Cereal_grains_for_the_food_and_beverage_industries_2075944_z_lib

24 Cereal grains for the food and beverage industries

1.6.1 Historical background
Wheat milling is an ancient craft, dating back thousands of years. It has
been said that if we compare humankind’s time on earth to a 60 min period,
milling started 55 min after their appearance. Agriculture started 4 min
later and recorded history 30 s after agriculture. These observations lead
one to believe that grain milling may be the oldest manufacturing process
in the world (Walker and Eustace, 2004). Figure 1.4 shows the possible lines
of evolution of the millstone. Primitive cultures ~10 000–12 000 years ago
are thought to have used a mortar and pestle to crush wheat to separate
ground kernels from hulls (Dexter and Sarkar, 2004). Later, as shown in
illustrations found in an Egyptian tomb built around 3660–80 BC, grain was
ground with saddlestones and the meal was separated with sieves made of
papyrus or horsehair. Around 800 BC, rotary motion was used to enable
humans or animals to power the mill by traversing a circular path. The
invention of the millstone in Roman times was certainly a great develop-
ment. Over time, stone shapes and sizes were improved. Water was used to
turn millstones around 19 BC by the Roman architect Vitruvius (Kozm´ in,
1917). Other means of power were used to drive the millstones, such as wind
and, eventually, steam power. Steam engines were applied to stone mills in
1786 allowing the construction of mills in areas that did not have reliable
water or wind sources. The roller mill, purifier and plansifter were devel-
oped in the eighteenth and nineteenth centuries, and led to the gradual
break and reduction system. The basic process remains similar today, but
advances in design of equipment for cleaning and milling have allowed
continuous improvement in reliability, production, sanitation, and overall
efficiency. Today, most flour mills feature computer control, and some are
virtually fully automated (Dexter and Sarkar, 2004).

1.6.2 Flour milling process
Before the wheat reaches the first milling stage, it has to undergo several
preliminary operations that ensure the correct performance of the main
process. The first of these is wheat cleaning. Foreign materials such as pieces
of metal, stones, badly damaged kernels and foreign seeds are easily sepa-
rated from wheat on the basis of size, shape, density or magnetism. After
cleaning, wheat is conditioned by addition of tempering moisture. Temper-
ing is one of the most important parts of the flour milling process. In this
stage, the moisture content of the kernel is increased by adding water and
by allowing the grain to sit for a period of time. Conditioning optimizes
separation of bran from the endosperm during milling. Tough bran and a
friable mealy endosperm are prerequisites for an efficient separation of the
two.As the bran becomes progressively tougher and less brittle with increas-
ing moisture content, milling will produce flour that is less contaminated by
bran dust, and is thus whiter and has a lower ash content.

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Wheat and other Triticum grains 25

Achieving optimum moisture level for milling is critical. If the wheat is
over-dampened, sifting becomes difficult and the capacity of the mill is
immediately reduced. Too little tempering moisture results in bran powder-
ing and the bran contaminates the flour. The amount of water added
depends both on the existing moisture content of the wheat and the hard-
ness of the grain. Hard (winter or spring) wheat is tempered to 16.5 %
moisture while soft wheat is usually tempered to 15.0–15.5 % moisture. The
optimum rest time varies from several hours to more than a day depending
on wheat moisture content and hardness. Soft wheat does not need to rest
as long before milling as hard wheat. This is because soft wheat endosperm
is more porous than hard wheat endosperm, so water penetrates into it
more quickly. Rest times for soft wheat are 6–18 h, whereas they are 10–36 h
for hard wheat. Tempering times also depend on whether the process is
carried out hot or cold, with hot tempering being much the quicker method.
A simplified wheat intake, cleaning and conditioning diagram is shown in
Fig. 1.5.

Flour milling is the process by which wheat kernel is transformed into a
form that is of use to the baking and other industries and the domestic
consumer. White flour is the final product of flour milling. The technological
challenge of the white flour milling is to separate the three main parts of
the wheat kernel (endosperm, bran and germ) as efficiently as possible. It
is complex because of the kernel shape, the crease and the aleurone layer
(this latter is difficult to separate from the bran). The efficiency of separa-
tion is estimated by calculating the amounts of the various end-products.
Milling is an articulate process that, via a series of grinding and sieving
stages, produces white flour of the desired quality and yield. The gradual
reduction system has enabled the production of flours of low ash content
and high yield. Figure 1.6 shows a general flow diagram of a mill, describing
the inputs and outputs of the milling major stages. There are four principal
stages within the process, known as the break system, the grading system,
the purification system and the reduction system. The break system is the
area of the process where most endosperm separation is achieved. The
objective of this step is to open the wheat kernel and remove the endosperm
and germ from the bran coat with the least amount of bran contamination.
This work is performed with the aid of corrugated or fluted iron rollers,
called break rollers, rotating in opposite directions. The rolls also run at
different speeds towards each other (the speed differential is approximately
1 : 2). Thus, in addition to the crushing action on a large particle as it passes
the narrow gap between the two rolls, there is also a shearing action because
of the speed differential. If the wheat kernels were merely crushed, the bran
would break up into tiny fragments that would mix with the endosperm so
thoroughly that they could never be separated properly. Their presence
would then discolour the flour badly and also reduce its quality. The break-
ing process includes successive milling steps, in which the corrugations of

© Woodhead Publishing Limited, 2013

© Woodhead Publishing Limited, 2013 Wheat intake Wheat storage Wheat cleaning Wheat tempering
Water Product control Tempering system
Rail (chemist inspect, wheat Magnetic separator (water tougher outer
Road quality control and (iron and steel) bran coats for easier
classify) separation – softens
Separator Aspirator endosperm)
(remove stone, sticks (remove lighter Tempering bins
and other coarse /fine impurities)
materials) Magnetic separator
Magnetic separator Separator
(iron and steel) (remove stone, sticks Scourer
and other coarse /fine
Storage bins materials)

Disc separator
(remove barley, oats
and other foreign
materials)

Scourer
(remove impurity and
roughage)

1st break

Fig. 1.5 A simplified wheat intake, cleaning and tempering flow sheet.

Wheat and other Triticum grains 27

Flour Cleaned and tempered wheat Bran,
germ
Break system

Sizing

Grading system

Sizing, endosperm/bran, bran and germ
Purification system

Large compounds endosperm/bran,
small compounds endosperm/bran

Sizing system

Relatively clean endosperm
(clean semolina, middlings)

Reduction system

Fig. 1.6 A simplified flow diagram of wheat flour milling.

the rollers become progressively finer and the milling gap (distance between
the rollers) smaller.

Wheat kernel breakage in the break system produce particles with dif-
ferent characteristics, such as the size and the level of bran attached to them.
Separating them into different groups based on their size occurs during the
grading stage, which takes place next. Under each pair of rollers a set of
horizontal sieves (plansifters) is placed so that the milled product is graded
according to size. End-products of the break system are bran, germ, coarse
endosperm particles (known as semolina) and a certain amount of flour.
The objective of the following stage – purification – is to separate, in simul-
taneous manner, bran and germ from endosperm particles based on differ-
ences in shape, size, air resistance and specific gravity.The purifier is basically
an inclined sieve that becomes coarser from head to tail, which is oscillated
and through which an air current passes upwards. The heavier particles of
endosperm remain on the sieve until they reach openings big enough for
them to fall through, while the air currents lift out the lighter branny
material and convey them out of the system (Webb and Owens, 2003). The
purification system separates the incoming mixture of material into (i) pure
endosperm, (ii) endosperm particles to which some bran is attached, bran
particles to which some endosperm is attached, and (iii) germ particles,
some of which are pure and some attached to bran. Material from the sifters
and purifiers is directed to the sizing rolls in the sizing system. The purpose

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28 Cereal grains for the food and beverage industries

of the sizing stage is to slowly and carefully separate attached bran and
endosperm without significant reduction of the particles. Sizing rolls can be
smooth or corrugated. Smooth rolls have less capacity than corrugated rolls
but do not cut the bran as much. The number of sizing stages is usually
smaller in flour milling (three stages) than in durum milling (five stages).

The reduction system is the main flour-producing part of the process. It
is also the area where mechanical starch damage is induced, through the
application of share and pressure to the starch granule, in order to increase
the water-absorbing capacity of the flour which, in turn, improves bread
yield. It involves a series of reduction steps in which, as in the case of break-
ing, the rollers are set progressively closer at each successive processing
step. The reduction rollers also operate in pairs. The roller mills used in the
reduction system are usually smooth surfaced and are operated at lower
differential speeds (Scanlon and Dexter, 1986) (4 :5 in Europe or 2 :3 in the
USA and Canada). Each reduction is again followed by a separation stage
using plansifters, which sift the ground material according to particle size.
The reduction process is repeated several times (between six and 10) until
ultimately most of the mealy endosperm is converted to flour. End-products
of the reduction system are mainly fine offals (shorts) and fine endosperm
particles (flour).

1.6.3 Recent developments in commercial milling
The most radical of recent developments has been the advent of debranning
of the wheat before milling (Dexter and Wood, 1996). The technology is
based on the removal the outer bran layers from the wheat kernel prior to
the main milling process. The level of removal of outer kernel layers can
reach up to 8 % depending on the wheat type, while kernel peeling is said
to remove 2–3 %. The debranning step has an additional advantage in that
it extensively removes undesirable bacteria, fungi and insecticide residues.
A recognized benefit of debranning is in the processing of sprouted wheat
in which the starch-hydrolysing α-amylase, associated with the poor pro-
cessing performance of flour produced from sprouted wheat, is more effi-
ciently removed by debranning than by conventional roller milling (Henry
et al., 1987).

The removal of outer layers before grinding results in a significant reduc-
tion in the number of stages in the following milling process as well as in
better flour and semolina extraction (Dexter and Sarkar, 2004). Debranning
lowers capital investment because the mill flow is shortened (the break
system is almost eliminated), permitting more compact plants for a given
capacity.

During debranning, individual bran layers are stripped off in sequence,
whereas all bran layers are removed together by conventional roller milling.
Each bran layer has distinct physicochemical and nutritional properties,
giving debranning by-products great promise as novel food ingredients

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Wheat and other Triticum grains 29

(Dexter and Wood, 1996). Since early in the 1980s, there has been a transi-
tion to mill automation. Computerized process control has reduced labour
requirements in flour mills. So-called ‘lights out’ mills have been constructed
in various parts of the world. A lights-out mill is a highly automated flour
mill where the mill runs for extended periods without staff present in the
mill building. Moreover, some air stabilization systems have been operating
around the world since the 1960s, allowing the control of the ambient tem-
perature and the relative humidity in the mill space. Many millers feel that
a relative humidity of 60 % and a temperature about 22 ºC should be main-
tained in the mill. However, temperature and humidity parameters should
be optimized in accordance with the seasons. Finally, since the 1990s,
demands and regulations by government agencies and consumers have
generated various standard methods for plant inspection and control. The
International Organization for Standards (ISO), the system of Hazard
Analysis and Critical Control Point (HACCP) and Good Manufacture
Process (GMP) were developed to improve processing and hygiene of final
products.

1.6.4 Flour quality
Quality of flour should always be defined from the consumer’s perspective,
never the manufacturer’s. Essentially, quality means satisfying bakers’
requirements for consistent performance from flour. The challenge for
millers is to achieve this while maintaining acceptable performance from
the mill. Flour is the major raw material in bread and fermented goods and
needs to be the same quality all of the time, so that the bakers, in turn,
achieve high manufacturing efficiencies and provide their customers with a
product of consistent quality. Several factors influence flour quality before,
during and after wheat processing (Table 1.7). However, the extraction level
of the process has the major impact on the performance of the flour pro-
duced since it indicates to a significant extent the amount of bran and
mineral contamination of the final flour. Figure 1.7 shows the yields of
wheat flour and its by-products. Extraction rates are calculated as the per-
centage of flour obtained from clean, dry wheat. Table 1.8 lists the defini-
tions of milling products terms commonly used by millers and bakers (Zelch
and Ross, 1989). A composite of all the flours produced by the mill is
referred to as ‘straight flour’ and normally represents about 72–75 % of the
total products. The other products from the mill are named the ‘mill run’
or ‘wheat feed’, i.e. bran (large pieces consisting of pericarp, seed coat,
nucellar, epidermis and aleurone layer), shorts (pieces of endosperm with
bran attached) and germ.

From the point of view of bread-making, the miller must supply flour
that will produce a loaf of bread with the correct crumb structure, volume
and colour, both inside and out. The miller must also supply flour that will
deliver adequate yield, i.e. that has sufficient water absorption, which is

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30 Cereal grains for the food and beverage industries

Table 1.7 Factors influencing flour quality

Before wheat processing
Wheat variety
Presence of impurities
Drying
Storage conditions

During wheat processing
Flow sheet employed
The condition of the roll mills and other processing equipments
Tempering
Atmospheric conditions (temperature and relative humidity)
Extraction level of the process

After wheat processing
Storage conditions (temperature and relative humidity)
Accuracy of sampling and transported flour

Red dog (7 %)

Patent flour (65 %)

Straight flour (72–75 %)

Shorts (12–15 %)

Bran (11–12 %)

Germ (0.5–1 %)

Whole wheat meal of flour (100 %)

20 40 60 80 100
% Extraction

Fig. 1.7 Milling flour of hard wheat and its by-products.

directly linked to bread yield. Water absorption is influenced by the hard-
ness of the wheat kernel and by the blend of different wheats (commonly
known as grist) but also by the amount and type of grinding performed
during milling (Moss et al., 1994). Water absorption in flour is manipulated
by disrupting the starch granules that form the endosperm of the wheat
grain. Roller mills cause more starch damage than pin mills and so are
preferred in mills producing bread-making flours (Moss et al., 1994). A
limited level of damaged starch seems to be necessary in bread-making
formulas containing little or no added sugar. The (partial) hydrolysis of
starch by α–amylase releases maltose, which can then be fermented by yeast

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Wheat and other Triticum grains 31

Table 1.8 Definition of milling product term commonly used by millers and bakers

Milling products Definitions

Bran The coarse outer layers of the wheat kernel that are
Germ separated from the cleaned and scoured kernel. It consists
Shorts mainly of the large pieces of bran remaining after the
Straight flour flour has been extracted from the wheat.
Patent flour
Red dog The most viable portion of the wheat kernel, the embryo
extracted from the grain kernels.
Wholewheat flour
An inseparable mixture of bran, endosperm and germ, which
remains after flour extraction (milling) has been
completed; usually used for animal feed.

A flour milled from the entire contents of the endosperm
available from milling without division or addition of flour
from other runs, excluding only the bran and germ; it is
usually 72–75 % of the wheat kernel.

The most highly refined flour from the front of the mill,
lower in ash and protein with good dress and colour and,
marketwise, is considered highest in value.

Offal from the tail end of the mill together with the fine
particles of wheat bran, germ, and flour. Red dog contains
more floury particles than any of the other types of flour
and feed and has high ash, high protein, poor dress and
dark colour.

Flour prepared by grinding clean wheat kernel and includes
bran and germ.

Sources: Zelch and Ross (1989), US FDA (2003).

to form carbon dioxide, resulting in the dough rising. However, if the level
of damaged starch becomes too high, the dough rheology and baking per-
formance are negatively affected, producing weak crumb side walls and a
sticky crumb. Both colour and ash content reflect the amount of bran
powder present. Generally, the whiter the flour the better the bread-making
properties. This fact is recognized in some countries like in Italy, where the
maximum ash content of soft wheat flours is defined in law. There are three
main categories, defined on a dry solid basis: (i) Flour type OO = 0.50 %,
(ii) Flour Type O = 0.65 %, and (iii) Flour Type I = 0.80 %.

When wheat is blended, before processing, the final product quality is
influenced significantly by the milling process, the environment, and other
variables in the mill. As a result, the quality of the flour is not always within
the specified range expected from the prepared wheat blend. The blending
process can be as sophisticated or as simple as required. In its most basic
form, the flours can be metered together volumetrically using variable-
speed screw conveyors or other dosing equipment on the bottom of the
bins. In more sophisticated batch blending using high-speed batch mixers,
the flour is weighed into the mixer along with any other additions. The final
handling of flour includes addition of additives. These represent the final

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32 Cereal grains for the food and beverage industries

tool available for the millers to help them improve the performance and
consistency of their products. The level of additives is in the range of few
milligrams per kilogram of flour. While flour improvers or enhancers (ascor-
bic acid, enzymes, malt flour, protease, hemicelluloses) can be added at the
maximum levels prescribed by law either at the mill or by the flour end-user,
flour fortification (calcium carbonate to provide Ca ions, Fe, thiamine, nico-
tinic acid) should be the responsibility of the miller. The level and type of
fortification is the subject of governmental regulation.

1.7 Bakery products based on wheat

In the milling process, bran and germ sections of the grain are separated
from the white floury endosperm, which is then reduced to a fine powder
(flour) as previously described. The production of semolina, generally
milled from durum wheat from pasta manufacture, does not required this
second stage of reduction of particle size. The array of foods made from
wheat is enormous, ranging from bread in its different forms, through cakes,
biscuits/cookies and pastries to noodles, Chinese steamed bread and many
types of flat bread (Quail, 1996). Couscous and burghul (bulgur) are further
forms of wheat-based foods; they do not involve complete milling, but
pearled or broken/cracked wheat grains are used. Table 1.9 shows the main
ways in which cereals and pseudo-cereals are eaten. Only two cereals, wheat
and rye, are suited to the preparation of leavened bread. All cereals are
consumed as whole grains, porridge and unleavened bread. All cereals are
also used to make fermented/unfermented drinks such as whiskey and beer
(barley, sorghum), vodka (wheat), American bourbon (rye), Japanese sake
(rice), often by toasting the grain first.

Table 1.9 Main ways in which cereals and pseudo-cereals are eaten

Cereal Whole Porridge Leavened Unleavened Beer Snack Starch
baked goods baked goods Spirits Breakfast Glucose

Wheat + + + + ++ +
Rye + + +
Rice + ++
Maize +
Sorghum + + ++
Millet + +
Teff + ++ +
Oats + +
Barley + ++
Amaranth +
Quinoa + +
Buckwheat +
++

++

+

+

+

+

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Wheat and other Triticum grains 33

Wheat is closely associated with human food uses. It is estimated that
nearly two-thirds of wheat produced in the world is used for food; the
remaining one-third is used for feed, seed and non-food applications. In
many countries, wheat is the major component of the diet. It has a good
nutritional profile and allows the manufacture of a wide variety of interest-
ing, enjoyable and satisfying products. These products require flour of
selected characteristics which are achieved through a proper balance of
grain hardness and protein content. So for the production of cake, biscuits
and pastry, soft wheat flour with a protein content less than 10 % is sufficient
while, on the other hand, durum wheat flour with protein content between
14 and 15 % is required for the production of pasta. For bread production,
wheat flour with a protein content between 12 and 13 % is necessary in
order to obtain a final product with high volume, texture and structure.

Bread has been a staple food for many cultures across the world. It is
one of the earliest ‘processed’ foods made and consumed by humankind.
Archaeological evidence indicates that a relatively sophisticated bread
manufacturing ‘industry’ had developed in Egypt more than 5000 years ago
(3000 BC) to provide nourishment for the substantial labour force neces-
sary to build pyramids and other structures. The production of wheat loaf
bread was considered by Romans to be a sign of a high degree of civiliza-
tion and a sign of outstanding power. Indeed, the control of the production
(Coulton, 2010) and distribution (Veyne, 1990) of bread has been used as
a means of exercising political influence over the populace for at least the
last 2000 years. Nowadays, baked goods are still at the basis of the daily diet
in many countries and bread, considered the ‘staff of life’, still plays an
important role, of religious significance in the sacred rituals of many cul-
tures (Powers, 1967; Kahn, 1984). Despite obvious increases in the size and
scope of the bread-baking industry, the historical record has revealed that
ancient bread-making is not all that different from modern bread manufac-
turing practices. Given the simplicity of the process, perhaps this observa-
tion is not surprising.After all, bread-making requires only a few ingredients,
a few simple mixing and incubation steps, and an oven for baking. The
proliferation of bread varieties is mainly due to the unique properties of
wheat proteins to form gluten and to the bakers’ ingenuity in manipulating
the gluten structures formed within the dough. The unique properties of the
proteins in wheat with their ability to form a cohesive mass of dough once
the flour has been hydrated and subjected to the energy of mixing, even by
hand, provides the basis of the transition from flour to bread. Of all the
cereals, wheat is almost unique in this respect.

The minimum formula for bread production consists of flour, water, yeast
and salt. However, as people have learned over time, only two ingredients
are absolutely necessary to make a palatable loaf of bread, those being
wheat flour and water. As time went by, humans discovered that salt and
yeast added flavour and lightness to the bread. Wheat flour, in combination
with water, can form a strong gluten network able to trap the gas produced

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34 Cereal grains for the food and beverage industries

by yeast of baking powders. Water is not only important for forming a
gluten network in dough, but also for modifying dough properties and
improving the solubilization of flour constituents. In Fig. 1.8 is possible to
observe the evolution of the structure of the starch granules and gluten
from flour to the final bread. During dough development, the gluten network
covers the starch granules (Fig. 1.8b). In bread, it is possible to observe the
crumb matrix interrupted by holes of different size (Fig. 1.8c).Yeast, other
than affecting the rheological properties of dough, is needed to convert
fermentable carbohydrates into carbon dioxide and ethanol. The gas that
results from this conversion provides the lift that produces a light, leavened
loaf of bread. Salt contributes to taste and affects a dough’s rheological
properties and the shelf-life of the final product. The main functions of
bread ingredients are reported in detail in Table 1.10. Today, non-essential
ingredients are used in bread-making to meet the demands of the modern
consumer, namely, longer shelf-life, better flavour, softer texture and other
physical and sensory improvements. When contemplating their use in
bread-making, it would be wise to bear in mind that: (i) each non-essential
ingredient has a specific function and an optimum level of use, (ii) they can
only be used in carefully balanced combinations to compensate for minor
variations and deficiencies in flour quality and/or in plant and processing
conditions.

1.7.1 ‘Dough-making’ processes
Bread owes its uniqueness not only to the ingredients and equipment used
in its manufacture, but also to the different processes by which dough is
made.The dough-making process is the key to producing quality dough and,
thereby, bread with good-quality crumb texture and structure. The bread-
making process can be divided into three basic operations: mixing or dough
formulation (preparation, weighing, mixing), fermentation/dough process-
ing and baking (Fig. 1.9). Different procedures can be used. The processing
stages, which occur after dividing the bulk of the dough, such as shaping,
proving, weighing and baking, are largely common to all bread-making
processes and so the main differences in the bread-making process are
related to the methods which are used to produce a developed dough ready
for dividing and further processing. In the next paragraphs, the straight-
dough, sponge-dough, liquid-sponge, Chorleywood and sourdough bread-
making systems are briefly described.

Straight dough process
As shown in Fig. 1.10, this a simplest bread-making process whereby all the
formula ingredients are mixed into a developed dough which is then allowed
to ferment for a period of 1–4 h, during which the dough is usually punched
at least once. After the fermentation period, the dough is divided into loaf-
sized pieces, rounded and moulded. The dough is then given an additional

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Wheat and other Triticum grains 35

5 kV ×2, 000 10 μm AMRF, UCC
(a)

5 kV ×1, 500 10 μm AMRF, UCC
(b)

5 kV ×1, 500 10 μm AMRF, UCC

(c)

Fig. 1.8 Scanning electron microscope (SEM) micrographs (1500/2000x) of wheat
flour starch granules of irregular shape (a); blanket-like covered starch granules in

dough (b); and air holes in bread (c).

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36 Cereal grains for the food and beverage industries

Table 1.10 Function of essential/non-essential bread ingredients

Ingredients Function(s)

Essential ingredients

Wheat flour Forms structure and provides body

Contributes gluten-forming protein

Contributes to the gas-retention properties of the dough

Contributes starch for heat-induced formation of crumb

Water Hydration damages starch and proteins in the flour

Promotes the solubilization and dispersion of ingredients in the

dough

Contributes to the formation of gluten in dough

Controls dough temperature

Contributes to shelf-life

Salt Contributes to product flavour

Controls product water activity

Contributes to the spoilage-free shelf-life

Strengthens the gluten network

Controls fermentation rate

Yeast Provides leavening

Metabolizes fermentable sugars into carbon dioxide and ethanol

Fermentation products contribute to bread flavour

Non-essential ingredients

Sweeteners Contribute to the gas-producing ability of yeast

Enhance flavour of product

Affect the water activity of the product

Confer sweetness and colour (Maillard reaction) to the product

Act as product tenderizers

Affect the gelatinization temperature of the starch

Contribute to the spoilage-free shelf-life

Shortening Contributes to expansion of gas cell in dough

Lubricates dough system

Tenderizes the crust

Dairy products Contribute to the crust colour

Provide dough buffering

Enhance flavour of product

Enhance the nutrition profile of product

Wheat gluten Improves water absorption

Provides greater baked loaf volume

Strengthens the dough

Enzymes Improve dough rheology, gas retention (α-amylase), crumb

softness

Contribute to the anti-staling effect (α-amylase)

Improve bread volume (zylanases, lipases)

Shorten dough mixing time (protease)

Strengthen dough (glucose oxidase, xylanase)

Extend shelf-life (amylases)

Preservatives Retard bacteria/mould growth

Contribute to shelf-life

Fibre Improves nutritional/sensory properties to the bread

Solid fat Improves the gas-retention properties of the dough

Inhibits the gas-bubble coalescences

Contributes to crumb softness

© Woodhead Publishing Limited, 2013

© Woodhead Publishing Limited, 2013 Process stage Raw material additive Process function
Intermediate products
Preparation Raw materials and additives Flour ageing
Weighting and metering Solubilization/dispersion of raw
Mixing Flour, water, yeast-suspension, materials and additives
salt-solution, additive
Moist curing/solubilization/swelling
Dough Gluten network formation
Enzymolysis
Dough-processing Mature dough
Moulded dough piece Swelling
Final stage of dough network formation
Baking Mature dough piece Gas-cell formation
Maturation of baked products Baked product Formation of aroma and flavour by fermentation

Baked product for consumption Orientation of gluten structure to final shape

Gas-cell formation
Aroma and flavour formation by fermentation
Ezymolysis
Cell formation/crumb formation from
denaturated protein and starch/crust formation
Flavour form ation by non-enzymic browning
Loss of part of the water by evaporation
Loss of steam/water migration
Flavour migration/loss of aroma volatiles
Retrogradation of various components
Energy loss

Fig. 1.9 Relation between the processing stages and the changes in the composition and structure of various dough
components.

38 Cereal grains for the food and beverage industries

Straight dough Sponge dough Liquid sponge
process process process

All Flour, yeast, Flour, yeast,
ingredients water water
Sponge
Mixer mixer Liquid sponge
10–25 min 2–4 min mixer

Bulk Sponge Fermentation
fermentation fermentation tank 1–3 h

1–4 h 3–4 h Heat
Remaining exchanger
Divider ingredients
Refrigerated
Rounder Horizontal holding tank
mixer Remaining
Intermediate ingredients
proofer 8–20 min Horizontal
2–15 min Floor time
0–30 min mixer
Sheeter 8–20 min
Divider
Moulder Divider
Rounder
Proofer Rounder Oven 16–30 min
50–60 min Intermediate
proofer Intermediate Proofer
Oven 2–15 min proofer 50–60 min
16–30 min 2–15 min Moulder
Sheeter
Oven Sheeter
Moulder 16–30 min

Proofer
50–60 min

Fig. 1.10 Bread-making systems: straight dough process, sponge-dough process
(US pan bread), liquid sponge process.

fermentation in order to increase its size. After the dough has reached the
desired size, it is placed in the oven and baked. The bread made using this
process has coarser cell structure than any of the other processes, and it is
generally considered to have less flavour.

Sponge dough process
This process is the most popular in North America. In this process, part of
the dough formulation receives a prolonged fermentation period before
being added back to the remainder of the ingredients for further mixing to
form the final dough (Fig. 1.10). After mixing, the dough is given an inter-
mediate proof for 20–30 min (flour time). The flour time allows the dough
to relax. It is then divided, moulded and proofed as is done in the straight-
dough process. The bread made using this process has fine cell structure,
and it is generally considered to have well-developed flavour.

Liquid sponge process
The liquid sponge process can be viewed as a modification of the above two
procedures. In this process, the fermentation is carried out when the dough

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Wheat and other Triticum grains 39

is in a liquid state instead of a sponge. The chilled liquid sponge is directly
pumped to the dough mixer with a reduction of the processing time. Nor-
mally, the fermentation time is shorter than for sponge dough, usually in
the order of 60 min to 3 h (Fig. 1.10).

Chorleywood process
In the Anglo-Saxon countries, and particularly in Great Britain, the Chor-
leywood bread-making process is widely utilized. Developed in the 1960s
by the British Baking Industries Research Association (Martin et al., 2004),
this process is used worldwide to produce bread from lower protein flours.
It is characterized by a drastic reduction of the proofing time due to intense
mixing, sometimes with partial vacuum in a Tweedy mixer, that ensures the
inclusion of a large quantity of air into the dough mass. After the mixing
process, the developed dough is sent to the successive steps as described in
Fig. 1.11.

Sourdough process
The sourdough process can be considered, without doubt, one of the most
delicate and complex transformations found in food technology. This
process is the oldest and most time-consuming among the methods dis-
cussed, and is used to produce breads, among other products, with rich and
complex flavours and textures. Sourdough bread-making processes are still
widely used in northern Europe and in Italy. Sourdough is a mixture of flour
and water fermented with lactic acid bacteria (LAB) and yeasts, which
determine its characteristics in terms of acid production, aroma and leaven-
ing (Hammes and Gänzle, 1998). Sourdough is a unique food ecosystem in
that it selects for LAB which are adapted to the environment and hosts
LAB communities specific for each sourdough (De Vuyst and Vancanneyt,
2007). Sourdoughs are generally classified in three types: type I, type II and
type III (Böcker et al., 1995). Type I sourdough is characterized by continu-
ous daily propagation, which keeps the microorganisms in an active state.
Type II are semi-liquid doughs fermented at high temperatures (> 30 °C)
for long periods (from two to five days), often used in industrial processes
as souring supplements. Type III sourdoughs are dried sourdoughs initiated
by defined cultures of LAB resistant to the drying process. Sourdough
technology has been mainly used for wheat and rye bread production.
Figure 1.11 reports the pane di Altamura bread-making procedure as an
example of the sourdough process, Altamura being a small town not far
from Bari. The Altamura bread is a typical sourdough (type I) bread from
the Apulia region and was the first bread in Europe to be recognized with
the label of Protected Designation of Origin (PDO) (European Commis-
sion, 2003).

The list of bakery products in the world is endless, and it would be impos-
sible to describe all of them. Suffice to say that if there are four bakers in
a town, there will be four different kinds of bread. This is due to the fact

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40 Cereal grains for the food and beverage industries

Chorleywood process Sourdough process

All Mother dough,
ingredients sourdough

Tweedy mixer Flour, water
3–5 min
Mixer
Divider First refreshment

Rounder Bulk Oven
fermentation 16–30 min
Intermediate
proofer 90 min Resting,
2–15 min 30 min
Flour, water
Sheeter Weighing,
Mixer 2nd
Moulder Second
refreshment shaping
Proofer
50–60 min Bulk Resting,
fermentation 30 min
Oven
16–30 min 90 min Weighing,
Flour, water 1st,

Mixer shaping
Third
refreshment

Bulk
fermentation

90 min

Flour, water,
salt

Mixer

Bulk Final dough
fermentation

90 min

Fig. 1.11 Bread-making systems: Chorleywood process and Sourdough process.
This latter represent the flow sheet and operation of the pane di Altamura (PDO)

bread-making.

that the secret of bread-making does not lie in the recipe but in the way
the product is actually made. Unlike botany and zoology, there has never
been a clear and specific taxonomy of baked products. This is also due to
the difficulties associated with translation from one language to another of
the terms and descriptors used for the products and their associated baking
processes. The classification of baked products can be based on a number
of criteria such as:

• leaving action, i.e. (i) biological leavened (yeast, sourdough bakery prod-
ucts), (ii) chemical leavened (soda bread, cookies) and (iii) physical
leavened (air/steam-leavened bakery products) (Campbell, 2003);

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Wheat and other Triticum grains 41

Savoury baked Sweet baked products
4.8 products

4.5 Bread Panettone Pandoro Sponge dough Soft/light baked products Crisp/friable baked products
4.2 (serving-size products, cakes)

3.9

3.6 Pan bread, Muffin, scone
buns, rolls

Specific volume [mL/g] 3.3
Puff or Danish pastry

3.0 (Croissant type)

2.7 Flat bread
(chapati, pitta, tortillas)

2.4

2.1

1.8

1.5

1.2 Cookie

0.9 Cracers, breadsticks Composite cake
0.6 (pane carasau) (wafer)

0.3

0.0
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100

Units of sugar to 100 units of flour

Fig. 1.12 A two-dimensional representation of bakery products based on ratio of
sugar to flour in the recipe and the texture properties (specific volume) of the final

product.

• specific volume, i.e. baked products with (i) high specific volume (pan
bread), (ii) medium specific volume (French bread, rye bread) and (iii)
low specific volume (flat breads) (Faridi and Faubion, 1995);

• ratio of sugar/flour and fat/flour (Cauvain and Young, 2007).

One of the simplest and most common classification schemes used in the
bakery sector is shown in Fig. 1.12 where baked products are plotted using
a two-dimensional diagram in which the x-axis shows the ratio of sugar to
flour in the recipe and the y-axis the texture properties (specific volume
mL/g). A product is said to be ‘light’ if its specific volume is higher than
2.5–3 mL/g, while a quantity of sugar equal to 10 % of the weight of the
flour conventionally represents the minimum threshold for classifying a
product as sweet (Pagani et al., 2007). However, it should be stated that
bakery products cannot be categorized in discretely-defined groups clearly
separated from one another by rigid rules. Indeed, many new products are
successful in the market because they break the conventional rule sets that
have evolved to define particular product areas. In countries where the
artisan baker is popular and the preferred place of purchase, like Italy,

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42 Cereal grains for the food and beverage industries

France, Belgium and Switzerland, it is possible to find a vast choice of
quality breads and sweet baked products, while in countries where the
industrial bakers dominate the market, such as the Netherlands, the UK
and the USA, products of mediocre quality and at relatively low price
dominate the bakery products sector. Figure 1.13 shows an overview of the
most interesting, well-known and appreciated breads and sweet baked
goods based on wheat flour produced in different European countries. The
reader is warned that some names are used variously in different regions
or communities, and those recipes and formulations vary, so the representa-
tion given in Fig. 1.13 is approximate and indicative rather than prescriptive
or authoritative. It is also incomplete.

1.8 Durum wheat products

Durum wheat products include most famously pasta in all its forms, but also
breads, couscous, bulgur and frekeh as well as noodles.

1.8.1 Pasta
Pasta is known as one of the most ancient nourishments and is a very ver-
satile dish, both from the nutritive and the gastronomic point of view
(Antognelli, 1980). There are very few documents attesting to the true
origin of pasta products and this therefore remains the subject of specula-
tion. A product similar to the current lasagna (derived from the Latin
lagana, meaning ‘fine sheet of dough’) was known to both the ancient
Romans and to the Etruscans (Serventi and Sabban, 2002). However, it
is possible to find documents about this food and references to it only
from the twelfth century onwards. The Arab geographer Al-Idris reported
the existence of the production of dried pasta in the Muslim Sicily. It
further moved up the Tyrrhenian coast, from Naples to Genoa, thanks to
its long-term preservation properties. In 1800, a mechanical device for
making pasta appeared in Italy (Banasik, 1981). The crucial ingredients of
pasta are semolina and water. All the other ingredients, such as eggs for egg
noodles or egg spaghetti, are optional and can be of greater or lesser
importance.

Semolina is simply larger-sized pieces of endosperm (130–550 μm, larger
than those found in flour), which are free of adhering bran. Semolina pro-
duces a strong and elastic dough that can easily be modelled into different
shapes because of the high level of gluten. To produce pasta, semolina is
first mixed with water in an approximate ratio of 30 :100 (water: semolina)
in a continuous, high-capacity auger extruder, which can be equipped with
a variety of dies that determine the shape of the product. After extrusion,
it is then dried and packaged for sale (Fig. 1.14).

© Woodhead Publishing Limited, 2013

snúoˇ ur Kanelbulle Setsuuri, Rieska
Iceland Smorgastarta Pulla

Sweden

Flatbrod, Lefse Finland

Stotty, Plain bread Norway

© Woodhead Publishing Limited, 2013 English muffin, Scone Morgenbro/ d, boller Doppelweck, Laugenbrezel, Semmel, Weissbrot
Soda bread, Brown bread
Babka
Barm brack Denmark Roggenmischbrot, Mohnfloesserl,
Semmelknoedel
Ireland Pannekoek Poland Strudl, Sachertcate, Linzertorte,
Waffles, Boterpistolets, Pain à la Grecque, Mastel United Kaiserschmarm–Germknoedel,
Kingdom Neth Buchteln
Crèpes, Baguette, Pain briare, La boule, Pain tradition,
Pan de mie, Fouace Bel.Germany Vazsonyi

Swiss roll, Zopf France Switz Austria Hungary Yuflka, Pide
Coca, Bimbo, Barra de pan, Tortillas, Italy
Bocadillo Turkey
Tsoure
Pao Alentejano, Broa da Covanca, Portugal
Fogacas de Palmela, Pao NAN,
Pao saloio, Regueifa

Pao de Lo, Tortas de Azeitao, Spain Greece
Pasteis de Feijao, Pasteis de Tentugal,
Azevias, Folar

Altamura bread, Chestnut bread, Carasau bread, Toscany bread, Focaccia, Pandoro, Veneziana, Baba,’ Cantucci di Prato, Panettone basso,
Ciabatta, Piadina, Pizza Panettone, Colomba

Fig. 1.13 Names of the most famous and appreciated breads (black colour) and sweet baked products (light grey) in Europe.

44 Cereal grains for the food and beverage industries

Semolina Water

Dosage and mixing
Kneading

Extrusion/sheeting

Drying Water

Dried pasta

Packaging
Fig. 1.14 A simplified flow diagram of pasta-making process.

Mixing, kneading and drying are critical steps to successful pasta manu-
facture. The protein must form a continuous matrix to entrap the starch
granules so that the pasta surface does not become sticky during cooking.
Useful parameters for identifying the different kinds of pasta are: (i) mois-
ture content (fresh pasta HR >24 %), stabilized pasta, HR ≤20 %, dried
pasta, HR ≤12.5 %); (ii) formulation (semolina pasta, egg pasta, special
pasta, stuffed pasta, dietetic pasta and gluten-free pasta); (iii) shape (short
pasta, long pasta, sheeted pasta and ‘Bologna’ style pasta); and (iv) con-
venience (precooked and frozen pasta, precooked–canned–frozen pasta
with sauces). In contrast to noodles, pasta is prepared from durum wheat
semolina. Although Italian in origin, pastas, such as spaghetti, macaroni,
lasagna and fettuccine, are now a common part of culture and language in
the USA and worldwide. Some pasta products contain fillings, such as tortel-
lini and ravioli with cheese, vegetables or meat. With an approximate

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Wheat and other Triticum grains 45

consumption of 26 kg per capita/year, pasta plays a crucial part in the Italian
diet, providing significant quantities of complex carbohydrates, proteins,
B-vitamins and Fe and low in Na, amino acids and total fat (Douglass and
Matthews, 1982). Pasta’s versatility, long shelf-life in dry form, availability
in numerous shapes and sizes, high digestibility, good nutritional profile and
relatively low cost are increasingly attractive to consumers as they become
more concerned about their health. Many countries produce, export and
import pasta. About 12.8 million tonnes of pasta are produced worldwide.
Italy currently dominates world pasta production, manufacturing more than
3 million tonnes annually. Italy is followed by the USA and Brazil, produc-
ing about 2.5 and 1.3 million tonnes,respectively (http://www.pasta.unfpa.org
2010).

1.8.2 Other durum wheat products
The major durum wheat products other than pasta include bread, couscous,
bulgur and freekeh. Durum bread is prepared from durum flour rather than
semolina. Compared to soft wheat flours, durum wheat flours have stronger
gluten with lower extensibility, higher dough stability, a greater level of
starch damage, higher water absorption capacity and coarser, larger parti-
cles. Durum flour has also a yellow colour. Due to its greater water absorp-
tion capacity, durum bread stales much more slowly and consequently has
a longer shelf-life than wheat bread. Depending on the country and the
amounts of other flours in the blend, several types of bread are made from
durum wheat. Two-layered bread, Khobez, is the most popular bread in
Syria, Lebanon and Jordan. In Egypt, two-layered bread is called Baladi
and Shami. Single-layer breads are also popular, including Tannur and Saaj
(Syria and Lebanon), Markouk (Lebanon) and Mehrahrah (Egypt) (Gordon
and Nancy, 2010). In Turkey, flat bread, Tandir Ekmegi, is made from durum
wheat. Several kinds of durum wheat bread are also produced in Italy,
particularly in the Apulia region (Sada, 1982), such as Fresedde, Frasella,
Cafone, Rote and Sckanate.

Couscous, a paste product made from mixing semolina with water, is
considered one of the major food staples in Egypt, Libya, Tunisia, Algeria
and Morocco. Couscous is prepared from semolina by hydrating, shaping,
steaming, drying, cooling and grading the resultant particles. Couscous is
then rehydrated with oil and meat and/or vegetable sauce when eaten.
Bulgur is used as a main dish or as one of the ingredients in most meals
consumed in Turkey, Syria, Jordan, Lebanon and Egypt. It is prepared from
whole or cracked kernels by soaking in water, parboiling, drying and milling
in three or four size grades: coarse, fine, very fine and flour. Prior to eating,
bulgur is boiled or steamed. Coarse bulgur is cooked and eaten in a similar
way to rice. Fine bulgur is mixed with meat or poultry. Frekeh is a staple
food in North Africa and the Middle East, especially Syria. Frekeh is parched
green wheat that is used in the same way as rice, bulgur and couscous.

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46 Cereal grains for the food and beverage industries

Frekeh is either boiled or steamed and served with lamb or poultry. In many
villages in Northwestern Syria, frekeh is one of the most important sources
of income (Williams and El-Haramein, 1985).

1.8.3 Noodles
Noodles have been the staple foods for many Asian countries since ancient
time. They can be made from wheat, rice and other raw materials such as
buckwheat, and starches derived from potato, sweet potato and pulses.

Wheat noodles are produced mainly from flour, water and salt, and the
basic steps of noodles production include dough mixing, sheeting, combin-
ing of sheets, resting, rolling and cutting, followed by different processing
treatments (drying, boiling, steaming, frying and freezing) or a combination
of these.

Noodles may be generally classified based on; (i) raw materials such as
wheat and non-wheat noodles; (ii) salt composition (presence or absences
of alkaline salts mainly Na2CO3 and/or K2CO3); (iii) manufacturing process
(fresh, semi-dried, dried, boiled, steamed, steamed and hot-air dried noodles,
steamed and deep-fried instant noodles, frozen boiled noodles and steril-
ized boiled noodles); (iv) noodle size (rectangular or square cross-section)
(Fu, 2008). In wheat noodles, the unique properties of gluten and starch
significantly influence the structure of final product. The level of amylose
in the wheat starch affects the texture of the noodles. In this regard, Guo
et al. (2003) showed that noodle processing and textural (eating) qualities
of Asian salted noodles were significantly affected by the amylose content,
indicating 21–24 % as the optimal amylose percentage.

Protein content is positively correlated with noodle firmness and some-
times negatively correlated with elasticity. Thus, a correct range of protein
content is important for textural characteristics (Park and Baik, 2004; Zhao
and Seib, 2005). Its range varies accordingly to the type of noodles pro-
duced, such as white salted noodles (8–11 % protein), yellow alkaline
noodles (9–13 % protein) and instant noodles (8.5–12.5 % protein). Dried
noodles generally require higher protein content than that for fresh or
boiled noodles, since the noodles must be able to resist the drying process
without breakage. Wheat noodles nomenclature based on origin, salt com-
position and processing method is summarized in Table 1.11.

Depending on the type of end-product, the wheat flour should also have
a particular degree of refinement as measured by ash content. High ash
content normally leads to greyer noodles with a higher tendency to darken
during dough processing while low ash levels are preferred for the manu-
facture of noodles that retain a clean, bright appearance after cooking
(Crosbie and Ross, 2004). Most noodle flours require ash content below
0.5 %, but premium quality noodles are often made from flours of 0.4 % or
less ash.

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Wheat and other Triticum grains 47

Table 1.11 Classification of wheat noodles

Country Salt composition Processing methods

Noodle type of region Alakaline Nonalkaline Fresh Dried Steamed Boiled

Udon Japan + ++
So-men Japan + ++
Hiya-mugi Japan + ++
Hira-men Japan ++
Gua mian China + ++
Mee sua SE Asia + + ++
Mee teow SE Asia + + ++
Ramen Japan
Chukamen China + +
Yahisoba Japan + +
+ +
(Kata-Yakisoba) Japan
Chinese noodles Asia + + +
Cantonese SE Asia
Hokkien mee China + + +
Xiam Mian SE Asia + + +
Mee pok SE Asia +
Mee kia SE Asia +
Wanton mee
SE Asia +
– Singapore
style Thailand +
Wanton mee SE Asia +
– Hong Kong
style
Bamee
Instant steamed
and fried

Additionally, the presence of enzymes such as α-amylase, protease and
polyphenoloxidase is particularly problematic for fresh noodles, altering the
cooked noodle texture (α-amylase, protease) (Cato et al., 2006) and colour
(discolouration) (polyphenoloxidase) (Gordon and Nancy, 2010).

1.9 Products based on other types of wheat

Products are also made from other types of wheat, including emmer wheat,
einkorn wheat and spelt.

1.9.1 Emmer wheat products
Emmer wheat (T. turgidium var. dicoccum) is the evolutionary precursor to
durum wheat and has traditionally been grown in arid areas. Its main use
is for human food, though it is also used for animal feed (Marconi and
Cubadda, 2005). Nowadays, it is mainly grown in Italy, Spain,Turkey,Austria

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48 Cereal grains for the food and beverage industries

and the Czech Republic. Increasing interest in natural and organic products
has led to the ‘rediscovery’ of emmer, mainly thanks to its suitability for
preparing many different foods. Whole, pearled, broken kernels can be
included in many different dishes and its semolina and flour can be used to
make biscuits, pasta and bread. These latter, when combined with legumes,
represent an ideal meal for vegetarians because emmer contains high levels
of fibre, protein, minerals, carotenoids, antioxidant compounds and vita-
mins. Moreover, Galterio and colleagues (1994) reported a higher lysine
content (3.1 %) in emmer grain than that normally encountered in wheat
(2.9 %). Emmer wheat baking studies conducted as early as 1918 indicated
that some emmer lines had baking qualities superior to that observed in
durum wheat (LeClerc et al., 1918). However, the quality of emmer bread
is not as good as bread made with common wheat. This is mainly due to the
poor quality of its gluten compared with that of wheat (Galterio et al., 1994).
Emmer bread is widely available in Switzerland and found as pane di faro
in bakeries in some areas of Italy. In response to the growing health food
market, emmer pasta has also been produced, though the texture of final
product has been judged as unattractive. In some rural areas of Italy and
Iran, emmer is used like rice. Hard porridge is also produced by mixing
emmer bulgur with boiling water and butter.

1.9.2 Einkorn wheat products
Einkorn (T. monococcum) was likely the first domesticated hulled wheat.
It was one of the founder grain crops of Neolithic agriculture in the Near
East, and a principal species in the early stages of crop introduction to
Europe. However, since the Bronze Age, its importance declined gradually
and it is now a relic crop, only being sporadically grown in marginal moun-
tain areas of the Mediterranean region, Turkey, Morocco, Balkan countries,
Spain, southern Italy and France. The grains are often used for animal
feeding. As a result of this abandonment, the technological properties of
einkorn wheat have been the subject of only a very few fragmentary inves-
tigations. Prior to 1920, einkorn flour was known to have poor dough mixing
and baking properties and so the grain was mainly pearled for use in soups
salads, casseroles and sauces (Percival, 1921). However, in recent years the
trend towards low-impact and sustainable agriculture coupled with a
stronger interest in the ancient cereals like einkorn has increased, particu-
larly with regard to their use in speciality bakery products and organic
foods.

The renewed nutritional interest in this cereal is related to its high
protein and yellow pigment contents (Borghi et al., 1996; Corbellini et al.,
1999), as well as its putative low allergenicity (Molberg et al., 2005). Einkorn
is also characterized by a lipid fraction rich in monounsaturated fatty
acids. The yellow pigments, as in other wheats, consists mostly of lutein
(Abdel-Aal et al., 2002); in whole einkorn flours, lutein content is around

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Wheat and other Triticum grains 49

8.5 mg/kg (dm) with an average value four times higher than bread wheat
(Abdel-Aal et al., 2002). Degidio et al. (1993) compared the flour and dough
characteristics of 12 einkorn varieties to those of durum and common
wheats. The einkorn flours were characterized by high protein, high ash,
very high carotene contents and small flour particle size when compared to
the modern bread wheats. Dough characteristics of the einkorn accessions
were significantly inferior to those of the modern wheats.The gluten strength
was similar to that of soft wheat, but the dough remained sticky, with a low
water retention capacity. White breads made from einkorn were considered
to be inferior to emmer or spelt breads (LeClerc et al., 1918; Bond, 1989).
Corbellini (1999) stated that the breads made from einkorn white flour
following standard micro-baking tests showed a broad volume variation,
ranging from very poor to outstanding with the finest samples comparing
favourably with the best bread wheat. Even if only some einkorn genotypes
are suitable for bread-making, all the varieties show excellent suitability for
the preparation of other bakery products, such as biscuits and pastry.

1.9.3 Spelt products
Spelt (Triticum aestivum subsp spelta) is a primitive wheat. Until the begin-
ning of the 20th century, it was the main grain used for bread production
in south-western Germany and parts of Switzerland and Austria. Currently
it is cultivated in several central and middle European countries such as
Belgium and Germany, covering 10 000 and 23 000 ha, respectively (Statis-
tisches Bundesamt Deutschland – 2008, http://www.destatis.de). In agro-
nomic terms, spelt was found to perform well under suboptimal growing
conditions (Ruegger et al., 1990), and to better utilize nutrients when grown
in a low-input system (Moudrý and Dvorˇáček, 1999), and it shows more
resistance to number of pathogens (Kema and Lange, 1992) than common
wheat.

Over the past few decades spelt has attracted renewed and increasing
interest as human food due to its image as a ‘healthier, more natural, less
‘over-bred’ cereal than modern wheat. For example, in Canada organic spelt
is used to make a diverse array of bread and pastry products, which are
favourably perceived by consumers. Spelt has a higher protein (18–40 %)
content than wheat (Abdel-Aal et al., 1995; Bonafaccia et al., 2000); however,
its lysine content is lower. Compared to its wheat parent, spelt is also char-
acterized by a higher lipid content, especially in Δ7-avenasterol (Ruibal-
Mendieta et al., 2002) and higher zinc, iron, phosphorus, copper and
magnesium contents (Ruibal-Mendieta et al., 2005). The common method
of consuming spelt is as bread and baked products because it is a hexaploid
wheat (42 chromosomes) with rheological and technological properties
close to those of soft wheat. Baking qualities of spelt cultivars available in
the early 1900s were evaluated by LeClerc et al. (1918).The authors reported
that good loaves of bread could be produced from spelt flours. However,

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50 Cereal grains for the food and beverage industries

making bread from spelt flour requires adapted baking methods. As far as
baking procedures are concerned, those for wheat flour breads cannot be
directly applied to spelt flours whose dough, after kneading, is very soft and
sticky; handling it is therefore more difficult, although it becomes firmer
over time, Therefore, a long resting time and, consequently, a long fermenta-
tion at moderate temperature are required. Finally, the loaf volume is
generally lower than with modern wheat cultivars (Schober et al., 2002).
However, the technological potential of spelt for milling and bread-making
seems promising (Bonafaccia et al., 2000; Schober et al., 2002). Evaluations
of spring spelt varieties for bread and pasta products have been conducted
in Canada (Hucl et al., 1995). Results indicated that spelt flours treated with
an oxidant produced loaf volumes similar to bread wheats.

Spelt can also be successfully used for pasta making. Marconi et al. (1999)
showed that spelt could be successfully used in the preparation of alimen-
tary pasta and that its pasta-making potential was not directly dependent
on the cultivar, but rather on protein content and the drying technologies
adopted. A further investigation into spelt pasta quality elucidated that, as
long as the protein content is >13.5 % (corresponding to ~15 % protein
content in grains) and high drying temperatures are used, spelt flours can
be processed in manufacturing pasta with satisfactory cooking quality
(Marconi et al., 2002). Spelt products are available through organic health
food stores as grain, whole-grain and white flours, and processed products.
The processed products available include assorted pasta, cold and hot
cereals, and pre-packaged bread, muffin and pancake mixes.

1.10 Beverages based on wheat

A variety of alcoholic beverages can be produced from wheat.These include
wheat beer, beers made from emmer wheat and spelt and the Egyptian
bouza.

1.10.1 Wheat beer
The term beer refers to any drinks that are produced by the fermentation
of sugar derived mostly or entirely from malted cereal and flavoured with
hops. The production of beer is tied to three consecutive biochemical pro-
cesses: the formation of enzymes in germinated grain, the breakdown of
starch to sugar by these enzymes and the resulting fermentation of the sugar
to alcohol and carbon dioxide. A detailed description of the basic stages of
brewing is presented in Chapter 4 on barley, the most important cereal used
in brewing. Wheat is the second most important cereal used in brewing.

In recent years, an increasing number of wheat beers have been pro-
duced worldwide (Mejlholm and Martens, 2006). Moreover, many beers are
brewed from wort to which some malted wheat is added during processing

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Wheat and other Triticum grains 51

(Depraetere et al., 2004; Lu and Li, 2006). However, the term wheat beer is
generally used to indicate only those beers that have sufficient malted
wheat to give a recognizable wheat character (≥40 %).

Wheat varieties characterized by a low protein modification and low
viscosity during the brewing process are particularly indicated for the pro-
duction of wheat malt. Generally, winter varieties are preferred because of
their lower protein content and higher extract content. In addition, they
give a paler beer. Due to the absence of the husk, wheat kernels absorb
steep water very quickly and require a light steeping programme (steeping
times of 38–55 h being common) compared to barley (steeping times of
50–75 h being common at 15–10 °C). The lack of husk also allows the wheat
to pack down tightly in the steep, the germination compartment in the kiln.
To avoid this, the grain should be turned more often compared to barley.
This latter operation should be also be performed gently in order to avoid
damage to the coleoptile tissue, as it is more fragile than that of barley.
Damage to the coleoptile causes impaired malting and there is a risk of
mould growth on the damaged tissue. The initial steeping is to a water
content of 37–38 %, but the water content should be increased during the
steeping and germination time (seven days) up to 44–46 %. Generally, ger-
mination is performed at a temperature a little lower than that used for
barley, but the temperature is raised during the last days of germination
(17–20 ˚C) to promote cytolysis of the cell wall. During germination, enzymes
not only form and increase in quantity but also cause changes which lead
to the production of low molecular weight degradation products from high
molecular weight compounds.The changes to storage materials in the wheat
grains during germination are: (i) the degradation processes known as
‘modification’, driven by enzymes which produce degradation products that
are subsequently used to build new cell material in the seeding; (ii) starch
degradation; (iii) protein degradation; and (iv) fat degradation. In Fig. 1.15a
it is possible to see the intact starch granules in the wheat endosperm held
together before germination as if in a firmly packed sack. Large starch
granules (up to 25 μm in size) and very small granules (up to 5 μm in size)
can be also detected. With the increase in water content of the wheat kernel,
respiration becomes more intense. The seedling then needs sugar for respi-
ration, and this is formed by enzymatic breakdown of starch near the seed-
ling. Figure 1.15b shows the enzymatic attack and the further degradation
of the starch granules, initially only in the cells close to the seedling. The
layered, onion-like structure of the starch granules can also be clearly seen.

The initial process of drying of the steeped grain begins at 40 ˚C and ends
at 60 ˚C. By using different curing temperature, different types of wheat malt
can be obtained: (i) pale wheat malt, rapidly cured at 80 ˚C which has a
colour that normally reaches 3–4 EBC (European Beer Colour) and (ii)
dark wheat malt, which is cured at 100–110 ˚C, conferring a colour ranging
between 15 and 17 EBC. This type of wheat malt is predominately used for
the production of dark wheat beers.

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52 Cereal grains for the food and beverage industries

5 kV ×1, 700 10 μm AMRF, UCC
(a)

5 kV ×3, 500 5 μm AMRF, UCC

(b)
Fig. 1.15 Unmalted (a) and malted (b) wheat.

In the brewing process, the inclusion of wheat, normally characterized
by a higher protein content compared to barley (13 % vs 10 %), has a
remarkable influence on the aroma profile, flavour stability, colour and
visual properties of beer. In particular, wheat beers are often distinguished
by spicy, fruity and biscuit notes and a creamy and stable head foam (Brijs
et al., 2002). It has been suggested that the typical foam characteristics are
related to the presence of high molecular weight wheat proteinaceous
material (Leach, 1968), more specifically glycoproteins (Anderson, 1966),
higher beer viscosity and/or a finer foam bubble size distribution (Depraetere
et al., 2004). Wheat arabinoxylans and β-glucans have been claimed to
increase beer viscosity reducing the drainage of liquid from foam, thereby
increasing foam stability (Kolbach and Kremkov, 1968). Furthermore,

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Wheat and other Triticum grains 53

Kakui et al. (1999) found that the bubble size of wheat beer was much
smaller than that of barley beer, which may account for the creaminess of
wheat beer foam.

While turbidity is unacceptable in Pilsner beers, in wheat beers intensity
and stability of the haze are quality characteristics. The major constituents
of the colloidal haze in wheat beers are proteins in conjunction with poly-
phenols (Siebert, 2010) and starch or degraded starch (Delvaux et al., 2000).
However, scientific literature on this topic is conflicting. On the one hand,
Delvaux et al. (2001) observed that high molecular weight proteins from
wheat decreased the colloidal stability of Belgian wheat beers and this
effect was predominantly caused by water-soluble or (as a result of brewing)
solubilized gluten proteins. On the other hand, Birtwistle et al. (1962)
reported that replacement of parts of the barley malt by unmalted
wheat or wheat flour in lager beers led to an increased colloidal stability
because of protein/polyphenol diluting effects. Further studies (Delvaux
et al., 2003) revealed that at low gluten levels haze is formed but when the
gluten level is increased (by inclusion of a large proportion of wheat), the
levels of the insoluble protein–polyphenol complex become too large and
settle, resulting in a decrease in haze intensity. Brijs et al. (2002) suggested
that precipitates rather than hazes are formed when the MW of the proteins
is too high.

Additionally, the same authors also pointed out the importance of the
mash pH. Acidifying of the mash at pH 4.0, where proteolytic activity is
maximal, results in stronger solubilization (less precipitate) and proteolysis
of the wheat gluten proteins that leads to the production of high and inter-
mediate molecular weight protein influencing the colloidal stability, foam
stability (Leach, 1968) and fullness of beer.

From the point of view of the brewer, when high levels of wheat are
included in the brewing process an increase in wort viscosity, slower wort
separation and lower wort fermentability are the major difficulties encoun-
tered. Moreover, high protein levels in the wheat endosperm limit the
endosperm hydration and enzyme modification during the malting process
(Darlington and Palmer, 1996).Therefore, a low grain protein concentration
is desirable for malt and beer production (See et al., 2002).

Wheat is famous for its inclusion in German and Belgian-style wheat
beers. Traditionally, German wheat beers are brewed with 50–80 % of
malted wheat while the Belgian-style beers are generally brewed with 60 %
of barley malt and 40 % of unmalted wheat. Germany is the leading expo-
nent of wheat beer. German wheat beers fall into two major categories:
Weizen/Weissbier, prominent in Bavaria and Franconia, and Berliner Weisse,
from the north, especially Berlin. They differ in alcohol content: ∼3.5 %
alcohol by volume (ABV) for the Weisse and >5 % ABV for the Weissbier.
This difference in alcohol content is mainly due to the diverse quantity
and quality (malted or unmalted) of wheat used in the brewing process.
The Weisse beer differs also from the other wheat beers because

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54 Cereal grains for the food and beverage industries

the fermentation process is dominated by LAB. All wheat beers are top
fermented and many are available in bottle-conditioned form, whence they
are known as Hefeweizen. Many are cloudy and are meant to be drunk as
such. Specialty brewers in the USA have recently begun to create American
wheat beers, which are comparable to the German and Belgian white beers,
but do not have the spicy or phenolic flavour.

German wheat beer
‘Weizen’ or ‘Weißbier’ is a type of beer produced using water, small amounts
of hops, wheat malt, barley malt and top fermenting yeasts. Based on the
German purity law from 1516 and the provisional beer law (Republic of
Germany, ‘Vorläufiges Biergesetz, 1993)(Narziss, 2005), the total amount of
wheat malt has to be a minimum of 50 % (Narziss, 2005) and the original
wort content has to be between 11 and 14 %. However, darker wheat beer
varieties have stronger alcohol contents than the others and they are called
‘Weizenbock’. Wheat beers are low hopped (about 15 bitterness units – BU)
and are therefore slightly bitter. In Germany, the wheat beer yield has
changed over the last 50 years. In the early 1960s, the Bavarian wheat beer
yield was not even 500 000 hl per year. Subsequently, wheat beer has
increased in popularity and production reached more than 11 million hl in
2009. There is a large variation in production and brewing processes among
wheat beers, enormously influencing the aroma and taste profiles of the
final product.

The development of the beer flavour is mainly due to the interactions
among different flavour compounds like alcohols, esters, carbonyl com-
pounds, organic acids, phenolic substances and sulfuric compounds. Back
et al. (1998) divided wheat beers into four different groups, based on their
dominant aromatic profile:

(i) ester-like:
– typical: fruity, banana taste (isoamylacetat),
– atypical: dissolvent taste (ethylacetat), apple taste (hexylacetat);

(ii) phenolic-like:
– pleasant, clove taste [4 -Vinylguajacol (4-VG), 4-Vinylphenol
(4-VP)],
– unpleasant: hard, bitter,
– ‘medical’ (p-cresol, high concentrations of 4-VG and 4-VP);

(iii) neutral;
(iv) yeast typed.

Esters have major impacts on the flavour of wheat beers. Thus, the focus of
research, regarding aroma compounds in wheat beer, is ester profiles. Their
sensorial thresholds are very low and can influence the aromatic profile of
the final products at marginal concentrations. Classic wheat beers from
southern Germany include Spaten Franziskaner, Hofbräuhaus Edel Weizen,
Schneider (many brands) and Riedenburger Weisse. From the north come

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Wheat and other Triticum grains 55

Schultheiss Berliner Weisse, Berliner Kindl Weisse and Haake-Beck Bremer
Weisse.

Belgian wheat beer
Belgian wheat beer, also called Witbier or bierè blanche, has a long tradition
in Belgian. Belgian wheat beers are top fermented beers, low in bitterness
and slightly sour in taste with a spicy character.This aroma profile originates
from diverse freshly ground spices, such as coriander and bitter orange peel,
which are used as adjuncts during the brewing process, added only before
the end of boiling (Oliver, 2011). Witbier have a typically yellow-whitish
colour, are high in carbonic acid content and show blond and strong foam
(Jackson and Bamforth, 1983). An intense and stable haze is an essential
quality characteristic of this beer type. The top fermenting yeast strains
produce relative fruity and dry beers (Trayner, 2003). As reported before,
Belgian wheat beers are generally brewed with 60 % barley malt and 40 %
raw wheat. The brewing process is comparable to lager beers, but unmalted
wheat needs fine milling to maximize extractability and fermentability.
Lactic or citric acid are normally used to adjust the pH of mash and wort.
Furthermore, to avoid strong colorations and precipitation of proteins and
polyphenols, the wort boiling time is kept short. Classical Belgian wheat
beers include Hoegaarden, Lefebvre Blanches Bruxelles and Gouden Boom
Brugs Tarwebier.

1.10.2 Spelt and emmer beers
Spelt (Triticum spelta) and Emmer (T. monococcum) wheat are character-
ized by higher protein (up to 17 % for Dinkel) and phenolic compound
contents compared to the modern wheat (Triticum aestivum). This means
that they are either dehusked before mashing or are limited to less than
50 % of the raw material used. This process ensures a smooth flavour of the
beer. Spelt grain can be malted in the same way as wheat and the resulting
spelt malt can be used in the production of top fermented spelt beer.
Emmer is occasionally malted to form diastatic malt or in very rare cases
processed into special beer. Famous examples of German spelt and emmer
wheat beers are Riedenburger Emmer Bier and Neumarkter Lammsbräu
Dinkel.

1.10.3 Bouza
Bouza, a fermented alcoholic beverage produced from wheat in Egypt, has
been known since the times of the pharaohs (Morcos et al., 1973). It is a
thick, pasty yellow sour drink with a pleasant taste and produces a sensation
of heat when consumed. It is mainly consumed in Egypt, Turkey and in
some Eastern Europe countries (Morcos et al., 1973). It is prepared by
coarsely grinding wheat grains, placing a portion of them (three-quarters)

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56 Cereal grains for the food and beverage industries

in a wooden basin and kneading them with water into a dough. The dough
is cut into thick loaves, which are lightly baked. The remainder of the grains
(approximately one-quarter of the total amount of wheat grains) is moist-
ened with water, germinated for three to five days, dried, ground and mixed
with the loaves of bread, which are soaked in water. Bouza from a previous
brew is added to serve as inoculum. The low pH (3.9–4.0) and the high
acidity of bouza indicate a fermentation by LAB, while the alcohol produc-
tion (3.8–4.2 % within a 24-hour period) is due to yeast fermentation
(Morcos et al., 1996). The mixture is allowed to ferment at room tempera-
ture for a 24-hour period, following which the product is sieved to remove
large particles and diluted with water to a desired consistency. Like other
opaque beers, bouza has a very short shelf-life and is expected to be con-
sumed within a day.

1.11 Conclusions

Wheat is one of the world’s most important field crops and the third most
produced after maize (corn) and rice. Wheat is a unique grain, mainly due
to its protein quality which confers the visco-elastic properties that allow
dough to be processed into bread, pasta, noodles and other food products.
This exceptional property is the reason why wheat is cultivated in all con-
tinents (except Antarctica), producing more than 650 million tonnes of
grain from about 217 million hectares.

Wheat is primarily used for direct human consumption because of the
high-quality flour it produces, which is a major ingredient in many different
food products. Moreover, wheat provides essential amino acids, vitamins,
minerals, beneficial phytochemicals and dietary fibre components to the
human diet, particularly when whole-grain products are consumed. Never-
theless, wheat is also known to be responsible for a number of adverse
reactions in humans, including wheat intolerances (CD) and allergies
(bakers’ asthma).

1.12 Future trends

Wheat provides 20 % of the calories to the world’s population and a similar
proportion of daily protein for about 2.5 billion people in less developed
countries (Braun et al., 2010). Since the 1970s, wheat productivity has risen
steadily, through the availability of better varieties, agriculture practices and
markets and management (Dixon, 2007). However, a strong improvement
in wheat yield is required considering the predicted increase in demand for
wheat at a rate of around 1.7 % p.a. until 2050 (Rosegrant and Agcaoili,
2010), while productivity is increasing globally at only 1.1 % p.a (Dixon
et al., 2009) and even seems to be stagnating in some regions (Brisson et al.,

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Wheat and other Triticum grains 57

2010). Much of the increase is expected to come from developing countries
(Marathee and Gomez-MacPherson, 2001). Wheat breeding for increased
productivity represents the most direct solution to these problems even
though significant problems, such as new pathogens, increases in the prices
of chemical fertilizer and oil and a gradual reduction of water availability,
will have repercussion for the cost-price squeeze.

Additionally, besides wheat breeding, conservation (stabilization and
improvements of soil fertility) and precision agriculture (meteorological
and hydrological data, soil characteristics) approaches can help farmers
choose when best to sow and how much fertilizer and water to apply to
maximize yields and/or profit margins (Reynolds et al., 2012).

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zohary, d. and hopf, m. (2000). Domestication of Plants in the Old World: The Origin
and Spread of Cultivated Plants in West Asia, Europe, and the Nile Valley. New
York: Oxford University Press.

© Woodhead Publishing Limited, 2013

Pericarp

Aleurone layer

Proteins

Starch granules

Plate I Confocal laser scanning microscope (CLSM) micrograph of the aleurone
layer and endosperm of wheat kernel, stained with three fluorescence dyes: red:

proteins, yellow: cell walls, green: starch granules; magnification = 40×.

50.0 µm
Plate II Confocal laser scanning microscope (CLSM) micrograph section of the
maize kernel showing starch storage granules stained with fluorescein isothiocya-

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

© Woodhead Publishing Limited, 2013

2

Maize

DOI: 10.1533/9780857098924.67

Abstract: Maize (Zea mays), also known as corn, is one of the world’s leading
cereal grains along with rice and wheat. In 2010, the world production was about
844.4 million tonnes of grain with the USA, China, Brazil and Mexico being the
world’s leading suppliers. Polysaccharides, proteins and lipids represent the three
major constituents of the maize kernel. A typical maize kernel is composed of
70–75 % starch, 8–10 % protein, 4–5 % lipid, 1–3 % sugar and 1–4 % ash. It also
contains high levels of phytosterols which have been shown to reduce circulatory
cholesterol concentrations. The acceptance of maize as a crop is mainly due to its
various functionalities as a food and feed source. Kernels can be used for the
production of flour, bread (tortillas, arepa), snacks, porridge, gruel, steamed
products, alcoholic (beer) and non-alcoholic beverages, and breakfast cereals
(corn flakes). Investigational studies to increase our understanding of how future
changes in the climate will affect maize yields are currently underway. This will
aid in determination of the roles maize could potentially play in terms of food
security.

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

2.1 Introduction

Along with rice and wheat, maize (Zea mays L.) is the one of the most
extensively cultivated cereal grain crops in the world and represents a
crucial source of food, feed, fuel and fibres (Tenaillon and Charcosset, 2011).
Maize is also called corn, a term which is also used in Scotland and Ireland
to designate wheat, oats and other farmed cereals (rye), and in some parts
of Africa to indicate the grain sorghum (Farnham et al., 2003). Maize was
domesticated at least 8700 years ago in the highlands of Mexico (Piperno
et al., 2009; Ranere et al., 2009). It is a tall annual diploid plant with 10
chromosomes (x = 10, 2n = 20) and belongs to the grass family (Poaceae),
which includes crops such as rice, wheat, barley, sugar cane, pearl millet, and
sorghum. A highly photosynthetic-efficient C4 grass, maize has the widest
cultivated geographical range of all crops, from the south of Chile 40 °S to
Canada 50 °N, and from the Andean mountains where it can grow at

© Woodhead Publishing Limited, 2013

68 Cereal grains for the food and beverage industries

altitudes of 3400 m above sea level to Caribbean islands (Tenaillon and
Charcosset, 2011).

The maize grain represents about 15–56 % of the total daily calories in
diets of people in approximately 25 developing countries, particularly in
Africa and Latin America (FAO, 1992), where animal protein is scarce,
expensive and, consequently, unavailable to a vast sector of the population.
Present world production is about 844.4 million tonnes of grain from about
161.9 million hectares (FAO/UN, 2012). The USA alone represents the
highest maize producer with 316 million tonnes of maize harvested (37 %
of the total world maize production) from about 329 million hectares. In
terms of chemical composition, 72–73 % of the whole kernel is composed of
starch, of which 98 % is in the endosperm (Earle et al., 1946) where protein
is also concentrated (74 % of the kernel protein). The embryo contains 83 %
of the total kernel lipids, 70 % of the kernel sugar, 78 % of the kernel miner-
als and 26 % of the kernel protein (Watson, 2003). Regarding vitamins,
maize contains two fat-soluble vitamins, A (β-carotene) and E, and most of
the water-soluble vitamins excepting vitamin B12 (Log and Wright, 2003).
Maize is generally used for animal feed, particularly in the USA, and for the
production of flour, bread (tortillas, arepa), snacks, porridge, steamed prod-
ucts, alcoholic (beer) and non-alcoholic beverages, and breakfast cereals
(corn flakes). Corn starch is generally converted into syrups, sweeteners and
industrial products (biodegradable bags) (Rooney and Serna-Saldivar,
2003). Furthermore, an absence of gliadin and the presence of easily digested
carbohydrates have made maize one of the most suitable cereal grain flours
for preparing foods for coeliac patients (Zannini et al., 2012).

2.1.1 History, production, price, yield and area
The most recent maize archaeological evidence proves the presence of
maize in the Balsas river valley region of Mexico around 8700 years ago.
This was followed by a northward migration to Canada and southward to
Argentina (Fig. 2.1). In Europe, and in particular in Germany and Italy, the
use of ‘Turkish corn’ as a local name for maize was first taken as evidence
for its introduction from the Middle East (Janick and Caneva, 2005).
However, its American origin has since been well established by the histo-
rian Matthiole (Matthiole, 1579). Following the European discovery of the
Americas, maize moved quickly to Europe, Africa and Asia. The first his-
torical record corroborating the European introduction of maize is from
the Caribbean to Spain by Columbus in 1493. From there, maize spread to
northward to France, Germany, Austria, Eastern Europe (Revilla et al.,
2003) and southward to Italy (Tenaillon and Charcosset, 2011) (Fig. 2.1).

World production of maize has increased in the last decade (FAO/UN,
2012) (Table 2.1). This increase has been partially due to the increase in
land mass destined for maize production, moving from 137 × 106 ha in 2000
to 162 × 106 ha in 2010. Additionally, the increased yield per unit (ha) of

© Woodhead Publishing Limited, 2013

Northern USA and Canada Maize 69

Corn belt <1539o Pyrenees-
Galicia
–1900a
Caribbean
Southwestern –2100b 1800c
Lowland middle
USA Columbus. 1493p South American

Northern –7300e –1350d
Mexico –8700f
–4500g

Lowland –4440h

Mexico –5500i
–7800j
Highland –7500k
Mexico –5300l

Guatemala and –4000m

Southern Mexico

Northern –4700n
South American

Andean

Fig. 2.1 Domestication centre and hypothetical diffusion of maize through the
Americas and Europe. Solid Shading = maize major groups; dots = recent hybridiza-
tions. Reprinted from Tenaillon, M. I. and Charcosset, A. 2011. A European perspec-
tive on maize history. Comptes Rendus Biologies, 334, 221–228, with permission from

Elsevier.

land, moving from 592 × 106 tonnes in 2000 to 844 × 106 tonnes in 2010, has
contributed to increased world maize production. As illustrated in Table
2.1, throughout the last 10 years, maize production has gradually increased
by approximately 30 %, due to increases in yield and land area of ≈ 17 %
and 15 %, respectively (Table 2.1).

Depending on the climate, soil conditions, maize variety, agricultural
practices and other conditions, maize yields can range from 0.2 (Cape
Verde) to 28 (Israel) tonnes/ha (FAO/UN, 2012). Nowadays, maize yields
worldwide tend to be around 4.8 tonnes/ha on average (FAO/UN, 2012)
(Table 2.1). Maize is cultivated in 164 countries, and the USA is currently,
and has historically been, the world’s leading maize-producer. Table 2.2 lists
the top 10 maize-producing countries over the five-year period 2006–2010.
During this period (2006–2010), the USA contributed almost 40 % of the
world’s maize production from 33 % of the world’s maize-growing area,
while the second leading producer country, China, contributed 20.7 % of
the production from 32.5 % of the area. In the last five years, the increase

© Woodhead Publishing Limited, 2013

Table 2.1 Maize and total cereal grain production and producer price in the world from 2000–2010a

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

2000 592.4 2044 29.0 137.0 4.3 193.7
2001 615.5 2093 29.4 137.4 4.5 186.7
2002 604.8 2077 29.1 137.3 4.4 182.0
2003 645.1 2260 28.5 144.7 4.5 197.0
2004 727.4 2247 32.4 147.5 4.9 211.1
2005 713.6 2219 32.2 147.4 4.8 218.1
2006 706.8 2335 30.3 148.4 4.8 236.9
2007 789.3 2503 31.5 158.2 5.0 291.4
2008 827.4 2470 33.5 161.2 5.1 335.8
2009 819.7 2472 33.2 158.8 5.2 315.5
2010 844.4 2412 35.0 161.9 5.2
Average 716.9 2285 31.4 149.1 4.8 –
236.8

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

Maize 71

Table 2.2 Maize production estimates in the 10 leading producing countries;
five-year average 2006–2010a

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

1 USA 310.9 32.9 9.4 39.6
20.7
2 China 162.3 32.5 6.9 6.6
2.9
3 Brazil 52.0 12.8 4.1 2.4
2.1
4 Mexico 22.6 7.1 3.2 1.9
1.8
5 Argentina 18.8 2.9 6.5 1.3
1.3
6 India 16.9 7.1 2.4 80.9

7 Indonesia 15.4 4.1 3.8

8 France 14.4 1.5 9.6

9 Canada 10.5 1.2 8.8

10 South Africa 10.3 2.7 3.8

Total 634.1 95.8 6.6a

a Average of maize yield among the 10 leading producing countries.
Source: Data from FAO/UN (2012).

in maize production in the USA and China has been due to both the
increase of land area (13.27 % and 12.40 %, respectively) and yield per unit
of land area (15.39 % and 14.53 %, respectively). In contrast, in Brazil, the
increase in maize production was primarily due to increased yield per unit
of this area (+ 23.9 %) as the increase of land area for maize cultivation was
less than 1.6 % (FAO/UN, 2012).

During the last decade, maize prices increased about 26 % from 132.1
US $/tonnes to 178.6 US $/tonnes (Table 2.3). There are broad variations
in maize prices amongst the top 10 producer countries, with Argentina and
China having the lowest (93.8 US $/tonnes) and highest (221.2 US $/tonnes)
maize prices, respectively (Table 2.3). In the USA, the maize price has
increased by 50 % over the last 10 years from 73.0 US $/tonnes in 2000 to
146.0 US $/tonnes in 2009. However, amongst the 10 leading producing
countries, it still represents the second cheapest producer price, only after
Argentina (Table 2.3).

2.1.2 Phytology, classification and cultivation
The cultivated maize (Z. mays L.), a diploid plant with 10 chromosomes
(x = 10, 2n = 20), is a member of the grass (Poaceae) family, which includes
crops such as rice (Orzya sativa), wheat (Triticum aestivum), barley
(Hordeum vulgare), sugar cane (Saccharum ssp.), pearl millet (Pennisetum
glaucum) and sorghum (Sorghum bicolor) (Lee, 2004). There are four
wild species of the genus Zea found in Mexico and northern Central
America. These include two annuals, Z. luxurians (2n = 20) and Z. Mexicana

© Woodhead Publishing Limited, 2013

Table 2.3 Maize prices (US $/tonne) in the 10 leading-producing countries from 2000–2009

© Woodhead Publishing Limited, 2013 Rank Country Crop years
2004 2005 2006
2000 2001 2002 2003 2007 2008 2009 Average

1 USA 73.0 78.0 91.0 95.0 81.0 79.0 120.0 165.0 160.0 146.0 108.08
193.4 218.3 243.0 221.2
2 China 410.7 155.9 146.2 213.8 189.7 189.2 252.1 171.6 215.8 158.4 126.0
223.5 253.1 207.7 178.2
3 Brazil 110.4 69.1 89.3 102,9 103.6 119.0 120.7 118.6 137.7 113.5 93.8
137.8 193.1 186.1 137.0
4 Mexico 159.5 155.3 155.4 150.0 148.8 144.9 184.5 186.9 257.7 264.5 167.1
256.7 174.0 151.4 142.4
5 Argentina 82.0 84.0 78.3 79.6 81.1 70.3 93.3 148.7 185.6 158.8 120.4
206.0 201.7 156.3 137.3
6 India 110.8 99.9 105.3 108.1 131.7 127.9 169.3 180.8 199.7 178.6

7 Indonesia 110.5 119.9 130.2 146.3 153.1 138.1 164.0

8 France 95.9 94.7 93.5 149.0 116.2 128.6 164.9

9 Canada 90.2 97.5 116.0 102.1 109.3 90.0 106.7

10 South Africa 78.5 103.0 129.5 123.5 129.8 99.3 145.9

Average 132.1 105.7 113.4 127.0 124.4 118.6 152.1

Source: Data from FAO/UN (2012).