
Amongst the cultural practices, increasing plant space (low plant densities)
is particularly effective in increasing the protein content of the rice grain,
probably because more nitrogen is available per plant (De Datta et al.,
1972). Nitrogen fertilization, particularly if applied during the reproductive
stage, almost always increases the protein content of rice (De Datta et al.,
1972).

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126 Cereal grains for the food and beverage industries

Traditionally, cereal proteins are classified into albumin, globulin,
prolamin and glutelin according to their solubility, as described by Osborne
(1924). The outer tissues of the rice kernel are rich in albumin (66–98 %)
and globulin, whereas the starchy endosperm (milled rice) is richest in
glutelin (Zhou et al., 2002; Champagne et al., 2004). Prolamin is a minor
constituent of all milling fractions of the rice grain (Shih, 2004). Indeed, in
milled rice, the soluble fractions of rice protein are ≈9.7–14.2 % albumin
(water-soluble proteins), 13.5–18.9 % globulin (salt-soluble proteins),
3.0–5.4 % prolamin (alcohol-soluble proteins) and 63.8–73.4 % glutelin
(alkali-soluble proteins) (Zhou et al., 2002; Juliano, 2003).

Although ‘Osborne fractionation’ is still widely used, it is more usual
today to classify seed proteins into three groups: storage proteins, structural
and metabolic proteins, and protective proteins. Seed storage proteins fall
into three different Osborne fractions and occur in three different tissues
of the grain (Shewry and Halford, 2002).

The rice embryo contains globulin storage proteins, with sedimentation
coefficients of about 7 (7S globulin). It is readily soluble in a dilute salt
solution and appears to function solely as storage protein (Shewry and
Halford, 2002). Rice storage globulins of 11–12S are located in the starchy
endosperm and account for about 70–80 % of the total protein. These rice
proteins are not readily soluble in dilute salt solutions and, hence, are clas-
sically defined as glutelins, but they clearly belong to the 11–12S globulin
family (Shewry and Halford, 2002).

Brown rice is generally regarded as having the lowest protein content
among the common grains. However, the net protein utilization and digest-
ible energy in rice are the highest amongst the common cereal grains
(Childs, 2004).

Rice protein is unique amongst the cereal proteins as it is richest in
glutelin and lowest in prolamin (Kaul and Raghaviah, 1975). The prolamin
fraction is poorest in lysine but rich in sulphur amino acids. The generally
high lysine content of rice protein is due to the low prolamin (high sulphur
amino acids/low lysine fraction) content. Because of that, rice protein,
together with oat protein, has a higher lysine content (3.8 and 4.0 g/16 g of
N, respectively) than the other cereals such as wheat (2.3 g/16 g of N), corn
(2.5 g/16 g of N), barley (3.2 g/16 g of N), sorghum (2.7 g/16 g of N), millet
(2.7 g/16 g of N) and rye (3.7 g/16 g of N) (Childs, 2004). Rice proteins are
also relatively rich in the essential amino acid methionine (Wang et al.,
1978) (Table 3.6). However, despite the high lysine content in rice, this
amino acid is still the first limiting essential amino acid in the crop (Alekaev,
1976), based on the human requirements as estimated in the WHO (1973)
amino acid pattern.

Protein is a major factor in determining the texture, pasting capacity and
sensory characteristics of milled rice. Many studies found that protein plays
a significant role in determining the functional properties of starch, includ-
ing inhibiting the swelling of starch granules, reducing the pasting and

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Table 3.6 Range of amino acid composition
(g/16.8 g N) of brown rice and milled rice

Amino acids Brown rice Milled rice

Alanine 5.8 5.6–5.8
Arginine 8.5–10.5 8.6–8.7
Aspartic acid 9.0–9.5 9.1–9.6
Cysteine 1.8–2.6 1.9–2.1
Glutamic acid 19.9–17.6 18.3–18.5
Glycine 4.7–4.8 4.5–4.8
Histidine 2.4–2.6 2.3–2.7
Isoleucine 3.6–4.6 3.7–4.8
Leucine 8.3–8.9 8.4–8.6
Lysine 3.9–4.3 3.4–4.2
Methionine 2.3–2.5 2.3–3.0
Phenylalanine 5.0–5.3 5.3–5.5
Proline 4.8–5.1 4.6–5.1
Serine 4.8–5.8 5.3–5.9
Threonine 3.9–4.0 3.7–3.9
Tryptophan 1.3–1.5 1.3–1.8
Tyrosine 3.8–4.6 4.4–5.5
Valine 5.0–6.6 4.9–6.8

Source: Adapted from Shih (2004).

crystallizing capacities of starch, and increasing the pasting temperature of
the isolated rice starch (Shih, 2004). Additionally, high protein content in
rice causes longer cooking time and firmer structure and is negatively cor-
related with reduced smoothness, stickiness, taste and overall palatability
(Mutters and Thompson, 2009).

3.3.2 Lipids
Rice grains contain low levels of lipids (approximately 2.2 % of total grain
weight) when compared to other cereals such as corn (4.9 %), barley (3.4 %),
oats (5.9 %) sorghum (3.9 %) and millet (4.7 %) (Childs, 2004). Only wheat
and rye showed a lower lipid content, having a concentration equal to 1.9
and 1.5 % of total grain weight (data quoted at 14 % moisture), respectively
(Childs, 2004). Fat distribution within the rice caryopsis is not uniform with
lipid being primarily concentrated in the bran fraction and in the embryo
(Table 3.7) (Choudhury and Juliano, 1980; Godber and Juliano, 2004).
Within the endosperm, lipids were unevenly distributed, with the lowest
amount in the centre of the kernel and increasing progressively towards the
outer layer of the endosperm (Normand et al., 1966). Linoleic acid is the
major fatty acid present in brown rice, at an average of 38 %, followed in
decreasing amounts by oleic (35 %), and palmitic acid (23 %) (Table 3.7).
In contrast, in the hull, oleic acid represents the major fatty acid (Table 3.7).

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Table 3.7 Lipid concentration and lipid distribution in rice caryopsis

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Fraction Lipid Fatty acid composition (wt %) Neutral lipids Glycolipids Phospholipidis
content Palmitic Oleic Linoleic Othersa (% of total lipids) (% of total lipids) (% of total lipids)
(wt %)

Hulls 0.4 18 42 28 12 64 25 11

Brown 2.7 23 35 38 4 86 5 9

Milled (starchy endosperm) 0.8 33 21 40 6 82 8 10

Bran 18.3 23 37 36 4 89 4 7

Embryo 30.2 24 36 37 3 91 2 7

Polish 10.8 23 35 38 4 87 5 8

a Trace to 3 % myristic, 2–4 % stearic and 1–2 % linoleic.
Source: Adapted from Godber and Juliano (2004).

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In accordance with Mano et al. (1999), cereal lipids can be separated into
neutral lipids, glycolipids and phospholipids. Neutral lipids, principally tri-
glycerides, are evenly distributed amongst the different structural parts of
the grain even though the highest proportion is localized to the bran and
in the embryo. Conversly, glycolipids and phospholipids are concentrated
in the hulls and in the hulls/endosperm, respectively (Table 3.7).

Based on cellular distribution and association, rice lipids can be classified
into two basic fractions – non-starch lipids and starch lipids. Non-starch
lipids are stored in oil droplets called spherosomes, about 0.1–1 μm in size
(Bechtel and Pomeranz, 1978) and are distributed throughout the kernel
(Choudhury and Juliano, 1980). Choudhury and Juliano (1980) found that
the highest content of non-starch lipids in brown rice was concentrated in
the bran (39–41 %) followed by polish (15–21 %), embryo (14–18 %), sub-
aleurone layer (12–14 %) and the inner endosperm (12–19 %). Starch
lipids typically comprise 0.5–1 % of the milled rice and include those lipids
(mainly monoacyl lipids, i.e. fatty acids and phospholipids) in complexes
with amylose in the starch granules of the rice kernels. Their content differs
between waxy and non-waxy varieties with the latter having more starch
lipids and less non-starch lipids in brown and milled rice than the former
(Choudhury and Juliano, 1980). The predominant fatty acids in rice starch
were linoleic (C18:2) and palmitic (C16:0) acids (Kitahara et al., 1997).

The existence of starch–lipid complexes has several consequences. For
example, complex development impacted on the formation of resistant
starch (RS) (Kitahara et al., 1996, 1997) and, additionally, yields of RS
(Mangala et al., 1999) were increased significantly by the removal of lipids
from rice starch. Guraya et al. (1997) reported that the amylose–lipid
complex formation with long-chain saturated monoglycerides generally
increases the resistance of the in vitro digestion over complexes with shorter
chains or more unsaturated monoglycerides. This is due to the increase of
the amylose–lipid structure stability. Amylose–lipid complexes also impact
pasting behaviour by decreasing the water-solubility in rice pastes cooked
for 30–90 min (Kaur and Singh, 2000) and increasing the pasting tempera-
ture and peak viscosity, as determined using a Brookfield viscometer. Toco-
pherols and tocotrienols, collectively called tocols or the vitamin E complex,
is an important group of nutrients associated with rice lipids due to their
non-polar solubility which will be discussed further in the following section.

3.3.3 Vitamins
Vitamins are nutritional components produced by plants. Cereal grains are
well known to be good sources of certain vitamins, particularly some of the
B-complex vitamins. The rice kernel contains little or no vitamin A, C or D.
Vitamin A deficiency (VAD) is prevalent among the poor in Asia, because
their diets are totally dependent on rice, which does not contain vitamin A
precursors (Juliano, 1993).

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130 Cereal grains for the food and beverage industries

Golden Rice (GR), is a new rice variety that has been genetically modi-
fied to contain β-carotene (Datta and Khush, 2002), a source of vitamin A
in the endosperm of the rice grain, providing a new alternative intervention
to combat VAD (Toenniessen, 2001). Nestlé (2001) report that the extent
to which the β-carotene in GR can compensate for biological, cultural, and
dietary barriers is limited. Thus, it should be viewed as a complement to
existing interventions (Dawe et al., 2002). To have greatest impact, GR
varieties should be suited for widespread adoption in Asia and should
deliver as much β-carotene as possible (Dawe et al., 2002).

Vitamin B1 (thiamine) is distributed throughout the rice caryopsis. Wang
et al. (1950) reported that vitamin B1 is mainly concentrated in the scutellum
(more than 55 %) and this, along with the aleurone layer, accounts over
80 % of the vitamin B1. Similar findings were reported by Hinton (1948a)
who identified the scutellum as the rice structure containing the highest
amount of vitamin B1 with 47 %, followed by the combined pericarp, seed
coat, nucellus and the aleurone layer with 34 %, the embryo with 11 %, and
finally, the endosperm with 8 %. An overview of the vitamin content of
brown rice is given in Table 3.8. Due to the practice of polishing the grain
to remove the bran layer and the germ, which contain the B-complex vita-
mins, persons who eat rice as their staple diet have developed a thiamine
deficiency disease called beriberi. This syndrome has caused huge suffering
in the Far East, particularly in earlier periods 1870–1910, and may originally
have meant ‘great weakness’ (Carpenter, 2004). Characteristically, it includes
symptoms of weight loss, emotional disturbances, impaired sensory percep-
tion, weakness and heart failure (Thomas, 2006). However, parboiling rough
rice permits the water-soluble vitamins and mineral salts to spread through

Table 3.8 Mineral and vitamin composition of brown rice

Minerals Vitamins (μg/g at 14 %
moisture)

Main (mg/g at 14 % moisture) 0.1–0.5 Thiamin (B1) 2.9–6.1
Ca 0.6–2.8 Riboflavin (B2) 0.4–1.4
K 0.2–1.5 Cyanocobalamin (B12)
Mg 1.7–4.3 Pyridoxine (B6) 0–0.004
P 0.3–1.9 Pantothenci acid 5–9
S 0.6–1.4 Biotin 9–15
Si 0.04–0.10
17–340 Folic acid
Minor (μg/g at 14 % moisture) 1–6 Retinol (A) 0.1–0.5
Na 2–52 Vitamin E 0–011
Cu 2–36 Niacin 9–25
Fe 6–28 35–53
Mn 210–560
Zn
Cl

Source: Data from Champagne et al. (2004).

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Rice 131

the endosperm and the proteinaceous material to sink into the compact
mass of gelatinized starch. This results in a smaller loss of vitamins, minerals
and amino acids during the milling of parboiled grains (Mickus and Luh,
1991), thus explaining why the consumption of parboiled rice was associ-
ated with immunity from beriberi (Bhattacharya, 2004).

Rice bran oil contains about 0.1–0.14 % vitamin E components and
0.9–2.9 % oryzanol, with their concentrations varying substantially accord-
ing to the origin of the rice bran (Lloyd et al., 2000). Vitamin E was first
discovered in 1922 as a micronutrient supporting fertility (Evans and
Bishop, 1922). For this reason, vitamin E was scientifically named tocophe-
rol (Toc).The word ‘tocopherol’ comes from the Greek words tokos meaning
childbirth, phero meaning to bring forth and ‘ol’ indicating the alcoholic
properties of the molecule (Miyazawa et al., 2011).Vitamin E is a generic
term for a group that comprises four tocopherols and four tocotrienols (α,
β, γ and δ), which differ only in the degree of saturation of their hydrophobic
tails (Chaudhary and Khurana, 2009). Among them, α-tocopherol has the
highest biological activity (Duvernay et al., 2005) working as a chain-
breaking antioxidant that prevents the propagation of free radical reactions
(Becker et al., 2004), thus ensuring inhibition of lipid peroxidation (Niki
and Noguchi, 2004).

Oryzanol is the other antioxidant found in rice bran oil and represents
a mixture of esters of ferulic acid with sterols and triterpene alcohols (Zigo-
neanu et al., 2008). Cycloartenol, β-sitosterol, 24-methylene-cycloartanol
and campesterol (4-desmethysterols) are the most prevalent oryzanol com-
ponents found in the rice bran (Lloyd et al., 2000). Vitamin contents of the
rice caryopsis can be affected by cultural practice and/or grain processing.
Taira et al. (1976) showed how ‘topdressing’ rice with nitrogen fertilizer at
panicle initiation and again at full heading stage decreases the riboflavin
content (B2) from 1.41–1.43 μg/g to 1.16–1.27 μg/g and increases the nico-
tinic acid content from 54.7–55.4 μg/g to 58.3–62.1 μg/g. In contrast, thia-
mine (B1) and folic acid (B9) were not affected by nitrogen fertilization.
Additionally, during the normal milling process extensive losses of vitamins
have been reported. These losses include thiamin (B1) by 68–82 %, ribofla-
vin (B2) by 57 %, niacin (B3) by 64–79 %, biotin (H) by 86 %, pantothenic
acid (B5) by 51–67 %, B6 by 43–86 %, folic acid (B9) by 60–67 %, vitamin E
by 82 % (Luh, 1991b; Dexter, 1998).

3.3.4 Minerals
Rice mineral content ranges from 1.0–1.5 % (Childs, 2004), decreasing from
the outer bran layers in to the endosperm (Itani et al., 2002; Lamberts et al.,
2007). The bran contains about 51 % of total amount of minerals, followed
by 28 % in the milled rice fraction and 10 % each in the germ and polish
(Childs, 2004). The most abundant macro-elements found in rice are P and
K, whilst Cl, Na and Zn are the primary micro-element representatives

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132 Cereal grains for the food and beverage industries

(Table 3.8). Phosphorus is the most important element in nutritional terms;
however, in rice bran, a major proportion (90 %) of it exists as phytin phos-
phorus. Wang et al. (2011) examined phytic acid (PA) and six mineral ele-
ments, including; Mg, Ca, Mn, Fe, Zn and Se, in rice to reveal their distribution
in the different fractions to investigate the effect of degree of milling
(DOM) on the loss of these constituents during the milling process. They
found that most of the mineral elements and PA were present in the frac-
tions of the outermost part (bran and outer endosperm fraction), whereas
only small amounts are accumulated in the core endosperm fraction of the
rice kernels. Generally, the mineral content in rice followed the order Mg
> Ca > Mn > Zn > Fe > Se. P, Mg, Ca, Mn and Fe are mainly located in the
outer layer of the rice kernel. In contrast, Zn and Se seem to be evenly
distributed through the rice caryopsis (Wang et al., 2011). Milling was shown
to have a large effect on mineral element concentrations and using this
technique to adjust the flour yield allows improvement of the elemental
composition of rice flour (Wang et al., 2011). Antoine et al. (2012) analysed
the mineral composition of 25 rice brands available on the Jamaican market
in addition to a local field trial sample. Brown rice was found to contain,
on average, significantly greater concentrations of Cr, Cu, K, Mg, Mn, Na,
P and Zn, in comparison with the white rice samples. White rice does not
significantly contribute to mineral nutrition for most essential elements.

3.3.5 Phytochemicals
Phytochemicals are non-nutritive components present in a plant-based diet
that exert protective or disease-preventing effects. Rice bran contains a
significant amount of natural phytochemicals such as oryzanols, tocopherols
and tocotrienols that have been reported as the strongest antioxidants in
rice bran (Orthoefer and Eastman, 2004). Polyphenols in rice are also of
particular interest due to their multiple biological activities. These phenolic
compounds, that include ferulic acid and diferulates, anthocyanins, anthocy-
anidins and polymeric proanthocyanidins (condensed tannins) (Chun et al.,
2005), have a protective effect on cell constituents against oxidative damage.
Additionally, epidemiological studies have shown that they can prevent
cancers, cardiovascular and nerve diseases (Kehrer, 1993), as well as
possessing remarkable anti-inflammatory properties (Hou et al., 2012).
However, some of these bioactive components are heat labile and are often
lost during the high heat processing treatments (Pascual et al., 2012).

3.4 Rice processing

Rice processing comprises parboiling, followed by the various stages in the
milling process. The complex processing steps are detailed in the following
sections.

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3.4.1 Parboiling rice
Parboiling paddy (or rough rice) is a hydro-thermal treatment aimed at
inducing milling, nutritional and organoleptic improvements in rice (Kar
et al., 1999). It is an alternative method to prolong rice storage, reduce
broken grain, increase head rice yield and reduce nutritional loss during
the polishing process (Bhattacharya, 2004). The meaning of parboiled
rice, as the name implies, is rice that has been partially boiled, i.e. cooked
(Bhattacharya, 2004). Parboiled rice originated in ancient India and, nowa-
days, is applied to one-quarter of the world’s paddy produce (Kar et al.,
1999). Industrially, this pre-cooking procedure consists of water and heat
which are applied separately to avoid over-imbibition and bursting or
deshaping of the rice caryopsis. In practice, the process consists of soaking
rough rice in water until it is saturated, draining the excess of water and
then steaming or otherwise heating the grain to gelatinize the starch, with
subsequent drying and packaging of the grains (Bhattacharya, 2004). Drying
methods are the key factors influencing the milling quality of the rice (Bhat-
tacharya and Indudhara Swamy, 1967). Several processes have been used
to dry parboiled rice such as sun drying, hot air drying, vacuum drying and
superheated steam drying (Bhattacharya, 2004; Soponronarit et al., 2004;
Taechapairoj et al., 2004).

Parboiling rice is also an economical way to improve the storage stability
(reduction of insect infestation) and significantly increase the nutritive
value of the rice. In this regard, during the parboiling treatment, vitamins
and minerals seep into the endosperm from their natural place of residence
in the bran and aluerone layer. Thus, post-milling parboiled rice contains
much greater amounts of B vitamins, minerals (especially Ca, P, and Fe),
and free amino acids than raw rice (Bhattacharya, 2004). Additionally, the
loss of nutrients during washing is also greatly reduced. From a technologi-
cal viewpoint, parboiled grains do not mash together after cooking, thus
remaining whole, and making rice suitable for making products which are
canned, expanded or flaked.

However, the parboiling of rough rice also has certain disadvantages. The
rice husk represents a hurdle for the entire parboiling process because it
has a poor thermal conductivity resulting in increased time and heat energy
required for wetting and heating. Moreover, the husk is also a barrier during
the drying operation after parboiling, and the final rice is more prone to
oxidative rancidity. Kar et al. (1999) developed a method for parboiling
dehusked rice, thus saving processing time, cooking energy and maintaining
satisfactory sensory quality of the final product.

3.4.2 Rice milling
The objective of milling is to remove the rice hull, bran and germ, with
minimum endosperm breakage (Owens, 2001). Each milling step is briefly
described below.

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Precleaning/destoning
Preliminary cleaning is the first step in advance of milling rice, and it is
carried out to eliminate immature rough rice and unfilled grains from
paddy, foreign grains as well as vegetable (weed seeds, straw, chaff), animal
(rodent, excreta and hairs, insects and insect frass, mites) and mineral (mud,
dust, stones, sand, metal objects, nails, nuts) impurities. The large light and
large heavy impurities are removed by a rotating screen, while the smaller
ones are removed by an oscillating sieve. The small stones are removed by
a destoner or gravity separator, in conjunction with air current aspiration,
using the difference in density weight of rough rice and stones as the mecha-
nism of separation. A permanent rotating and self-cleaning electromagnet
is normally installed to trap iron or steel particles from the paddy (Bond,
2004).

Husking/husking aspiration
Husk is not edible and therefore must be removed from paddy. The husk
is not tightly bound to the kernel and so it is easily removed. Generally,
rubber-roll hullers are used to dehull rough rice. This machine consists of
two rubber-rolls of identical diameter, one rotating clockwise and the
second counter clockwise. One roll moves about 25 % faster than the other.
The difference in peripheral speeds subjects the paddy grains, which fall
between the rolls, to a shearing action that strips off the husk (Wimberly,
1983). The clearance between the two rolls is based on the length of the
grain (Bond, 2004). Payman et al. (2007) studied the factors that affect
the operation of a rubber-roll hulling machine in an effort to decrease the
amount of rice breakage. They found that linear speed differences of rollers
of 229.3 m min−1 ensure the least rice breakage. However, other factors such
as the rice variety and grain humidity influence the efficiency of the husking
process. After the husking, the detached husk is removed using a double
air-trap aspiration system, in which the hull is in part removed by aspiration
as the grain passes over the coarse bran sieve and the remaining hull is
aspirated upwards by an air-trap system positioned above the rough rice
separator (Bond, 2004).

Paddy separation
The paddy must be separated before the brown rice goes to the bran
removal stage (Wimberly, 1983). The separating machine separates the
product of the husking operation into three parts – brown rice, paddy and
a mixture of the two. Brown rice is fed to the whitening machine, paddy is
sent back for husking and the mixture is returned to the separator (Fouda,
2011). Natural differences between the paddy and brown rice aid the paddy
separation process, such as (i) the average weight of paddy by volume is
less than that of brown rice; and (ii) the paddy grains are longer, wider and
thicker than those of brown rice. The paddy separator commonly used

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today is the tray type. It consists of several indented trays mounted one
above the other about 5 cm apart, clamped together and attached to an
oscillating frame. The assembly of trays has a double inclination. The table
inclination is adjustable to meet different paddy varieties and conditions
and to achieve maximum separation capacity. The tray section moves up
and forward, making a slight jumping movement. Paddy moves onto each
tray from the highest corner of the double-inclined tray. As it moves across
the tray downward towards the end of the tray opposite the feeding end,
the brown rice separates from the paddy. The brown rice has a smoother
surface and a greater bulk density and moves to the top of the tray (highest
corner) where it is conveyed to the polishers. The paddy moves to the lower
part of the tray (lowest corner) where it is conveyed back to the husker.
Some of the unseparated paddy moves to the centre of the tray where it is
returned to the inlet of the separator.

Whitening (bran removal)
In this process, bran – which is tightly attached to brown rice – is removed
from the rice kernel. Therefore, during this process rice kernels are subject
to intensive mechanical and thermal stress which causes some rice kernel
damage and breakage. The most common whitening machines, the abrasive-
type whitener and the friction-type whitener, use the abrasive and friction
process for bran removal, as the equipment names suggest. The abrasion
process uses a coarse surface to break and peel the bran off the rice grain.
The friction process uses the friction between the grains themselves to
break and peel off the bran (Wimberly, 1983).

Polishing
The aim of the polishing step is to remove the loose bran which, even after
the whitening process, still adheres to the surface of the milled rice. There
is a rubber polisher that polishes the whitened rice using a rubber brush;
however, the friction-type whitener is sometimes used as a polisher. Gener-
ally, the polishing machine has a cone shape that is covered with leather
strips, which gently brush the grain as it passes through the machine which
operates at a lower rpm. The leather strips roll the whitened rice over and
over against the screen. Under slight pressure, the remaining bran is
removed from the milled rice passing through these screens and the rice
becomes shinier and glossier (Wimberly, 1983; Bond, 2004).

Grading
After the whitening operation, the unbroken rice is still mixed with differ-
ent sized broken rice pieces, bran and dust. Bran and dust particles are
separated by air aspiration, while the small broken rice and germs are sepa-
rated by a vibrating sieve or rotary cylinders called trieurs. The latter is
mainly composed of a slowly indented rotating cylinder that is installed at
a slight incline. Each indent has the ability to catch grains or grain particles,

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136 Cereal grains for the food and beverage industries

which are then lifted from the grain mass and discharged by gravity when
the indent cannot hold the grain any longer (Wimberly, 1983; Bond, 2004).

Milling
Three methods, namely wet, dry and semi-dry milling, have been used to
grind polished rice kernels or brokens into flour (Chiang and Yeh, 2002).
Wet grinding is a traditional process used to prepare rice flour and includes
five successive steps: soaking, adding excess water during grinding, filtering,
drying and sieving. This process comprises the use of several machines and
much manpower. Additionally, this process is known to have significant
flour loss and high energy consumption (Yeh, 2004). Dry grinding does
not use water (no waste water generation) and is characterized by its
limited consumption of energy. Herein, the rice kernel is ground with dry
grinding machinery such as a hammer mill, pin mill, roller mill or disc mill,
etc. Nevertheless, many food items made of dry ground flour (for instance,
noodles) have inadequate rheological properties for many consumer uses
(Yeh, 2004).

In the semi-dry grinding methods, the properties of flour are inter-
mediate to those of both dry and wet ground flour from the perspectives
of particle size, viscosity, damaged starch, etc. (Ngamnikom and
Songsermpong, 2011). The semi-dry grinding process is characterized by
three consecutive steps: soaking, drying to remove excess water (15–17 %
wet basis) and grinding with dry grinding machinery (Yeh, 2004). Neverthe-
less, the semi-dry method has some disadvantages, such as the longer time
required to adjust the rice kernel moisture content, the high energy con-
sumption needed for the drying step, the excessive consumption of water
and the generation of waste water. Generally, wet-milled flour is superior
to dry-milled flour for making traditional baked products (Bean et al., 1983)
and Thai rice-based snack food (Jomduang and Mohamed, 1994). The supe-
rior quality of wet-milled flour is mainly due to its low proportion of
damaged starch and finest relative particle size (Chen et al., 1999).

Ngamnikom and Songsermpong (2011) investigated the performance of
a new grinding process, which includes freezing rice with liquid nitrogen
prior to dry grinding. In terms of damaged starch content, average particle
size, particle size distribution, microscopic structures and energy consump-
tion, they found that the freeze grinding resulted in (i) reduced particle size
and damaged starch content due to the extremely low temperature of the
sample prior to grinding, and (ii) a smaller flour particle size than from dry
grinding resulting in a greater yield after sieving. Moreover, freeze grinding
produced a higher flour yield after sieving in comparison with dry grinding
using an identical grinder. Finally, the energy consumption of freeze grind-
ing was similar to dry grinding and much lower than that detected for the
wet grinding process. Consequently, the authors conclude that the freeze
grinding process was a viable alternative to the traditional wet grinding
process.

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3.5 Food and beverage applications of rice

Rice consumption falls into the following three categories: direct food use,
processed foods use and brewer’s use. After hulling, brown rice can be
processed in different ways. It can be (i) decorticated by abrasion ‘milling’
to obtain white polished rice, (ii) parboiled, thus retaining more original
minerals and vitamin B1 compared with polished white rice, or (iii) not
decorticated and consumed as brown rice. However, parboiled rice and
brown rice are generally not as appreciated because of their darker colour
compared to white polished rice. Polished rice may also be ground into a
powder (flour), which enters the food industry in the form of cakes, noodles,
baked products, puddings, snack foods, infant formulas, fermented goods
and other industrial products (Kiple and Ornelas, 2000).

Cooking of all types of rice is performed by applying heat (boiling or
steaming) to soaked rice until the starch grains are fully gelatinized and
excess water is expelled from the cooked product. Cooked rice can be used
for making porridge (thick gruel) or congee (thin soup), or lightly fried in
oil to make fried rice.

Rice, which is low in sodium, fat and cholesterol-free, serves as an aid in
treating hypertension. It is also free from allergens and now widely used in
baby foods (James and McCaskill, 1983). Rice starch can also serve as a
substitute for glucose in oral rehydration solution for infants suffering from
diarrhoea (Childs, 2004).

Either uncooked or fully cooked, rice combines well with protein-rich
foods such as meat, poultry, fish, cheese and eggs for two reasons. Firstly,
rice is bland and thus serves to carry the flavour of the mixed ingredients.
Secondly, from a dietary perspective, rice is low in protein and thus mixtures
with protein-rich foods provide additional nutritional dimensions to rice
foods. Rice can be lightly fried before boiling (Middle East), combined with
salt, butter or margarine after soaking (Americans) or cooked in extra
water to produce porridge (thick gruel) or congee (thin soup) (China,
Korea and Japan). Rice can also be cooked with curries (in India and
Malaysia), sauces (in the Philippines) or with combinations of various ingre-
dients, including pork, shrimp, chicken and vegetables (in China) (Boesch,
1967). Detailed methods and recipes for rice food preparations were
described by Luh (1999), Owen (1993), Jeffrey and Duguid (1998) and Luh
(1991b).

3.5.1 Bakery products from rice
The production of bakery products based on rice presents several techno-
logical problems, when compared to their wheat counterparts, due to
the absence of gluten protein which gives the wheat its unique ability to
form highly expanded, tender, white and flavoursome yeast leavened or
chemically leavened baked products (Matz, 1996). In a dough system the

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main function of gluten is to swell and hold water, forming cells with strong
elastic walls which capture carbon dioxide formed during fermentation.
However, a yeast leavened bread made with 100 % rice flour was devel-
oped by Nishita et al. (1976), who found that hydroxy propyl methyl cel-
lulose (HPMC) was the only hydrocolloid for making rice bread that
provided the proper dough viscosity and film-forming characteristics. The
positive effect of the HPMC (between 1.5 and 3.0 %) on rheological prop-
erties of the rice dough was also confirmed by the study conducted by
Sivaramakrishnan et al. (2004). Besides the use of hydrocolloids as a gluten
mimicking agent, specific physico-chemical properties of rice flour, such as
low amylose content, low gelatinization temperature, low amylograph vis-
cosity of paste cooled to 50 °C and soft eating equality of milled rice, were
found to be useful characteristics for predicting good bread-making prop-
erties (Nishita and Bean, 1979). In contrast, Mi et al. (1997a, c) found that
high-amylose rice was most suitable for rice bread-making. Specifically,
they observed that the amylose content of milled rice was found to have
a close negative association with gel consistency and positive association
with springiness of rice bread. Additionally, the same authors reported that
several hydrocolloids (1.0–4.5 % HPMC, 1.5 % locust bean gum and 1.0 %
each of guar gum, carrageenan, xanthum gum and agar) resulted in the
successful formation of rice bread showing optimum volume expansion (Mi
et al., 1997b).

Small amounts of rice flour can be included in wheat-based products,
using wheat flour baking technology. Noomhorm et al. (1994) found that a
wheat replacement up to 150 g/kg with rice flour did not affect the overall
acceptability of the product. Recently, Veluppillai et al. (2010) evaluated the
possibility of substituting wheat flour with malted whole rice flour for the
preparation of bread, with the aim to improve the textural, sensory and
nutritional properties of the final bread. They found that the bread formula-
tion as follows – malted rice flour 35 %, wheat flour 65 %, fat 2 %, baking
powder 1 %, yeast 2 %, bread improver 4 %, sugar 3 % and salt 1.67 % –
resulted in the best bread physical and sensory qualities. The effect of
protease treatment of brown rice batters on the baking quality of brown
rice bread was investigated by Renzetti and Arendt (2009). Interestingly,
the authors observed that enzymatic treatment improved bread quality by
significantly increasing specific volume, while decreasing crumb hardness
and chewiness. Specifically, protein hydrolysis lowered the resistance to
deformation of batters during proofing and in the early stages of baking as
well as preserving batter elasticity and the increased paste stability, thus
positively affecting the bread-making performance.

3.5.2 Cakes
Rice cakes are made in many cultures and have a wide range of processing
and product characteristics. The Filipino rice cake, puto, is consumed daily

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as a breakfast, dessert or snack food. The product is made from rice that is
soaked overnight, ground and mixed with sugar and coconut milk. The
resulting batter is then fermented for several hours, during which time
acidification and leavening occur. The fermented batter is steamed for
approximately 30 min before serving (Kelly et al., 1995). Idli cakes are a
very popular fermented food consumed in the Indian subcontinent (Ghosh
and Chattopadhyay, 2011). Eaten at breakfast in South India and Sri Lanka,
in combination with coconut chutney and sambar (stew of tamarind and
pigeon pea) (Nout, 2009), they are small, white, acidic, leavened and steam-
cooked cakes which are the product of a lactic fermented thick batter made
from polished rice and dehulled black gram dhal, a pulse. The fermentation
of idli is natural; no back-slopping technique is used, although the use of
the same vessels and utensils may help to stabilize a mixed LAB microflora
(Nout, 2009). The cakes are soft, moist and spongy with a desirable sour
flavour (Steinkraus, 1983). It has also been reported that during fermenta-
tion, vitamins B and C increase, and also phytate is hydrolysed almost to
50 % of its original content (Ghosh and Chattopadhyay, 2011).

MiGao is a kind of steam cooked Chinese cake obtained from rice flour
and sticky rice flour (in the ratio of 2 :3) by steaming in a bamboo steamer.
It is famous for its soft and sticky texture and it is habitually served as a
dessert. Traditionally, these products are packaged in polyethylene bags
after steaming and cooling (Ji et al., 2007b). It has a short shelf-life (two
days) and loses its softness, quickly becoming stale and hard (Ji et al.,
2007b). Ji et al. (2007a) investigated the evolution of Enterobactericeae,
LAB, Gram-positive, catalase-positive cocci, Staphylococcus aureus, Bacil-
lus strains, yeasts and moulds in MiGao during its shelf-life in order to select
the most suitable strains as starter or protective cultures. During the first
two days, they found that Gram-positive bacteria were dominant, mainly
represented by S. epidermidis and S. aureus. Bacillus (mainly Bacillus brevis)
strains occurred by the third day, reaching a maximum level of 1 × 106 CFU/g
after five days of storage. No Enterobactericeae or LAB were detected in
the processed products throughout the storage period. The count of yeasts
and moulds increased slowly but remained low throughout the storage
period. The amount and type of foodborne pathogens and food spoilage
microorganisms identified in this product was extensive. In order to improve
the microbial safety of this traditional Chinese steamed cake, several pre-
servative strategies, such us combined pH, temperature and natural preser-
vatives, should be developed (Ji et al., 2007a).

Mochi, a kind of glutinous rice (waxy or sweet rice) cake, is particularly
common in Oriental areas such as Taiwan, China and Japan and is a special
rice cake for the celebration of the Chinese Lunar New Year. It consists of
high moisture, soft and slightly sticky dough served as a dessert. Conven-
tionally, glutinous rice is washed, cooked with water and pounded right after
cooking to ensure loss of the rice kernel integrity and allow formation of
the visco-elastic mixture (Chuang and Yeh, 2006). For better flavour, mochi

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is sometimes sweetened with sugar or enriched with lard and cinnamon
flour. There are many other types of rice cakes made in Asia. For example,
biko, cuchinta (or kutsinta), suman and other rice cakes are made in the
Philippines.

3.5.3 Rice breakfast cereals
Rice breakfast cereals can be classified into hot cereals – those the need to
be cooked or mixed with hot water before serving such as instant rice gruel,
and granular products such as cream of rice, and ready-to-eat (RTE) break-
fast cereals – those that can be eaten directly from the package such as
gun-puffed rice cereals, oven-puffed rice cereals, extruded-puffed rice and
shredded rice cereal (Luh, 1991a; Yeh, 2004). The shelf-life of RTE rice
breakfast cereals is expected to be 12 months at 20 °C. However, suboptimal
conditions may lead to a decreased shelf-life, and shelf-life depends on
parameters, such as packaging material, sealing and storage, which should
be adequate to avoid a loss of crispness and flavour, and to prevent water
uptake by hygroscopic products or hydrolytic rancidity due to oxidative
deterioration (Luh, 1991a).

3.5.4 Rice crackers
Rice crackers are popular in China, Japan and other Asian countries. They
are made from rice cakes using glutinous or non-glutinous rice as the
primary ingredient. After being washed and soaked in water for a couple
of hours, rice is steamed in a steamer. When the steamed rice is kneaded,
the resulting rice dough material has a homogeneous viscosity.After cooling,
rice dough is shaped into the form of the final product with a cutting
machine or punching tool. These pellets are then dried thoroughly (mois-
ture content drops to 10 %) and are then baked in an oven at a temperature
ranging from 200 to 260 °C. Thereafter, the expanded final product has a
moisture content of 3–5 % (Koizumi and Kamedamachi, 1975; Lu, 2004).

3.5.5 Noodles
Rice noodles, in various contents, formulations and shapes, are one of the
principal forms of rice products consumed in Southeast Asia since ancient
times (Yeh, 2004). To prepare for consumption, the noodles may either be
stir-fried by mixing with meats and vegetables, or boiled in a broth and
served as a soup noodle. Due to the absence of gluten, rice proteins are
unable to form continuous visco-elastic dough; thus it is common to subject
part of the rice flour to pre-gelatinization to create a binder for the remain-
ing flour. Depending on the production process, rice noodles can be made
by sheeting a batter, which is used to produce sheets and flat noodles, or by
extrusion, which is used to produce vermicelli types. For the production of

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sheeted rice noodles, particularly popular in most parts of Southeast Asia,
southern China and Japan, a wet-milled rice batter is layered onto a rotating
heated drum and the formed sheet is stripped off and conveyed to a steam-
ing tunnel where the gelatinization process takes place. The noodles can be
then cut into 1 cm wide strips to make fresh rice ribbon noodles or dried
before sale.

In rice vermicelli noodle production, milled rice is filtered, pulverized
and moulded into balls that are precooked in boiling water for about 20 min
or steamed to allow surface gelatinization. The partially cooked rice balls
are then kneaded to evenly distribute the gelatinized rice throughout the
dough where it will function as a binder. The kneaded dough is extruded
through a die.The extruded noodles are then further steamed for 10–15 min,
followed by a washing step under running water, and finally are dried in
trays. Alternatively, the extruded noodles are partially cooked in boiling
water and cooled in cold water. The noodles are then subject to the drying
(Fu, 2008). Good-quality noodles can generally be recognized by the bright-
ness of their colour, retarded discoloration, reduced microbial and chemical
(rancidity) deterioration and appropriate flavour and textural characteris-
tics which will vary according to the noodle type and region.

3.5.6 Germinated brown rice
Germinated brown rice, produced by soaking brown rice grains in water
until they begin to sprout (Komatsuzaki et al., 2007), is becoming popular
in Japan and Korea as an alternative to brown rice with improved texture.
The germination process involves a destructuration of starch, fibres
and proteins, resulting in generating physiologically active intermediates
(Palmiano and Juliano,1972;Komatsuzaki et al.,2007),such as γ-aminobutyric
acid (GABA) (Moongngarm and Saetung, 2010), and in an improvement
of flavour, digestibility and organoleptic and nutritional quality (Hunt et al.,
2002; Tian et al., 2004; Chung et al., 2012b). Therefore, germinated brown
rice has been suggested to be utilized as a healthy ingredient in a variety
of foods. In the study conducted by Chung et al. (2012a), germinated brown
rice was tested as a partial replacement of wheat flour in noodle-making,
and the effect of heat–moisture treatment of germinated brown rice on the
texture and cooking quality of the noodles was investigated. They found
that replacement of germinated brown rice flour with wheat flour signifi-
cantly degrades the cooking and textural quality of cooked noodles, result-
ing in increased cooking loss and softness. However, noodles made from
the flour containing heat–moisture treated germinated brown rice showed
substantially improved cooking and textural qualities comparable to the
control wheat noodle. Consequently, treated germinated brown rice can be
successfully used as a replacement of wheat flour for noodle-making with
additional health-promoting and nutritive values. Nevertheless, heat–
moisture treatment normally induces darkening and flavour modification

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due to the Maillard reaction, which should be carefully considered for the
use of treated germinated brown rice.

3.5.7 Infant foods
Although baby foods can be in the form of rice flour, waxy rice flour, par-
boiled rice, rice polishing, rice oil or granulated rice, generally precooked
milled rice is a dominant carbohydrate source to wean infants up to one
year of age. This is due to its tastelessness, low allergen potential and nutri-
tional value, including its lack of potentially allergenic gluten (Mennella
et al., 2006; Meharg et al., 2008b). The latter trait is particularly important
for infants with coeliac disease (Meharg et al., 2008a, b). The key to making
this type of cereal is ensuring the ease of reconstitution with milk or
formula in a homogeneous manner. The process to produce precooked rice
essentially consists of preparing a cooked rice slurry which is then dried
on a double-drum atmospheric dryer, flaked and subsequently packaged
(Kelly, 1985).

Recently, several studies have shown that rice and rice-based infant
products contain elevated contents of both total and inorganic arsenic
(Meharg et al., 2008b; Ljung et al., 2011). These elements are known to
increase infant morbidity and mortality. Moreover, Wang et al. (2012) iso-
lated S. aureus in infant rice cereal sold in the Shaanxi province in China,
and many S. aureus isolates exhibited resistance to different antimicrobials
and show expression of various toxin genes. Additionally, Richards et al.
(2005) demonstrated that reconstituted infant rice cereal can support luxu-
riant growth of Enterobacter sakazakii, a pathogenic microorganism known
to cause illness in preterm neonates, infants and children from three days
to four years of age. For this reason, reconstituted cereal that is not imme-
diately consumed should be discarded or stored at lower temperatures to
inhibit E. sakazakii, and other foodborne pathogen, growth.

3.5.8 Canned rice
For consumer convenience, canned rice is produced in Japan, Korea, the
USA and other countries. Two types of canned rice are produced today.
After precooking, canned rice is sold by wet pack, which is defined as a
product with an excess of liquid, such as soup, and dry pack, which is defined
as a product with free and separate grains without unbound or excess mois-
ture. The major problem that afflicts these products is the change of the rice
grain textural properties during storage. This is due to complete breakdown
of the kernels and/or the formation of rice clumps and development of
unpleasant mouthfeel. The use of parboiled rice helps prevents the disinte-
gration of the rice kernel (Demont and Burns, 1968). Azanza (2003) devel-
oped a thermally processed rice-based product for the Philippine military.
The canned rice prototype (CR) which was developed was favourably

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accepted by the panellists and was adopted as military food ration, particu-
larly suitable in areas with minimum or absent kitchen facilities.

3.5.9 Vinegar
Rice vinegar is an ancient and common product in the Far East. It is made
by a series of microbial processes which take one to three months
and, unlike other types of fermentation, three microbiological processes
are known to occur simultaneously or sequentially and proceed in a single
pot (so-called triple fermentation). These fermentations include saccharifi-
cation of the gelatinized rice starch using an inoculums of rice koji (mouldy
steamed rice grain populated by the genera Aspergillus) (Hesseltine, 1965;
Steinkraus, 1996), alcohol fermentation of the sugar released with
Saccharomyces sake and, finally, the acetic acid fermentation (oxidation of
ethanol to acetic acid) using unfiltered fresh vinegars from a previous
batch as inoculum to provide the necessary microorganisms for the acetic
acid fermentation. Haruta et al. (2006), Koizumi et al. (1996) and Entani
and Masai (1985) investigated the succession of bacterial and fungal
communities during the fermentation of rice vinegar. The microbial succes-
sion was dominated by A. oryzae (saccharification), Saccharomyces sp.,
Zygosaccharomyces sp. and Candida sp. (alcohol fermentation), Lactobacil-
lus acetotolerans, Acetobacter pasteurianus, A. aceti and A. xylinum (acetic
fermentation).

Two Japanese traditional rice vinegars, komesu, which is a polished
amber rice vinegar, and kurosu, which is an unpolished black rice vinegar,
are known for their health benefits via the prevention of inflammation and
hypertension (Murooka and Yamshita, 2008). In addition to vinegar, rice
koji is also used as the primary ingredient for a number of other condiments
and seasoning sauces, such as shoyu (soy sauce), miso (umami flavoured
sauce), mirin (sweet syrup) and alcoholic beverages, as described in the next
section.

3.5.10 Alcoholic rice beverages

Sake
In Japan, the use of rice for brewing sake (Japanese rice wine) ranks second
only in importance to its primary use as food. It is not produced by a con-
ventional beer brewing process, but there are several similarities between
beer and sake (Hardwick, 1995). Sake is made from steamed rice by a
double fermentation process involving koji (A. oryzae) and yeast (S. cerevi-
siae) (Kamara et al., 2009). The first step in sake brewing is polishing of rice.
This process, as previously described, involves the abrasive removal of
the protein, lipids and minerals mainly localized in the germ and in the
outer part of the rice kernel. Then the milled rice is washed, steeped in
water and steamed for 30–60 min (Yoshizawa and Ogawa, 1985). The first

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144 Cereal grains for the food and beverage industries

step of fermentation is the production of a seed mash. The steamed rice is
mixed with water, yeast and koji which is then fermented for 15 days at
approximately 20 °C. Due to the presence of LAB, the mash is acidified.
This naturally acidified mash is mixed with water, steamed rice and koji at
8 °C. After a few days, the mash is warmed slowly to about 15 °C. The seed
mash is then cooled and stored for five to seven days before it is used for
the main mash. Subsequently, steamed rice, koji and water are added to the
seed mash at 12 °C. The quantity added is about twice that of the seed mash.
An essential difference between beer and sake is that for the latter the
natural enzymes contained in the rice kernel are not used to break down
the starch and are, in fact, deliberately inactivated before the saccharifying
steps of the sake brewing. The solubilization of rice starch is ensured by
amylolytic action of the fungal enzymes derived from koji, which is domi-
nated by A. oryzae. Koji contains α- and β-amylases capable of starch
liquefaction to glucose. The acidic characteristic of koji, resulting from lactic
acid fermentation or lactic acid adjunct addition, inhibits the growth of
wild microorganisms that may compromise the quality of the fermentation
process.

As soon as the fungal population reaches its highest concentration
(108 CFU/g) originally present in the koji (generally after two days of fer-
mentation at 12 °C), one part steamed rice and one part water is added
again. A third addition is performed the following day and the vigour of
the fermentation is enhanced by increasing the temperature to 18 °C. After
an additional 13–17 days, the fermentation almost ceases and the alcohol
content rises to 17–20 %, which is a world record as the highest ethanol
content to be obtained by fermentation without distillation.

A turbid filtrate is normally obtained from the fermented mash by char-
coal filtration through canvas bags (to adjust flavour and colour). It is then
usually pasteurized to kill yeast and harmful microorganisms (if present),
to inactivate enzymes and to adjust the maturation velocity – a process
which takes approximately three to eight months. At the end of maturation,
but before the bottle-pasteurization, sake is blended with water to reach
the appropriate alcohol content (15–16 %) and then filtered through acti-
vated carbon to adjust the colour, taste and flavour (Yoshizawa and Ogawa,
1985).

Several indigenous rice beer-like products are produced around the
world such as sujen, which is a popular local rice beer of Assam (India)
(Deori et al., 2007). Additionally, distilled rice-based beverages exist, such
as shochu which is a popular alcoholic drink that is distilled from sake or
related alcohol in beverages (Murooka and Yamshita, 2008).

Rice is also widely used as brewing adjunct in the USA and in Japan
after maize (Childs, 2004). As an adjunct, rice is favoured by some brewers
because of its lower lipid and protein contents as compared with those of
corn grits. Broken rice, obtained as a by-product of the edible rice milling
industry, or rice grist is generally used in brewing. Rice is characterized by

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a neutral aroma and flavour and, when converted efficiently to fermentable
sugars, yields a clean tasting, light beer (Coors, 1976).

3.6 Conclusions

Rice is consumed in various forms including plain rice, noodles, puffed rice,
breakfast cereals, cakes, fermented sweet rice, snack foods, beer, wine and
vinegar. It is grown in every continent (except Antarctica), in over 114
countries from 53° north to 40° south, and from sea level to an altitude of
3000 m, thus representing the best cereal crop in terms of food energy per
production area. As reported by Fitzgerald et al. (2009), rice production is
endangered by several factors, such as increasing urbanization leading to
loss of farming land, urban migration resulting in fewer food-producing
farmers, biofuel policies that negatively affect the availability of grain for
consumption, decreased funding for rice research and issues of climate
change. All of these factors, either directly or indirectly, influence both the
quantity and the quality of rice that is available for food-based consump-
tion. A smart integration of different disciplines, such as soil and water
management, agricultural practices, plant breeding, post-harvest technology
and food processing, could offer a valid solution for current and emerging
or future problems associated with food production, security, distribution
and quality.

3.7 Future trends

Nearly 50 % of the global population, mostly concentrated in less-developed
countries, depend on rice as their major energy source. The question, of
course, is whether the rice-producing countries, supported by ongoing tech-
nological developments, can keep production levels ahead of population
growth. Over the longer term, a rice yield growth of 1.0–1.2 % annually will
be needed to feed the world at an affordable cost. The real cutting edge
solutions to the problems of rice production lie in developing and/or adapt-
ing strategies to break the yield barrier, thus improving the input efficiency
and, additionally, emphasis must be put on ways to disseminate the modern
scientific knowledge and technology to farmers. While these approaches
could lead to sustained productivity using current rice varieties, efforts to
develop new varieties that have adapted to and can respond to the specific
farming conditions, should be vigorously pursued. Lastly, from a techno-
logical viewpoint, production and processing conditions remarkably influ-
ence the nutritional performance of the final rice products. Increasing the
consumption of brown rice and germinated brown rice, both characterized
by a higher content of healthy beneficial food components (Roy et al.,
2011), compared to the well-milled white rice, will significantly help to

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146 Cereal grains for the food and beverage industries

avoid malnutrition and other dietary and food-related diseases in the
future.

3.8 References

abdul-hamid, a. and luan, y. s. (2000). Functional properties of dietary fibre pre-
pared from defatted rice bran. Food Chemistry, 68, 15–19.

alekaev, n. s. (1976). Amino acid composition and biological value of rice proteins.
Voprosy Pitaniia, 76–79.

antoine, j. m. r., hoo fung, l. a., grant, c. n., dennis, h. t. and lalor, g. c. (2012).
Dietary intake of minerals and trace elements in rice on the Jamaican market.
Journal of Food Composition and Analysis, 26, 111–121.

azanza, m. p. v. (2003). Canned rice products as Philippine military food ration.
International Journal of Food Sciences and Nutrition, 54, 235–240.

azudin, m. n. and morrison, w. r. (1986). Non-starch lipids and starch lipids in milled
rice. Journal of Cereal Science, 4, 23–31.

baldwin, p. m. (2001). Starch granule-associated proteins and polypeptides: a review.
Starch, 53, 475–503.

ball, s., guan, h. p., james, m., myers, a., keeling, p., mouille, g., buléon, a., colonna,
p. and preiss, j. (1996). From glycogen to amylopectin: A model for the biogenesis
of the plant starch granule. Cell, 86, 349–352.

bean, m. m., ellistonhoops, e. a. and nishita, k. d. (1983). Rice flour treatment for
cake-baking applications. Cereal Chemistry, 60, 445–449.

bechtel, d. b. and pomeranz, y. (1978). Ultrastructure of the mature ungerminated
rice (Oryza sativa) caryopsis.The starchy endosperm. American Journal of Botany,
65, 684–691.

becker, e. m., nissen, l. r. and skibsted, l. h. (2004). Antioxidant evaluation proto-
cols: Food quality or health effects. European Food Research and Technology, 219,
561–571.

bergman, c. j., bhattacharya, k. r. and ohtsubo, k. (2004). Rice end-use quality
analysis. In: champagne, e. t. (ed.) Rice: Chemistry and Technology (3rd edn). St
Paul, MN: AACC International, Inc.

bhattacharya, k. r. (2004). Parboiling of rice. In: champagne, e. t. (ed.) Rice: Chem-
istry and Technology (3rd edn). St Paul, MN: AACC International, Inc.

bhattacharya, k. r. and indudhara swamy, y. m. (1967). Conditions of drying par-
boiled paddy for optimum milling quality. Cereal Chemistry, 44, 592–600.

boesch, m. j. (1967). The World of Rice. New York: Dutton.
bond, n. (2004). Rice milling. In: champagne, e. t. (ed.) Rice: Chemistry and Technol-

ogy (3rd edn). St Paul, MN: AACC International, Inc.
buléon, a., colonna, p., planchot, v. and ball, s. (1998). Starch granules: structure

and biosynthesis. International Journal of Biological Macromolecules, 23, 85–112.
carpenter, k. j. (2004). NUTRITION | Beriberi, a deficiency related to grains. In:

wrigley, c., corke, h. and walker, c. (eds) Encyclopedia of Grain Science. Oxford:
Elsevier.
champagne, e. t., wood, d. f., juliano, b. o. and bechtel, d. b. (2004). The rice grain
and its gross composition. In: champagne, e. t. (ed.) Rice: Chemistry and Technol-
ogy (3rd edn). St Paul, MN: AACC International, Inc., 77–107.
chandrasekhar, u. and mulk, m. (1970). Nutritive value of high yielding rice variet-
ies Jaya, Padma and Hamsa. Indian Journal of Nutrition and Dietetics, 7,
240–242.
chang, t. t. (1964). Varietal differences in lodging resistance. International Rice
Communications Newsletter, 13, 1–11.

© Woodhead Publishing Limited, 2013

Rice 147

chang, t.-t. (1976). The origin, evolution, cultivation, dissemination, and diversifica-
tion of Asian and African rices. Euphytica, 25, 425–441.

chang, t. t. (1985). Crop history and genetic conservation in rice – a case study. Iowa
State Journal of Research, 59, 405–455.

chang, t. t. and bardenas, eliseo a. (1965). The Morphology and Varietal Charac-
teristics of the Rice Plant, Technical Bulletin 4. Los Baños, Laguna: IRRI.

chaudhary, n. and khurana, p. (2009). Vitamin E biosynthesis genes in rice: molecu-
lar characterization, expression profiling and comparative phylogenetic analysis.
Plant Science, 177, 479–491.

chen, j. j., lu, s. and lii, c. y. (1999). Effects of milling on the physicochemical char-
acteristics of waxy rice in Taiwan. Cereal Chemistry Journal, 76, 796–799.

chiang, p. y. and yeh, a. i. (2002). Effect of soaking on wet-milling of rice. Journal
of Cereal Science, 35, 85–94.

childs, n. w. (2004). Production and utilization of rice. In: champagne, e. t. (ed.)
Rice: Chemistry and Technology (3rd edn). St Paul, MN: AACC International, Inc.

choudhury, n. h. and juliano, b. o. (1980). Effect of amylose content on the lipids
of mature rice grain. Phytochemistry, 19, 1385–1389.

chrastil, j. (1990). Protein-starch interactions in rice grains. Influence of storage
on oryzenin and starch. Journal of Agricultural and Food Chemistry, 38,
1804–1809.

chuang, g. c.-c. and yeh, a.-i. (2006). Rheological characteristics and texture attri-
butes of glutinous rice cakes (mochi). Journal of Food Engineering, 74, 314–323.

chun, o. k., kim, d.-o., smith, n., schroeder, d., han, j. t. and lee, c. y. (2005). Daily
consumption of phenolics and total antioxidant capacity from fruit and vegetables
in the American diet. Journal of the Science of Food and Agriculture, 85,
1715–1724.

chung, h.-j., cho, a. and lim, s.-t. (2012a). Effect of heat-moisture treatment for
utilization of germinated brown rice in wheat noodle. LWT – Food Science and
Technology, 47, 342–347.

chung, h.-j., cho, d.-w., park, j.-d., kweon, d.-k. and lim, s.-t. (2012b). In vitro starch
digestibility and pasting properties of germinated brown rice after hydrothermal
treatments. Journal of Cereal Science, 56, 451–456.

coors, j. (1976). Practical experience with different adjuncts. Technical Quartenly
– The Master Brewens Association of the American, 13, 117–119.

datta, s. k. and khush, g. s. (2002). Improving rice to meet food and nutritional
needs: biotechnological approaches. Journal of Crop Production, 6, 229–247.

dawe, d., robertson, r. and unnevehr, l. (2002). Golden rice: what role could it play
in alleviation of vitamin A deficiency? Food Policy, 27, 541–560.

de datta, s. k., obcemea w. n. and jana, r. k. (1972). Protein content of rice grain as
affected by nitrogen fertilizer and some triazines and substituted ureas. Agron-
omy Journal, 64, 785–788.

delcour, a. and hoseney, c. r. (2010). Structure of cereals. In: delcour, a. and
hoseney, c. r. (eds) Principles of Cereal Science and Technology. St Paul, MN:
AACC International, Inc.

demont, j. i. and burns, e. e. (1968). Effects of certain variables on canned rice
quality. Food Technology, 22, 1186–1188.

denyer, k., hylton, c. m., jenner, c. f. and smith, a. m. (1995). Identification of mul-
tiple isoforms of soluble and granule-bound starch synthase in developing wheat
endosperm. Planta, 196, 256–265.

deori, c., begum, s. s. and mao, a. a. (2007). Ethnobotany of Sujen – A local rice beer
of Deori tribe of Assam. Indian Journal of Traditional Knowledge, 6, 121–125.

dethloff, h. c. (1982). The colonial rice trade. Agricultural History, 56, 231–243.
dexter, p. b. (1998). Rice Fortification For Developing Countries. Arlington, VA:

OMNI/USAID.

© Woodhead Publishing Limited, 2013

148 Cereal grains for the food and beverage industries

duvernay, w. h., assad, j. m., sabliov, c. m., lima, m. and xu, z. (2005). Microwave
extraction of antioxidant components from rice bran. Pharmaceutical Engineer-
ing, 25, 126–130.

entani, e. and masai, h. (1985). Identification of yeasts, lactic acid bacteria and acetic
acid bacteria isolated from fermented mash of Fukuyama rice vinegar. Journal of
the Brewing Society of Japan, 80, 200–205.

evans, h. m. and bishop, k. s. (1922). On the existence of a hitherto unrecognized
dietary factor essential for reproduction. Science, 56, 650–651.

fao/un (2012). FAOSTAT database: http://faostat3.fao.org/home/index.html.
fitzgerald, m. a., mccouch, s. r. and hall, r. d. (2009). Not just a grain of rice: the

quest for quality. Trends in Plant Science, 14, 133–139.
fouda, t. z. (2011). Engineering studies on the performance of paddy and rice sepa-

rator. AMA, Agricultural Mechanization in Asia, Africa and Latin America, 42,
85–90.
fu, b. x. (2008). Asian noodles: history, classification, raw materials, and processing.
Food Research International, 41, 888–902.
gepts, p. (2010). Crop domestication as a long-term selection experiment. Plant
Breeding Reviews, 24, 1–44.
ghosh, d. and chattopadhyay, p. (2011). Preparation of idli batter, its properties and
nutritional improvement during fermentation. Journal of Food Science and Tech-
nology, 48, 610–615.
gidley, m. j. and bulpin, p. v. (1987). Crystallisation of malto-oligosaccharides as
models of the crystalline forms of starch: minimum chain-length requirement for
the formation of double helices. Carbohydrate Research, 161, 291–300.
godber, j. s. and juliano, b. o. Rice lipids. In: champagne, e. t. (ed.) Rice: Chemistry
and Technology (3rd edn). St Paul, MN: AACC International, Inc.
gomez, k. a. (1979). Effect of environment on protein and amylose content of rice.
In: irri (ed.) Chemical Aspects of Rice Grain Quality. Los Baños, Laguna: IRRI.
56–68.
guimarães, e. p. (2009). Rice breeding. In: carena, m. j. (ed.) Cereals: Handbook of
Plant Breeding. New York: Springer.
guraya, h. s., kadan, r. s. and champagne, e. t. (1997). Effect of rice starch-lipid
complexes on in vitro digestibility, complexing index, and viscosity. Cereal Chem-
istry, 74, 561–565.
hardwick, w. a., van oevelen, d. e. j., novellie, l. and yoshizawa, k. (1995). Kinds
of beer and beerlike beverages. In: hardwick, w. a. (ed.) Handbook of Brewing.
New York: Marcel Dekker.
haruta, s., ueno, s., egawa, i., hashiguchi, k., fujii, a., nagano, m., ishii, m. and
igarashi, y. (2006). Succession of bacterial and fungal communities during a tra-
ditional pot fermentation of rice vinegar assessed by PCR-mediated denaturing
gradient gel electrophoresis. International Journal of Food Microbiology, 109,
79–87.
hesseltine, c. w. (1965). A millennium of fungi, food, and fermentation. Mycologia,
57, 149–197.
hinton, j. j. (1948a). Parboiling treatment of rice. Nature, 162, 913–915.
hinton, j. j. c. (1948b). The distribution of vitamin B1 in the rice grain. British
Journal of Nutrition, 2, 237–241.
hizukuri, s., kaneko, t. and takeda, y. (1983). Measurement of the chain length
of amylopectin and its relevance to the origin of crystalline polymorphism of
starch granules. Biochimica et Biophysica Acta (BBA) – General Subjects, 760,
188–191.
hou, z., qin, p., zhang, y., cui, s. and ren, g. (2012). Identification of anthocyanins
isolated from black rice (Oryza sativa L.) and their degradation kinetics. Food
Research International.

© Woodhead Publishing Limited, 2013

Rice 149

hunt, j. r., johnson, l. k. and juliano, b. o. (2002). Bioavailability of zinc from
cooked Philippine milled, undermilled, and brown rice, as assessed in rats by using
growth, bone zinc, and zinc-65 retention. Journal of Agricultural and Food Chem-
istry, 50, 5229–5235.

ibpgr-irri rice advisory committee (1980). Descriptors for rice Oryza sativa L. Los
Baños, Laguna: IRRI.

itani, t., tamaki, m., arai, e. and horino, t. (2002). Distribution of amylose, nitrogen,
and minerals in rice kernels with various characters. Journal of Agricultural and
Food Chemistry, 50, 5326–5332.

james, c. and mccaskill, d. (1983). Rice in the American diet. Cereal Foods World,
28, 667–669.

jane, j. l., kasemsuwan, t., chen, j. f. and juliano, b. o. (1996). Phosphorus in rice
and other starches. Cereal Foods World, 41, 827–832.

jeffrey, a. and duguid, n. (1998). Seductions of Rice: A Cookbook. New York:
Artisan.

ji, y., zhu, k., qian, h. and zhou, h. (2007a). Microbiological characteristics of cake
prepared from rice flour and sticky rice flour. Food Control, 18, 1507–1511.

ji, y., zhu, k., qian, h. and zhou, h. (2007b). Staling of cake prepared from rice flour
and sticky rice flour. Food Chemistry, 104, 53–58.

jomduang, s. and mohamed, s. (1994). Effect of amylose/amylopectin content, milling
methods, particle size, sugar, salt and oil on the puffed product characteristics of
a traditional thai rice-based snack food (Khao Kriap Waue). Journal of the Science
of Food and Agriculture, 65, 85–93.

juliano, b. o. (1993). Rice in Human Nutrition. Rome: FAO; Los Baños, Laguna:
IRRI.

juliano, b. o. (2003). RICE. In: caballero, b., trvgo, c. and fingcas, p. m. (eds) Ency-
clopedia of Food Sciences and Nutrition (2nd edn). Oxford: Academic Press.

juliano, b. o. and perez, c. m. (1983). Major factors affecting cooked milled rice
hardness and cooking time. Journal of Texture Studies, 14, 235–243.

juliano, b. and villareal, c. (1993). Grain Quality Evaluation of World Rices. Los
Baños, Laguna: IRRI.

juliano, b. o., perez, c. m., blakeney, a. b., castillo, t., kongseree, n., laignelet, b.,
lapis, e. t., murty, v. v. s., paule, c. m. and webb, b. d. (1981). International
cooperative testing on the amylose content of milled rice. Starch, 33, 157–
162.

kadan, r. s., robinson, m. g., thibodeaux, d. p. and pepperman, a. b. (2001). Texture
and other physicochemical properties of whole rice bread. Journal of Food
Science, 66, 940–944.

kamara, j. s., hoshino, m., satoh, y., nayar, n., takaoka, m., sasanuma, t. and abe, t.
(2009). Japanese sake-brewing rice cultivars show high levels of globulin-like
protein and a chloroplast stromal HSP70. Crop Science, 49, 2198–2206.

kar, n., jain, r. k. and srivastav, p. p. (1999). Parboiling of dehusked rice. Journal of
Food Engineering, 39, 17–22.

kaul, a. k. and raghaviah, p. (1975). Influence of nitrogen fertilization on some
nutritional quality characters in rice. Plant Foods for Human Nutrition (formerly
Qualitas Plantarum), 24, 391–403.

kaur, k. and singh, n. (2000). Amylose-lipid complex formation during cooking of
rice flour. Food Chemistry, 71, 511–517.

kehrer, j. p. (1993). Free radicals as mediators of tissue injury and disease. Critical
Reviews in Toxicology, 23, 21–48.

kelly, w. j. (1985). Rice in infant foods. In: juliano, b. o. (ed.) Rice: Chemistry and
Technology. St Paul, MN: AACC International, Inc.

kelly, w. j., asmundson, r. v., harrison, g. l. and huang, c. m. (1995). Differentiation
of dextran-producing Leuconostoc strains from fermented rice cake (puto) using

© Woodhead Publishing Limited, 2013

150 Cereal grains for the food and beverage industries

pulsed-field gel electrophoresis. International Journal of Food Microbiology, 26,
345–352.
kennedy, g. and burlingame, b. (2003). Analysis of food composition data on rice
from a plant genetic resources perspective. Food Chemistry, 80, 589–596.
kent, n. l. and evers, a. d. (1994). Storage and pre-processing. In: kent, n. l. and
evers, a. d. (eds) Kent’s Technology of Cereals (4th edn). Oxford: Pergamon.
kiple, k. f. and ornelas, k. c. (2000). The Cambridge World History of Food. Cam-
bridge: Cambridge University Press.
kitahara, k., suganuma, t. and nagahama, t. (1996). Susceptibility of amylose-lipid
complexes to hydrolysis by glucoamylase from Rhizopus niveus. Cereal Chemis-
try, 73(4), 428–432.
kitahara, k., tanaka, t., suganuma, t. and nagahama, t. (1997). Release of bound
lipids in cereal starches upon hydrolysis by glucoamylase. Cereal Chemistry, 74,
1–6.
koizumi, e. and kamedamachi, n. (1975). Process for the production of rice crackers.
Japan patent application 583,428.
koizumi, y., hashiguchi, k., okamoto, a. and yanagida, f. (1996). Identification of
lactic acid bacteria, yeasts and acetic acid bacteria isolated during manufacturing
process of pot vinegar. 3. Studies on the pot vinegar. Journal of the Japanese
Society for Food Science and Technology–Nippon Shokuhin Kagaku Kogaku
Kaishi, 43, 347–356.
komatsuzaki, n., tsukahara, k., toyoshima, h., suzuki, t., shimizu, n. and kimura,
t. (2007). Effect of soaking and gaseous treatment on GABA content in germi-
nated brown rice. Journal of Food Engineering, 78, 556–560.
kovach, m. j., sweeney, m. t. and mccouch, s. r. (2007). New insights into the history
of rice domestication. Trends in Genetics, 23, 578–587.
lamberts, l., de bie, e., vandeputte, g. e., veraverbeke, w. s., derycke, v., de man,
w. and delcour, j. a. (2007). Effect of milling on colour and nutritional properties
of rice. Food Chemistry, 100, 1496–1503.
latham, a. j. h. (1998). Rice: The Primary Commodity. London: Routledge, Taylor
& Francis Group.
ljung, k., palm, b., grandér, m. and vahter, m. (2011). High concentrations of essen-
tial and toxic elements in infant formula and infant foods – A matter of concern.
Food Chemistry, 127, 943–951.
lloyd, b. j., siebenmorgen, t. j. and beers, k. w. (2000). Effects of commercial pro-
cessing on antioxidants in rice bran. Cereal Chemistry Journal, 77, 551–555.
lu, s. (2004). RICE | Chinese food uses. In: wrigley, c., corke, h. and walker, c.
(eds) Encyclopedia of Grain Science. Oxford: Elsevier.
luh, b. s. (1991a). Breakfast rice cereals and baby foods. In: luh, b. s. (ed.) Rice,
Volume II: Utilization. New York: Van Nostrand Reinhold.
luh, b. s. (1991b). Rice, Volume II: Utilization. New York, Van Nostrand
Reinhold.
luh, b. s. (1999). Rice products. In: ang, c. y. w., liu, k. and huang, y.-w. (eds) Asian
Foods: Science and Technology. Lancaster, PA: Technomic.
maclean, j., dawe, d., hardy, b. and hettel, g. (2002). Rice Almanac (3rd edn). Los
Baños, Laguna: IRRI.
mangala, s. l., udayasankar, k. and tharanathan, r. n. (1999). Resistant starch
from processed cereals: the influence of amylopectin and non-carbohydrate con-
stituents in its formation. Food Chemistry, 64(3), 391–396.
manners, d. j. (1979). The enzymic degradation of starches. In: blanshard, j. m. v.
and mitchell, j. r. (eds) Polysaccharides in Food. London: Butterworth.
manners, d. j. (1997). Observations on the specificity and nomenclature of starch
debranching enzymes. Journal of Applied Glycoscience, 44, 83–85.

© Woodhead Publishing Limited, 2013

Rice 151

mano, y., kawaminami, k., kojima, m., ohnishi, m. and ito, s. (1999). Comparative
composition of brown rice lipids (lipid fractions) of Indica and Japonica rices.
Bioscience Biotechnology and Biochemistry, 63, 619–626.

marshall, w. e. and wadsworth, j. i. (1994). Introduction. In: marshall, w. e. and
wadsworth, j. i. (eds) Rice Science and Technology. New York: Marcel Dekker.

matz, s. (1996). Chemistry and Technology of Cereals as Food and Feed. New
Delhi: CBS.

meharg, a. a., deacon, c., campbell, r. c. j., carey, a.-m., williams, p. n., feldmann,
j. and raab, a. (2008a). Inorganic arsenic levels in rice milk exceed EU and US
drinking water standards. Journal of Environmental Monitoring, 10, 428–431.

meharg, a. a., sun, g., williams, p. n., adomako, e., deacon, c., zhu, y.-g., feldmann,
j. and raab, a. (2008b). Inorganic arsenic levels in baby rice are of concern. Envi-
ronmental Pollution, 152, 746–749.

mennella, j. a., ziegler, p., briefel, r. and novak, t. (2006). Feeding infants and
toddlers study: The types of foods fed to hispanic infants and toddlers. Journal of
the American Dietetic Association, 106, S96–S106.

mercier, c., linko, p. and harper, j. m. (1989). Extrusion Cooking. St Paul, MN:
AACC International, Inc.

mi, y. k., hyun, m. s. and hae, c. c. (1997a). Varietal variation in gelatinisation and
adaptability to rice bread processing and their interrelation. Korean Journal of
Crop Science, 42, 344–351.

mi, y. k., yeong, h. c. and hae, c. c. (1997b). Effects of gums, fats and glutens adding
on the processing and quality of milled rice bread. Journal of the Korean Society
of Food Science and Nutrition, 29, 700–704.

mi, y. k., yeong, h. c. and hae, c. c. (1997c). Interrelation between physicochemical
properties of milled rice and retrogradation of rice bread during cold storage.
Journal of the Korean Society of Food Science and Nutrition, 26, 886–891.

mickus, r. r. and luh, b. s. (1991). Rice enrichment with vitamins and amino acids.
In: luh, b. s. (ed.) Rice, Volume II: Utilization. New York: Van Nostrand
Reinhold.

miyazawa, t., nakagawa, k. and sookwong, p. (2011). Health benefits of vitamin E
in grains, cereals and green vegetables. Trends in Food Science & Technology, 22,
651–654.

moongngarm, a. and saetung, n. (2010). Comparison of chemical compositions and
bioactive compounds of germinated rough rice and brown rice. Food Chemistry,
122, 782–788.

moritaka, s. (1972). The effect of sulfhydryl groups on storage deterioration of
milled rice, Eiyo To Shokuryo, 25, 59–62.

murooka, y. and yamshita, m. (2008). Traditional healthful fermented products of
Japan. Journal of Industrial Microbiology and Biotechnology, 35, 791–798.

mutters, r. g. and thompson, j. f. (2009). Rice quality in the global market. In:
mutters, r. g. and thompson, j. f. (eds) Rice Quality Handbook. California: Uni-
versity of California, Agriculture and Natural Resources.

nakamura, y. (2002). Towards a better understanding of the metabolic system for
amylopectin biosynthesis in plants: rice endosperm as a model tissue. Plant and
Cell Physiology, 43, 718–725.

nemoto, k., morita, s. and baba, t. (1995). Shoot and root development in rice related
to the phyllochron. Crop Science, 35, 24–29.

nestle, m. (2001). Genetically engineered ‘Golden’ rice unlikely to overcome
vitamin A deficiency. Journal of the American Dietetic Association, 101, 289–290.

ngamnikom, p. and songsermpong, s. (2011). The effects of freeze, dry, and wet grind-
ing processes on rice flour properties and their energy consumption. Journal of
Food Engineering, 104, 632–638.

© Woodhead Publishing Limited, 2013

152 Cereal grains for the food and beverage industries

niki, e. and noguchi, n. (2004). Dynamics of antioxidant action of vitamin E.
Accounts of Chemical Research, 37, 45–51.

nishita, k. d. and bean, m. m. (1979). Physico-chemical properties of rice in relation
to rice bread. Cereal Chemistry, 56, 185–189.

nishita, k. d., roberts, r. l., bean, m. m. and kennedy, b. m. (1976). Development of
a yeast-leavened rice-bread formula. Cereal Chemistry, 53, 626–635.

noda, t., nishiba, y., sato, t. and suda, i. (2003). Properties of starches from several
low-amylose rice cultivars. Cereal Chemistry Journal, 80, 193–197.

noomhorm, a., bandola, d. c. and kongseree, n. (1994). Effect of rice variety, rice
flour concentration and enzyme levels on composite bread quality. Journal of the
Science of Food and Agriculture, 64, 433–440.

normand, f. l., soignet, d. m., hogan, j. t. and deobald, h. j. (1966). Content of
certain nutrients and amino acid patterns in high-protein rice flour. Rice Journal,
69, 13–18.

nout, m. j. r. (2009). Rich nutrition from the poorest – cereal fermentations in Africa
and Asia. Food Microbiology, 26, 685–692.

orthoefer, f. t. and eastman, j. (2004). Rice bran and oil. In: champagne, e. t. (ed.)
Rice: Chemistry and Technology (3rd edn). St Paul, MN: AACC International, Inc.

osborne, t. b. (1924). The Vegetable Proteins. New York: Longmans Green and Co.
owen, s. (1993). The Rice Book. New York: St Martin’s Press.
owens, g. (2001). Cereals Processing Technology. Cambridge: Woodhead.
palmiano, e. p. and juliano, b. o. (1972). Biochemical changes in the rice grain during

germination. Plant Physiology, 49, 751–756.
pascual, c. d. s. c. i., massaretto, i. l., kawassaki, f., barros, r. m. c., noldin, j. a. and

marquez, u. m. l. (2012). Effects of parboiling, storage and cooking on the levels
of tocopherols, tocotrienols and γ-oryzanol in brown rice (Oryza sativa L.). Food
Research International, doi: 10.1016/j.foodres.2011.07.93.
payman, m., bagheri, i., alizadeh, m. r. and roohi, r. (2007). Effective parameters of
broken rice during paddy hulling using rubber roll huller. Journal of Biological
Sciences, 7, 47–51.
pomeranz, y. and ory, r. l. (1982). Rice processing and utilization. In: wolff, i. a.
(ed.) Handbook of Processing and Utilization in Agriculture. West Palm Beach,
FL: CRC Press.
renzetti, s. and arendt, e. k. (2009). Effect of protease treatment on the baking
quality of brown rice bread: From textural and rheological properties to biochem-
istry and microstructure. Journal of Cereal Science, 50, 22–28.
resurrection, a. p., juliano, b. o. and tanaka, y. (1979). Nutrient content and dis-
tribution in milling fractions of rice grain. Journal of the Science of Food and
Agriculture, 30, 475–481.
resurreccion, a. p., li, x., okita, t. w. and juliano, b. o. (1993). Characterization of
poorly digested protein of cooked rice protein bodies. Cereal Chemistry, 70,
101–104.
richards, g. m., gurtler, j. b. and beuchat, l. r. (2005). Survival and growth
of Enterobacter sakazakii in infant rice cereal reconstituted with water, milk,
liquid infant formula, or apple juice. Journal of Applied Microbiology, 99,
844–850.
roy, p., orikasa, t., okadome, h., nakamura, n. and shiina, t. (2011). Processing
conditions, rice properties, health and environment. International Journal of Envi-
ronmental Research and Public Health, 8, 1957–1976.
sano, y. (1984). Differential regulation of waxy gene expression in rice endosperm.
TAG Theoretical and Applied Genetics, 68, 467–473.
savitha, y. s. and singh, v. (2011). Status of dietary fiber contents in pigmented and
non-pigmented rice varieties before and after parboiling. LWT – Food Science
and Technology, 44, 2180–2184.

© Woodhead Publishing Limited, 2013

Rice 153

shewry, p. r. and halford, n. g. (2002). Cereal seed storage proteins: structures,
properties and role in grain utilization. Journal of Experimental Botany, 53,
947–958.

shih, f. f. (2004). Rice proteins. In: champagne, e. t. (ed.) Rice Chemistry and Tech-
nology (3rd end). St Paul, MN: AACC International, Inc.

shiina, r. p. and global, t. (2010). Environment, biofuel: sustainable food production
and distribution. In: riccardo, c. and monte, g. (eds) Global Environmental Poli-
cies: Impact, Management and Effects. New York: Nova Science Publishers.

sivaramakrishnan, h. p., senge, b. and chattopadhyay, p. k. (2004). Rheological
properties of rice dough for making rice bread. Journal of Food Engineering, 62,
37–45.

soponronarit, s., taechapairoj, c. and prachayawarakorn, s. (2004). New technique
producing parboiled rice. The Journal of the Royal Institute of Thailand, 29, 78–86.

steinkraus, k. h. (1983). Lactic acid fermentation in the production of foods from
vegetables, cereals and legumes. Antonie van Leeuwenhoek, 49, 337–348.

steinkraus, k. h. (1996). Handbook of Indigenous Fermented Foods (2nd edn). New
York: Marcel Dekker.

taechapairoj, c., prachayawarakorn, s. and soponronnarit, s. (2004). Characteris-
tics of rice dried in superheated-steam fluidized-bed. Drying Technology, 22,
719–743.

taira, h., taira, h., matsuzaki, a. and matsuzaki, s. (1976). Effect of topdressing on
B-vitamin content of rice grain. Nippon Sakumotsu Gakkai Kiji, 45, 69–74.

tanaka, a. (1965). Examples of plant performance. In: irri (ed.) The Mineral Nutri-
tion of the Rice Plant. Proceedings of a Symposium at the International Rice
Research Institute. Baltimore, MD: Johns Hopkins University Press, 37–49.

tateoka, t. (1964). Notes on some grasses. XVI. Embryo structure of the genus
Oryza in relation to the systematics. American Journal of Botany, 51, 539–543.

thomas, d. r. (2006). Vitamins in aging, health, and longevity. Clinical Interventions
in Aging, 1, 81–91.

tian, s., nakamura, k. and kayahara, h. (2004). Analysis of phenolic compounds in
white rice, brown rice, and germinated brown rice. Journal of Agricultural and
Food Chemistry, 52, 4808–4813.

toenniessen, g. h. (2001). Vitamin A Deficiency and Golden Rice: The Role of the
Rockefeller Foundation. Available at: http://www.rockefellerfoundation.org/news/
publications/vitamin-deficiency-golden-rice-role [accessed November 2012].

tzvelev, n. n. (1989). The system of grasses (Poaceae) and their evolution. Botanical
Review, 55, 141–204.

vandeputte, g. e. and delcour, j. a. (2004). From sucrose to starch granule to starch
physical behaviour: a focus on rice starch. Carbohydrate Polymers, 58, 245–266.

vandeputte, g. e., vermeylen, r., geeroms, j. and delcour, j. a. (2003). Rice starches.
I. Structural aspects provide insight into crystallinity characteristics and gelatini-
sation behaviour of granular starch. Journal of Cereal Science, 38, 43–52.

vaughan, d. a. (1994). The Wild Relatives of Rice, A Genetic Resources Handbook.
Los Baños, Laguna: IRRI.

veluppillai, s., nithyanantharajah, k., vasantharuba, s., balakumar, s. and
arasaratnam, v. (2010). Optimization of bread preparation from wheat flour and
malted rice flour. Rice Science, 17, 51–59.

wang, y. l., yang, k. c. and cheng, s. m. (1950). Vitamin-B1 in the rice grain and the
distribution of nicotinic acid. Chung Kuo Ko Hsueh, 1, 99–107.

wang, h. l., swain, e. w., hesseltine, c. w. and gumbmann, m. r. (1978). Protein quality
of wild rice. Journal of Agricultural and Food Chemistry, 26, 309–312.

wang, k. m., wu, j. g., li, g., zhang, d. p., yang, z. w. and shi, c. h. (2011). Distribution
of phytic acid and mineral elements in three indica rice (Oryza sativa L.) cultivars.
Journal of Cereal Science, 54, 116–121.

© Woodhead Publishing Limited, 2013

154 Cereal grains for the food and beverage industries
wang, x., meng, j., zhang, j., zhou, t., zhang, y., yang, b., xi, m. and xia, x. (2012).

Characterization of Staphylococcus aureus isolated from powdered infant
formula milk and infant rice cereal in China. International Journal of Food
Microbiology, 153, 142–147.
who (1973). Energy and Protein Requirements. Geneva: World Health
Organization.
wimberly, j. e. (1983). Milling. In: wimberly, j. e. (ed.) Technical Handbook for
the Paddy Rice Postharvest lndustry in Developing Countries. Los Baños,
Laguna: IRRI.
yanai, s. i. and kojo, t. (1979). Influence of gaseous environment on the hermetic
storage of milled rice. Nippon Shokuhin Kogyo Gakkaishi, 26, 145–150.
yeh, a.-i. (2004). Preparation and applications of rice flour. In: champagne, e. t. (ed.)
Rice: Chemistry and Technology (3rd edn). St Paul, MN: AACC International, Inc.
yoshida, s. (1981). Fundamentals of Rice Crop Science. Los Baños, Laguna: IRRI.
yoshizawa, k. and ogawa, y. (2004). Rice in brewing. In: champagne, e. t. (ed.) Rice:
Chemistry and Technology (3rd edn). St Paul, MN: AACC International, Inc.
zannini, e., jones, j. m., renzetti, s. and arendt, e. k. (2012). Functional replace-
ments for gluten. Annual Review of Food Science and Technology, 3, 227–245.
zhou, z., robards, k., helliwell, s. and blanchard, c. (2002). Composition and
functional properties of rice. International Journal of Food Science & Technology,
37, 849–868.
zigoneanu, i. g., williams, l., xu, z. and sabliov, c. m. (2008). Determination of
antioxidant components in rice bran oil extracted by microwave-assisted method.
Bioresource Technology, 99, 4910–4918.

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4

Barley

DOI: 10.1533/9780857098924.155

Abstract: Barley (Hordeum vulgare L.) has been one of the most important food
grains since ancient times. Amongst cereals, it ranks fourth in quantity produced
and cultivation area in the world. Barley has been cultivated commonly for
centuries due its versatility, ability to adapt to unfavourable climate and soil
conditions, and superior properties for the malting and brewing industries. The
increased interest in barley as a human food ingredient results from studies which
have shown barley to be an excellent source of dietary fibre and, in particular,
β-glucan. Barley kernels contain complex carbohydrates (mainly starch), have a
low fat content and are moderately well-balanced in terms of protein to meet
amino acid requirements, as well as minerals, vitamins (particularly vitamin E)
and antioxidant polyphenols. In addition to its use in the production of malt for
brewing, barley is used as whole-grain, pearled, raw-grain flour, whole roasted-
grains mature barley flour and roasted-grain flour for the production of breakfast
cereals, stews, soups, pastas and noodles, as a coffee substitute and in porridges,
sauces and baked products (including bread and flat bread). Given the greater
consumer and manufacturer focus on the physiological benefits and nutritional
properties of barley and associated by-products, newly emerging opportunities
exist for the incorporation of barley into human foods.

Key words: barley, chemical composition, barley utilization in food and beverages.

4.1 Introduction

Barley belongs to the family Poaceae and the genus Hordeum, the most
common form being Hordeum vulgare. It has been one of the most impor-
tant food grains since ancient times and nowadays has one of the highest
lands industrial use. It ranks fourth in quantity produced and cultivation
area of cereals in the world (Zhou, 2010). Barley has a long history of use as
a source of human nutrition, with archaeological studies revealing the culti-
vation of two-row barley in Iran from 8000 BC and six-row barley from
around 6000 BC (von Bothmer and Jacobsen, 1985). The increasing use of
wheat, rice and maize in the human diet has led to a drastic decrease in
human barley use and consumption, except for the production of alcoholic
beverages such as beer. Thus, currently its primary use is in the brewing

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156 Cereal grains for the food and beverage industries

industry and as animal feed. In recent times, approximately two-thirds of the
barley crop has been used for animal feed, one-third for malting and approx-
imately 2 % directly for food (Baik and Ullrich, 2008). However, since year
2000, interest in barley as a human food source has increased. This is a result
of past studies which have shown barley to be an excellent source of dietary
fibre and, in particular, β-glucan. The latter is a soluble fibre that has many
health benefits, including decreasing the risk of heart disease and lowering
blood glucose serum concentrations (Huth et al., 2000; Pins and Kaur, 2006).
The prevalence of obesity and increases in chronic diseases such as cancer
in recent years have led to an increased consumer awareness of the health
impact of their diet and, as such, there has been an increased interest in the
consumption of healthy, natural foods (Huth et al., 2000).

4.1.1 History, production area and price
Barley cultivation probably originated in the highlands of Ethiopia and
Southeast Asia about 10 000 years ago. It is believed to extend back to
6000 BC in Egypt with evidence of its use in ancient Mesopotamia, north-
western Europe and China (Sun and Gong, 2010; Zhou, 2010). Archaeologi-
cal remains of barley grains found at various sites in the Fertile Crescent
(the ancient name of the area that includes Iraq, with small portions of Iran,
Kuwait, Turkey, Syria, Jordan, Israel, Lebanon and the West Bank) (Zohary
and Hopf, 1993) indicate that the crop was domesticated about 8000 BC.
Previous reviews show evidence that barley may have had a multicentre
origin (Nilan and Ullrich, 1993; Newman and Newman, 2008; Sun and Gong,
2010). The transformation of ‘wild barley’, H. spontaneum C. Koch, into a
cultivated crop, H. vulgare L., was a process of naturally selecting the best
variety for human harvest which occurred over thousands of years. It is
believed that most of the biological traits of ancestral and modern barley
are identical. Barley followed the movement of human civilization and
agricultural expansion. For several thousand years, barley was used by
ancient populations from different cultures in Asia, North Africa and
Europe as an important dietary constituent of the basic diet and as a staple
food. Barley was used to make bread, as well as alcoholic and non-alcoholic
barley beverages. Its historical importance is even reflected in its former
use as a currency and as a medicine (Pellechia, 2006). The first barley beer
was probably produced accidentally (Brothwell and Brothwell, 1998).
Roman records indicated that barley was the food of the gladiators, used
to increase their resistance and strength (Percival, 1921). Barley was always
the grain of choice for cultivation due to its ability to tolerate adverse
weather and soil conditions which other crops cannot.

For centuries, barley has been grown mainly for malt production and as
an animal feed, whilst other food grains (wheat, rye, oats) became more
popular for human consumption. Depending on the climate, soil conditions,
variety, agricultural practices and other conditions, barley yields can range

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Barley 157

from 0.3 to 8.3 tonnes/ha (FAO/UN, 2012). In dry regions, irrigation con-
tributes to increased output. Nowadays, barley yields worldwide tend to be
higher than 2.6 tonnes/ha on average (FAO/UN, 2012) (Table 4.1). The
Russian Federation is currently, and has historically been, the world’s
leading barley-producing country.Table 4.2 lists the top 10 barley-producing
countries over the five-year period 2006–2010. Interestingly, Germany and
France produced higher amounts of barley than the Russian Federation
(22.40 vs 16.59 million tonnes per year, 2006–2010) but from less than half
the barley cultivation area (3.6 vs 8.0 million hectares per year, 2006–2010)
(FAO/UN, 2012) (Table 4.2).

Until recently, barley production worldwide was always above 140
million tonnes per year with annual fluctuations, mainly due to changes in
climatic conditions in the main producer countries; the greatest production
was during 2008/09 with 154.70 million tonnes produced (Table 4.1) (FAO/
UN, 2012). It should be noted that EU countries, such as France and
Germany, always had consistently higher yield (6.05–6.36 tonnes/ha) than
other countries. Due to the lower production during 2007 (Table 4.1), which
was a result of bad weather conditions in Canada, Russia and parts of
Europe, the world average barley prices increased from 133.44 US $/tonnes
in 2006 to 250.66 US $/tonnes in 2008 an increase of more than 30 % (Table
4.3). This increased profitability in the sector also provided attractive condi-
tions for an increase in the global barley area planted in the short-term,
according to the International Grain Council forecast (IGC, 2012). Barley
is the most recent grain to be excluded from the EU’s intervention storage
and much of its cultivation area was shifted into higher priced crops like
wheat and rapeseed. The total cultivation areas for barley in France,
Germany and Spain are down from last year by 0.2 million hectares for
each country, and by 0.3 million hectares in the UK (USDA, 2010).

4.1.2 Phytology, classification and cultivation
Barley (H. vulgare L.) is a cereal grain grass belonging to the Poaceae family
(also known as Gramineae), the tribe Triticeae and the genus Hordeum.
There are 32 species within the Hordeum genus, all with a basic chromo-
some number of x = 7. The genus Hordeum is unusual among the Triticeae
as it contains both annual species (H. vulgare and H. marinum) and peren-
nial species (H. bulbosum) (von Bothmer, 1992). Most evidence indicates
that the immediate ancestor of cultivated barley is the two-rowed wild
barley H. spontaneum and that the genomes of H. vulgare (cultivated
barley) and H. vulgare subsp. Spontaneum (wild barley) are identical and
interfertile (Fedak, 1985; Nilan and Ullrich, 1993).

H. vulgare comprises two subspecies – the cultivated form and the wild
form. The former is H. vulgare subsp. vulgare and is both 2R and 6R with
non-shattering spikes, which is an advantage during harvesting. Cultivated
barley is a self-pollinating, diploid species, with 14 chromosomes (2n = 14),

© Woodhead Publishing Limited, 2013

Table 4.1 Barley and total cereal grain production and producer prices in the world from 2000 to 2010

© Woodhead Publishing Limited, 2013 Year Total barley Total cereal Barley as % Area barley Barley yield Producer price
production (Mt) production (Mt)a of total grains harvested (Mha) (t/ha) (US $/tonnes)

2000 133.1 2044 6.5 54.5 2.4 158.20
153.28
2001 144.0 2093 6.9 56.2 2.6 147.67
167.80
2002 136.7 2077 6.6 55.3 2.5 181.13
183.29
2003 142.5 2260 6.3 57.7 2.5 191.80
251.85
2004 153.8 2247 6.8 57.5 2.7 297.49
249.77
2005 138.6 2219 6.2 55.3 2.5
–
2006 139.5 2335 6.0 56.4 2.5

2007 134.1 2503 5.4 55.7 2.4

2008 154.7 2470 6.3 56.3 2.7

2009 151.8 2472 6.1 54.2 2.8

2010 123.6 2412 5.1 47.5 2.6

Average 141.1 2285 6.2 55.1 2.6

aTotal cereal production includes corn, rice, wheat, barley, sorghum, millet, oats, rye, mixed grain.
Source: Data from FAO/UN (2012).

Barley 159

Table 4.2 Barley production estimates in the 10 leading producer countries; five-
year average the 2006–2010

Rank Country Production Area Barley yield World
(Mt) harvested (t/ha) production
(Mha) (%)

1 Russian Federation 16.59 8.00 2.04 11.79

2 Germany 11.40 1.88 6.05 8.10

3 France 11.00 1.72 6.36 7.82

4 Ukraine 10.05 4.56 2.19 7.14

5 Canada 9.89 3.20 3.10 7.03

6 Spain 9.37 3.16 2.94 6.66

7 Turkey 7.46 3.13 2.37 5.30

8 Australia 6.92 4.52 1.52 4.92

9 Morocco 5.67 2.09 1.04 4.03

10 USA 4.52 1.28 3.56 3.21

Source: Data from FAO/UN (2012).

and a low occurrence of cross-pollination. It has ears with long awns and is
classified into two types and many varieties, normally either two-row (2R)
or multirow (e.g. six-row – 6R), depending on the physical arrangement of
the kernels on the plant. The wild form is described as H. vulgare subsp.
spontaneous with brittle spikes, which is useful for ripe seed dispersal by
wind or rain (Nilan and Ullrich, 1993).

The principal identifying taxonomic characteristic of Hordeum is its single
floret in each spikelet.There are three spikelets at each rachis node, alternat-
ing on opposite sides of the barley head or spike. When only the central
spikelet is fertile, only one grain develops at each node, while the other two
are reduced. This condition produces the 2R barley cultivars. Conversely,
when all of the florets are fertile,each of these,after pollination,develops into
a barley grain resulting in the production of 6R barley varieties.

2R barleys produce plumper, heavier kernels than 6R varieties which
have thinner, finely wrinkled husks. 6R varieties, on the other hand, usually
have more seeds per inflorescence. Consequently, 2R varieties have rela-
tively larger amounts of useful content and fewer husks, thus having a
lower protein content and fewer polyphenols or bitter substances (Kunze,
2010). The grains are all uniform and their extract content is comparatively
higher. 2R barleys are normally grown as spring barleys and combine all
the desirable features for malt and beer production for which it has been
specifically bred.

Since the grains do not have sufficient room to grow fully, 6R barleys
produce grains of uneven size. Those in the rows from the lateral florets are
thinner and grains are curved at the distal end where the awn is attached,
and are called twisted grains (Riahi and Ramaswamy, 2003; Kunze, 2010).
Depending on the sowing time, barley can also be divided into winter barley,
when the seeds are sown in mid-September, and spring barley, which is sown

© Woodhead Publishing Limited, 2013

Table 4.3 Barley prices (US $/tonne) in producer countries from 2000–2009

© Woodhead Publishing Limited, 2013 Crop years

Rank Country

2000 2001 2002 2003 2004 2005 2006 2007 2008 2009

1 Russian Federation 64.8 62.5 47.8 63.2 87.3 90.5 103.2 172.0 194.5 120.6
128.1 231.6 247.6 133.3
2 Germany 94.1 88.2 81.9 107.2 135.5 114.6 138.9 229.2 218.3 124.9
95.2 176.0 159.3 92.4
3 France 99.2 94.9 91.0 119.6 117.7 115.4 88.2 155.2 197.7 140.4
157.8 251.6 248.6 173.2
4 Ukraine 68.7 65.9 57.1 95.3 72.8 95.5 196.6 265.8 370.3 261.9
112.2 204.6 262.5 183.3
5 Canada 71.4 82.0 96.2 93.5 94.7 75.1 183.2 288.4 385.8 199.0
131.0 165.0 222.0 230.0
6 Spain 105.3 111.2 111.1 137.7 156.7 165.7 133.44 213.94 250.66 165.9

7 Turkey 129.8 100.1 116.1 158.9 206.6 223.3

8 Australia 99.7 102.9 113.0 165.4 124.5 121.5

9 Morocco 213.6 193.8 148.8 156.7 181.7 220.2

10 USA 97.0 102.0 125.0 130.0 114.0 116.0

Average 104.36 100.35 98.8 122.75 129.15 133.78

Source: Data from FAO/UN (2012).

Barley 161

in March and April. Winter barley has a potentially higher yield than spring
barley in areas where it is adapted. However, winter barley varieties are
generally not as cold-tolerant as other winter cereals (Kling et al., 2004).

The advantage of producing winter barley, 2R or 6R, is that it can benefit
from autumn seasonal soil moisture, which ensures higher yields when
compared with spring barley (FAO, 2009). The yield of winter barley is
about 6 tonnes/ha, which is substantially higher than that of spring barley
(about 4 tonnes/ha), and this is due to the shorter growing season for the
latter (150 days as opposed to 300 days for winter barleys). For this reason,
much more winter barley is produced in most countries (Kunze, 2010).

Hull-less or ‘naked’ barley (H. vulgare L. var. nudum Hook. F.) is a form
of domesticated barley which has an easily removable hull. Hull-less barley
has been investigated for several potential new applications as a whole-
grain ingredient in value-added products, like bran and flour for multiple
food applications, and to increase the digestible energy of the grain. Hull-
less types are produced for various food and beverage uses in East Asia,
primarily, China, Japan and Korea. Hull-less barley is an important subsis-
tence crop in the Andes, Himalayan regions and in Ethiopia. In Canada,
hull-less varieties are commonly grown as swine feed (Kling et al., 2004).

4.1.3 Structure of the cultivated barley kernel
Barley grains (Fig. 4.1) are generally larger and more pointed than wheat
and have a bright, light yellow colour. However, the colour can vary from
light yellow to purple, violet, blue and black, which is mainly caused by the
level of anthocyanins in the hull, pericarp and/or aleurone layer (Baik and
Ullrich, 2008). Highly coloured types have a ventral crease which is thinner
than those of wheat and rye, and its presence is masked by the adherent
palea (Kent and Evers, 1994a). These types receive attention for their appli-
cations in functional foods due to their antioxidant properties (Satué-
Gracia et al., 1997; Nam et al., 2006).

The anatomical structure of the barley kernel is presented in Figs 4.2 and
4.3. It consists of the surrounding husk – formed from the lemma (dorsal
husk or hull) and palea (ventral husk or hull), pericarp, testa, aleurone layer,
endosperm and germ or embryo.

The palea is overlapped along the edges by the dorsal husk which, in
most cultivars, terminates apically in a long awn. In the ventral furrow
(crease) of the kernel there is the rachilla, a hairy structure, remains of an
infertile floret (Kunze, 2010). Some of the kernel characteristics are valu-
able in distinguishing one cultivar from another, particularly when charac-
terization has to be done from the threshed grain. In hulled barley, the husks
remain attached to the caryopsis when the grain is threshed (Kent and
Evers, 1994a), whereas in hull-less barley the caryopsis husks are lost when
the grain is threshed.

Husk and pericarp consist primarily of cellulose, hemicellulose, lignin
and lignan – the major constituents of insoluble fibre. The husk consists

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162 Cereal grains for the food and beverage industries

Fig. 4.1 Barley grains.

mainly of cellulose and small amount of polyphenols, bitter substances, and
testinic acid which can have an adverse effect on beer quality. It also con-
tains the highest amount of minerals followed by embryo and the endo-
sperm (Izydorczyk and Dexter, 2004).

The pericarp develops from ovary walls and acts as a protective cover
over the entire kernel which is surrounded by the testa or seed coat. The
testa is a hard membrane composed of cellulose that allows only pure water
through excluding the salts dissolved therein, due to its semi-permeable
nature.

The aleurone layer (Fig. 4.3) surrounds the endosperm and consists of
protein-rich cells containing enzymes involved in endosperm reserve mobi-
lization (Jadhav et al., 1998). The aleurone plays a critical role in regulating
the expression of endosperm-degrading enzymes during germination. Other
substances, such as fats, polyphenols and colouring materials, are deposited
in the stable protein structure of this layer.

Representing up to approximately 75 % of the barley grain, the endo-
sperm is a starchy mass embedded in a protein matrix and is a source of
nutrients for the developing embryo (Jadhav et al., 1998). The stored starch
granules are both large (A-type) and small in size (B-type) (Morrison,
1993), and the gaps between the individual starch granules are more or less
filled with an endosperm matrix containing protein (Kunze, 2010) (Fig. 4.3).
The large lenticular granules (type A) are 25–40 μm long, are lower in
number but represent up to 85–90 % of the total weight of starch. The small
(type B), spherical granules are < 10 μm in diameter, representing about

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Barley 163

Husk
Testa
Aleurone layer

Endosperm

Scutellum
Germ

Fig. 4.2 A barley kernel in longitudinal cross-section.

70–95 % of the total number of granules, but only 10–15 % of the total
starch weight (Goering et al., 1973b). (See Plate IV in the colour section
between pages 230 and 231). The embryo is located at the end of the cary-
opsis on its dorsal side and is separated from the endosperm by a thin tissue
layer, the scutellum (Fig. 4.2). The embryo represents approximately 2.5 %,
by weight, of the barley grain and is rich in protein (34 %), lipids (14–17 %)
and ash (5–10 %), as well as being very rich in sugars (sucrose, 15 %; raffi-
nose, 5 %; and fructosans 10 %) (Izydorczyk and Dexter, 2004). The cell
walls of the scutellum are composed mainly of hemicellulose and protein
(17–20 %), and also contain some phenolics (mainly ferulic acid), minerals,
phytin and sugars (including sucrose, raffinose, stachyose, verbascose and
fructans) (Izydorczyk and Dexter, 2004). This tissue secretes hormones
which stimulate enzyme release and synthesis. The enzymes hydrolyse

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Husk
Pericarp and testa
Aleurone layer

Endosperm Aleurone cell

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(a) (b) (c)
Aleurone layer

Crease

Husk

Fig. 4.3 Structure of the barley kernel sectioned transversely (a) with detailed husk (b) and starchy endosperm (c). (a): magnification 63×
(scale bar represents 200 μm); (b): magnification 1230× (scale bar represents 20 μm); (c): magnification 5000× (scale bar represents 2 μm).

Barley 165

starch and protein constituents of the endosperm to produce nutrients for
the growing seedling.

4.2 Barley carbohydrate composition and properties

As reviewed by Baik and Ullrich (2008), the whole barley grain consists of
about 65–68 % starch, 8–17 % protein, 3.6–9 % β-glucan, 2–3 % free lipids
and 1.5–3 % minerals (Table 4.4). Total dietary fibre ranges from 11 to 34 %
and soluble dietary fibre from 3 to 20 % (Fastnaught, 2001) (Table 4.5).
Dehulled barley grain typically contains less total dietary fibre; 11–20 %,
with 11–14 % accounting for insoluble dietary fibre and 3–10 % for soluble
dietary fibre.

Starch, fibre and protein make up the largest portion of the kernel, and
variation in one of these components will influence the amounts of the
other two. Furthermore, starch level correlates inversely with the protein
level (Newman and Newman, 2008).

4.2.1 Starch
In general, starch is most abundant in the endosperm fraction of the barley
kernel (Table 4.5) and, in turn, it is the major component of flour. Smaller

Table 4.4 Barley composition

Constituent Content (%, dry weight)

Carbohydrates 78–83
Starch 60–68
Arabinoxylans 4.4–7.8
β-glucans 3.6–9
Cellulose 1.4–5
Simple carbohydrates 0.41–2.9

(glucose, fructose, sucrose, 0.16–1.18
maltose)
Oligosaccharides (raffinose, 2–3
fructosans) 8–17
Lipids 3.5–4.5
Proteins 3–5
Albumins and globulins 3–5
Hordeins 1.5–3
Glutelins 5–6
Minerals
Othersa

aBarley also contains small quantities of B complex vitamins,
including thiamine (B1), riboflavin (B2), nicotinic acid, pyridox-
ine (B6), pantothenic acid, biotin and folic acid, and vitamin E.
Sources: adapted from MacGregor and Fincher (1993), Baik
and Ullrich (2008).

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166 Cereal grains for the food and beverage industries

Table 4.5 Carbohydrate content in the barley kernel

Carbohydrate Amount References
(%, dry weight)

Starch 57.1–59.5 Aman and Newman, 1986
Fibre
Total dietary fibre 11.0–34.0 Aman and Newman, 1986
Fastnaught, 2001
Soluble dietary fibre 3.0–20.0 Fastnaught, 2001
Arabinoxylans 4.0–7.0 Hashimoto et al., 1987
Cellulose 2.0–2.9 Xue et al., 1997
Lignin 0.9–2.0 Newman and Newman, 2008
Total β-glucans 4.0–7.0 Newman and Newman, 2008
Soluble β-glucans Xue et al., 1997
Mono/oligosaccharides 2.6
Glucose Cerning and Guilbot, 1973
0.02–0.11 MacLeod and Preece, 1954
Fructose MacLeod and Preece, 1954
0.03–0.2 Aman and Newman, 1986
Sucrose Henry, 1985
0.74–1.9 Cerning and Guilbot, 1973
Maltose Aman and Newman, 1986
Raffinose 0.1 MacLeod, 1952
Fructans 0.3–0.8 Henry, 1985
0.3–0.78 MacLeod, 1954

concentrations of starch also are present in the aleurone, subaleurone and
germ tissues of the kernel (Izydorczyk et al., 2000; Flores et al., 2005).
Studies have been carried out on the pasting properties of barley starches.

Starch granules are mainly composed of two distinct polymer fractions
with clear differences in molecular weight and structural organisation, i.e.
amylose and amylopectin. Amylopectin molecules are about 10 times larger
than amylose molecules.They consist of up to 40 000 glucose molecules, with
6–7 % of 1–6 bonds, making up the greater part of the starch granule
(72–78 %), and amylose contributing the remaining 22–28 %.

The variation of amylose content in regular starches of barley species is
quite limited, although barley mutants with different amylose–amylopectin
ratios have been found. Starch with a higher content of amylopectin (up to
100 %) is called waxy starch and is found in waxy barley. Barley that has
starch with unusually high levels of amylose (up to 70 %) is known as ‘amy-
lotype’ (Delcour and Hoseney, 2010a). Waxy barley starches, which contain
low levels of both amylose and lipids, swell to a greater extent than normal
starches (Goering et al., 1973a) and are more susceptible to the enzymatic
hydrolysis than normal barley starch (Goering and Eslick, 1976). It appears
that the amylopectin fraction is responsible for the swelling power of a
given starch (Jadhav et al., 1998).

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Barley 167

Ragaee and Abdel-Aal (2006) found that whole-grain barley starch had
a peak viscosity and final viscosity that were significantly higher than that
of hard wheat starch, but lower than soft wheat. The authors studied the
addition of 15 % barley whole-grain starch to both hard and soft wheat
starch. They found that the addition led to an increase in both peak and
final viscosities of the hard wheat formulations, while the addition of barley
led to a decrease in the pasting attributes of the soft wheat formulations.
This suggests that the addition of barley to hard wheat would be more likely
to produce an end-product with increased rates of starch retrogradation.
Therefore, this would have to be accounted for when formulating a barley-
containing product. Purified starch granules contain low, but varying
levels, of lipids, free fatty acids (FFA) and proteins (Morrison et al., 1986;
Mcdonald and Stark, 1988). The lipid fraction (0.5–1.0 %) associated with
starch consists of lysophospholipids and, to a lesser extent, FFA which are
both present in proportions positively correlated with amylose content. The
most abundant fatty acids in cereal starches are linoleic and palmitic acids.
Phosphorus is the most abundant mineral in starch.All starches also contain
low levels of nitrogen (< 0.05 %). Part of this is from lipids, and the remain-
der is mostly proteinaceous.

4.2.2 Dietary fibre
The non-starch polysaccharides (NSP) in barley include cell wall compo-
nents such as arabinoxylan (or pentosans), β-glucan, cellulose, fructan and
glucomannan (Morrison, 1993), and together represent the total dietary
fibre (TDF) in barley. Cellulose, silica and lignin are mainly concentrated
in the husk and other outer layers. Up to 96 % of the total grain cellulose
is present in the hull, with very little present in the aleurone (2 %) and
endosperm (2 %) (Morrison, 1993), and none in the embryo. In contrast,
arabinoxylan and (1–3), (1–4)-β-glucan represent about 20 % and 75 % by
weight of the starchy endosperm cell walls and 67 % and 26 % of the aleu-
rone cell walls, respectively (Morrison, 1993). Small amounts of glucoman-
nan and (1,3)-β-glucan are found in the aleurone and endosperm cell walls
(Newman and Newman, 2008).

Cellulose is a long-chain polymer of (1,4)-β linked glucose molecules,
which renders it insoluble and indigestible by humans. Barley contains
between ∼5 % (hulled barleys) and ∼3 % (hull-less barleys) cellulose (Xue
et al., 1997). Cellulose acts as a structural substance by forming an aggregate
structure of cellulose, lignin and silica that affords protection against insect
and microbial penetration, possibly reducing desiccation under limited
moisture conditions (Fincher and Stone, 1986).

Arabinoxylans are pentose polymers primarily consisting of xylose and
arabinose. Arabinoxylans consist of long chains of 1,4-d-xylose residues
to which 1–2 or 1–3 bond arabinose residues are linked in some places
(Kunze, 2010). With different molecular sizes, compositions, structures and

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168 Cereal grains for the food and beverage industries

solubilities, the arabinoxylans are particularly abundant in the walls of the
aleurone cells (86 % w/w), in the starchy endosperm cell walls (20–25 %
w/w) and, to a minor extent, in the husk (Aspinall and Ross, 1963). Arabi-
noxylan content of barley grain is estimated to range from 4 to 7 % by
weight, being primarily concentrated in the aleurone (71 %) and starchy
endosperm (20 %) (Henry, 1987; Morrison, 1993).

4.2.3 b-glucan
Of all the TDF components of barley, β-glucans are probably the most
important in terms of human diet and health benefits. β-glucans are a
heterogeneous group of polymers with a general structure consisting of
long, linear chains of β-1,4- and β-1,3-linked d-glucopyranosyl residues. On
average, about 30 % of the glucose residues are connected by β-1,3 and 70 %
by β-1,4 bonds. β-glucans are the most significant material of the barley
endosperm cell wall (75 % w/w) and are also found in appreciable quantities
(26 % w/w) in the cell wall of aleurone tissue (Fincher, 1975; Bacic and
Stone, 1981; Henry, 1987). The β-glucans in the endosperm cell walls
may be covalently bound to protein, forming large molecules of 107 Da
(Macdougall and Selvendran, 2001).

The barley grain usually contains 2–10 g β-glucan/100 g dry matter
(Henry, 1987), with genotype having the greatest effect. In this regard, a
β-glucan rich hull-less waxy barley isolate ‘Prowashonupana’ contains
15–18 % β-glucan (Aman and Newman, 1986; Andersson et al., 1999).
However, there is also environmental variation (Tiwari and Cummins,
2008). Excessive precipitation, drought, heat-stress, foliage diseases and
nitrogen fertilizer regimes affect the β-glucan content of barley (Guler,
2003; Hang et al., 2007; Tiwari and Cummins, 2008).

The United States Food and Drug Administration (FDA) has allowed
whole-grain barley products that can supply β-glucan at levels of 0.75 g per
serving or 3 g per day to carry a claim that they reduce the risk of coronary
heart disease (CHD) (USDA, 2005). Clinical studies have shown that the
intake of β-glucan from either barley or oat-based products helps to control
cardiovascular disease (CVD) (Keogh et al., 2003; Shimizu et al., 2008) and
lower blood glucose levels in humans (Cavallero et al., 2002; Casiraghi
et al., 2006), even though evidence for long-term blood glucose maintenance
is lacking (European Food Safety Authority, 2010). A study conducted by
Mitsou et al. (2010) revealed that barley β-glucan induced a strong bifido-
genic effect in older healthy volunteers, suggesting a potential prebiotic
effect of barley β-glucan.

Due to its functional properties, worldwide efforts are being made to
isolate and purify β-glucan from barley in order to incorporate it in other
foods. As a result, many commercial β-glucan powders are available in the
market today (Thondre et al., 2011). BarleyTrim™ is prepared by hydrolysis

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Barley 169

of barley flour with α-amylases under controlled conditions (Inglett, 1994).
After removal of the insoluble fractions, the remaining product is a water-
soluble mixture of amylodextrins and β-glucans. The dried solubilized
material from this process is called BarleyTrim. It can be used in fruit
juices for β-glucan enrichment or as a fat replacer in food products
and may provide considerable caloric reduction.

Recently, Thondre et al. (2011) showed that the antioxidant and phenolic
content present in β-glucan products can be regarded as an additional ben-
eficial health property of barley β-glucan supplementation. In particular,
they found that this was true in products which retain the molecular struc-
ture of β-glucans, such as those prepared by natural dry milling and separa-
tion processes like 70 % acetone extraction.

The ratio of the β-(1/3) and (1/4)-linkages, the molecular size and the
concentration of β-glucans are important variables in determining the
physical properties of these polymers, such as solubility, viscosity and gel-
forming ability (Kalra and Joad, 2000; Wood et al., 2000). Thus, incorporat-
ing β-glucan-rich grain fractions or β-glucan concentrates into bakery
products is a challenging issue due to their remarkable influence on texture
and sensory quality of the final products. In this regard, Skendi et al. (2010)
showed that barley β-glucans decreases the firmness and contributes to
lower moisture loss in breads during storage. Moreover, the addition of
β-glucan increases the specific volume and number of gas cells, but it pro-
duces a coarser and darker crumb structure with less rounded cells. However,
the same authors highlighted that baking optimization trials are required,
since the effects of β-glucan on dough rheology and bread characteristics
strongly depends on the molecular size of the polysaccharide, the supple-
mentation level and the quality of the base-flour used.

Marklinder and Johansson (1995) studied the potential of barley flours
in the production of sourdough and, although it was possible to produce a
sourdough bread from barley, it was found that the β-glucan content was
significantly decreased during fermentation, suggesting that the use of fer-
mentation may not be beneficial in the creation of a bread where a high
β-glucan concentration is desirable.

Östman et al. (2006) studied the effect of barley breads with different
concentrations of β-glucan on healthy men. The authors used bread with
three different concentrations of β-glucan-rich barley (35 %, 50 % and
75 %), as well as a common barley (50 % concentration) and a 100 % wheat
bread control. The authors found that breads containing 50 % and 75 %
barley flour led to decrease of 40 and 48 %, respectively in the bread’s
glycaemic index (GI) value when compared with a wheat flour bread
control. The insulinaemic index (II) was also found to decrease by 37 % and
34 %, respectively.The authors concluded that the incorporation of β-glucan-
rich barley fractions into bread may lower both the GI and II properties of
the bread.

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170 Cereal grains for the food and beverage industries

4.3 Other constituents of the barley kernel

Even though present at a lower level in the barley kernel, other constitu-
ents, such as proteins, lipids, vitamins, mineral, and phytochemicals, have a
great impact on the technological and functional quality of barley-based
products and beverages likes bread and beer.

4.3.1 Protein
Barley protein contents range between 7 and 25 % (Ullrich, 2002) and can
be separated into four solubility groups: albumin (water-soluble fraction),
globulin (salt-soluble fraction), prolamin or hordein (alcohol-soluble frac-
tion) and glutelins (alkali-soluble fraction) as described by Osborne (1924).
In the kernel, barley proteins occur in many forms and are responsible for
metabolic activity, structural functions and providing nitrogen for the devel-
oping embryo during the germination phase.

Besides globulin and glutelins, the major storage proteins in barley are
represented by alcohol-soluble hordeins (prolamins), which comprise
30–50 % of the total grain protein (Jonassen et al., 1981; Kirkman et al.,
1982). Hordeins, the major storage proteins in the endosperm, have been
classified on the basis of amino acid composition into three groups: sulphur
rich (B + γ), sulphur poor (C) and high-molecular-weight prolamins (D)
(Newman and Newman, 2008). Hordein has a moderate nutritional quality;
however, high-lysine barley mutants, which contain 2–3 % greater lysine
than normal lysine types (w5–6 % vs w3 %) (Ullrich and Eslick, 1978a)
could provide high-quality enriched protein (Newman and Newman, 1991).
However, high-lysine barley has solely been commercialized for feed and
only to a limited extent in Denmark, due partly to negative effects on kernel
size, starch and grain yield (Ullrich and Eslick, 1978b, c).

The barley non-storage proteins are found primarily in the aleurone and
embryo, and account for 15–30 % of the total grain nitrogen with albumins
and globulins as the major representatives. In the barley kernel, these work
as structural components of cell walls and metabolic proteins (enzymes).
Since the albumin–globulin fraction contains about 5–7 % of lysine, com-
pared to less than 1 % in hordeins, they result in a more nutritionally bal-
anced protein source than the storage proteins (Shewry et al., 1984).
Generally, the barley protein content is highly dependent on the cultivar
(Qi et al., 2006) and differs with the growth conditions, particularly with the
rate and timing of nitrogen fertilization (Duffus and Cochrane, 1993).

The amino acid composition of barley protein is quite similar to the other
cereal grains. High glutamic acid and proline contents and relatively low
amounts of basic amino acids characterize the barley grain. The average
amino acid composition of typical hulled and hull-less barley is shown in
Table 4.6. As with most nutrients in barley, other than fibre, removal of the

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