Cereal_grains_for_the_food_and_beverage_industries_2075944_z_lib

368 Cereal grains for the food and beverage industries

tatham, a. s., fido, r. j., moore, c. m., kasarda, d. d., kuzmicky, d. d., keen, j. n. and
shewry, p. r. (1996). Characterisation of the major prolamins of tef (Eragrostis
tef ) and finger millet (Eleusine coracana). Journal of Cereal Science, 24, 65–71.

tefera, h., ayele, m. and assefa, k. (1975). Improved varieties of tef (Eragrostis tef)
in Ethiopia, releases of 1970–1995, Agricultural Research Station Bulletin No. 1.
Dire Dawa: Debre Zeit Agricultural Research Station. Alemaya University of
Agriculture.

teklu, y. and tefera, h. (2005). Genetic improvement in grain yield potential and
associated agronomic traits of tef (Eragrostis tef ). Euphytica, 141, 247–254.

trombino, s., serini, s., di nicuolo, f., celleno, l., andò, s., picci, n., calviello, g. and
palozza, p. (2004). Antioxidant effect of ferulic acid in isolated membranes and
intact cells: synergistic interactions with α-tocopherol, β-carotene, and ascorbic
acid. Journal of Agricultural and Food Chemistry, 52, 2411–2420.

unger, f. (1866). Botanische Streifzüge auf dem Gebiete der Culturgeschichte. VII.
Ein Ziegel der Dashurpyramide in Ägypten nach seinem Inhalte an organischen
Einschlüssen. Sitzungsberichte der Mathematisch-Naturwissenschaftlichen
Classe der Kaiserlichen Akademie der Wissenschaften. Wien: K.K. Hof und
Staatsdruckerei.

usda/ars (2012). USDA National Nutrient Database for Standard Reference, Release
25. Nutrient Data Laboratory Home Page, http://www.ars.usda.gov/ba/bhnrc/ndl
[accessed December 2012].

vavilov, n. i. (1951). The Origin, Variation, Immunity and Breeding of Cultivated
Plants. (translated from Russian by K. Starr Chester). New York: Ronald Press.

vogel, s. and gobezie, a. (1996). Ethiopian talla. In: steinkraus, k. h. (ed.) Hand-
book of Indigenous Fermented Food (2nd edn). New York: Marcel Dekker.

weber, e. j. (1987). Lipids of the kernel. In: watson, s. a. and ramstad, p. e. (eds)
Corn: Chemistry and Technology. St Paul, MN: AACC International, Inc.

zannini, e., jones, j. m., renzetti, s. and arendt, e. k. (2012). Functional replacements
for gluten. Annual Review of Food Science and Technology, 3, 227–245.

zegeye, a. (1997). Acceptability of injera with stewed chicken. Food Quality and
Preference, 8, 293–295.

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p
s

s

100.0 µm
Plate VI Confocal laser scanning microscope (CLSM) micrograph of portion of
starchy endosperm; s: starch; p: protein. The portion of the endosperm was stained
with fluorescein isothiocyanate (FITC) for starch (green) and with rhodamin B for

protein (red).

Starchy endosperm

50.0 µm

Vitreous endosperm

Plate VII Confocal Laser Scanning Microscope (CLSM) micrograph section of
the teff kernel with starch storage granules stained with fluorescein isothiocyanate

(FITC) for starch (green) and with rhodamin B for protein (red).

© Woodhead Publishing Limited, 2013

11

Buckwheat

DOI: 10.1533/9780857098924.369

Abstract: Common buckwheat (Fagopyrum esculentum Moench) is a pseudo-
cereal cultivated since at least 1000 BC in China and introduced to North
America by the colonists. The plant has very strong adaptability to adverse
environments and a very short growing span. Buckwheat contains high levels of
polyunsaturated essential fatty acids, high levels of minerals and vitamins, dietary
fibre, resistant starch, antioxidant compounds and protein of high nutritional
value. By mixing buckwheat with cereal grains that are low in lysine, a balanced
amino acid profile can be achieved. On the other hand, a low protein digestibility
has been recorded, possibly due to the presence of tannins, phytic acid and
protease inhibitors. The grain is generally used as animal or poultry feed and as
human food, with the dehulled groats being cooked as porridge and the flour
used in the preparation of biscuits, pancakes, noodles and breakfast cereals.
Malting is one of the most promising food processing operations for the
enhancement of protein and starch digestibility. However, results so far indicate
that the application of 100 % buckwheat malt in brewing is not feasible.
Nevertheless, through selective plant breeding and process optimization, this
pseudo-cereal in brewing will be a valuable gluten-free alternative to barley malt.

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

11.1 Introduction

Common buckwheat (Fagopyrum esculentum Moench) is an annual
meliferous crop with particular relevance in some regions of the world.
Buckwheat is not taxonomically related to wheat. It originated from North
or East Asia, has been cultivated since at least 1000 BC in China and was
introduced to North America by the colonists. It has very strong adaptabil-
ity to adverse environments and a very short growing span. Many varieties
are grown around the world, the majority of which are found in the north-
ern hemisphere. F. esculentum Moench is grown in many countries, includ-
ing Russia, China, the USA, Canada, France, Germany, Italy, Poland, Japan,
Korea and Nepal. F. tartaricum or Tartary buckwheat, a congener which is
also used as a food crop, is also available in some mountainous regions of

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370 Cereal grains for the food and beverage industries

Asia. Due to its frost tolerance, Tartary buckwheat is generally grown at
higher altitudes whereas common buckwheat is grown at the lower alti-
tudes. Buckwheat is used as a subsistence crop in many of the more moun-
tainous areas where it is often grown with barley.

The grain is generally used as human food and as animal or poultry feed,
with the dehulled groats being cooked as porridge and the flour used in the
preparation of biscuits, pancakes, noodles and breakfast cereals, etc. The
protein of buckwheat is of excellent quality and is high in the essential
amino acid lysine, unlike the protein of the common cereals. This, coupled
with the plant’s ability to do well on poorer soils, probably accounts for its
widespread usage. It is also regarded as a multipurpose crop. The small
leaves and shoots are used as leafy vegetables and the flowers and green
leaves are used for rutin extraction which is used as an ingredient in alter-
native medicine. Finally, the crop also produces honey of a very good
quality.

11.1.1 Production, price, yield and area
Common buckwheat is mainly produced in the Russian Federation, Ukraine
and Kazakhstan, although it is grown to a lesser extent in many other coun-
tries. There are no records of its production in Oceania. Tartary buckwheat
generally does not enter into international trade since it is only produced
for local consumption. Although there are yearly fluctuations in production,
there does not appear to be any noticeable trend and therefore production
appears to be fairly constant except in the Asian continent where, during
the last decade, buckwheat production and cultivation areas have reduced
by 51 % and 31 %, respectively (FAO/UN, 2012). In contrast, over the last
eight years, Europe, in particular the eastern part, has been the largest
producer of buckwheat in terms of yield and area harvested. In 2010,
Europe (mainly the Russian Federation) produced more than 1.4 million
tonnes (64 %), followed by Asia and the Americas with production of
652 734 million tonnes (29 %) and 139 300 million tonnes (7 %), respectively
(FAO/UN, 2012). As a consequence, the European continent is the prime
producer with regard to the area (in hectares) dedicated for buckwheat
cultivation. World cultivation of buckwheat has decreased over the last
century. The main reason for this decline is buckwheat self-incompatibility,
which led to breeding difficulties. In addition, buckwheat showed a poor
response to fertilizer applications in comparison to other crops (Marshall
and Pomeranz, 1982; Pomeranz, 1983). The producer price is highly variable,
depending on the production country. During the last eight years, Japan and
Brazil have always shown the highest (average of 1889 US $/tonne) and the
lowest producer prices (average of 39 US $/tonne), respectively. Brazil has
continually exported buckwheat to several European countries as well as
Japan (Defrancischi et al., 1994). An explanation of the low price producers

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Buckwheat 371

in Brazil receive for their buckwheat is the crop’s high yield in that area,
which in 2010 reached 1.23 tonnes/hectare, the highest in the world (FAO/
UN, 2012).

11.1.2 Phytology, classification and cultivation
In recent years, buckwheat has regained interest as an alternative crop for
organic cultivation and as a health food (Li and Zhang, 2001; Biacs et al.,
2002). It contains several compounds that may have potential in reducing
the risk of certain diseases (Mazza and Oomah, 2005). Common buckwheat
(F. esculentum Moench) is the most commonly grown species, while two
other species of buckwheat, F. tataricum Gaertner and F. emarginatum, have
been cultivated on a small scale (Marshall and Pomeranz, 1982; Mazza
and Oomah, 2005). The plant, which belongs to the family Polygonaceae,
is an annual and is characterized by large heart-shaped leaves. The tall
erect plant can grow to 0.6–1.5 m in height and can produce several
branches. The stems, which vary in colour from green to red and brown at
maturity, are hollow and the plant is very prone to lodging. Buckwheat has
a shallow tap root system, with numerous laterals extending to 0.9–1.2 m
in depth. The fruiting structure of buckwheat is on axillary or terminal
racemes with densely clustered flowers. Flowers can be white or white
tinged with pink.

Buckwheat is categorized as a so-called pseudo-cereal and shows both
differences from and similarities with common cereals. The main structural
difference is that buckwheat is a dicotyledonous plant in contrast to the
monocotyledonous cereals. The embryonic axis runs from the bottom of the
kernel to the top (Fig. 11.1a). The embryo proper is located in the pointed
(distal) part of the kernel and possesses two cotyledons as is shown in Figs
11.1b and 11.2. The hull (pericarp) has a hard fibrous structure and sur-
rounds the seed coat, endosperm and embryo tightly (Fig. 11.1b) (Wijn-
gaard et al., 2007). The endosperm cells have thin cell walls and consist
mainly of starch (Pomeranz, 1983; Steadman et al., 2001a) (Figs 11.3 and
11.4). It seems that buckwheat contains only small sized starch granules, all
of similar sizes, ranging from approximately 4 to 7 μm (Figs 11.3 and 11.5).
Cereals also contain starchy endosperms, and this is one of the main simi-
larities between cereals and buckwheat. In addition, both cereal grains and
buckwheat seeds are edible and have a non-starchy aleurone layer (Bonafac-
cia et al., 2003a). Although other parts of the buckwheat plant can be used
for human consumption and animal feed, buckwheat is now mainly grown
for the production of its seeds (Biacs et al., 2002; Mazza and Oomah,
2005). The seeds are wide at the base and triangular to almost round in
cross-section. They may be grey–brown or brown–black in colour while
size varies according to variety (Fig. 11.6). The seed comprises a thick outer
hull and an inner groat. Buckwheat seeds are usually processed into flour.

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372 Cereal grains for the food and beverage industries

EA

3.0 kV ×25 1 mm 0000 Test 1
(a)

E H
C

G

A
S

5 kV ×27 500 μm 0000 29/NOV

(b)

Fig. 11.1 (a, b) Scanning electron microsope (SEM) micrographs of a buckwheat
kernel with hull (H), seedcoat (S), aleurone layer (A), embryo proper (G), embry-
onic axis (EA), starchy endosperm (E) and cotyledons (C). With kind permission
from John Wiley and Sons: Microstructure of Buckwheat and Barley During Malting
Observed by Confocal Scanning Laser Microscopy and Scanning Electron Micros-
copy. H.H. Wijngaard, S. Renzetti, E.K. Arendt. Journal of the Institute of Brewing

113(1), 34–41, 2007.

Buckwheat seeds are dehulled before milling or the flour is sieved. Dehu-
lled seeds are called ‘groats’ (Marshall and Pomeranz, 1982; Ikeda, 2002).
The composition of buckwheat groats is shown in Table 11.1. In the follow-
ing sections, chemical and nutritional characteristics of buckwheat groats
and seeds will be discussed.

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Hypocotyl Buckwheat 373
Cotyledons
Endosperm Cotyledons
Endosperm

Fig. 11.2 Longitudinal cross-section of buckwheat kernel.

SG
CW

5 kV SG
×500 50 μm 0000 29/NOV/05

Fig. 11.3 SEM micrograph of cell of the endosperm of buckwheat with cell walls
(CW) and starch granules (SG). With kind permission from John Wiley and Sons:
Microstructure of Buckwheat and Barley During Malting Observed by Confocal
Scanning Laser Microscopy and Scanning Electron Microscopy. H.H. Wijngaard,

S. Renzetti, E.K. Arendt. Journal of the Institute of Brewing 113(1), 34–41, 2007.

11.2 Buckwheat carbohydrate composition and properties

Carbohydrate is the most abundant component of buckwheat grain. Starch
represents the most abundant carbohydrate and is mainly concentrated in
the kernel endosperm.

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374 Cereal grains for the food and beverage industries

E

C

Fig. 11.4 Confocal Scanning Laser Microscope (CSLM) micrograph (10x) of struc-
ture of buckwheat showing the starchy endosperm (E) and part of the two cotyle-
dons present (C). With kind permission from John Wiley and Sons: Microstructure
of Buckwheat and Barley During Malting Observed by Confocal Scanning Laser
Microscopy and Scanning Electron Microscopy. H.H. Wijngaard, S. Renzetti, E.K.

Arendt. Journal of the Institute of Brewing 113(1), 34–41, 2007.

CW

SG

5 kV ×2,500 10 μm 0000 29/NOV/05
Fig. 11.5 SEM micrograph of compact endosperm of buckwheat with cell walls
(CW) and starch granules (SG). With kind permission from John Wiley and
Sons: Microstructure of Buckwheat and Barley During Malting Observed by
Confocal Scanning Laser Microscopy and Scanning Electron Microscopy. H.H.
Wijngaard, S. Renzetti, E.K. Arendt. Journal of the Institute of Brewing 113(1), 3

4–41, 2007.

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Buckwheat 375

Fig. 11.6 Buckwheat grains.

Table 11.1 General composition of common buck-
wheat groats

Parameter Level (% (w/w)

Moisturea 11.8 ± 0.03
Starchb 54.5 ± 2.4
Protein 12.3 ± 0.0
Dietary fibre 7.0 ± 0.2
Lipids 3.8 ± 0.0
Minerals 2.4 ± 0.0
Soluble carbohydrates 1.6 ± 0.1
Other compounds
18.4

a On wet basis.
b On dry basis.

Source: Steadman et al. (2001a).

11.2.1 Starch
Buckwheat groats showed a total carbohydrate percentage of 68–70 % (Li
and Zhang, 2001; Steadman et al., 2001a), of which 54.5 % was found to be
starch (Steadman et al., 2001a). Buckwheat seeds exhibited a higher carbo-
hydrate percentage of 73 %, due to the presence of the pericarp, but con-
sisted of a similar starch percentage (56 %). The percentage of starch (57.4
± 0.1 %) found in Tartary buckwheat was slightly higher than in common
buckwheat, but this could be due to the cultivar analysed in this particular
study (Bonafaccia et al., 2003b).

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376 Cereal grains for the food and beverage industries

An apparent amylose content (amylose concentration indirectly deter-
mined by colorimetric measurement of the iodine–starch complex) as high
as 46.6 % was determined by Qian et al. (1998), but lower apparent amylose
contents of 21.1–27.4 % were reported in later publications (Noda et al.,
1998; Qian and Kuhn, 1999a; Yoshimoto et al., 2004). Noda et al. (1998)
studied 27 buckwheat samples and recorded amylose percentages of buck-
wheat starch samples ranging from 21.1 and 27.4 % with a mean value of
24.0 %.These ranges agree with amylose percentages found in cereals (Qian
and Kuhn, 1999b). No consistent differences existed between apparent
amylose percentages of common and Tartary buckwheat (Li et al., 1997).
When buckwheat starches are defatted, iodine affinity increases.This implies
the presence of amylose–lipid complexes (Qian et al., 1998; Yoshimoto
et al., 2004). This assumption was also supported by Qian et al. (1998). A
second melting transition peak temperature of 84.5 °C has been observed
by differential scanning calorimetry (DSC) analysis.These results may point
to the presence of amylose–lipid complexes.The formation of amylose–lipid
complexes could lead to the restriction of swelling power and solubility
(Qian et al., 1998).

Yoshimoto et al. (2004) determined a big difference between the actual
amylose content, which was 15.6–17.9 %, and the apparent amylose content
of 25.5–26.5 %. This difference indicates the presence of a large amount of
longer chain amylopectins that have the tendency to complex with iodine
(Yoshimoto et al., 2004).The presence of long-chain branched molecules was
confirmed by Praznik et al. (1999) and Noda et al. (1998). The degree of
polymerization (DP) of amylopectin depended on the botanical origin and
hence varied between buckwheat starches. In buckwheat, a high level of DP
implies the presence of a relatively higher level of supermolecular glucan
structures, which might affect the viscosity. During gelatinization, super-
molecular glucan structures can disintegrate, but they tend to reconstitute
during cooling (Praznik et al., 1999). In general, buckwheat starch exhibited
higher peak viscosities than cereal starches and its pasting behaviour more
closely resembled that of root and tuber starches (Qian et al., 1998; Qian
and Kuhn, 1999a; Yoshimoto et al., 2004). Besides supermolecular glucan
structures, these high viscosity values can be explained by the fact that
buckwheat starches exhibited a higher granule swelling and gelling tendency
than cereal starches (Yoshimoto et al., 2004). Peak gelatinization tempera-
tures differed slightly per buckwheat cultivar. Noda et al. (1998) reported
peak gelatinization temperatures for buckwheat starches ranging from 57.2
to 66.7 °C, but most peak gelatinization temperatures described have been
within a range 63.7–70.8 °C (Li et al., 1997; Qian et al., 1998; Qian and Kuhn,
1999a; Yoshimoto et al., 2004). It is important to note that the equipment
applied to determine gelatinization properties can affect gelatinization
curves. For instance, different onset temperatures of gelatinization (60 °C,
70 °C and 80 °C) have been reported with DSC analysis, rapid visco-analysis
and Brabender viscoamylography, respectively (Qian and Kuhn, 1999a).

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Buckwheat 377

According to Qian et al. (1998), the water-binding capacity of buckwheat
starch is 109.9 %, which is higher than the water-binding capacities of wheat
and corn starch. This high value can be explained by the small size (and
hence a bigger specific surface area) of buckwheat starch granules (Qian et
al., 1998). Buckwheat starch granules range in size from 2.9 to 9.3 μm with
a mean size of 5.8 μm and are round or polygonical shaped (Qian and Kuhn,
1999b). The appearance of the buckwheat starch granule is smooth with a
few pores, possibly caused by enzymatic breakdown (Qian and Kuhn,
1999b). Due to the presence of pores and the small starch granule size,
buckwheat starch is more susceptible to fungal α-amylase than corn and
wheat starch (Qian et al., 1998). In general, it can be said that buckwheat
starch has its own unique characteristics as some properties correspond
with tuber starches, such as high viscosity values, and others more with
cereal starches, such as shape and composition.

11.2.2 Resistant starch
Starches can be divided in three groups, depending on their rate and extent
of digestion in vitro: rapidly digestible starch, slowly digestible starch and
resistant starch (RS). RS can again be divided in three groups: physically
inaccessible starch, native granular starch and retrograded starch (Englyst
et al., 1992). Undigested starch may result in positive nutritional effects
in a similar way to fibre (Skrabanja and Kreft, 1998). Various factors,
such as the physical form of the starch, extent of retrogradation, amylose :
amylopectin ratio and non-starchy inhibitory components, affect the digest-
ibility of starch (Skrabanja and Kreft, 1998). In raw buckwheat groats with
a total starch content of 73.5 %, 33.5 % was RS (Skrabanja and Kreft, 1998).
It has been reported in literature that processing can affect RS in buck-
wheat. For instance, autoclaving decreased buckwheat RS from 33.5 % to
7.5 %. However, the level of retrograded starch (one form of RS) can be
increased by either autoclaving or boiling from 1 % to 4.7 % (Skrabanja
and Kreft, 1998; Skrabanja et al., 1998, 2001). Rats excreted ∼0 % starch
originating from native buckwheat groats compared to 1.0–1.6 % of hydro-
thermally processed buckwheat starch. Hence it was suggested that rats
(and possibly humans) can completely digest native buckwheat starch, but
not buckwheat starch that has been hydrothermally processed (Skrabanja
et al., 1998). Non-native buckwheat has therefore been suggested as an
ingredient for low glycaemic index (GI) foods. Low GI foods are important
in improving diabetic control and can be ranked according to their blood
glucose raising potential (Jenkins et al., 1981). Foods with higher levels of
RS usually have a low GI and are generally advantageous for most healthy
adults (Skrabanja et al., 2001). In comparison to white wheat bread
(GI = 100), boiled buckwheat groats had a GI of 61.2 and buckwheat bread
baked with 50 % buckwheat groats had a GI of 66.2 (Skrabanja et al., 2001).
As it is known that buckwheat flour extracts contain compounds such as

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378 Cereal grains for the food and beverage industries

tannins, phytic acid and proteinaceous inhibitors that can act against human
saliva amylase (Ikeda and Yamashita, 1994; Skrabanja et al., 2001), it would
be interesting to know what the relative contribution of RS itself is, when
designing low GI products.

11.2.3 Dietary fibre
Dietary fibre (DF) has been mentioned in many reports as potentially pro-
tective against certain diseases (Roberfroid, 1993). DF can be divided into
insoluble dietary fibre (IDF) and soluble dietary fibre (SDF). IDF generally
includes lignin and cellulose, while SDF includes pectin and gums (Rober-
froid, 1993; Steadman et al., 2001a). SDF in particular may contribute posi-
tively to human health, e.g. by reducing levels of blood cholesterol
(Roberfroid, 1993). In addition, though, DF can also have a negative role,
as it may bind proteins and minerals, inhibit digestive enzymes and, thereby,
lower digestibility or absorption of proteins and minerals, respectively
(Ikeda and Kusano, 1983; Steadman et al., 2001a). Bonafaccia et al. (2003b)
reported a DF content of 27.4 % in buckwheat seeds. DF is mainly present
in the outer seed coverings such as the seed coat and hull, which explains
the much lower DF percentage of ca 7 % in buckwheat groats (Steadman
et al., 2001a; Bonafaccia et al., 2003b). IDF and SDF of buckwheat groats
are similar to cereals, such as oats and wheat. An IDF content of 2.2 % has
been determined in buckwheat groats and hence an SDF content of 4.8 %
can be calculated. Indigestible oligosaccharides, such as fagopyritols are not
measured in SDF assays, since they dissolve in the solvents used. If total
α-galactosides were included in the assay, the SDF level would increase by
20–30 % (Steadman et al., 2001a).

11.2.4 D-chiro-inositol
D-chiro-inositol is an inositol isomer that occurs at relatively high levels in
buckwheat seeds (Steadman et al., 2000). Chemically synthesized D-chiro-
inositol has been demonstrated to lower elevated plasma glucose in spon-
taneously insulin-resistant rhesus monkeys, streptozotocin-treated
hyperglycaemic rats and normal rats when D-chiro-inositol was adminis-
tered either intravenously or orally (Ortmeyer et al., 1993, 1995). Since a
relatively high level of D-chiro-inositol was found in buckwheat, adminis-
tering doses of 10 and 20 mg of D-chiro-inositol in the form of natural
buckwheat concentrate decreased serum glucose concentrations by 12–19 %
in streptozotocin-diabetic rats. Although no study of the effect of D-chiro-
inositol on humans has been reported, buckwheat concentrate has been
suggested as a natural product to help in treating diabetes (Kawa et al.,
2003).

Steadman et al. (2000) described a free level of D-chiro-inositol in buck-
wheat groats, which ranged from 20.7 to 41.7 mg 100 g of dry weight (dw),

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Buckwheat 379

but most D-chiro-inositol in buckwheat is present in the form of fagopyri-
tols (Horbowicz et al., 1998). Fagopyritols are galactosyl derivatives of
D-chiro-inositol that can accumulate in the seeds of some species. Buck-
wheat embryos are unique because they accumulate galactosyl cyclitols and
not raffinose oligosaccharides (Horbowicz et al., 1998). Fagopyritols, along
with other soluble carbohydrates such as sucrose, are mainly localized in
buckwheat embryos (71.4 %). Fagopyritol B1 is the most abundant fagopy-
ritol in buckwheat seeds and represents 41.5 mg g−1 (dw) of the soluble
carbohydrates in the embryo. In addition to B1, four other fagopyritols have
been identified in embryos from common buckwheat seeds: fagopyritol A1
(mono-galactosyl D-chiro-inositol isomer), fagopyritol A2 and fagopyritol
B2 (di-galactosyl D-chiro-inositol isomers), and fagopyritol B3 (tri-
galactosyl D-chiro-inositol). These were present at levels of 4.67 and
1.02 mg g−1 (dw) of soluble carbohydrates in embryos and endosperm,
respectively. Tartary buckwheat contained 50 % of the level of fagopyritols
present in common buckwheat. Tartary buckwheat contained another
soluble carbohydrate that was not identified in common buckwheat culti-
vars. This compound was possibly rhamnosyl glucoside and was present at
a level of 31 % (Steadman et al., 2000). Malting is one possibile means to
increase fagopyritol levels. Germinating at 18 °C raised amounts of fagopy-
ritol B1, whilst germinating at 25 °C increased the levels of both A2 and B2
(Horbowicz et al., 1998).

The effects of D-chiro-inositol and fagopyritols on plasma glucose levels
in rats have been investigated by Kawa et al. (2003). The authors demon-
strate that a buckwheat concentrate is an effective source of D-chiro-
inositol for lowering serum glucose concentrations in rats and therefore
may be useful in the treatment of diabetes. The effects of D-chiro-inositol
and fagopyritols on plasma glucose levels in humans should be investigated.
These compounds may have positive effects for patients with diabetes and
products may be designed accordingly.

11.3 Buckwheat protein composition and properties

Protein content in buckwheat is particularly high when compared to other
grains such as wheat rice, maize and sorghum. Moreover, the amino acid
composition of buckwheat proteins is well balanced and of a high biological
value.

11.3.1 Storage proteins
All proteins can be divided in four groups based on their solubility: (i)
albumins (soluble in water and dilute buffers at neutral pH); (ii) globulins
(soluble in salt solutions but insoluble in water); (iii) glutelins (soluble in
dilute acid or alkali solutions); and (iv) prolamins (soluble in aqueous

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380 Cereal grains for the food and beverage industries

alcohols of 70–90 %) (Bewley and Black, 1985). In cereals, prolamins are
the major storage proteins, while in buckwheat, globulins are mainly found.
According to Ikeda et al. (1991), common buckwheat seeds consist of 64.5 %
globulin, 12.5 % albumin, 8.0 % glutelin and a small percentage of prola-
mins, 2.9 %. Similar ranges have been reported by Radovic et al. (1999).

The major storage proteins, globulins, consist of two major families which
differ in molecular weight (MW) and sediment with different sedimentation
coefficients (S values) of approximately 7 (average 7–8) and 11 (11–13)
during ultracentrifugation. Both are composed of regularly assembled sub-
units (Bewley and Black, 1985). In buckwheat, 13S globulin and 8S globulin
have been identified. The MW of 13S globulin is 280 000. It is a legumin-like
storage protein, composed of non-identical sub-units consisting of one
acidic and one basic polypeptide linked by disulphide bonds. 13S globulin
contributes 33 % of total seed proteins in buckwheat and is a major storage
protein (Radovic et al., 1996). The smaller 8S globulin is a trimer. It is com-
posed of sub-units having a MW of 57 000–58 000 and is similar to vicilin-
like storage proteins.The 8S globulin contributes ± 7 % of total seed proteins
in buckwheat (Milisavljevic et al., 2004).

In addition to globulins, 2S albumins have been identified in buckwheat.
These water-soluble proteins are single-chain polypeptides and have MWs
ranging from 8000 to 16 000 (Elpidina et al., 1991; Radovic et al., 1999). Most
of the protein in buckwheat is localized in protein bodies. Protein bodies
are special cellular organelles with average sizes of 1–10 μm in diameter
and are bound by a single membrane (Elpidina et al., 1991). The 13S protein
was only found in the cotyledons, while the 8S globulin was found in both
cotyledons and in the endosperm (Radovic et al., 1996).

11.3.2 Amino acids
Buckwheat does not belong to the cereal family and contains very low
levels of prolamins or none at all. This is the reason why coeliac sufferers
can consume buckwheat (Fasano and Catassi, 2001). In cereal grains, where
the percentage of prolamins is high, lysine is limiting, tryptophan is low and
threonine levels are nutritionally inadequate. The majority of buckwheat
proteins consist of globulins and albumins; buckwheat protein contains
therefore a wide range of amino acids. Pomeranz and Robbins (1972) ana-
lysed the amino acid composition of 10 samples of buckwheat seeds from
various origins as shown in Table 11.2 (Tkachuk and Irvine, 1969). A mean
percentage of 13.7 % protein has been found and 17 amino acids have been
identified. The first nine amino acids in Table 11.2 are essential and have to
be consumed, as the body is not able to produce them (Insel et al. 2004). In
comparison to cereal grains, buckwheat protein shows a high level of lysine
(6.1 % of 100 g amino acid recovered). In addition, buckwheat contains high
levels of arginine (9.7 %) and aspartic acid (11.3 %) and low levels of
proline (3.9 %) and glutamic acid (18.6 %), when compared to cereals

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Table 11.2 Mean, maximum value, minimum value and standard deviations for
crude protein and amino acid composition of ten buckwheat samples from various
origins

Protein and amino acids Maximum (%) Minimum (%) Mean ± sd

Proteina 15.4 12.6 13.7 ± 0.851

Essential amino acids 7.0 5.0 6.1 ± 0.460
Lysine (Lys) 3.1 2.3 2.7 ± 0.164
Histidine (His) 4.1 3.6 3.9 ± 0.138
Threonine (Thr) 5.4 4.8 5.1 ± 0.166
Valine (Val) 3.0 1.8 2.5 ± 0.344
Methionine (Met) 4.0 3.6 3.8 ± 0.098
Isoleucine (Ile) 6.6 6.1 6.4 ± 0.156
Leucine (Leu) n.d. n.d. 2.4b
Tryptophane 5.0 4.6 4.8 ± 0.127
Phenylalanine (Phe)
2.3 1.7 2.1 ± 0.164
Non-essential amino acids 11.6 8.5 9.7 ± 0.837
Ammonia (NH3) 12.1 10.8 11.3 ± 0.331
Arginine (Arg) 4.5 4.7 ± 0.198
Aspartic acid (Asp) 5.2 17.8 18.6 ± 0.404
Serine (Ser) 19.4 3.2 3.9 ± 0.353
Glutamic acid (Glu) 1.2 1.6 ± 0.162
Proline (Pro) 4.3 5.9 6.3 ± 0.186
Half cysteine (Cys) 1.8 4.2 4.5 ± 0.133
Glycine (Gly) 6.5 1.8 2.1 ± 0.235
Alanine (Ala) 4.7
Tyrosine (Tyr) 2.5

a% db of buckwheat kernels.
bTkachuk and Irvine (1969).

SD = Standard deviation.

Source: Pomeranz and Robbins (1972).

(Pomeranz and Robbins, 1972). Similar results have been reported by
Javornik et al. (1981) and Eggum et al. (1980). Relatively low levels of
proline and glutamic acid can be explained by the fact that prolamins, which
are high in proline and glutamic acid, are present in very low amounts in
buckwheat (Ikeda et al., 1991). In all parts of the buckwheat kernel apart
from the hulls, the amino acid composition was similar (Pomeranz and
Robbins, 1972).

11.3.3 Nutritional quality of proteins
The nutritional quality of a protein reflects its essential amino acid content,
digestibility and the bioavailability of its amino acids (FAO/UN, 1990).
Table 11.3 compares the nutritional quality of buckwheat protein to the
reference protein, which is based on the requirement of amino acids of a
preschool-age child. As reported in Table 11.3, the only limiting amino acid

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382 Cereal grains for the food and beverage industries

Table 11.3 Amino acid requirement pattern based on amino acid requirements of
preschool age child and amino acid pattern present in buckwheat

Essential amino acid Amino acid requirement Amino acid level in
buckwheat (mg g−1
pre-school age child
(mg g−1 crude protein)a crude protein)

Ile 28 38
Leub 66 64
Lys 58 61
Total sulphur amino acids 25 41

(Met and Cys) 63 93
Total aromatic aminoacids
34 39
(Tyr, Phe and Trp) 11 24
Thr 35 51
Trp 320 411
Val
Total

aFAO/WHO/UNU (1985).
bThe amino acid leucine (in italics) is the first limiting amino acid in buckwheat.

Source: Schaafsma (2000).

is leucine, in contrast to cereals, where lysine is limiting (Chung and Pomer-
anz, 1985). Leucine is present at a level of 64 mg g−1 protein, whereas it
should be at levels of 66 mg g−1 protein, based on the requirement of a
preschool-age child. Eggum et al. (1980) reported two different buckwheat
varieties, both with high protein quality, namely biological values of 93.1 %
and 90.5 %, respectively. This can be explained by high concentrations of
the most essential amino acids, especially lysine, threonine, tryptophan and
the sulphur-containing amino acids. However, when the buckwheat variet-
ies were fed to rats, values for true protein digestibility of 79.9 % and 78.8 %
were obtained (Eggum et al., 1980), which are low compared to cereals
(FAO/UN, 1990). These results were mainly due to the high contents of
crude fibre and tannins (Eggum et al., 1980). The results are in agreement
with data from Javornik et al. (1981), who demonstrated a true protein
digestibility of 79.9 % and 77.6 % in common and Tartary buckwheat
respectively.

11.3.4 Proteolysis
The break down of buckwheat protein represents a key factor in improving
its availability for gastrointestinal absorption and therefore its biological
value. Moreover, from the technological point of view, breakdown of buck-
wheat protein during malting is essential for the use of malt for brewing, as
it enables better extractability of starch and better access of the amylolytic
enzymes to the starch. Additionally, the protein breakdown products rep-
resent essential nutrients for yeast during the fermentation process as well

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Buckwheat 383

as contributing to foam stability and to the body of the final product (Arendt
and Hubner, 2010).

During germination, storage material in protein bodies is degraded and
the embryonic axis, which serves as a collector for the products of hydrolysis
of storage materials of the seed, is supplied with amino acids, phosphorous
compounds and inorganic cations. There are two stages in the breakdown
of the 13S storage globulin. The first stage can proceed without the presence
of the embryonic axis. Dunaevsky and Belozersky (1993) reported that the
absence of the embryonic axis has no effect on the presence and hydrolytic
activity of the enzyme that starts the initial transformation of 13S globulin.
This enzyme is already present in ungerminated buckwheat seeds (Elpidina
et al., 1991; Dunaevsky and Belozersky, 1993) and regulates the first phase
of proteolysis. It is a metalloproteinase, which is believed to be located
entirely in the protein bodies (Elpidina et al., 1991). The isolated metallo-
proteinase contains one Zn2+ion (1.2 g atom) per molecule and has a MW
of 34 000. It was found to exhibit maximum activity at pH 8.0–8.2, when
using the 13S globulin as a substrate. The enzyme degrades the 13S globulin
from buckwheat seed and the 11S globulin from soybean better than it
degrades haemoglobin and bovine serum albumin (BSA) (Belozersky et al.,
1990). During the first two days of seedling growth, the metalloproteinase
inhibitor activity is reduced and metalloproteinase activity doubles. Here-
after, the enzyme activity drops to a lower level than the initial activity.
Elpidina et al. (1991) suggested that metalloproteinase is activated by diva-
lent cations, such as Mg2+ ions. It has been proved that the presence of Mg2+
ions increases proteolytic activity. The Mg2+ cations compete with Zn2+,
which is located in the enzyme molecule, for binding to the active site of
the metalloproteinase inhibitor. Hereby the enzyme–inhibitor complex can
be destabilized and the metalloproteinase is activated. The metalloprotein-
ase then hydrolyses 1.5 % of the peptide bonds (Muntz et al., 2001). After
initial cleavage of globulin 13S by metalloproteinase, the storage protein
undergoes conformational change (Muntz et al., 2001). Hence, 13S globulin
can only be attacked by other proteases, after the protein has been digested
by the metalloproteinase.

The second stage of proteolysis is performed by de novo enzymes, mainly
cysteine proteinase. The optimum pH of cysteine protease is acidic in con-
trast to the basic optimum pH of the metalloproteinase (Dunaevsky and
Belozersky, 1989). During the second stage, the phytohormone abscisic acid
comes into play. When the level of abscisic acid has been reduced to
0.1–1.0 μM, proteases necessary for complete degradation of 13S globulin
are synthesized (Dunaevsky and Belozersky, 1993). Consequently, the level
of cysteine proteinase increases during seedling growth (Dunaevsky and
Belozersky, 1989). Cysteine proteinase is feedback inhibited, which means
that it is inhibited by its own products. The presence of the embryonic axis
is therefore essential during the second stage, since it seems to regulate the
efflux of proteolysis products to the growing part of the buckwheat plant.

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384 Cereal grains for the food and beverage industries

When proteolysis products, such as amino acids and peptides, have accu-
mulated in the cotyledons, proteolysis is inhibited (Dunaevsky and Beloz-
ersky, 1993). Furthermore, cysteine proteinase, carboxypeptidase and
aspartic proteinase have been isolated and localized in buckwheat cotyle-
dons (Elpidina et al., 1991). Carboxypeptidase and aspartyl proteinase are
involved during the last steps of protein hydrolysis and facilitate its comple-
tion (Dunaevsky and Belozersky, 1989). In intact seeds, globulin 13S was
completely degraded after four days of germination (Dunaevsky and Beloz-
ersky, 1993). In summary, activities of proteases are under the control by a
number of factors: protein inhibitors, concentration of bivalent metal ions,
pH, concentration of products of proteolysis and abscisic acid (Dunaevsky
and Belozersky, 1989).

11.3.5 Inhibitors
As mentioned above, buckwheat protein has been reported to have low
digestibility in various papers. Studies by Ikeda et al. (1991) concluded that
the poor digestibility of buckwheat protein is due to two factors: the sus-
ceptibility of the proteolytic enzymes to the protein fractions of buckwheat
and the occurrence of antinutritional components such as tannins and inhib-
itors. The presence of proteinase inhibitors in seeds is not completely under-
stood. They may exert the following functions: (i) to serve as storage protein
(in some cereals trypsin inhibitors can contribute 5–10 % of the water-
soluble proteins); (ii) to regulate the activity of endogenous proteinases;
and (iii) to protect plants against insect and pathogenic microflora (Ryan,
1981; Bewley and Black, 1985).

Several inhibitors have been identified in buckwheat seeds by various
authors. They can be separated in two main groups: anionic and cationic
inhibitors. In addition, they can be categorized by their MW. Kiyohara and
Iwasaki (1985) isolated seven main inhibitors. In another paper by Beloz-
ersky et al. (1990) seven inhibitors are also mentioned, but it remains unclear
whether they are similar to the seven found by Kiyohara and Iwasaki
(1985). Dunaevsky and Belozersky (1989) isolated three anionic (BWI-1a,
BWI-2a, BWI-4a) and two cationic (BWI-2c and BWI-4c) inhibitors from
buckwheat seeds. All of these inhibitors have been found to be small pro-
teins that are inactivated by pepsin at pH 2.2.The MWs of anionic inhibitors
range from 7700 to 9200, while the MWs of cationic inhibitors are around
6000. The identified inhibitors showed action against several proteases, such
as bovine trypsin, crab trypsin and trypsin-like proteases from the fungi
Alternaria alternata and Fusarium oxysporum (Dunaevsky et al., 1998;
Dunaevsky and Belozersky, 1989). Tsybina et al. (2004) identified four cati-
onic trypsin inhibitors, which they named BWI-1c, BWI-2c, BWI-3c and
BWI-4c.

In addition to activity against proteases from bacterial and animal origin,
these inhibitors showed activity against exo-proteases from some

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Buckwheat 385

filamentous fungi. Because researchers have given inhibitors different
names and have used various methods of isolation, the exact number of
protease inhibitors present in buckwheat seeds remains unclear. Besides
protease inhibitors, an α-amylase inhibitor has also been identified in buck-
wheat. This compound exhibits inhibitory activity against α-amylase from
human saliva and α-amylase from porcine pancreas, but not against
α-amylase from Bacillus subtilis and β-amylase from sweet potato (Ikeda
and Yamashita, 1994; Skrabanja et al., 2001). One possibility for increasing
the biological availability of amino acids in buckwheat would be to reduce
inhibitory activity by germination. Trypsin-inhibitory activity in buckwheat
seeds rapidly decreases during germination. On the 4th day of germination,
small or no detectable amounts of trypsin inhibitor remain in seedlings.
During germination the level of total nitrogen remains unchanged, whilst
the amino acid composition alters and the level of trichloroacetic acid
(TCA)-soluble proteins increases four-fold (Ikeda et al., 1984).

11.3.6 Buckwheat allergy
Buckwheat allergy can sometimes cause severe reactions that are similar
to those caused by soybean or peanut. The reaction is an IgE-mediated
immediate-type reaction (Wieslander, 1996). Most cases are known from
Japan and occurred in young children. In a screening of 92 680 children,
0.22 % had a buckwheat allergy. Symptoms are asthma, urticaria, wheezing,
atopic dermatitis and anaphylactic shock. In addition, people who are in
daily contact with buckwheat or buckwheat products are likely to become
allergic to buckwheat. It has been reported that health shop workers, bakers
using buckwheat flour and buckwheat noodle makers showed allergic
symptoms when handling buckwheat. Since buckwheat is a food often con-
sumed by coeliac patients, the incidence of buckwheat allergy among coeliac
sufferers has been established. Patients with coeliac disease (CD), com-
bined with other food allergies have an increased buckwheat intolerance
of 30 %. Normal coeliac sufferers show a buckwheat allergy of 1 %
(Wieslander and Norback, 2001). Park et al. (2000) reported that buckwheat-
allergic patients often complain about urticaria (nettle rash), dyspnea (dif-
ficulty with breathing), facial angioedema and gastrointestinal symptoms
such as vomiting and abdominal pain. They mentioned proteinaceous com-
pounds from buckwheat with MWs of 9000, 16 000, 24 000 and 29 000, which
have been proven to be potential major allergens. Matsumoto et al. (2004)
identified an allergenic protein with a MW of 10 000 belonging to the 2S
albumin family. It has been suggested that more attention should be drawn
to albumins since this protein group is known to contain major allergens in
walnuts and peanuts as well (Matsumoto et al., 2004).

Other than affecting protein digestibility, some protease inhibitors also
show IgE binding activity. Park et al. (1997) characterized two protease
inhibitors and tested their allergenic reactivity. Both inhibitors (BWI-1 and

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386 Cereal grains for the food and beverage industries

BWI-2b) showed low binding activities with IgE, which suggests that they
may be minor allergenic proteins in buckwheat seeds. In addition, Yano
et al. (1989) isolated three allergenic proteins from buckwheat seeds. One
of these proteins was found to be a trypsin inhibitor. The MW of each
protein varied between 8000 and 9000. These protein inhibitors were found
to still be reactive after heating for 60 min at 100 ºC (Yano et al., 1989).

11.3.7 Functional properties
Tomotake et al. (2002) have reported the various potential functional prop-
erties of a buckwheat protein product (BWP) that consists of 65.8 % w/w
protein, 22.0 % w/w lipids, 5.9 % w/w non-fibre carbohydrates and 3.1 %
w/w water. It is obtained by several extractions, a washing step, sterilization
and freeze-drying. Defatted BWP was not considered suitable for utiliza-
tion as a functional ingredient, since food intake in rats fed with defatted
BWP was significantly lower than in rats fed with BWP (Tomotake et al.,
2002). BWP has been claimed to exhibit several functional properties such
as hypocholesterolaemic activity in rats fed a high-cholesterol diet, suppres-
sion of body fat in rats (Kayashita et al., 1995, 1996) and suppression of
induced colon carcinogenesis in rats (Li and Zhang, 2001). BWP is soluble
over a wide pH-range and might therefore be used in functional beverages
(Tomotake et al., 2002).

11.4 Other constituents of buckwheat

Buckwheat grain is richer in lipids, mainly comprising unsaturated fatty
acids, minerals, vitamins (B group and vitamin E in particular), than most
cereals. Additionally, buckwheat is also rich in minor constituents with
functional effects such as flavonoids.

11.4.1 Lipids
In general, lipids comprise a small part of cereals and pseudo-cereals, but
they have an important physiological role (Chapkin, 2000). Lipids also play
a role in food quality as they may cause deterioration of stored seeds or
flours. In both common and Tartary buckwheat, lipids are concentrated in
the embryo. The embryo contains an average of 6.5 % oil, while the endo-
sperm contains less than 0.4 % oil (Dorrell, 1971). Since in buckwheat flour
the embryo is generally included (mostly in bran fractions), the risk of
deterioration by lipids is particularly important (Taira et al., 1986). Contents
of free, neutral and polar lipids are shown in Table 11.4 (Mazza, 1988).These
results have been confirmed by Bonafaccia et al. (2003b), but Kim et al.
(2002) and Dorrell (1971) have detected lower total lipid levels in common
buckwheat, varying from 1.9 to 2.4 %. Generally, the level of lipids

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Table 11.4 Lipids in common buckwheat

Polar lipids

Cultivar Total lipids Free lipids Neutral lipids Glycolipids Phospholipids
(% db) (% db) (% db)

(% db) (% db)

Mancan 3.2 2.6 2.6 0.15 0.33

Mancana 2.9 2.4 2.4 0.13 0.22

Manor 2.6 2.2 2.2 0.09 0.27

Tokyo 2.9 2.1 2.5 0.13 0.32

aStored for 25 months.
Source: Mazza (1988).

Table 11.5 Fatty acid composition in common and tartary buckwheat

Fatty acid Common buckwheat (%) Tartary buckwheat (%)

Myristic (C14 :0) 0.0 0.0
Palmitic (C16 :0) 15.6 19.7
Palmitoleic (C16 :1) 0.0
Stearic (C18 :0) 0.0 3.0
Oleic (C18 :1) 2.0 35.2
Linoleic (C18 :2) 37.0 36.6
Linolenic (C18 :3) 39.0 0.7
Arachidonic (C20 :0) 1.0 1.8
Eicosaenoic (20 :1) 1.8 2.0
Behenic (C22 :0) 2.3 0.8
Saturated 1.1 25.3
Unsaturated 20.5 74.5
Unsaturated/saturated 79.3 2.94
3.87

Source: Bonafaccia et al. (2003b).

in buckwheat groats can vary per cultivar. The differences between lipid
contents may be attributed to different sowing times, as early seeding cul-
tivars in Japan exhibit higher lipid contents than late seeding cultivars
(Taira et al., 1986). Lipase activity has been detected in buckwheat, its activ-
ity localized in the embryo of the pseudo-cereal. The isolated lipase was a
triacylglycerol lipase, which had an optimal temperature for enzyme activity
of 30 °C. It consisted of two isozymes, LIP I and LIP II, the former of which
showed lower levels of activity: 0.108 μmol fatty acid released min−1 mg−1
protein at 30 °C using triolein as substrate compared to 0.727 μmol fatty
acid released min−1 mg−1 protein at 30 °C using triolein as substrate (Suzuki
et al., 2004). Eighteen fatty acids have been identified in buckwheat, of
which 14 appear in all seed tissues. The eight main acids (oleic, linoleic,
palmitic, linolenic, lignoceric, stearic, behenic and arachidic) represent 93 %
of the total fatty acids detected (Dorrell, 1971). The fatty acid composition
of common and tartary buckwheat is shown in Table 11.5.

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388 Cereal grains for the food and beverage industries

Comparison of the fatty amino acid composition with other sources
revealed that similar fatty acid compositions have been found in amaranth
oil and cotton seed oil (Jahaniaval et al., 2000). The embryo contains most
of the unsaturated fatty acids, while the hull has a high level of saturated
fatty acids (Dorrell, 1971). Some fatty acids (linoleic acid and linolenic
acid) are polyunsaturated and cannot be produced by the human body
(essential fatty acids) and are therefore of special importance in the human
diet (Chapkin, 2000). One of these essential fatty acids (linoleic acid) is
the major fatty acid present in buckwheat; the level of linoleic acid is
particularly high in the seed coat (Dorrell, 1971; Taira et al., 1986; Mazza,
1988). Differences in the levels of the various fatty acids have been
reported in literature (Tsuzuki et al., 1991; Jahaniaval et al., 2000; Bonafac-
cia et al., 2003b). These differences may be attributed to a number of
factors, such as the cultivars, growth locations and seeding time (Tsuzuki
et al., 1991). Levels of some fatty acids can be increased by germination.
Buckwheat seeds have been germinated and the fatty acid level of the
sprouts analysed. The level of linoleic acid and linolenic acid increased
from 36.8 % up to 51 % and from 2.7 % up to 19 %, respectively (Kim
et al., 2004).

11.4.2 Minerals and vitamins
Minerals are important for various physiological functions in the human
body. The human body requires more than 100 mg day−1 of each major
mineral (Na, Mg, K, Ca, P, S and Cl) and less than 100 mg day−1 of trace
elements (Cr, Mn, Fe, Co, Cu, Zn, Se, Mo and I) (Insel et al., 2004). The
mineral composition of buckwheat groats is shown in Table 11.6.

Variations in mineral composition between cultivars and growth loca-
tions have been reported (Ikeda and Yamashita, 1994; Bonafaccia et al.,
2003a). Generally, buckwheat is a richer mineral source than many cereals
such as rice, sorghum, millet and maize (except for Ca). The levels of Mg,
Zn, K, P, Cu and Mn are especially high when compared to other cereals
(Mazza, 1988; Steadman et al., 2001b). Mg, Zn, K, P and Co are mainly
stored as phytate in protein bodies and are therefore not accessible to
humans (Elpidina et al., 1991; Steadman et al., 2001b). During germination,
phytin is hydrolysed and metal ions are released, which can be seen as posi-
tive since this allows the accessibility of the metals for their physiological
functions in the human diet (Bewley and Black, 1985). Buckwheat contains
10.0 mg g−1 phytic acid and the enzyme phytase that liberates 2.17 μmol
inorganic phosphate min−1 g−1 (Egli et al., 2003). Protein bodies (and there-
fore Mg, Zn, K, P and Co) are generally present in embryo tissues and in
the aleurone layer (Steadman et al., 2001b). Minerals such as Fe, Zn, Mn,
Cu, Mo, Ni and Al are primarily localized in both hull and seed coat. Ca
and B are present in hull fractions (Steadman et al., 2001a, b; Bonafaccia et
al., 2003a; Skrabanja et al., 2004).

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Table 11.6 Ash and mineral composition of common buckwheat

Cluster Element Amount ash (g kg−1 db) and mineral
composition (mg 100 g−1 db)

Cluster I Ash 24 ± 1
Cluster II K 565 ± 2.9
P 490 ± 5.8
Cluster III Mg 267 ± 0.9
Ca 19.7 ± 0.3
Fe 3.03 ± 0.11
Zn 2.92 ± 0.01
Mn 1.64 ± 0.02
Cu 0.71 ± 0.03
Mo 0.09 ± 0.02
Co 0.01 ± 0.01
Cr
B 0
Al 0.67 ± 0.02
Ni 0.36 ± 0.13
Cd 0.24 ± 0.01

0

Note: The first cluster of minerals contains major minerals for humans, while the second cluster
contains trace elements and the third remaining minerals.
Source: Steadman et al. (2001b).

Table 11.7 Vitamin levels in common buckwheat

Vitamin Level (mg 100 g−1)

A (carotenoids)a 0.21
B1 (thiamine)b 0.46
B2 (riboflavin)b 0.14
B3 (niacin)c 1.80
B5 (pantothenic acid)a 1.05
B6 (pyridoxine)b 0.73
C (ascorbic acid)d 5
E (tocopherols)e 5.46

a Gabrovská et al. (2002).
b Bonafaccia et al. (2003b).
c Geisler (2003).
d Lintschinger et al. (1997).
eZielinski et al. (2001).

Vitamins are a group of organic compounds which are essential in very
small amounts for the normal functioning of the human body. They vary
widely in their chemical and physiological functions, and are broadly dis-
tributed in natural food sources (Ball, 1998).The vitamin content of common
buckwheat groats is shown in Table 11.7 (Gabrovska et al., 2002; Bonafaccia
et al., 2003a; Geisler, 2003).

Thiamine (vitamin B1) is known to be strongly adhered to thiamine-
binding proteins in buckwheat seeds (Mitsunaga et al., 1986; Rapala-Kozik

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390 Cereal grains for the food and beverage industries

et al., 1999), and its bioavailability is uncertain. In general, higher levels of
vitamin B appear to be present in Tartary buckwheat than in common
buckwheat (Pomeranz, 1983; Bonafaccia et al., 2003a). Levels of vitamin C
and the sum of vitamin B1 and B6 can be increased by germinating buck-
wheat. The level of vitamin C can increase up to 25 mg 100 g−1 in buckwheat
sprouts (Lintschinger et al., 1997; Kim et al., 2004). Vitamin E includes all
naturally occurring tocopherols and tocotrienols (Zielinski et al., 2001). No
tocotrienols have been detected in buckwheat (Zielinski et al., 2001).
Tocopherols are naturally occurring anti-oxidants (Dietrych-Szostak and
Oleszek, 1999) and exist in α-, β-, γ- and δ- forms (Burton and Traber, 1990).
Buckwheat groats exhibited the maximum amount of tocopherols (5.46 mg
100 g−1) when compared with wheat, barley, oats and rye. Zielinski et al.
(2001) and Kim et al. (2002) reported γ-tocopherol as the main tocopherol,
while Przybylski et al. (1998) considered α-tocopherol, the most potent
biological and antioxidant form of the vitamin (Burton and Traber, 1990),
to be the major tocopherol present. Differences have been attributed to
different cultivars of common buckwheat (Przybylski et al., 1998; Zielinski
et al., 2001; Kim et al., 2002).

11.4.3 Phytochemicals
Phytochemicals are plant substances that may promote good health, but are
not essential for life (Insel et al., 2004). Oxidative stress, which releases free
oxygen radicals in the body, has been implicated in a number of disorders
including cardiovascular malfunction, cataracts, cancers and rheumatism.
Phytochemicals, present in fruits and vegetables, can act as antioxidants by
scavenging free radicals and saving the cell (Kaur and Kapoor, 2001).
Widely known antioxidants are vitamins A, C and E. Moreover, polyphe-
nolic compounds, such as flavonoids, have received interest due to their
antioxidant effect (Rice-Evans et al., 1997). Flavonoids are ubiquitous in
most plants and usually exist in glycosidic forms (Rice-Evans et al., 1997).
It has been reported that flavonoids in regularly consumed foods such as
tea, apples and onions may reduce the risk of death from coronary heart
disease (CHD) in elderly men (Hertog et al., 1993). Another well-known
case is the French paradox: people living in the Mediterranean region have
a low incidence of CHD despite their high fat diet and smoking tendencies
(Renaud and Delorgeril, 1992). This is attributed to the so-called Mediter-
ranean diet in which the high consumption of fruit and vegetable, as well
as fish, ensures an optimal intake of flavonoids. In many cases, flavonoids
show a greater efficacy than antioxidants in food systems, on a mole to mole
basis, than the antioxidants vitamin C, vitamin E and β-carotene (Table
11.8) (Rice-Evans et al., 1997).

Rutin and quercetin are the main flavonoids with antioxidant activity in
buckwheat (Oomah and Mazza, 1996; Steadman et al., 2001b). In Table 11.8,
it can be seen that quercetin shows a higher antioxidant activity than rutin,

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Buckwheat 391

Table 11.8 Antioxidant activities of various compounds from different sources

Antioxidant Source Antioxidant
activity* (mM)

Vitamins Fruit and vegetables 1.0 ± 0.02
Vitamin C Grains nuts and oils 1.0 ± 0.03
Vitamin E
Onion, apple skin, berries, black grapes, 4.7 ± 0.10
Flavon-3-ols tea, broccoli, buckwheat 1.3 ± 0.08
Quercetin
Endive, leek, broccoli, grapefruit and tea 2.4 ± 0.12
Kaempferol
Buckwheat, onion, apple skin, berries,
Flavones black grapes, tea and broccoli
Rutin

Note: Antioxidant activity measured as the TEAC (Trolox equivalent antioxidant activity) –
the concentration of Trolox with the equivalent antioxidant activity of a 1 mM concentration
of the experimental substance.
Source: Rice-Evans et al. (1997).

which is a glycoside of quercetin. It is generally known that glycolization
reduces antioxidant activities (Rice-Evans et al., 1997). Rutin and quercetin
levels in buckwheat depend greatly on growth location and cultivar (Oomah
and Mazza, 1996; Steadman et al., 2001b). In common buckwheat groats,
levels of rutin and quercetin are approximately 0.20 mg g−1 and 0.001 mg g−1,
respectively. Buckwheat hulls were found to contain higher levels: 0.84–
4.41 mg g−1 rutin and 0.009–0.029 mg g−1 quercetin (Oomah and Mazza,
1996). Tartary buckwheat is an excellent source of rutin, since groats of
Tartary buckwheat showed levels of rutin at 80.9 mg g−1.

Besides rutin and quercetin, Watanabe (1998) isolated four catechins
with antioxidant activity from ethanol extracts from buckwheat groats
(F. esculentum Moench cv Iwate zairai): epicatechin, catechin 7-O-β-d-
glucopyranoside, epicatechin 3-O-p-hydroxybenzoate and epicatchin 3-O-
(3,4-di-O-methyl) gallate. The catechins showed a higher antioxidant
activity than rutin (Watanabe, 1998).

Effects of processing on phytochemicals
When buckwheat is processed, flavonoid levels and therefore antioxidant
activity can be affected. One example is the heat treatment of buckwheat
at 150 °C which reduces the flavonoid concentration significantly. A reduc-
tion of flavonoid concentration by 20 % has been determined, when buck-
wheat is heated for 10 min at 150 °C and a reduction of 40 % has been
measured when buckwheat was heated for more than 1 h and 10 min at
150 °C. The concentration of flavonoids in hulls is also affected, but to a
much lesser degree than the concentration in groats (Dietrych-Szostak
and Oleszek, 1999). Flavonoid contents can be increased by producing

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392 Cereal grains for the food and beverage industries

buckwheat sprouts. Initial rutin and quercetin contents in seeds were 0.63
and 0.35 mg g−1, respectively. After seven days of germination, the rutin and
quercetin content in buckwheat sprouts was increased to a level of 22.4 and
23.1 mg g−1 respectively (Kim et al., 2004).

Effects of buckwheat flavonoids
Flavonoid glycosides are usually hydrolysed by intestinal microorganisms
(Rice-Evans et al., 1997). Eubacterium ramulus is a gut bacterium that has
been proved to degrade flavonoids from buckwheat. Dietary flavonoids
from buckwheat leaves act as a better substrate for E. ramulus than pure
rutin (Simmering et al., 2002). Several glucuronides have been identified as
quercetin metabolites in human blood. These potentially active glucuro-
nides are identical regardless of the type of quercetin glycosides adminis-
tered (Graefe et al., 2001). Buckwheat plant extract showed better effects
than pure rutin: the level of potentially bioactive quercetin metabolites in
plasma was 1.33 times higher when buckwheat plant extract was adminis-
tered to humans (Graefe et al., 2001). Boyle et al. (2000) revealed that by
supplementing quercetin, total quercetin levels in plasma of humans were
elevated, but the antioxidant status of the blood plasma was not affected.
On the other hand, serum antioxidant capacity increased significantly by
7 % when 25 people were administered with a natural product of buck-
wheat, buckwheat honey. Both rutin and quercetin have an additional
advantage besides their antioxidant activity; they can positively support the
treatment of chronic venous insufficiency (Erlund et al., 2000).

Toxic polyphenols
Fagopyrin is a complex polyphenol and is present in buckwheat. It can cause
photosensitization or so-called fagopyrism in light-skinned animals exposed
to sunlight. The seeds contain very few fagopyrins, but the whole plant
either dried or green can cause serious problems in livestock (Johnson,
1983; Cheeke and Shull, 1985).

11.5 Food and beverage applications of buckwheat

Buckwheat as been used in different forms for human food and for live-
stock and poultry feed. Almost all parts of the plant can be utilized, and a
wide range of applications has been reported (Table 11.9). Common buck-
wheat is consumed in many different preparations in different countries. In
Japan, it is mainly consumed as dumplings and soba (buckwheat noodles).
In Europe and North America, buckwheat flour is generally mixed with
wheat flour to prepare pancakes, biscuits, noodles, cereal and is used as a
meat extender (Park et al., 2000). In Russia and Poland, the groats and flour
are used to make porridge and soup. In Sweden, it is used to stuff fish. In
Southeast Asia, buckwheat is a staple food in many hilly areas. Here the

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Buckwheat 393

Table 11.9 Buckwheat utilization
Parts of the plant Utilization

Green plants, leaf A fine basic material for pharmaceutical rutin manufacture
flour
Used as a medicinal plant, the brew made of Fagopyri herb
Buckwheat grain was administrated against high blood pressure (utilizing
the rutin content)
Buckwheat hull
Buckwheat grain A material with curative effect in the treatment of light
Buckwheat sensitivity (hypericine)

flowers Formerly a source of alcohol by distillation, it is now a basic
Hulled grain material for high quality beer

Buckwheat hull Produced an excellent nectar for honey

Buckwheat hay, Basic material of traditional mush meals and of modern
straw, hydrothermal processing technologies (flaking and puffing,
extruding). With direct milling of clean grain, flour can be
or whole crop produced as a basic material for various traditional or
special dietetic meals

Used for filling of pillows, as a packing aid, rarely, as
pharmaceutical raw material, flue, in the extraction of
colouring agents

Animal feed, mainly mixed with other fodders

Source: Biacs et al. (2002).

flour is used to make unleavened bread chapattis. It is also mixed with water
and fried to produce a crisp pakora. The flour can be mixed with potatoes
to make parathas. It is also used for fasts and religious celebrations. Buck-
wheat is used also to make alcoholic drinks; medicinal qualities have been
ascribed to the liquor prepared from Tartary buckwheat, and in some areas
jang, a beer made from Tartary buckwheat, reaches a high price because of
its medicinal effects (Campbell, 1997). In China, it has been reported that
buckwheat is used for the production of vinegar. In Nepal, the consumption
of Tartary buckwheat is reported to alleviate stomach disorders.

11.5.1 Baking
Most studies on buckwheat baking have investigated pasta and bread pro-
duction from buckwheat flour for improving the poor nutritional properties
of gluten-free products. Gluten-free bread containing 8.5 % buckwheat
flour was produced by Moore et al. (2004), but the breads were brittle
after two days of storage. Torbica et al. (2010) aimed to produce gluten-free
bread by blending different ratios of rice and unhusked/husked buckwheat
flour. The results of this study indicated that using a rice flour/buckwheat
flour ratio of 70:30 did not affect the textural properties of the gluten-free

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394 Cereal grains for the food and beverage industries

BW0 BW1 BW10

Fig. 11.7 Bread slices from buckwheat (BW) flour formulations treated with dif-
ferent TGase levels (0, 1 and 10 U). With kind permission from Elsevier Limited.
Microstructure, fundamental rheology and baking characteristics of batters and
breads from different gluten-free flours treated with a microbial transglutaminase.

Renzetti, S., Dal Bello, F., Arendt, E.K. Journal of Cereal Science 48, 33–45.

bread, independent of the type of buckwheat flour (unhusked or husked)
used. However, increasing the amount of buckwheat flour in the bread
formulation resulted in a decrease in the quality of the protein structure,
manifested by cracking of the upper bread crust. Moreover, by increasing
the amount of husked buckwheat flour from 10 to 20 %, the taste of the
bread improved significantly. Unlike unhusked buckwheat flour, which
possesses a bitter taste predominantly found in the husk (Luthar, 1992)
which is mainly removed during the processing, husked buckwheat flour-
containing products express a more pleasant flavour and taste (Torbica
et al., 2010).

Addition of hydrocolloids, like propylene glycol alginate (PGA), to a
dough recipe allows the amount of buckwheat flour that is possible to add
in a bread recipe without any deleterious effect in terms of bread-making
performance to increase to 40 % (Peressini et al., 2011), as bread-making
performance in terms of specific volume, crumb firmness and crumb struc-
ture is improved.The effect of PGA on crumb structure at a low level (0.5 %
dw) could be due to the combined effect of batter viscosity developed by
the PGA and its ability to form elastic films at the gas–liquid interface
(Baeza et al., 2004). Recently, Renzetti et al. (2008) reported the successful
use of transglutaminase (TGase) in buckwheat bread. When 10 U (enzyme
units) of TGase were used, the pseudo-plastic behaviour of buckwheat
batter was significantly increased. The resulting buckwheat bread showed
improved baking characteristics as well as overall macroscopic appearance
(Fig. 11.7). Other recent studies conducted by Alvarez-Jubete et al. 2009,
2010) highlighted the fact that the addition of buckwheat flour in gluten-
free breads can increase the content of important nutrients such as protein,
fibre, calcium, iron and vitamin E. The resulting breads also had significantly
higher contents of polyphenol compounds with higher in vitro antioxidant
activity.

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Buckwheat 395

11.5.2 Pasta and biscuits
In Japan, buckwheat is used as a basic material for the preparation of soba,
a popular type of noodles. Soba are thin brownish noodles that can be made
either with buckwheat flour or from a mixture of buckwheat flour and
wheat flour. They have a light and sweet taste, are energy-giving and are
well-balanced in nutritional terms. The production of spaghetti using wheat
durum semolina as a base plus the addition of buckwheat and durum wheat
bran was investigated by Chillo et al. (2008). Durum wheat spaghetti semo-
lina enriched with buckwheat flour (10–30 %) and bran (15–20 %) demon-
strated good performance both in the dry state and during cooking, and had
fairly similar sensory properties to spaghetti made only from durum semo-
lina. Schoenlechner et al. (2006) incorporated either amaranth, quinoa or
buckwheat at levels of 25, 50, 75 and 100 % into a gluten-free biscuit for-
mulation. Biscuit crispiness was in the order buckwheat > quinoa > ama-
ranth, and biscuits containing buckwheat and amaranth were preferred by
a sensory panel.

11.5.3 Brewing
Recently, buckwheat has gained in popularity as a brewing ingredient. The
malting procedure for buckwheat has been optimized in various studies
(Phiarais et al., 2005; Wijngaard et al., 2005a, b). The aim of the germination
process is to generate a large amount of amylolytic enzymes and extensive
degradation of the cell walls surrounding the starch granules. Buckwheat
itself does not contain the enzymes required to hydrolyse starch, so addi-
tional enzymes are required. Buckwheat starch in the more compact struc-
ture appears to be covered with a layer containing protein, which was
clearly seen using confocal scanning laser microscopy (CSLM) (Fig. 11.8a).
Throughout germination, the proteinaceous layer covering the buckwheat
starch granule is lightly degraded, as shown in Fig. 11.9. The compact struc-
ture of the buckwheat endosperm is progressively degraded throughout the
germination process (Figs 11.8b and 11.9). When the proteinaceous layer
has been degraded, starch can be enzymatically digested (Fig. 11.9e). The
two most important parameters of the germination process (apart from the
enzymes present) are temperature and time. Additionally, air flow through
the grains, recirculation of the air and turning of the grains are influencing
variables which can be regulated. The literature shows that buckwheat does
not have the ability to deliver malt of comparable quality to barley malt
without additional inputs like the use of enzymes or energy-intensive
mashing procedures.

Wijngaard et al. (2005b) reported that steeping hulled buckwheat at 10 ºC
results in a very high water uptake rate. Beside temperature, the time of
steeping is also crucial; increasing steeping times generates higher levels of
steeping-out moisture (SOM). All outcomes on final malt quality associated

© Woodhead Publishing Limited, 2013

© Woodhead Publishing Limited, 2013 (a)

(b)
Fig. 11.8 Images of protein matrices (a) and starch (b) obtained through CSLM with, from left to right, unmalted buckwheat,
malted buckwheat, unmalted barley and malted barley. With kind permission from John Wiley and Sons: Microstructure of
Buckwheat and Barley During Malting Observed by Confocal Scanning Laser Microscopy and Scanning Electron Microscopy.

H.H. Wijngaard, S. Renzetti, E.K. Arendt. Journal of the Institute of Brewing 113(1), 34–41, 2007.

© Woodhead Publishing Limited, 2013 5 kV ×2,500 10 μm 0000 29/NOV/05 3.0 kV ×2,500 10 μm 0000 Test 1 3.0 kV ×2,500 10 μm 0000 Test 1
(a) (b) (c)

3.0 kV ×2,500 10 μm 0000 Test 1 3.0 kV ×2,500 10 μm 0000 Test 1 3.0 kV ×2,500 10 μm 0000 Test 1

(d) (e) (f)

Fig. 11.9 SEM micrographs of compact endosperm of buckwheat at various stages of the malting process. Unmalted (a), during
steeping (b), after 3 d germination (c), at the end of germination (d), kilned + located near cotyledons (e) and kilned + central endo-
sperm (f). With kind permission from John Wiley and Sons: Microstructure of Buckwheat and Barley During Malting Observed by
Confocal Scanning Laser Microscopy and Scanning Electron Microscopy. H.H. Wijngaard, S. Renzetti, E.K. Arendt. Journal of the

Institute of Brewing 113(1), 34–41, 2007.

398 Cereal grains for the food and beverage industries

with an increased SOM in malting barley were also found to be true when
barley was substituted with buckwheat. A higher enzymatic potential as
well as more extended cytolysis and proteolysis can be achieved with
increased SOM (Wijngaard et al., 2005b). Though optimal SOM values for
buckwheat have not been fully elucidated, a level of SOM from 35 to 40 %
is recommended. The optimum steeping time for buckwheat was found to
lie in the range of 7 to 13 h. (Wijngaard et al., 2005b).

Like steeping, the following germination step remarkably influenced the
quality of the resulting malt. When germination was performed at tempera-
tures of 10–20 ºC for 58–144 h, the resulting buckwheat malt had acceptable
malting loss values (however, they were still higher than a control of barley
germinated under the same conditions), but low enzymatic capacities were
associated with a low extraction level as well as a very high viscosity (Wijn-
gaard et al., 2005a, 2006). Wijngaard et al. (2005b) germinated buckwheat at
four different germination temperatures (9.5, 14.9, 16.5 and 20.2 ºC), and
the maximum apparent fermentability (56 %) was reached when buckwheat
was germinated at a temperature of 20.2 ºC. In general, amylolytic activities
were found to be low in comparison with barley malt. One of the sugges-
tions made was to increase malting time. The optimum germination time
was found to be four or five days (Wijngaard et al., 2006). Buckwheat with
hull was chosen over dehulled buckwheat, due to its better processing
quality.

The kilning process has also been optimized, and a two- stage kilning
process has been recommended (Phiarais et al., 2006). Aiming at improving
the enzymatic capacity of the final malt, the authors suggested a short initial
kilning step carried out at 45 ºC for 5 h followed by a second step at 50 °C
for 17 h. This regime resulted in malt with the highest protease and
α-amylase activities. However, the difference in these enzyme activities did
not have a positive impact on the final wort quality. In contrast, when the
recommended higher temperatures were used, a decrease in β-glucanase
activity and a subsequent higher viscosity of the wort were observed. This
indicates that the activity of cell wall degrading enzymes of buckwheat
green malt is very low and decreases noticeably with increased kilning
temperatures.

With regard to the mashing profile, optimum values for the following
parameters were found: grist size (as small as possible); the grist :liquor
ratio (1 :4); the mashing-in temperature (from 35–45 °C); α-amylase activ-
ity (at 65 °C); and mashing-off temperature (78 °C). Although the gelatini-
zation temperature of buckwheat was found to be 67 °C, the optimal
saccharification temperature was 65 °C. A single decoction process resulted
in a higher degree of starch gelatinization, but overall enzyme activity was
reduced. The infusion method under the following conditions was found
to be optimal: mashing-in: 15 min at 35 °C; 15 min at 45 °C; 40 min at 65 °C
and 30 min at 72 °C mashing-off: 10 min at 78 °C (Wijngaard and Arendt,
2006).

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Buckwheat 399

During malting buckwheat develops a particular nutty flavour, which
partially resembles that of pistachio. This flavour is carried over to the fin-
ished beer. The green malt as well as the kilned malt must be transported
with utmost care to avoid smutting and/or crumbling of the grain. Due to
their high viscosities, buckwheat congress wort (wort produced following a
standardized process instituted by the European Brewing Congress – EBC
in 1975) and mash cannot be easily filtered (Wijngaard et al., 2005a);
however, this problem is overcome by an upstream separation.

Buckwheat malt was produced by Zweytick et al. (2005), applying 2 h of
steeping, four days of germination and 26 h of kilning at 80 °C. Beer pro-
duced from this malt was opaque and had a brown colour. The foam stabil-
ity was poor and the taste too bitter. Wijngaard and Arendt (2006) take into
consideration that it is probably not possible to produce a traditional lager
beer from 100 % buckwheat without the addition of exogenous enzymes.

Despite these technological obstacles and the mediocre characteristics
of the standard malt, the absence of gluten and the presence of valuable
secondary metabolites make buckwheat potentially an attractive brewing
cereal. For instance, its content of rutin, a glycoside of the quercitin group
with distinctive antioxidative effects, as well as other tanning agents could
be increased seven-fold by altering the malting parameters (Zarnkow et al.,
2005). Buckwheat has already been used in microbrewing for the produc-
tion of gluten-free beer, added mainly as an unmalted adjunct (Maccagnan
et al., 2004). Of the gluten-free raw materials available, buckwheat is the
most suitable for beer-making in terms of the taste and appearance of the
finished product and thus can be used as partial replacement for barley.
However, as mentioned previously, buckwheat does not contain the enzymes
required to hydrolyse starch to maltose, and this makes it necessary to add
rice malt, which is also gluten-free.

It has also proved advantageous to replace a percentage of these cereals
with corn syrup, which makes it possible to dispense with the step of sac-
charification of the starch contained in the added cereal, thereby making
the process simpler and more cost-effective. A buckwheat: rice malt: corn
syrup weight ratio of 20/60/20 has been found to be advantageous (Mac-
cagnan et al., 2004). The presence of amylolytic enzymes and glucanase in
the starting material, in this case the buckwheat, is always preferable
(though not necessary), since it enables a product with standardized proper-
ties to be obtained, independent of the enzymes present in the rice malt.
α-amylase is the most important amylolytic enzyme when brewing with
buckwheat. This enzyme is capable of cleaving starch molecules at any
point, giving rise to dextrins, which are readily saccharifiable molecular
structures. The organoleptic properties and appearance of buckwheat beer
were entirely comparable with those of beer made from barley malt. Not
only the odour and the taste, but also the amount and the consistency of
the head formed when the beer is poured into a glass, were entirely similar
(Maccagnan et al., 2004).

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400 Cereal grains for the food and beverage industries

11.6 Conclusions

Overall, buckwheat, a pseudo-cereal, has major potential as a food ingredi-
ent, especially for the functional and health food industries. It contains
protein of high nutritional value, dietary fibre, RS, rutin, fagopyritols and
high levels of minerals and vitamins. In general, more studies should be
undertaken to determine the actual effect of buckwheat and its products
on humans. Most studies on the effects of D-chiro-inositol, fagopyritols
(galactosyl derivatives of D-chiro-inositol), RS and a buckwheat protein
product exhibited positive effects on rats. D-chiro-inositol and fagopyritols
reduced plasma glucose levels in rats and may possibly be used to assist in
the treatment of diabetes. RS may have similar effects to fibre. Buckwheat
protein product has been claimed to exhibit several functional properties
in rats such as hypocholesterolaemic activity in animals fed a high-
cholesterol diet, suppression of body fat and suppression of induced colon
carcinogenesis. Few studies have been carried out on quercetin and rutin
(a glycoside of quercetin), the two major antioxidants in buckwheat, and
their effect on humans. Several glucuronides have been identified as quer-
cetin metabolites in human blood. These potentially active glucuronides are
identical regardless of the type of quercetin glycosides administered, but
their actual antioxidant effect in vivo is still disputed. In addition, quercetin
and rutin have been mentioned in connection with the treatment of chronic
venous insufficiency in humans, but scientific proof has not yet been found.

With regard to buckwheat as a potential major ingredient in a daily diet,
e.g. coeliac sufferers and others with wheat intolerance, the following can
be said. Starch is present in buckwheat at similar levels as in cereals. The
shape and composition of the buckwheat starch itself are similar to those
of cereal starches, but other properties, such as the high viscosity value,
correspond more to the properties of tuber starches.

Buckwheat groats (dehulled seeds) contain similar amounts of fibre as
other cereals, while the hulls contain greater amounts of fibre. Protein in
buckwheat is of high nutritional quality because it contains a relatively high
amount of lysine compared to cereals. On the other hand, a low digestibility
has been recorded, possibly due to the presence of tannins, phytic acid and
protease inhibitors. At least seven protease inhibitors have been isolated,
all of proteinaceous origin. Possibilities for increasing protein and starch
digestibility by processing should be studied. In addition to degrading pro-
tease inhibitors, germination increases levels of essential fatty acids, miner-
als and vitamins. Another reason why more attention should be given to
protease inhibitors is that some have found to be allergenic to humans. The
main symptoms are asthma and skin disorders. More research should be
carried out to evaluate the allergenic compounds as other proteins may
cause allergic reactions as well. Precautionary measures when handling
buckwheat on a daily basis should be considered. With regard to fatty acids,
buckwheat contains a high level of polyunsaturated essential fatty acids,

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Buckwheat 401

since linoleic acid is the major fatty acid present in buckwheat. Several
vitamins, such as B1, C and E, are present. Buckwheat is a richer source of
minerals than many cereals such as rice, sorghum, millet and maize. Levels
of magnesium, zinc, potassium, phosphorus, copper and manganese are
particularly high when compared to cereals, but levels of calcium are low.

Malting is one of most promising food processing operations for the
enhancement of protein and starch digestibility. However, results so far
indicate that the application of 100 % buckwheat malt in brewing will
always required additional inputs, and the yield obtained with this gluten-
free material will be lower than that obtained using barley malt. Neverthe-
less, if the current difficulties are overcome by selective plant breeding and
process optimization, this pseudo-cereal in brewing will be a valuable
gluten-free alternative to barley malt.

11.7 Future trends

Buckwheat is one of the most important alternative crops and a valuable
raw material for functional foods production since it is rich in essential
amino acids, fatty acids and vitamins, and it is also a good source of miner-
als. Additionally, researchers in Spain (Prestamo et al., 2003) proved that
buckwheat could also behave as a prebiotic. They investigated the prebiotic
effect of buckwheat ingestion in a rat model analysing the microbial evolu-
tion of lactic acid bacteria, Bifidobacteria and Enterobacteria in the rat’s
intestine. The results showed an increase of aerobic mesophilic and lactic
acid bacteria content in the buckwheat diet when compared to a control.
In the buckwheat diet, there was also observed a slight decrease of Entero-
bacteria and fewer pathogenic bacteria. Thus, even through further studies
are required, the potential prebiotic effect of buckwheat places it in a prom-
ising position for developing new functional foods by (i) improving the
traditional foods based on buckwheat, (ii) designing novel foods fortified
with buckwheat by-products (i.e. with buckwheat bran, rich in minerals,
vitamins, dietary fibre and proteins), (iii) developing food additives with
exclusive biological effects from buckwheat (Krkosková and Mrázová,
2005). Much effort should be paid to the processing, acceptability and palat-
ability of buckwheat foods by improving modern food-processing tech-
niques since the consumers’ preference is deeply influenced by the
rheological characteristics of buckwheat food products.

11.8 References

alvarez-jubete, l., holse, m., hansen, a., arendt, e. k. and gallagher, e. (2009).
Impact of baking on vitamin E content of pseudocereals amaranth, quinoa, and
buckwheat. Cereal Chemistry, 86, 511–515.

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402 Cereal grains for the food and beverage industries

alvarez-jubete, l., wijngaard, h., arendt, e. k. and gallagher, e. (2010). Poly-
phenol composition and in vitro antioxidant activity of amaranth, quinoa buck-
wheat and wheat as affected by sprouting and baking. Food Chemistry, 119,
770–778.

arendt, e. k. and hubner, f. (2010). Studies on the Influence of germination condi-
tions on protein breakdown in buckwheat and oats. Journal of the Institute of
Brewing, 116, 3–13.

baeza, r., sanchez, c. c., pilosof, a. m. r. and patino, j. m. r. (2004). Interfacial and
foaming properties of prolylenglycol alginates – effect of degree of esterification
and molecular weight. Colloids and Surfaces B – Biointerfaces, 36, 139–145.

ball, g. f. m. (1998). Physiological aspects of vitamin bioavailablity. Bioavailability
and Analysis of Vitamins in Foods. London: Chapman and Hall.

belozersky, m. a., dunaevsky, y. e. and voskoboynikova, n. e. (1990). Isolation and
properties of a metalloproteinase from buckwheat (Fagopyrum esculentum)
seeds. Biochemical Journal, 272, 677–682.

bewley, j. d. and black, m. (1985). Seeds: Physiology of Development and Germina-
tion. New York: Plenum Press.

biacs, p., aubrecht, e., léder, i. and lajos, j. (2002). Buckwheat. In: belton, j. t. and
taylor, j. r. n. (eds) Pseudocereals and Less Common Cereals: Grain Properties
and Utilization Potential. Berlin: Springer.

bonafaccia, g., gambelli, l., fabjan, n. and kreft, i. (2003a). Trace elements in flour
and bran from common and tartary buckwheat. Food Chemistry, 83, 1–5.

bonafaccia, g., marocchini, m. and kreft, i. (2003b). Composition and technological
properties of the, flour and bran from common and tartary buckwheat. Food
Chemistry, 80, 9–15.

boyle, s. p., dobson, v. l., duthie, s. j., hinselwood, d. c., kyle, j. a. m. and collins, a.
r. (2000). Bioavailability and efficiency of rutin as an antioxidant: a human supple-
mentation study. European Journal of Clinical Nutrition, 54, 774–782.

burton, g. w. and traber, m. g. (1990). Vitamin E – antioxidant activity, biokinetics,
and bioavailability. Annual Review of Nutrition, 10, 357–382.

campbell, c. g. (1997). Buckwheat, Fagopyrum esculentum Moench. Rome: IPGRI.
chapkin, r. s. (2000). Reappraisal of the essential fatty acids. In: chow c. k. (ed.)

Fatty Acids in Foods and Their Health Implications. New York: Marcel Dekker.
cheeke, p. r. and shull l. r. (1985). Natural Toxicants in Feeds and Poisonous Plants.

Westport, CT: AVI.
chillo, s., laverse, j., falcone, p. m., protopapa, a. and del nobile, m. a. (2008). Influ-

ence of the addition of buckwheat flour and durum wheat bran on spaghetti
quality. Journal of Cereal Science, 47, 144–152.
chung, o. k. and pomeranz, y. (1985). Amino acids in cereal proteins and
protein fractions. In: finley, j. w. and hopkins, d. t. (eds) Digestibility and
amino acid availability in cereals and Oilseeds. St Paul, MN: AACC International,
Inc.
defrancischi, m. l. p., salgado, j. m. and leitao, r. f. f. (1994). Chemical, nutritional
and technological characteristics of buckwheat and non-prolamine buckwheat
flours in comparison of wheat-flour. Plant Foods for Human Nutrition (formerly
Qualitas Plantarum), 46, 323–329.
dietrych-szostak, d. and oleszek, w. (1999). Effect of processing on the flavonoid
content in buckwheat (Fagopyrum esculentum Moench) grain. Journal of Agricul-
tural and Food Chemistry), 47, 4384–4387.
dorrell, d. g. (1971). Fatty acid composition of buckwheat seed. Journal of the
American Oil Chemists Society, 48, 693–696.
dunaevsky, y. e. and belozersky, m. a. (1989). The role of cysteine proteinase and
carboxypeptidase in the breakdown of storage proteins in buckwheat seeds.
Planta, 179, 316–322.

© Woodhead Publishing Limited, 2013

Buckwheat 403

dunaevsky, y. e. and belozersky, m. a. (1993). Effects of the embryonic axis and
phytohormones on proteolysis of the storage protein in buckwheat seed. Physio-
logia Plantarum, 88, 60–64.

dunaevsky, y. e., pavlukova, e. b., beliakova, g. a., tsybina, t. a., gruban, t. n. and
belozersky, m. a. (1998). Protease inhibitors in buckwheat seeds: comparison of
anionic and cationic inhibitors. Journal of Plant Physiology, 152, 696–702.

eggum, b. o., kreft, i. and javornik, b. (1980). Chemical composition and protein
quality of buckwheat (Fagopyrum esculentum Moench). Plant Foods for Human
Nutrition (formerly Qualitas Plantarum), 30, 175–179.

egli, i., davidsson, l., juillerat, m. a., barclay, d. and hurrell, r. (2003). Phytic acid
degradation in complementary foods using phytase naturally occurring in whole
grain cereals. Journal of Food Science, 68, 1855–1859.

elpidina, e. n., voskoboynikova, n. e., belozersky, m. a. and dunaevsky, y. e. (1991).
Localization of a metalloproteinase and its inhibitor in the protein bodies of
buckwheat seeds. Planta, 185, 46–52.

englyst, h. n., kingman, s. m. and cummings, j. h. (1992). Classification and measure-
ment of nutritionally important starch fractions. European Journal of Clinical
Nutrition, 46, S33–S50.

erlund, i., kosonen, t., alfthan, g., maenpaa, j., perttunen, k., kenraali, j., paran-
tainen, j. and aro, a. (2000). Pharmacokinetics of quercetin from quercetin
aglycone and rutin in healthy volunteers. European Journal of Clinical Pharma-
cology, 56, 545–553.

fao/who/unu (1985). Energy and protein requirements; report of a joint FAO/WHO/
UNU expert consultation, WHO Technical Report Series 724. Geneva: WHO.

fao/un (1990). Protein quality evaluation: report of a Joint FAO/WHO Expert Con-
sultation. Rome: FAO.

fao/un (2012). FAOSTAT database: http://faostat3.fao.org/home/index.html.
fasano, a. and catassi, c. (2001). Current approaches to diagnosis and treatment of

celiac disease: an evolving spectrum. Gastroenterology, 120, 636–651.
gabrovská, d., fiedlerova, v., holasova, m., maskova, e., smrcinov, h., rysova, j.,

winterova, r., michalova, a. and hutar, m. (2002). The nutritional evaluation of
underutilized cereals and buckwheat. Food and Nutrition Bulletin, 23, 246–249.
geisler, g. (2003). aufhammer, w., (2000). Pseudogetreidearten – Buchweizen, Reis-
melde und Armarant; Herkunft, Nutzung und Anbau. Journal of Agronomy and
Crop Science, 189, 197.
graefe, e., wittig, j., mueller, s., riethling, a., uehleke, b., drewelow, b., pforte,
h., jacobasch, g., derendorf, h. and veit, m. (2001). Pharmacokinetics and bio-
availability of quercetin glycosides in humans. The Journal of Clinical Pharmacol-
ogy, 41, 492–499.
hertog, m. g. l., feskens, e. j. m., hollman, p. c. h., katan, m. b. and kromhout, d.
(1993). Dietary antioxidant flavonoids and risk of coronary heart disease – the
Zutphen elderly study. Lancet, 342, 1007–1011.
horbowicz, m., brenac, p. and obendorf, r. l. (1998). Fagopyritol B1, O-α-D-
galactopyranosyl-(1→2)-1D-chiro-inositol, a galactosyl cyclitol in maturing buck-
wheat seeds associated with desiccation tolerance. Planta, 205, 1–11.
ikeda, k. (2002). Buckwheat: composition, chemistry, and processing. Advances in
Food and Nutrition Research, 44, 395–434.
ikeda, k. and kusano, t. (1983). In vitro inhibition of digestive enzymes by indigest-
ible polysaccharides. Cereal Chemistry, 60, 260–263.
ikeda, s. and yamashita, y. (1994). Buckwheat as a dietary source of zinc, copper and
manganese Fagopyrum, 14, 29–34.
ikeda, k., arioka, k., fujii, s., kusano, t. and oku, m. (1984). Effect on buckwheat
protein quality of seed germination and changes in trypsin-inhibitor content.
Cereal Chemistry, 61, 236–238.

© Woodhead Publishing Limited, 2013

404 Cereal grains for the food and beverage industries

ikeda, k., sakaguchi, t., kusano, t. and yasumoto, k. (1991). Endogenous factors
affecting protein digestibility in buckwheat. Cereal Chemistry, 68, 424–427.

insel, p., turner, r. e. and ross, d. (2004). Nutrition. Sudbury, MA: Jones and Bartlett.
jahaniaval, f., kakuda, y. and marcone, m. f. (2000). Fatty acid and triacylglycerol

compositions of seed oils of five Amaranthus accessions and their comparison to
other oils. Journal of the American Oil Chemists Society, 77, 847–852.
javornik, b., eggum, b. o. and kreft, i. (1981). Studies on protein fractions and protein
quality of buckwheat. Genetika, 13, 115–121.
jenkins, d. j. a., wolever, t. m. s., taylor, r. h., barker, h., fielden, h., baldwin, j. m.,
bowling, a. c., newman, h. c., jenkins, a. l. and goff, d. v. (1981). Glycemic index
of foods – a physiological basis for carbohydrate exchange. American Journal of
Clinical Nutrition, 34, 362–366.
johnson, a. e. (1983). Photosensitizing toxins from plants and their biologic effects.
In: keeler, r. f. and tu, a. t. (eds) Handbook of Natural Toxins: Plant and Fungal
Toxins. New York: Marcel Dekker.
kaur, c. and kapoor, h. c. (2001). Antioxidants in fruits and vegetables – the millen-
nium’s health. International Journal of Food Science and Technology, 36,
703–725.
kawa, j. m., taylor, c. g. and przybylski, r. (2003). Buckwheat concentrate reduces
serum glucose in streptozotocin-diabetic rats. Journal of Agricultural and Food
Chemistry, 51, 7287–7291.
kayashita, j., shimaoka, i. and nakajyoh, m. (1995). Hypocholesterolemic effect of
buckwheat protein extract in rats fed cholesterol-enriched diets. Nutrition
Research, 15, 691–698.
kayashita, j., shimaoka, i., nakajoh, m. and kato, n. (1996). Feeding of buckwheat
protein extract reduces hepatic triglyceride concentration, adipose tissue weight,
and hepatic lipogenesis in rats. Journal of Nutritional Biochemistry, 7, 555–559.
kim, s. l., kim, s. k. and park, c. h. (2002). Comparisons of lipid, fatty acids and
tocopherols of different buckwheat species. Food Science and Biotechnology, 11,
332–336.
kim, s. l., kim, s. k. and park, c. h. (2004). Introduction and nutritional evaluation of
buckwheat sprouts as a new vegetable. Food Research International, 37, 319–327.
kiyohara, t. and iwasaki, t. (1985). Purification and some properties of trypsin-
inhibitors from buckwheat seeds. Agricultural and Biological Chemistry, 49,
581–588.
krkosková, b. and mrázová, z. (2005). Prophylactic components of buckwheat. Food
Research International, 38, 561–568.
li, s. q. and zhang, q. h. (2001). Advances in the development of functional foods
from buckwheat. Critical Reviews in Food Science and Nutrition, 41, 451–464.
li, w., lin, r. and corke, h. (1997). Physicochemical properties of common and
Tartary buckwheat starch. Cereal Chemistry, 74, 79–82.
lintschinger, j., fuchs, n., moser, h., jager, r., hlebeina, t., markolin, g. and gossler,
w. (1997). Uptake of various trace elements during germination of wheat, buck-
wheat and quinoa. Plant Foods for Human Nutrition (formerly Qualitas Planta-
rum), 50, 223–237.
luthar, z. (1992). Polyphenol classification and tannin content of buckwheat seeds
(Fagopyrum esculentum Moench). Fagopyrum, 12, 36–42.
maccagnan, g., pat, a., collavo, f., r., g. l. and bellini, m. p. (2004). Gluten-free beer
containing rice malt and buckwheat. European Patent patent application EP
0949328B1.
marshall, h. g. and pomeranz, y. (1982). Buckwheat: description, breeding, produc-
tion, and utilization. In: pomeranz, y. (ed.) Advances in Cereal Science and Tech-
nology, Vol. 5. St Paul, MN: AACC International, Inc.

© Woodhead Publishing Limited, 2013

Buckwheat 405

matsumoto, r., fujino, k., nagata, y., hashiguchi, s., ito, y., aihara, y., takahashi, y.,
maeda, k. and sugimura, k. (2004). Molecular characterization of a 10-kDa buck-
wheat molecule reactive to allergic patients’ IgE. Allergy, 59, 533–538.

mazza, g. (1988). Lipid content and fatty acid composition of buckwheat seed.
Cereal Chemistry, 65, 122–126.

mazza, g. and oomah, b. d. (2005). Buckwheat as a food and feed. In: abdel-aal, e.
and wood, p. (eds) Speciality Grains for Food and Feed. St Paul, MN: AACC
International, Inc.

milisavljevic, m. d., timotijevic, g. s., radovic, s. r., brkljacic, j. m., konstantinovic,
m. m. and maksimovic, v. r. (2004). Vicilin-like storage globulin from buckwheat
(Fagopyrum esculentum Moench) seeds. Journal of Agricultural and Food Chem-
istry, 52, 5258–5262.

mitsunaga, t., matsuda, m., shimizu, m. and iwashima, a. (1986). Isolation and prop-
erties of a thiamine-binding protein from buckwheat seed. Cereal Chemistry, 63,
332–335.

moore, m. m., schober, t. j., dockery, p. and arendt, e. k. (2004). Textural comparisons
of gluten-free and wheat-based doughs, batters, and breads. Cereal Chemistry, 81,
567–575.

muntz, k., belozersky, m. a., dunaevsky, y. e., schlereth, a. and tiedemann, j. (2001).
Stored proteinases and the initiation of storage protein mobilization in seeds
during germination and seedling growth. Journal of Experimental Botany, 52,
1741–1752.

noda, t., takahata, y., sato, t., suda, i., morishita, t., ishiguro, k. and yamakawa, o.
(1998). Relationships between chain length distribution of amylopectin and gela-
tinization properties within the same botanical origin for sweet potato and buck-
wheat. Carbohydrate Polymers, 37, 153–158.

oomah, b. d. and mazza, g. (1996). Flavonoids and antioxidative activities in buck-
wheat. Journal of Agricultural and Food Chemistry, 44, 1746–1750.

ortmeyer, h. k., huang, l. c., zhang, l., hansen, b. c. and larner, j. (1993). Chiro-
inositol deficiency and insulin resistance. II. Acute effects of D-chiroinositol
administration in streptozotocin-diabetic rats, normal rats given a glucose load,
and spontaneously insulin-resistant rhesus monkeys. Endocrinology, 132,
646–651.

ortmeyer, h. k., larner, j. and hansen, b. c. (1995). Effects of D-chiroinositol added
to a meal on plasma glucose and insulin in hyperinsulinemic rhesus monkeys.
Obesity Research, 3 Suppl 4, 605S-608S.

park, s. s., abe, k., kimura, m., urisu, a. and yamasaki, n. (1997). Primary structure
and allergenic activity of trypsin inhibitors from the seeds of buckwheat (Fago-
pyrum esculentum Moench). Febs Letters, 400, 103–107.

park, j. w., kang, d. b., kim, c. w., ko, s. h., yum, h. y., kim, k. e. and hong, c. s. (2000).
Identification and characterization of the major allergens of buckwheat. Allergy,
55, 1035–1041.

peressini, d., pin, m. and sensidoni, a. (2011). Rheology and breadmaking perfor-
mance of rice-buckwheat batters supplemented with hydrocolloids. Food Hydro-
colloids, 25, 340–349.

phiarais, b. p. n., wijngaard, h. h. and arendt, e. k. (2005). The impact of kilning on
enzymatic activity of buckwheat malt. Journal of the Institute of Brewing, 111,
290–298.

phiarais, n. b. p., wijngaard h. h. and k. e., a. (2006). Kilning conditions for the
optimisation of enzyme levels in buckwheat. Journal of the American Society of
Brewing Chemists, 64, 187–194.

pomeranz, y. (1983). Buckwheat – Structure, Composition, and Utilization. Critical
Reviews in Food Science and Nutrition, 19, 213–258.

© Woodhead Publishing Limited, 2013

406 Cereal grains for the food and beverage industries

pomeranz, y. and robbins, g. s. (1972). Amino-acid composition of buckwheat.
Journal of Agricultural and Food Chemistry, 20, 270-274.

praznik, w., mundigler, n., kogler, a., pelzl, b. and huber, a. (1999). Molecular
background of technological properties of selected starches. Starch, 51,
197–211.

prestamo, g., pedrazuela, a., penas, e., lasuncion, m. a. and arroyo, g. (2003). Role
of buckwheat diet on rats as prebiotic and healthy food. Nutrition Research, 23,
803–814.

przybylski, r., lee, y. c. and eskin, n. a. m. (1998).Antioxidant and radical-scavenging
activities of buckwheat seed components. Journal of the American Oil Chemists
Society, 75, 1595–1601.

qian, j. y. and kuhn, m. (1999a). Evaluation on gelatinization of buckwheat starch: a
comparative study of Brabender viscoamylography, rapid visco-analysis, and dif-
ferential scanning calorimetry. European Food Research and Technology, 209,
277–280.

qian, j. y. and kuhn, m. (1999b). Physical properties of buckwheat starches from
various origins. Starch, 51, 81–85.

qian, j., rayas-duarte, p. and grant, l. (1998). Partial characterization of buckwheat
(Fagopyrum esculentum) starch. Cereal Chemistry, 75, 365–373.

radovic, s. r., maksimovic, v. r. and varkonjigasic, e. i. (1996). Characterization of
buckwheat seed storage proteins. Journal of Agricultural and Food Chemistry, 44,
972–974.

radovic, r. s., maksimovic, r. v., brkljacic, m. j., gasic, i. e. v. and savic, p. a. (1999).
2S albumin from buckwheat (Fagopyrum esculentum Moench) seeds. Journal of
Agricultural and Food Chemistry, 47, 1467–1470.

rapala-kozik, m., chernikevich, i. p. and kozik, a. (1999). Ligand-protein interaction
in plant seed thiamine-binding proteins. Binding of various thiamine analogues
to the sepharose-immobilized buckwheat-seed protein. Journal of Protein Chem-
istry, 18, 721–728.

renaud, s. and delorgeril, m. (1992). Wine, alcohol, platelets, and the French
paradox for coronary heart-disease. Lancet, 339, 1523–1526.

renzetti, s., dal bello, f. and arendt, e. k. (2008). Microstructure, fundamental
rheology and baking characteristics of batters and breads from different gluten-
free flours treated with a microbial transglutaminase. Journal of Cereal Science,
48, 33–45.

rice-evans, c. a., miller, j. and paganga, g. (1997). Antioxidant properties of phe-
nolic compounds. Trends in Plant Science, 2, 152–159.

roberfroid, m. (1993). Dietary fiber, inulin, and oligofructose – a review comparing
their physiological effects. Critical Reviews in Food Science and Nutrition, 33,
103–148.

ryan, c. a. (1981). Proteinases inhibitors. In: marcus, a. (ed.) The Biochemistry of
Plants. New York: Academic Press.

schaafsma, g. (2000). The protein digestibility-corrected amino acid score. Journal
of Nutrition, 130(7), 1865S–1867S.

schoenlechner, r. g., kaczyc, l. l. and berghofer, e. (2006). Production of short
dough biscuits from the pseudocereals amaranth, quinoa and buckwheat with
common bean. Ernahrung, 30, 101–107.

simmering, r., pforte, h., jacobasch, g. and blaut, m. (2002). The growth of the
flavonoid-degrading intestinal bacterium, Eubaeterium ramulus, is stimulated by
dietary flavonoids in vivo. Fems Microbiology Ecology, 40, 243–248.

skrabanja, v. and kreft, i. (1998). Resistant starch formation following autoclaving
of buckwheat (Fagopyrum esculentum Moench) groats. An in vitro study. Journal
of Agricultural and Food Chemistry, 46, 2020–2023.

© Woodhead Publishing Limited, 2013

Buckwheat 407

skrabanja, v., laerke, h. n. and kreft, i. (1998). Effects of hydrothermal processing
of buckwheat (Fagopyrum esculentum Moench) groats on starch enzymatic avail-
ability in vitro and in vivo in rats. Journal of Cereal Science, 28, 209–214.

skrabanja, v., elmstahl, h. g. m. l., kreft, i. and bjorck, i. m. e. (2001). Nutritional
properties of starch in buckwheat products: studies in vitro and in vivo. Journal
of Agricultural and Food Chemistry, 49, 490–496.

skrabanja, v., kreft, i., golob, t., modic, m., ikeda, s., ikeda, k., kreft, s., bonafaccia,
g., knapp, m. and kosmelj, k. (2004). Nutrient content in buckwheat milling frac-
tions. Cereal Chemistry, 81, 172–176.

steadman, k. j., burgoon, m. s., schuster, r. l., lewis, b. a., edwardson, s. e. and
obendorf, r. l. (2000). Fagopyritols, D-chiro-inositol, and other soluble carbohy-
drates in buckwheat seed milling fractions. Journal of Agricultural and Food
Chemistry, 48, 2843–2847.

steadman, k. j., burgoon, m. s., lewis, b. a., edwardson, s. e. and obendorf, r. l.
(2001a). Buckwheat seed milling fractions: description, macronutrient composi-
tion and dietary fibre. Journal of Cereal Science, 33, 271–278.

steadman, k. j., burgoon, m. s., lewis, b. a., edwardson, s. e. and obendorf, r. l.
(2001b). Minerals, phytic acid, tannin and rutin in buckwheat seed milling frac-
tions. Journal of the Science of Food and Agriculture, 81, 1094–1100.

suzuki, t., honda, y. and mukasa, y. (2004). Purification and characterization of
lipase in buckwheat seed. Journal of Agricultural and Food Chemistry, 52,
7407–7411.

taira, h., akimoto, i. and miyahara, t. (1986). Effects of seeding time on lipid content
and fatty acid composition of buckwheat grains. Journal of Agricultural and Food
Chemistry, 34, 14–17.

tkachuk, r. and irvine, g. n. (1969). Amino acid compositions of cereals and oilseed
meals. Cereal Chemistry, 46, 206–219.

tomotake, h., shimaoka, i., kayashita, j., nakajoh, m. and kato, n. (2002). Physico-
chemical and functional properties of buckwheat protein product. Journal of
Agricultural and Food Chemistry, 50, 2125–2129.

torbica, a., hadnadev, m. and dapcevic, t. (2010). Rheological, textural and sensory
properties of gluten-free bread formulations based on rice and buckwheat flour.
Food Hydrocolloids, 24, 626–632.

tsuzuki, w., ogata, y., akasaka, k., shibata, s. and suzuki, t. (1991). Fatty-acid com-
position of selected buckwheat species by fluorometric high-performance liquid-
chromatography. Cereal Chemistry, 68, 365–369.

tsybina, t., dunaevsky, y., musolyamov, a., egorov, t., larionova, n., popykina, n. and
belozersky, m. (2004). New protease inhibitors from buckwheat seeds: properties,
partial amino acid sequences and possible biological role. Biological Chemistry,
385, 429–434.

watanabe, m. (1998). Catechins as antioxidants from buckwheat (Fagopyrum escu-
lentum Moench) groats. Journal of Agricultural and Food Chemistry, 46,
839–845.

wieslander, g. (1996). Review on buckwheat allergy. Allergy, 51, 661–665.
wieslander, g. and norback, d. (2001). Buckwheat allergy. Allergy, 56, 703–704.
wijngaard, h. h. and arendt, e. k. (2006). Optimisation of a mashing program for

100 % malted buckwheat. Journal of the Institute of Brewing, 112, 57–65.
wijngaard, h. h., renzetti, s. and arendt, e. k. (2007). Microstructure of buckwheat

and barley during malting observed by confocal scanning laser microscopy and
scanning electron microscopy. Journal of the Institute of Brewing, 113, 34–41.
wijngaard, h. h., ulmer, h. m. and arendt, e. k. (2005a). The effect of germination
temperature on malt quality of buckwheat. Journal of the American Society of
Brewing Chemists, 63, 31–36.

© Woodhead Publishing Limited, 2013

408 Cereal grains for the food and beverage industries
wijngaard, h. h., ulmer, h. m., neumann, m. and arendt, e. k. (2005b). The effect of

steeping time on the final malt quality of buckwheat. Journal of the Institute of
Brewing, 111, 275–281.
wijngaard, h. h., ulmer, h. m. and arendt, e. k. (2006). The effect of germination
time on the final malt quality of buckwheat. Journal of the American Society of
Brewing Chemists, 64, 214–221.
yano, m., nakamura, r., hayakawa, s. and torii, s. (1989). Purification and properties
of allergenic proteins in buckwheat seeds. Agricultural and Biological Chemistry,
53, 2387–2392.
yoshimoto, y., egashira, t., hanashiro, i., ohinata, h., takase, y. and takeda, y. (2004).
Molecular structure and some physicochemical properties of buckwheat starches.
Cereal Chemistry, 81, 515–520.
zarnkow, m., kessler, m., burberg, f., kreisz, s. and back, w. (2005). Gluten-free beer
from malted cereals and pseudocereals. Proceedings of the 30th European Brewery
Convention Congress in Prague. Nürnberg: Fachverlag Hans Carl.
zielinski, h., ciska, e. and kozlowska, h. (2001). The cereal grains: focus on vitamin
E. Czech Journal of Food Sciences, 19, 182–188.
zweytick, g., sauerzopf, e. and berghofer, e. (2005). Production of gluten-free beer.
AACC Annual Meeting, 20–23 September, Orlando, FL.

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12

Quinoa

DOI: 10.1533/9780857098924.409

Abstract: Quinoa seed (Chenopodium quinoa Willd.) is a pseudo-cereal that has
been cultivated in the Andean region for thousands of years. Quinoa is a
gynomonoecious annual plant with an erect stem and can be cultivated from sea
level up to an altitude of 3800 m. Quinoa is receiving increasing attention because
of the nutritional value of its protein rich in amino acids like lysine and
methionine that are deficient in cereals. Quinoa can be eaten as a hot breakfast
cereal or as a rice replacement, can be sprouted or popped like popcorn or
ground and used as flour for making biscuits, bread and processed food. Due to
the high proportion of d-xylose, maltose and fructose, quinoa would be also a
useful ingredient in malted drink formulations. Quinoa holds exceptional promise
as a weaning food for infants, especially in nutritionally-deficient areas in the
developing world.

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

12.1 Introduction

Quinoa is a seed crop originating in the Andes region near Lake Titicaca
in Peru and Bolivia. It has been cultivated in this area since 3000 BC,
(Tapia, 1979) and occupied a place of prominence in the Inca empire second
only to maize (Cusack, 1984). To the Incas, quinoa (Chenopodium quinoa
Willd) was a food so vital that it was considered sacred. In their language,
Quechua, it is referred to as chisiya mama or ‘mother grain’. However,
after the Spanish conquest, in 1532 AD, quinoa was only found in
areas where Europeans did not settle and introduce grains such as
wheat, rye and oat. Examples of these areas are the Altiplano in the High
Andes 3500 m above sea level or isolated regions where roads are cut off
in winter or where ancient cultures still remain strong and attached to their
agricultural practices and traditional food consumption habits. The genus
Chenopodium (family Chenopodiaceae) comprises about 250 species
(Giusti, 1970), which include herbaceous, suffrutescent and arborescent
perennials, mostly which colonize annually (Wilson, 1990). Quinoa belongs
to the group of crops known as pseudo-cereals (Koziol, 1990), which includes
other domesticated chenopods, amaranths and buckwheat.

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410 Cereal grains for the food and beverage industries

There is a renewed interest in quinoa, as well as in other ancient crops
like amaranth, since these small grains contain protein of outstanding
quality and are better balanced in terms of amino acid composition than
most other cereals (Ruales and Nair, 1992b; Tapia, 2000). The Food and
Agricultural Organization (FAO) observed that quinoa is closer to the ideal
protein balance than any other grain (Gross et al., 1989). The protein iso-
lated from quinoa resembles cow’s milk protein in quality (Kozioł M, 1992).
The UN Food and Agriculture Organization, the US Agency for Interna-
tional Development and the Canadian International Development Research
Centre all investigated the expanded use of quinoa as a protein source for
marginalized populations during the 1970s and 1980s (Alberta Agriculture
Food and Rural Development, 2005). Recently, there has been growing
interest in the crop in in different continents (Europe, North America, Asia
and Africa), thus initiating the introduction and commencement of research
work on quinoa in those countries (Jacobsen, 2003).

European countries, like Spain, Denmark, Finland and England, are
studying the adaptation of quinoa to Mediterranean climates and are inter-
ested in its cultivation (Vilche et al., 2003). Quinoa has also been considered
a potential ‘new’ crop for NASA’s Controlled Ecological Life Support
System (CELSS). The CELSS concept will utilize plants to remove carbon
dioxide from the atmosphere and generate food, oxygen and water for
human crews on long-term space missions. Criteria for the selection of
potential crops include nutritional composition, harvest index, canopy
stature and life-cycle duration (Schlick and Bubenheim, 1996).

Quinoa can be eaten as a hot breakfast cereal or, as a rice replacement,
or it can be boiled in water to make infant cereal food. The quinoa seeds
can even be popped like popcorn or ground and used as flour or sprouted
(Valencia Chamorro, 2003). Quinoa flour can be mixed with maize or
wheat flour for producing bread, noodles and pasta and sweet biscuits
(Valencia Chamorro, 2003). In addition to this, quinoa flour can also be
drum-dried and extruded, providing products with good sensorial and
nutritional qualities. Additionally, solid-state fermentation of quinoa with
Rhizopus oligosporus Saito provides a good-quality tempe (Valencia
Chamorro, 2003).

12.1.1 Production area, price and yield
Quinoa is grown in a wide range of environments in the South American
region (especially in and around the Andes), at latitudes from 20ºN in
Columbia to 40ºS in Chile, and from sea level to an altitude of 3800 m (Risi
and Galwey, 1989). In the late 1970s, the main production areas of quinoa
were Colombia, Chile, the Andean valleys in Peru, in Bolivia and the high-
lands of Ecuador, broadly speaking (Fig. 12.1). In Peru and Bolivia, this crop
has been of great importance in its areas of cultivation not only for domestic
consumption but also for export. Recently, it has been introduced into

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Quinoa 411

Venezuela
Colombia

Ecuador

Brazil

Peru

Bolivia

Paraguay

Chile
Argentina
Uruguay

Fig. 12.1 Geographical distribution of quinoa coltivation. It is mainly restricted to
Bolivia and Peru (dense dot pattern) where it is grown mainly in backyards, field

margins and as an intercrop.

Europe, North America, Asia and Africa. In the 1980s, in the USA, quinoa
was cultivated in the Colorado Rockies. Nowadays, it has become a com-
mercial crop in general. Quinoa has also been grown commercially in the
UK since in 1989 as well as in Manitoba, Canada, and Denmark.The harvest
in these countries is so low that they are not listed in the FAO statistics on
production data of cereal. Quinoa is listed as a crop grown only in Ecuador,

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412 Cereal grains for the food and beverage industries

Peru and Bolivia (FAO/UN, 2012). The main area of cultivation has tra-
ditionally been Ecuador, but it is also cultivated in Bolivia and Peru to a
much smaller extent. Although there are yearly fluctuations in production,
for all the producer countries it is possible to highlight a slight increase in
quinoa production during the last decade.

The milder climate of the ‘green Andes’ of Ecuador and northern Peru,
characterized by adequate rainfall and little climatic variability, provides
good growth conditions for this up-and-coming crop. Yields of quinoa in
the Andean countries are low compared to the production levels of grains
such as wheat and also in comparison with quinoa grown in the developed
countries. While the average yield per hectare of quinoa in 2000–2010 was
between 0.5 and 1.1 tonnes in Ecuador, Peru and Bolivia (FAO/UN, 2012),
yield of wheat in Europe averaged 3.7 tonnes. Work on the profitability of
quinoa cultivation in Europe carried out by a project funded by the FAO,
CIP and the Danish aid organization, DANIDA project, suggest yields in
Europe of 2–4 tonnes/ha. A cause for concern is the noticeably increasing
price trend for quinoa. Specifically, in Bolivia the farm-gate prices of quinoa
rose by more than 50 % between 2000 and 2010 from 583 US $/tonne in
2000 to 1332.6 US $/tonne in 2010, which can be attributed to the increased
demand for this highly nutritious grain. Over the last 20 years, a general
trend for so-called health foods has been observed, which has been driven
by the consumer. This increased demand which resulted in higher prices for
quinoa provides an export market in Andean countries based around a
healthy, environmentally-beneficial product, which helps farmers in these
countries.

12.1.2 Phytology, classification and cultivation
From a botanical point of view, quinoa is assigned to the Chenopodiceae
family (Table 12.1) and its botanical name is Chenopodium quinoa, Willd.
Quinoa is a gynomonoecious annual plant with an erect stem, which bears
alternate leaves that are variously coloured from white, yellow or light

Table 12.1 Botanical classification of quinoa

Classification Quinoa

Sub-class Dicotyledoneae
Group Thalamiflorae
Order Caryophyllales
Family Chenopodiaceae
Genus Chenopodium
Species quinoa

Source: Benson (1957).

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Quinoa 413

brown to red due to the presence of β-cyanins. Most varieties of quinoa
commonly differ in their morphology and phenology and in the chemical
composition of their tissues (Bertero et al., 2004). Quinoa is not a true cereal
grain: it is a so-called pseudo-cereal, which is dicotyledonous. In contrast,
cereals are monocotyledonous. In spite of this, pseudo-cereals are similar
in composition. Quinoa, depending on the sowing density, can grow from 1
to 3 m high. The roots can reach a depth of up to 1.5 m below the surface,
which protects the plant against drought. The stem is cylindrical, 3.5 cm in
diameter, and it can be either a straight or branched. The leaves exhibit
polymorphism, the upper leaves being lanceolate, while the lower leaves
are rhomboidal (Hunziker, 1943).

The flowers are incomplete and do not have petals.As a gynomonoecious
plant, quinoa has both hermaphrodite flowers, which are located at the
distal end of a group, and female flowers, which are located at the proximal
end (Simmonds, 1965; Valencia-Chamorro, 2003). The arrangement of the
flowers in a raceme is considered to be the panicle; the length of the panicle
varies from 15 to 70 cm. Specifically, the inflorescence of quinoa is a panicle
with a principal axis, from which secondary and tertiary axes originate (Risi
and Galwey, 1984). Two types of inflorescences have been described for
quinoa: amaranthiform and glomerulate. In the amaranthiform type, the
glomeruli (short branches bearing a group of flowers or grains) are inserted
directly on second-order axes, while in the glomerulate type, the glomeruli
are inserted on third-order axes (see diagrams of inflorescence types in Fig.
12.2). The fruit of quinoa is an achene. It produces small, flattened and
circular-shaped seeds which may measure from 1.5 mm in diameter to
4 mm (about 350 seeds weigh 1 g) (Ruales and Nair, 1993b). Seed colours
vary from white to grey or black, potentially having tones of yellow, rose,
red and purple and violet, often with very colourful mixes in the same
panicule. Black is dominant over red and yellow, which in turn are dominant
over the white seed colour (Fig. 12.3).

The quinoa seed comprises several layers, e.g. pericarp, seed coat and
perisperm (Risi and Galway, 1984) from outside inwards (Figs 12.4 and
12.5), and may be conical, cylindrical or ellipsoidal, with saponins concen-
trated in the pericarp. In the mature seed, the endosperm is present only in
the micropylar region of the seed and consists of one to two cell-layered
tissues surrounding the hypocotyl–radicle axis of the embryo (Fig. 12.6).
Compositional and nutritional evaluation of quinoa whole-grain flour and
mill fractions (Gross et al., 1989; Becker and Hanners, 1990) showed that
the bran contained most of the sapogenins, protein, fat, fibre and ash, while
the perisperm was rich in starch. The perisperm consisted of uniform, non-
living, thin-walled cells full of starch grains which were angular in shape
(Fig. 12.7a). Simple and compound starch grains occur in the same cells
(Fig. 12.7b).

Quinoa is also referred as a pseudo-oilseed crop (Cusack, 1984) due to
the exceptional balance between protein and fats. The perisperm, embryo

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414 Cereal grains for the food and beverage industries

Tertiary axis Glomerule

Secondary axis

(a) Main axis (b)

Fig. 12.2 Inflorescence types: (a) glomerulate inflorescence; (b) amaranthiform
inflorescence. Reprinted from Bertero et al., 1996, with permission from Oxford

University Press.

BRAPA (Br) 072RM (Pe) 079BB (Pe) AMM (Pe) BAER II (Cl) CICA127 (Pe)

CICA17 (Pe) ECU (Ec) EDK (Dk) G205 (NI) HUA (Pe) ILL (Pe)

ING (Ec) JUJUY (Ar) KAM (Bo) KNC (Pe) NAR (Co) NL6 (NI)

OLL (Bo-Cl) PAN (Bo) RAT (Bo) REA (Bo) RU2 (UK) RU5 (UK)

3 mm

SAL (Pe)

Fig. 12.3 Images,codes and geographical provenance of the 25 quinoa seed varieties.
Geographical provenance: Ar (Argentina), Bo (Bolivia), Br (Brazil), Cl (Chile), Co
(Colombia), Dk (Denmark), Ec (Ecuador), Nl (Netherlands), Pe (Peru), UK (United

Kingdom). Reprinted from Medina et al. (2010) with permission from Elsevier.

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Cotyledons Quinoa 415

Seed coat
Shoot apex

Pericarp

Ensosperm Hypocotyl radicle axis
Radicle

Funicle Perisperm

Fig. 12.4 Chenopodium quinoa: median longitudinal section of the grain. Pericarp
covers the seed. The embryo consists of a hypocotylradicle axis and two cotyledons.

Endosperm is present in the micropylar region.

E C
F S

R

Perisperm
P

SC

5 kV H AMRF,
×35 500 μm

Fig. 12.5 Scanning electron microscope (SEM) micrograph of the longitudinal
section of quinoa grain. Hypocotylradicle axis (H), cotyledons (C) endosperm (E),

funicle (F), perisperm (P), seed coat (SC), radicle tip (R), shoot apex (S).

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416 Cereal grains for the food and beverage industries

SC EN
R

P

5 kV ×250 100 μm AMRF, UCC

Fig. 12.6 A section of part of the hypocotyl-radicle axis: P, perisperm; SC, seed
coat; R, radicle tip ; EN; endosperm (white arrow).

Table 12.2 Chemical composition of quinoa and some cereals

Composition Quinoa Oat Wheat Barley Corn Rice
(g/100 g dw)

Carbohydrate 61–74 58.7 69 70 66 78

Protein 14–16.5 14 14 12 13 8

Fat 5–10 8 2 1 41

Fibre 2–3 8 2.3 4 3 2

Ash 3 1.8 2 2–3 2 1

Moisture 10–13 8.5 13 13 15 15

Sources: Chauhan et al. (1992a), Gopalan et al. (1985), Ruales and Nair (1992), Singhal and
Kulkarni (1988), Valencia-Chamorro (2004).

and endosperm are the three areas containing food reserves in a quinoa
seed (Prego et al., 1998). Protein and lipids are stored in the endosperm and
embryo, and starch in the perisperm. In general, the quinoa seed is charac-
terized by higher contents of protein and lipid and lower starch contents
relative to the major cereals (wheat, barley, maize and rice). Quinoa seeds
are also particularly rich in essential amino acids, especially lysine, trypto-
phan and cysteine (Ruales and Nair, 1992b). Likewise, quinoa seeds have
a higher quantity of minerals (calcium, iron, manganese, magnesium,
copper and potassium) than other cereals (Konishi et al., 2004). Table 12.2
gives the average chemical composition of quinoa in comparison with some
other food grains (wheat, barley, maize and rice). In the following sections,
the chemical and nutritional characteristics of the quinoa seed will be
discussed.

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