4
Cereals of the World:
0 rig i n, CI assif icatio n, Types,
Quality
Wheat derived from separate ancestors, and which differ
in chromosome numbers. One classification of
the races, with the probable wild types, chromo-
some numbers (2n) and the cultivated forms is
shown in Table 4. 1.
Einkorn, emmer and spelt are husked wheats,
i.e. the lemma and palea form a husk which remains
around the kernel after threshing. Emmer was used
for human food in prehistoric times (cf. p. 95);
there is archaeological evidence that it was grown
about 5000 B.C. in Iraq. The principal wheats of
commerce are varieties of the species T. aestivum,
T. durum (cf. p. 86) and T. compactum (cf. p. 85).
Common or Bread Wheat, T. aestivum (hexa-
ploid 2n = 42) is an allopolyploid; three genomes,
each corresponding to a normal diploid set of
chromosomes, are distinguishable and are known
to have had separate origins in the past.
Origin
The cultivation of wheat (Triticum spp.) reaches
far back into history, and the crop was predomi-
nant in antiquity as a source of human food. It
was cultivated particularly in Persia (Iran), Egypt,
Greece and Europe. Numerous examples of ancient
wheat have been unearthed in archaeological
investigations; the grains are always carbonized,
although in some cases the anatomical structure
is well preserved.
Races and species of wheat
The many thousands of known species and
varieties of the genus Triticum (wheat) can be
grouped into three distinct races which have been
TABLE 4.1
Wild and Cultivated Wheat Types
~
Cultivated forms
Race Wild type 2n Species name Common name
Small spelt T. aegilopoides 14 T. mmococcum Einkorn
Emmer T. dicoccoides 28 T. dicoccum Emmer
T. durum Macaroni wheat
T. polonicum Polish
T. turgidum Rivet, Cone
probably 42 T. aestivum Bread wheat
T. mmococcum T. spelta Dinkel, Spelt
X T. speltoides T. compactum Club
x Ae. squarrosa T. sphaerococcum Indian Dwarf
(durum)
1
Large spelt
Dinkel
7a
CEREALS OF THE WORLD 79
The hexaploid wheats are believed to have
arisen by hybridization of the diploid species T.
tauschii (Aegilops squawosa) with the tetraploid
speltoides), two diploid species, with doubling of
the chromosomes. Evidence points to the spelta
the aestivum group having arisen from the spelta
group by mutation of a single gene, and the
compacturn and sphaerococcum groups having arisen
Vitreous and mealy wheats
The endospem texture may be viveous (steely,
flinty, glassy, horny) or mealy (starchy, chalky).
mealy, or may consist of a mixture of vitreous
and mealy grains, with one type predominating.
or completely mealy, but grains which are partly
vitreous and partly mealy ('piebald' or 'metadink')
are frequently encountered. The specific gravity
hybrid Of T. monococcum and T. spe1toides (Ae.
Samples may be entirely vitreous or entirely
group as being the Oldest Of the hexap1oids, with
Individual gr,&s are generally completely vitreous
from aestivum simi1ar1y by the mutation Of sing1e
of vitreous grains is generally higher than that of
genes. The evidence is presented by Quisenberry
mealy grains: 1.422 for VitreOUS, 1.405 for mealy
and Reitz (1967). (Bailey, 1916).
Cultivated varieties, which are of widely differ-
ing pedigree and are grown under varied condi-
tions of soil and climate, show wide variations in
characteristics.
The climatic features in countries where spring
wheat is grown - maximum rainfall in spring
and early summer, and maximum temperature in
the mid- and late-summer - favour production
of rapidly maturing grain with endosperm of
vitreous texture and high protein content, tradi-
tionally suitable for breadmaking. Winter wheat,
grown in a climate of relatively even temperature
crop of higher yield and lower nitrogen content,
better suited for biscuit and cake-making than
The vitreous or mealy character is hereditaw,
but is also affected by environment. Thus, T.
aegilopoides, T. dicoccoides, T. monococcum and T.
durum are species with vitreous kernels, whereas
T. turgidurn and many varieties of T. compactum
and T. aestivum are mealy (Percival, 1921). How-
ever, the vitreous/mealy character may be modi-
fied by cultural conditions. Mealiness is favoured
by heavy rainfall, light sandy soils, and crowded
planting, and is more dependent on these condi-
tions than on the type of grain grown. Vitreousness
can be induced by nitrogenous manuring or
with high protein content; mealiness is positively
correlated with high grain-yielding capacity.
and rainfa11, matures more slOwlY, producing a
commercial fertilizing and is positively correlated
for bread, a1though in the U.K., where winter
wheat comprises about 96y0 Of the tota1 (cf.
PP' 87), winter wheat is used for breadmaking'
The yield Of durum wheat (cf' P' 86), which is
Vitreous kernels are translucent and appear
bright against a strong light, whereas mealy
kernels are opaque and appear dark under similar
circumStanceS. The opacity of mealy kernels is
an optical effect due to the presence of minute
vacuous or air-filled fissures between and perhaps
internal reflecting surfaces, preventing light trans-
mission, and giving the endosperm a white appear-
ance. Such fissures are absent from vitreous
endosperm.
The development of mealiness seems to be
of all wheat types are vitreous, and vitreous grains
are found on Plants that grow and ripen quickly:
spring wheats, and those growing in dry conti-
nental climates. Mealy grains are characteristic
of varieties that grow slowly and have a long
maturation period.
grown in drier areas, is lower than that of bread
wheat.
for use in the Green Revolution (cf. p. 6), make
chapatties (cf. p. 270) of indifferent quality (Brown,
1972).
The high-yielding Indian wheats, deve1oped
within the endosperm cells. The fissures form
Wheat types
ing to (1) the texture of the endosperm, because
this characteristic of the grain is related to the
way the grain breaks down in milling, and (2)
the protein content, because the properties of the
flour and its suitability for various purposes are
related to this characteristic.
In a general way, wheats are classified accord-
connected with maturation, since immature grains
80 TECHNOLOGY OF CEREALS
Vitreous kernels sometimes acquire a mealy comprised five polypeptides, but of higher M,:
appearance after being conditioned in various 59-149 k. It has also been found that one particular
ways, e.g. by repeated damping and drying, or polypeptide of the surface SGP, with M, 15 k, is
by warm conditioning (cf. p. 122). The proportion strongly present in all soft wheats examined, but
of vitreous kernels in a sample is a characteristic only weakly present in hard (T. aestzvurn) wheats,
used in grading some types of U.S. wheat (cf. p. and completely absent from the very hard durum
85). (T. durum) wheats. Hardnesslsoftness of wheat
endosperm is known to be genetically controlled
(Berg, 1947) by a gene, Ha, which is located on
the 5D chromosome, and it was subsequently
Hard and soft wheats
Wheat types may also be classified as hard or discovered that the gene controlling the formation
soft, and as strong or weak (see below). Vitreous of the M, 15 k protein is also situated on the 5D
grains tend to be hard and strong, mealy grains chromosome, and is either identical with the Ha
to be soft and weak, but the association is not gene, or is located quite close to it. The M, 15 k
invariable. protein has been named ‘friabilin’ and it appears
‘Hardness’ and ‘softness’ are milling characte- to act as a ‘non-stick’ agent, since it is strongly
ristics, relating to the way the endosperm breaks present in soft-endosperm wheats that fragment
down. In hard wheats, fragmentation of the easily and at random, but is only weakly present
endosperm tends to occur along the lines of in, or entirely absent from, hard wheats that frag-
the cell boundaries, whereas the endosperm of ment only with difficulty, and generally not along
soft wheat fractures in a random way. This the interface between starch granule and surround-
phenomenon suggests a pattern of areas of mech- ing protein matrix (Schofield and Greenwell,
anical strength and weakness in hard wheats, but 1987; Greenwell, 1987; Greenwell and Schofield,
fairly uniform mechanical weakness in soft wheat. 1989).
One view is that ‘hardness’ is related to the degree Hard wheats yield coarse, gritty flour, free-
of adhesion between starch granules and the flowing and easily sifted, consisting of regular-
surrounding protein, viz. that differences in endo- shaped particles, many of which are whole
sperm texture must be related to differences in the endosperm cells, singly or in groups. Soft wheats
nature of the interface between starch granules give very fine flour consisting of irregular-shaped
and the protein matrix in which they are embedded fragments of endosperm cells (including a propor-
(Barlow et al., 1973; Simmonds, 1974). The tion of quite small cellular fragments and free
interface was shown to be rich in water-extractable starch granules), with some flattened particles,
proteins, although no specific biochemical com- which become entangled and adhere together, sift
ponent that might control the adhesion between with difficulty, and tend to clog the apertures of
starch granules surface and protein matrix was sieves (cf. p. 144). The degree of mechanical
identified (Simmonds et al., 1973). damage to starch granules produced during mill-
Well-washed prime starch separated from wheat ing is greater for hard wheats than for soft (cf.
endosperm contains some 0.15-0.2% by weight of pp. 62 and 149).
protein - ‘starch granule protein’ (SGP) - and Hardness affects the ease of detachment of the
the SGP comprises about 1% of the total protein endosperm from the bran. In hard wheats the
of the grain. Part of the SGP is located on the endosperm cells come away more cleanly and tend
surface of the granules, the remainder is an to remain intact, whereas in soft wheats the sub-
integral part of the granule structure. Character- aleurone endosperm cells tend to fragment, a
ization of the SGP by polyacrylamide gel electro- portion coming away while the rest remains
phoresis in the presence of sodium dodecyl sulphate attached to the bran.
has shown that the surface SGP comprized five The granularity of flour gives a measure of the
polypeptides of low relative molecular mass (M,) relative hardness of the wheat, the proportion of
from 5 to 30 k, while the integral SGP also the flour passing through a fine flour silk (when
CEREALS OF THE WORLD 81
Protein content per se is not a factor determin-
ing milling quality, except in so far as the protein
content tends to be higher in vitreous than in
mealy wheats, and vitreousness is often associated
with hardness and good milling quality. Samples
of the English soft wheat varieties Riband or
Galahad may have high protein content and a
large proportion of vitreous grains and yet mill
as soft wheats; on the other hand, a low-protein,
predominantly mealy-grained sample of the hard
varieties Hereward or Mercia will mill as a hard
wheat. The protein content of the endosperm -
its quality and its chemical structure - is,
however, a most important characteristic in deter-
mining baking quality (cf. p. 66).
Strong and weak wheats
Wheats yielding flour which has the ability to
produce bread of large loaf volume, good crumb
texture, and good keeping properties (cf. pp. 174
and 192) generally have a high protein content
and are called 'strong', whereas those yielding
flour from which only a small loaf with coarse
open crumb texture can be made, and which are
characterized by OW protein content, are called
'weak'. The flour from weak wheats is ideal for
biscuits (cookies) and cakes, although unsuitable
for breadmaking unless blended with stronger
flour.
Flour from strong wheats is able to carry a
proportion of weak flour, Le. the loaf maintains
its large volume and good crumb structure even
when a proportion of weak flour is blended with
it; it is also able to absorb and retain a large
Approximate quantity of water.
protein range The main types of wheat are classified accord-
("1
Wheat type
1c16.5 strong: CWRS (Manitoba), American HRS,
HRS (United States)
Durum
Plate (Argentina) 10-16 Russian Spring, some Australian;
CWRS (Manitoba) 9-18 medium: American HRW, Plate, S.E. Euro-
Russian 9-14.5
Australian 8-13.5 weak: N.W. European, American SRW,
English 8-13 American Soft White, Australian Soft.
Other European 8-11.5
SRW (United States) 8-1 1 Hardness (milling character) and strength
(baking character) are inherited separately and
White (United States) 8-10.5
independently (Berg, 1947). Hence, it should be
milled under standard conditions) decreasing with
increasing hardness. Greer (1949) found that the
percentage of the total flour passing through a No.
16 standard silk (aperture width: 0.09 mm) under
standard conditions was 49-56% for four related
varieties of hard English wheat, whereas it was 63-
71% for ten unrelated varieties of soft English wheat.
The granularity of flour can also be expressed as
the Particle Sue Index, as determined by means of
an Alpine air-jet sieve. Ease of sifting, however, is
affected by other factors besides hardness of
endosperm, e.g. moisture content (cf. p. 152).
The principal wheats of the world are arranged
according to their degree of hardness as follows:
extra hard: Durum, some Algerian, Indian;
hard: CWRS (Manitoba), American HRS,
Australian Prime Hard;
medium: Plate, Russian, some Australian,
American HRW, some European;
soft: Some European, some Australian,
American sRw7 American 'Oft
White.
Protein content
The protein content ofwheat varies Over a wide
range (621%) and is influenced less by heredity
than by edaphic factors - soil and climatic
conditions - prevailing at the place of growth,
and by fertilizer treatment. Ranges of protein
content encountered among samples of various
wheat types are shown in Table 4.2.
TABLE 4.2
Protein Content Ranges of Whear Types*
ing to their baking strength as follows:
11.5-18
pean, Australian Prime Hard;
HRW (United States) 9-14.5
* Sources: Schruben (1979); Kent-Jones and Amos (1947).
82 TECHNOLOGY OF CEREALS
possible, through breeding, to combine good EC (mainly Canadian). Proportionately more
milling quality with, for example, the type of ‘imported, non-EC’ wheat is used for breadmak-
gluten associated with weak wheats, to produce ing and less (possibly none) for making biscuits
agoodmilling biscuit wheat. Thevarieties Slejpner, and cakes, for household flour, and for flour for
Haven and Maris Huntsman are hard but pos- other purposes. Thus, in 1978-1980 the average
sess no particular baking strength; Minaret and composition of the grist used for breadmaking in
Flanders are soft wheats which are generally the U.K. was 41% home-grown, 9% other EC,
acceptable for breadmaking. and 50% imported, non-EC.
However, since 1981 there has been a consider-
able reduction in the quantity of imported wheat
used for breadmaking (for reasons explained in
Grain size and shape
The maximum yield of white flour obtainable Ch. 8, p. 193). Thus, in 1990/91, while the total
from wheat in milling is ultimately dependent wheat milled in the U.K. comprised 87% home-
upon the endosperm content, and the latter is grown, 6% other EC, and 7% imported non-EC,
affected by the size and shape of the grain, and the average composition of the breadmaking grist
by the thickness of the bran. was approximately 79% home-grown, 10% other
The specific (bushel) weight (bu wt) measure- EC, and 11% imported non-EC (see also Fig. 8.1).
ment (test wt per bu in the U.S.A.; hectolitre wt
or natural wt in Europe) estimates the weight of
America
a fixed volume of grain, and gives a rough
indication of kernel size and shape. Wheats of The principal wheat-producing countries of the
high bu wt are usually considered to mill the more American continent are Canada, U.S.A. and
readily and to yield more flour. However, these Argentina.
measurements can be misleading, as soft mealy
Canada
wheats often have high bu wt. Moisture content
also affects bu wt.
Shellenberger (1961) found that the volumetric The wheat grown in western Canada is segre-
bran content is lower in large than in small grains, gated into five classes according to season of
viz. 14.1% and 14.6%, respectively, from samples sowing (spring or winter), grain colour (red or
of the same types of wheat, showing the economic white), grain texture (hard or soft), and species
importance of large kernel size. (T. aestivum or T. durum). Spring-sown types
predominate - over 95% of the Canadian wheat
crop is spring sown - and there is more red than
white, and more hard than soft. The classes are
World wheats
wide range in quality and characteristics. In an
endeavour to produce flour of regular quality, the
British flour miller makes a ‘milling grist’ by
blending together various types of wheat so that
particular properties lacking in one component
of the grist may be provided by another.
In recent years, the sources of imported wheat
used by U.K. flour millers have been more
restricted than formerly, and comprise principally
the EC countries (mainly France) and Canada.
Of the total wheat milled in the U.K. in 1978-
1980 (5 million t per an.), 56% was home-grown,
7% was other EC wheat, and 37% imported, non-
U.K.-grown and imported wheats cover a further described as follows.
Canada Western Red Spring (C WRS)
CWRS wheat - formerly known as ‘Manitoba’
- is grown in the provinces of Manitoba, Sas-
katchewan and Alberta. It is a high protein wheat
of excellent milling and baking qualities. It can
be used alone, or in blends with lower-protein
wheat, to produce hearth breads, noodles, flat
breads and steam breads. CWRS wheat is marketed
in three grades, of which the primary grade
characteristics are shown in Table 4.3. The mini-
mum content of hard, vitreous kernels is 65% for
CEREALS OF THE WORLD 83
TABLE 4.3
Grade Characteristics of Canada Western Red Spring Wheat and Canada Utility Wheat, 1991 *
Maximum limits (Oh) of
Foreign material Wheat of other classes
Minimum
test weight Other than Contrasting
Grade 1 bibu kgihl cereal grains Total classes Total
Canada Western Red Spring
No. 1 CWRS 60.1 75.0 0.2 0.75 1 .o 3.0
No. 2 CWRS 57.7 72.0 0.3 1.5 3.0 6.0
No. 3 CWRS 55.3 69.0 0.5 3.5 5.0 10.0
Canada Western Utility
No. 1 CWU 60.1 75 .O 0.3 2.0 3.0 10.0
No. 2 CWU 57.7 72.0 0.5 4.0 5.0 20.0
CW Feed no min. 1 .o 10.0 no limit, but not more
than 10% amber durum
* Source: Official Grain Grading Guide, 1991 edition. Canadian Grain Commission, Winnipeg.
No. 1 CWRS, and 35% for No. 2 CWRS. No being grown on only 6% of the wheat area in
minimum is prescribed for No. 3 CWRS. western Canada.
The protein content of CWRS wheat ranges 9- The grading (Table 4.3) includes a maximum limit
18%, but Nos 1 and 2 CWRS can be supplied at for ‘wheat of other classes’. Until recently, ‘wheat
guaranteed minimum protein levels of 11 Soh, of other classes’ meant ‘wheat of classes or varieties
12.5%, 13.5% and 14.5% (on 13.5% m.c. basis). not equal to Marquis’, but Marquis was replaced
The average yield in 1989 was 18 q/ha (22 q/ha in as the standard variety by Neepawa in 1987.
1986), the yield and protein content tending to be Neepawa was bred from (Thatcher x Frontana) x
related inversely. The moisture content at harvest (Thatcher X Kenya Farmer) x (Thatcher x
is usually 11-13%, and for inclusion in the straight Frontana-Thatcher), and is superior to Marquis in
grades the moisture content must not exceed resistance to stem rust. The variety of CWRS most
14.5%. Wheat with 14.6-17.0% m.c. is graded widely grown at present is Katepwa: it is resistant
‘tough’; with 17.1% m.c. or over, ‘damp’. to stem rust (Puccinia graminis tritici) and common
Marquis is a variety of CWRS wheat which was root rot, and moderately resistant to leaf rust
grown extensively for a long period. It was bred (Puccinia triticzna) and loose smut, though modera-
by crossing Red Fife, a good milling variety which tely susceptible to speckled leaf disease (Septoria).
was liable to frost damage, with Hard Red The Export Standards for the CWRS grades,
Calcutta, an Indian early-ripening variety. Marquis shown in Table 4.4, are somewhat stricter than the
inherited the good milling and early ripening primary grade characteristics, shown in Table 4.3.
characters of its parents. However, Marquis was Early frosts may reduce the Yield of grain and
susceptible to rust (cf. p. 7) and has been largely lower its milling quality by increasing the Propor-
replaced by other varieties, such as Thatcher, tion Of smafl Shrivelled grains With low endosFm
bred from the double cross (Marquis x Iumillo) content, and adversely affect baking quality,
x (~~~~~i~ x Kanred), and Selkirk, bred from because the milled flour is of high maltose content
(McMurachy x Exchange) x Redman. The variety and produces a flowy dough-
Selkirk is equal to Marquis in breadmaking
Canada Western Utility (CWU) wheat and
quality and, in addition, is resistant to stem rust
Feed wheat
race 15B. In 1958 Selkirk comprised over 80%
of the spring wheat area in Manitoba and 28% of Red Spring Wheat which does not attain the
that grown in Saskatchewan, but by 1969 it was required standards for Nos 1-3 CWRS may be
84 TECHNOLOGY OF CEREALS
TABLE 4.4
Export Standards For Canadian Wheats, 1991-1 992*
Maximum limits (“h) of
Foreign material Wheat of other classes
Minimum
test weight Other than Contrasting
Grade lblbu kglhl cereal grains Total classes Total
Canada Western Red Spring
No. 1 CWRS 62.5 78.0 0.2 0.4 0.3 1.5
No. 2 CWRS 61.7 77.0 0.2 0.75 1.5 3.0
No. 3 CWRS 60.1 75.0 0.2 1.25 2.5 5.0
Canada Western Red Winter
No. 1 CWRW 62.5 78.0 0.2 1 .o 1.0 3.0
No. 2 CWRW 59.3 74.0 0.2 2.0 2.0 6.0
No. 3 CWRW 55.3 69.0 0.2 3.0 3.0 10.0
Canada Western Soft White Spring
No. 1 CWSWS 62.5 78.0 0.2 0.75 - 1.5
No. 2 CWSWS 60.9 76.0 0.2 1 .o - 3.0
No. 3 CWSWS 60.1 75.0 0.2 1.5 - 5.0
Canada Prairie Spring
No. 1 CPS 61.7 77.0 0.2 0.75 3.0 5.0
No. 2 CPS 60.1 75.0 0.2 1.5 5.0 10.0
Canada Western Utility
No. 1 CWU 62.5 78.0 0.2 1.0 3.0 5.0
No. 2 CWU 60.9 76.0 0.2 2.0 5.0 10.0
Canada Western Amber Durum
No. 1 CWAD 64.2 80.0 0.2 0.5 2.0 3.0
No. 2 CWAD 63.8 79.5 0.2 0.8 2.5 5.0
No. 3 CWAD 62.5 78.0 0.2 1.0 3.5 7.0
No. 4 CWAD 56.9 71.0 0.5 3.0 10.0 15.0
Canada Western Feed Wheat
59.3 74.0 0.5 5.0
- -
* Source: Grains from Western Canada, 1991-1992. The Canadian Wheat Board, Winnipeg.
graded as Nos 1 or 2 Canada Western Utility
wheat or as Feed Wheat, the grade characteristics
for which are shown in Table 4.3, and the Export
Standards in Table 4.4. Canada Western Feed
Wheat may contain up to 10% of Amber Durum
and up to 5% of heat-damaged grains. CWU
wheat is a medium protein red wheat with hard
kernel characteristics. It can be used to make pasta
kernel characteristics, suitable for the production
of French-style hearth breads and of noodles, flat
breads and steam breads. Export Standards are
listed in Table 4.4.
Canada Western Soft White Spring (CWSWS)
cwsws wheat is grown under irrigation in the
southern regions of weStern Ontario and in British
Or, when b1ended with Other wheat, to make bread.
Acceptab1e reference varieties for cwu wheat are
Glenlea, Wildcat and Bluesky* The cw Feed
Colombia. fie prolein COntent of the top grades
nomdy ranges from 9.0 to 10.0% (14% m.c. basis),
and the flour is suitable for m&ng c&es, biscuits
and crackers, and also, either alone or in blends,
Wheat, as its name implies, is suitable, alone or
b1ended with Other grains, for feeding to animals*
for mhg flat bread and noodles. See Table 4.4.
Canada Western Red Winter (CWRW)
CWRW wheat is grown in southern Alberta.
It is a medium protein, strong wheat with hard
Canada Prairie Spring (CPS)
CPS wheat is a relatively new class of Canadian
wheat, now available as CPS White wheat and
CEREALS OF THE WORLD a5
CPS Red wheat. It is a semi-hard wheat with
12-13% protein content (13.5% m.c. basis) of
excellent milling quality, suitable for making
French-type breads and, in blends, for making
noodles, steam breads, pan breads, crackers and
related products. See Table 4.4.
Canada Western Amber Durum (CWAD)
CWAD wheat, a tetraploid (2n = 28), has a
particularly hard grain and is milled to provide
semolina (cf. p. 154) for making pasta products
(see Ch. 10). The flour is unsuitable for bread-
making. CWAD wheat is graded into four grades
according to test weight, content of foreign mate-
rial, other cereal grains and seeds, content of
wheat of other classes and varieties of durum not
equal to Hercules, and content of immature
kernels (see Table 4.4).
The wheat known as Canada Eastern is low in
protein content (about 9%): it is suitable for high
ratio cake flour (cf. p. 178) and for biscuits, when
mixed with more extensible wheats. Being low in
diastatic power, it is also suitable for sausage rusk,
which requires flour of low maltose content and
high absorbency.
United States
Five principal types of wheat are grown in the
U.S.A.: their names, the proportion that each
contributed to the total crop in 1991/92, and their
bu wt ranges are shown in Table 4.5.
Hard Red Winter (HRW)
HRW wheat is grown in Texas, Oklahoma,
Kansas, Colorado, Nebraska, Montana, South
Dakota and California. HRW wheat is used for
making yeasted bread and hard rolls. Grading of
HRW wheat, according to content of dark, hard
and vitreous kernels, as formerly practised, was
officially discontinued in December, 1979.
Soft Red Winter (SRW)
SRW wheat is grown in Missouri, Illinois,
Ohio, Indiana, Arkansas and Michigan States.
That grown east of the Great Plains region is
called Red Winter; the remainder is Western
Red. SRW wheat mills well but is a weak wheat,
low in protein content. The flour is used for
biscuits (cookies) and crackers, cakes and pastries.
Hard Red Spring (HRS)
HRS wheat is grown in Minnesota, North
Dakota, Montana and South Dakota. The milling
quality is only slightly inferior to that of CWRS,
and the protein content is comparable. HRS
wheat is graded according to content of dark,
hard and vitreous kernels into Dark Northern
Spring (75% or more), Northern Spring (25-75%)
and Red Spring (less than 25%). HRS wheat is
used for quality yeasted bread and rolls.
White wheat
This includes hard and soft types. Hard White
must contain 75% or more of hard kernels. Soft
White, also known as Pacific White in Britain,
contains less than 75% of hard kernels. White
wheat is grown in the west coast States and in
Michigan and New York States. The flour from
White Wheat is unsuitable for breadmaking, but
Type % (1b) (kg) is ideal for biscuits (cookies), crackers, cakes and
pastries. The Soft White is similar to Canada
Eastern White wheat, but slightly stronger and
Hard Red Winter (HRW) 44
Soft Red Winter (SRW) 17 60-64 74.8-79.8
Hard Red Spring (HRS) 23 63-64 78.6-79.8 higher in protein content. The diastatic power
White 11 61-63 76.1-78.6 tends to be low.
TABLE 4.5
Characteristics of US. Wheat Types*
Proportion Bushel Hectolitre
(1991192 crop) wtt wtt
62-64 77.3-79.8
Durum 5 63-64 78.6-79.8
* Data from Dah1 (1962), Johnson (1962), Shellenberger
(1961),MiZlingandBakingNms(19 Feb. 1980), U.S. Wheat
Reviews, HGCA (1991).
t llb/bu = 1.247 kgihl.
Club d7eat
Club wheat or Triticum compactum, is a hexaploid
white wheat grown principally in Washington
86 TECHNOLOGY OF CEREALS
State, U.S.A. The flour milled from it is similar
in characteristics to that milled from white wheat
of T. aestivum, and is used for making biscuits
(cookies).
Durum wheat
Durum wheat OrTriticum durum, is a tetraploid
wheat grown in North Dakota (85y0 Of the croP
in 1990) and California, and is used for making
pasta products (see Ch. 10). Hard Amber Durum
has 75% or more of hard and vitreous kernels
of amber colour; Amber Durum has 60-75%;
Durum has less than 60%.
U.S. wheat grading
The main classes of wheat are graded according
to test wt Per bu, content of damaged and
shrunken kernels, foreign material and wheat of
other classes, as shown in Table 4.6. Parcels which
do not fall within the limits of grades U.S. Nos.
1-5, or are of low quality in certain respects, and
durum wheat of over 16% m.c., are designated
‘sample grade’. ‘Ergoty wheat’ contains more
than 0.3% of ergot (cf. p. 15). ‘Smutty wheat’
contains more than 30 smut balls per 250g (cf.
p. 8). ‘Garlicky wheat’ contains more than 2
green garlic bulbils per kg. ‘Infested wheat’ is
wheat infested with live weevils or other insects
injurious to stored grain (cf. p. 106). ‘Treated
wheat’ has been scoured, limed, washed, sulphured,
or treated in such manner that the true quality is
not reflected by either the numerical grade or
sample grade designation alone (Federal Register,
30 June, 1987).
The (U.S.) Food and Drug administration
announced in July 1977 that grain is subject to
seizure if it contains 32 or more insect-damaged
kernels per 100 g or 9 mg or more rodent pellets
and/or fragments of rodent excreta pellets per kg.
Wheat so adulterated may be used for animal feed
but not for human food (Federal Register, 12 July,
1977).
Protein testing
The U.S. Federal Grain Inspection Service
authorized the official protein testing of HRW
and HRS wheats under the Grain Standards Act
on 1 May 1978 and for all other classes of U.S.
wheat except mixed and unclassed from 1 M~~
1980. Protein content will be determined either
by a near-infra red reflectance (NIR) method or
by the Kjeldahl method (u.s. Wheat ~~~i~~,
M~~ 1980).
U.S. wheat surplus
The surplus of wheat left over at the end of
the season in the U.S.A. when the new crop is
coming in is known as the ‘carry over’. Since
1952 the carry over has greatly increased, and by
1962 amounted to 37 million tonnes, considerably
more than one entire U.S. wheat harvest (31.3
million t in 1962). Subsequently the carry over
deceased, partly because of wheat-area restric-
tion, and partly because of increased exports to
TABLE 4.6
Grade Characteristics of US. Wheat*
Minimum test wt Maximum limits (%) of
HRS, Other Heat- Damaged Shrunken Wheat of
White Club classes damaged kernels Foreign and broken Defects other classes
kgihl lbibu kgihl lbibu kernels (total) material kernels (total) Contrasting Total
Grade
U.S. No. 1 72.3 58 74.8 60 0.2 2 0.4 3 3 1 3
US. No. 2 71.1 57 72.3 58 0.2 4 0.7 5 5 2 5
U.S. No. 3 68.6 55 70.0 56 0.5 7 1.3 8 8 3 10
U.S. No. 4 66.1 53 67.3 54 1.0 10 3.0 12 12 10 10
US. No. 5 62.3 60 63.6 51 3.0 15 5.0 20 20 10 10
* Source: U.S. Dept. Agric. (1991).
1 lbibu = 1.247 kgihl.
CEREALS OF THE WORLD 87
TABLE 4.7
Composition of U.S. Wheat Cay Over* (million bu)f
Year HRW SRW HRS Durum White Total
1976177 605 72 250 92 93 1112
1979180 45 1 39 317 78 89 974
1989190 297 40 216 60 81 694
1991192 151 46 117 50 50 414
* Sources: Milling and Baking News, 19 February 1980; 15 August, 1989; 17 December, 1991.
t 1 million bu of wheat = 27,223 metric tonnes of wheat.
countries, such as the former Soviet Union, India making noodles and ethnic breads. The grains
and China, which had suffered loss of crops. In are large, brittle and slightly elongated, with thin
million tonnes, the carry over was 22.3 for 1969, bran of white or yellow colour. The moisture
9.2 for 1973/74, 32.0 for 1977178, 18.9 for 1989/ content is seldom above 11%, and the grain is
90 and 11.3 for 1991/92. Composition of the carry millable up to 16% m.c. Nos 1 and 2 Prime Hard
over for 1976/77, 1979/80, 1989/90 and 1991/92, wheat are traded with guaranteed protein levels
by wheat type, is shown in Table 4.7. of 13.0%, 14.0% and 15.0% (natural m.c. basis).
Attempts to raise the protein content by under-
sowing with clover have produced promising
results.
Argentina
Argentina is the main producer of bread wheat
in South America. The wheat is classified as Hard
Former Soviet Union
Red Winter, and is known as 'Plate' wheat. The
grain is hard, red and semi-vitreous, small, thin Good-quality Hard Red Spring, Hard Red
and elongated in shape. In quality, the wheat is Winter and Durum wheats are produced in the
strong, with about 12% protein content, but the former Soviet Union. The grains of the HRS and
gluten has limited extensibility, and the wheat is HRW wheats are small, red, hard and horny, and
low in diastatic power, and suitable only as a filler the wheat may contain frosted grains and grains
in breadmaking grists. damaged by wheat bug (cf. p. 9). The big
The types of Plate wheat are named after the climatic variation within the former Soviet Union
ports of shipment: Rosafe, grown in the north gives rise to a wide range of wheat quality from
around Rosario, and Santa Fe are shipped from very strong to medium strong. Average Russian
Rosario; Baril, grown in the central area, from wheat is weaker than CWRS in baking strength
Buenos Aires; Barusso, grown in the south, from and is suitable as a filler-wheat. The protein
Bahia Blanca. Barusso is a softer wheat, with averages 12%.
lower protein content, than the other types.
Britain
Winter and spring types are grown, although
Australia
Wheat is grown in the relatively high rain- winter wheat comprised about 97% of the total
fall areas of New South Wales, Victoria, South in 1991. Average yield of wheat in the U.K. in
Australia and Queensland. There are two classes: 1991 was 72 qha (H-GCA, 1991). The bran colour
hard and soft wheats. The hard type is of medium is generally red. Much of the grain is harvested
strength, and is suitable as a filler in breadmaking at relatively high moisture contents (16-20°/0) and
grists. The soft type is weak, and the flour is good needs drying. Varieties grown in 1991 that were
for biscuits and pastry production. Australian suitable for inclusion in breadmaking grists were
wheat exports are mostly of the soft type and are Avalon, Camp Remy, Mercia and Urban (winter
marketed mainly in the Mid- and Far-East for wheats); Alexandria, Axona and Tonic (spring
88 TECHNOLOGY OF CEREALS
wheats), all of which have hard endosperm texture.
Varieties most favoured for use in biscuit grists
were the winter varieties Apollo, Beaver, Brock,
Galahad, Hornet, Longbow, Norman and Riband,
all of soft endosperm texture. In 1989, the varieties
Mercia and Avalon made up about 37% of total
seed sales, Galahad, Apollo and Brock about 23%
of the total.
The protein content may range from 8% to 13%,
according to locality, within one season. At any
one locality, the average range of protein contents
among varieties would be about 2%, the higher-
yielding varieties having the lower protein contents.
Alpha-Amylase activity of wheat is not a factor
determining milling quality. Nevertheless, flour
milled from wheat with excessively high activity
of alpha-amylase may not be suitable for baking,
and therefore the flour miller generally applies the
Falling Number (FN) test (formerly known as
the Hagberg Falling Number test; cf. p. 183) to
his wheat as a guide to the suitability of the milled
flour for further processing. He would reject
parcels giving FN of less than 180 (based on a 7
g sample) for milling into flour for breadmaking
and for cream crackers, or less than 140 for flour
for biscuits.
Grading
There is no official grading scheme for wheat
in Britain. Wheat is described as ‘millable’ or
‘non-millable’, but the large variation in quality
within the former class is not recognized by any
official system of price support. However, since
1971 , if supplies of high quality wheat are short,
the larger milling combines have offered financial
premiums for high quality wheat of selected
varieties, the level of such premiums varying
according to supply and demand, but probably
averaging 10% over the price of ‘other milling
wheat’ for wheat of 11% protein content (on 14%
m.c. basis), or 7.5% premium for 10.5-10.9%
protein content, provided the moisture content
does not exceed 16% and the FN is 200 or more.
A voluntary grading scheme, or marketing
guide, for U.K.-grown milling wheat was in-
augurated by the Home-Grown Cereals Authority
in January 1975. The 1991 edition of the is shown in Fig. 4.1.
H-GCA’s ‘Marketing Guide’ specifies the following
requirements for Milling wheat:
- freedom from objectionable smells, pest infes-
tation, discoloured grains, ergot and other
injurious material;
- not overheated during drying or storage;
- moisture content not exceeding 15% or 16%
- content of admixture and screenings not ex-
- pesticide residues within the limits prescribed
In addition, the Marketing Guide classifies
U.K.-grown wheat varieties as ‘favoured for
breadmaking’, ‘others - hard’ (which may be
incorporated in some grists or used for animal
feed), and ‘others - soft’ (which can be suitable
for biscuit-making, used in other grists, or for
animal feed). The Guide recommends a minimum
protein content of 11% (on 14% m.c. basis) for
breadmaking wheat, although 10.5% protein con-
tent may be acceptable in some years, and a
Falling Number of 250 or more (on 7 g sample).
For biscuit-making, the Guide specifies a soft-
milling wheat with a low capacity for water
absorption, a protein content of 9-lo%, and a
Falling number of 140 or more.
The requirements specified for Standard Feed
Wheat by the H-GCA are as follows: the wheat
shall be suitable for use as animal feed, be of typical
colour, free from objectionable smell and free from
living pests; 16% max m.c.; 68 kgM min. sp.wt;
0.05% max. ergot content and 3% max. miscel-
laneous impurities; 5% max. other cereals, and 12%
max. total impurities (which include, besides those
already mentioned, sprouted, broken, shrivelled
grains, and grains damaged by heat or insects).
The National Institute of Agricultural Botany
(headquarters at Cambridge) undertakes thorough
examination of new wheat varieties and issues
recommendations to British farmers. The milling
and baking qualities of contemporary varieties
are assessed by the Flour Milling and Baking
Research Association: a section of their 1991
edition of ‘Classification of Home-Grown Wheat
Varieties’ (by Stewart, Susan Salmon and Lindley)
(according to contract);
ceeding 2%;
by U.K. or EC legislation.
CEREALS OF THE WORLD 89
P-W
- (us 11 IC. dsSmT&n)
Endm mr 0W.d cM4
rimy. -0 SdW, om dm .dm =.+am
v- 'p"" ~lar Fbw .bs=.7- mkIw 0mu~ d
kl B "I( M*,lr I "om" - HCdpeh%
I#_
vim7En w*um
-. MC c c c
C A
0 D uu Ma", PlouQhrn." I &Ita
Gor MIN Maan x Kmmwl
A 8 D UK Ificedo I Walonl x Moulm
*.w. MC 0 A C C C F, [pa*,+ x M.~S ~eawn) II
- MDDC C
Armmda) x hlwal
IWgshog L Normml I Marlin
wd0 C A
A- wrdB 0 C A
0 A
A B C
0 B UK uuls nun-n x bim
0 8 C UK (Ylill r MMn YIR) x Hunk
UK
UI GMn )i RPB 181POD
BM WDCD D
- Had0 c 0
8.kBrr Hard 0 A 0
m MC B 0 C D A M HOM Y)n I: Tam
w.p,d WD c c c
M WC C A
C D 0 UK F? I [yIm x iccm x sw.n)~
D.rr Ham B 0 B 0
D UK Cks-3ntlmxNomun
-* nard0 C B
0 B 1.1 YIlfh mmd. . vmve
D 0 UK IlMana Rangar I Dum) I H.ru
Beam) I HoMl ',ab'
B C F, ~h~npm I m201r3~
D D "I F1 I [YllS I (Coo" I Sw."Il
D C UI Nm 'sb I Illpansn(
C D UK wtram I F( 3575
D C UI (Ass Camber x Dum1 I How
hnnn SokC 0 C C
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w Hard* c c 0
Fonmn SdC 0 c 0
- HardB B C 8
ham nard 0 A A
w.h.d MCC c c
wn MOO c c D C "I Ovnn .3c"".tne , B"9'"d
B D C UK (Hedgehog x Nwxmanl x Moulin
B 0 0 UI Nam 'sib' x Di-enf
A C D UK Mourn L MOOoml
'nb
D 0 "I( Norm." I &dgt)nog
1-1 e) UK Squedra I Rendenour
Hnsl Hard 0 B 0
m H.40 A A
Homd SonD C C C
Hvhm .seU.n~H-nun
Hvrvr H.d0 0 c 1-1
Irm Hard A 0 B C 0 6, lCh.mp*l" x c.ppel&%wmzl "
021
C 0 0 UK [[Yams Ranger x Dum1 I Mans
Be.mo1 x Hobbn 'Sib
Lon- MC B 0
yndl MCD c D
wmd- Ham A 0
0 C UK Noman x Hedgehop
D C UK [IC, I2633 x c*asllboswRIz~ x
Hybnd 46) x Prdcusur Muo%aI
yuCHubmnH.rdB D C C
0 A D "I t!oldtul I cqPolloxwm1
B 0 D UK paism . wue) I anden en y16. Pard0 B A
C 0 UK ((Mans Rawer I hm) x Ma-
Beawn1 " MMn 'SO
Nay. %kC 0 C C
I 0 D UK Grant8 " wm.n
A 0 D uI( ,en. . Nm"
A 8 0 UI (YPM x How 'sW1 x Wnvc
D D 0 UI No-" x (Matis Hun(Imn x
kl 1-1 (-1 UK FIambeau x TJ0OW
0 C C Swa W102 I C0r49) I Mvlr
"""&nu" . 0dt.l
I4 0 uI( Squ.drsn. Remd.no"S
6 C 0 Fr u) US (J- x TW
1-1 1.1 UK G.I.Nd x Ham-
A B D Ger [H~nsnun x Sna I WS 132 x
0 D C UK (Clsrn", . M.hurY") x 0rm
A 0 D UK Rands- x (Moulin x Mwcul
P- ".re B c 0
P-. Had0 &. A
Rlld.rmr H.rd B B 0
M SokC 0 0
lw*II1
s**. Sonc c B
y*, -0 B C
solda Had0 0 c B
m WrdA 0 A
sl.p MC C B I4
Tdm. H.d0 B A
T.+ MC A C
To.Md.. H.m0 0 c
ulbn H.dA A B A 0 D Gsr oBMmn " xI.",dl
ym- Hnrd 0 B C 0 D D UK U.N H"""nu" . Dvnn
W.9 WC c 0 C 1-1 0 UK Galahad I her
HunU""")l
WidQa . se# Man$ Wdgm
I\ 0 D Nelh Baltlon I Mlrn&la
B B (-1 NB(h Leu, I [IN16 I UGH65371 x
c.nar Hard A A 8 I 0 D srs (ISlnO r 1250221 . SWl I
-n Hwd & 6 I\ 0 C I+ UK W175 x TIS 70611912
M nard A c 0 A B 1.1 Fr S9G10 x 235-25
0 0 UI RPB 81-73 x RP0 DC13
0 kl UK Norman I MmkM
TCdC Ham A D C A
1- Ham* 0 0 A
TW-
Axom Hac0 A B C A B C Net" HPG 522166 x M- OOM
SPRNG wHE*m
-d Had B C C
-. Hard A A I\
Mllbol
KadSn
0 0 e1 UU TAS 80115R x 5ooo Had A A A
nb;
(.I
ma - m - m "mn rarub hrm. w hs .*e2 - d ryI: imn*6d Wb nul mr)r raq.
i"dlUIB, mal ma nnsw **I "01 faled lor Ih" sh.r.CI.r
.
Tldr ,tama,,m m mol. nne,,,l,.l ,I M re, CdWE
FIG 4.1 Classification of British-grown wheat varieties according to their value for milling and baking
purposes, by B. A. Stewart, Susan E. Salmon and J. A. Lindley (Flour Milling and Baking Research
Association, 1991) reproduced by kind permission of the FMBRA. The characteristics in the second
to seventh columns are graded on a four-point scale, A-D, A indicating superior, D inferior, qualities.
In the fifth column, A indicates greater, D smaller, water absorption by the flour.
90 TECHNOLOGY OF CEREALS
Utilization TABLE 4.9
Minimum Quality Requirements for French Wheat Classes
About 3% of British-grown wheat is used for
seed and about 3% for industrial purposes; the
remainder is shared almost equally between flour-
milling and animal feeding requirements. Approxi- 1 13 38
I1 12 28
11 18
mately 5 million tonnes of wheat are milled
111
annually in the U.K. Utilization of British-grown IV 10 13
and imported wheat milled in the U.K. in 1990/
91, according to purpose, was approximately as
shown in Table 4.8.
Protein* Zeleny
(Yo) Sedimentation testt Class
* Dry basis.
.,. See p. 183.
Within each class, the wheat is graded into one
Grades 1 and 2 are shown in Table 4.10. Grain
which does not conform to these requirements,
Purpose grown EC p Other Total but reaches the required standards for interven-
tion (see below), is ‘hors grade’, i.e. outside
Bread 50 6
Biscuits 15
2 Cakes 2
6 Household flour 6
All 87 6 7 100
TABLE 4.8
Wheat Milled in the U.K. 1990/91* (percentages of Total Wheat
Milled)
Of three grades* The quality requirements for
British Im orted
7 !z grade.
- -
- -
- -
Other 14 - - 14 Utilization
Of the 11 million tonnes of wheat used domes-
tically in 1987/88 in France, about 9% was used
for seed, about 1% for industrial purposes, and
the remainder equally divided between human
foods and animal feed (45% each).
EC grain standards
Wheat grown in the countries comprising the
European Community (EC) may be offered into
Intervention (i.e. purchase by a national interven-
tion authority). The intervention authority is
committed to buy, in unlimited quantities, any
lots of the cereal offered which meet the minimum
quality and quantity requirements.
A three-tier intervention system operates in the
U.K., wheat of breadmaking quality being pur-
chased at a ‘reference price’ which is fixed 5-7.5%
above the intervention price for feed wheat.
Breadmaking wheat and feed wheat offered into
intervention in the U.K. must be of sound, fair
A system for classifying and grading French and marketable quality (defined as being of
typical colour of the grain, free from abnormal
smell and free from live pests (including mites)),
and must meet the quality standards set out in
Table 4.11. Breadmaking wheat is subdivided into
Premium Wheat and Common Wheat according
* Sources: MAFF, NABIM, H-GCA.
Other Western European wheat
Wheat from France, Germany, Belgium and
the Baltic States is similar to U.K.-grown wheat,
but is harvested somewhat drier (15-17% m.c.)
and is a little stronger.
France
Production of wheat in France averaged 9
million tonnes per annum during 1950/59, the
harvested area averaging 4.2 million ha, giving
an average annual yield of 21.4 q/ha. By 1989,
production had increased to 32 million tonnes on
an area only a little larger, 5.0 million ha, because
yield had increased to 63.7 q/ha. Total storage
capacity in 1978 was 34.6 million tonnes, of which
31% was on farms and 69% with co-operatives
and merchants.
wheat was introduced in 1969. The price of wheat
for domestic consumption is fixed according to
its class and grade. There are four classes, for
which the minimum requirements are as shown
in Table 4.9.
CEREALS OF THE WORLD 91
TABLE 4.10
Quality Requirements for French Wheat Grades
Minimum limits Maximum limits
Hectolitre Hagberg Moisture Broken Total
weight Falling content kernels impurities
Grade (kglhl) Number (%) (%) (Yo)
1 76 200 15.5 4 2
2 75 150 16.0 5 3
TABLE 4.11
U.K. Standards for Wheat, Barley and Rye for Interuention, 1990-1991*
Feed
Breadmaking wheat
Premium Common wheat Rye Barley
Minimum quantity, t 100 100 100 100 100
Maximum total impurities, YO 10 10 12 12 12
Broken grains 5 5 5 5 5
Grain impurities, 10 10 12 5 12
Maximum moisture content, YO 14.5 14.5 14.5 14.5 14.5
Minimum specific wt, kg/hl 72 72 72 68 63
of which:
of which:
Other cereals and grains
5
Sprouted grains 6 6 6 6 6
-
damaged by pests 5 5 5
Grain overheated during drying 0.5 0.5 3 3 3
Miscellaneous impurities, 3 3 3 3 3
of which:
Noxious seeds 0.1 0.1 0.1 0.1 0.1
Damaged by spontaneous overheating 0.05 0.05
Ergot 0.05 0.05 0.05 0.05
Minimum protein content, % (d.b.) 14.0 11.5 NIA
Minimum Zeleny test 35 20 N/A
Minimum Hagberg Falling Number 240 200 NIA
EC dough machinability test Pass Pass NIA
* Source: Intervention Board, 1990.
NIA not applicable.
to quality, as measured by protein content, World wheat stocks
Number. The Intervention buying-in price for
Common Wheat is about 5% above that for
Zeleny sedimentation teSt and Hagbe% Fa11ing
Between 1952 and 1970 a large surplus ofwheat
gradually built up in wheat-exporting countries
until, by 1970, 64 million tonnes (one-fifth of
Feed Wheat; that Of 'remiurn Wheat about 7y0
above that for Feed Wheat (Intervention Board7
the annual world production at that time) were
available for export. Since 1970, stocks have
rapidly diminished, and by mid 1973 there was
an acute shortage; prices, in consequence, rose
steeply. The average market price for wheat in
England and Wales, which was about &23 per
tonne in 1970, rose to about &58 per tonne
in 1973, and has continued to rise, reaching
about 2100 per tonne in 1980, and 2126 per
tonne in 1990/91 (Common Breadmaking Wheat:
1990).
South-eastern Europe
Wheat from Bulgaria and Romania is some-
what harder and stronger than that from the west
of Europe and can be used as a filler in bread-
making grists.
92 TECHNOLOGY OF CEREALS
Intervention buying-in price) (Intervention Board,
1990).
- cut back on planted areas of wheat, particu-
larly in Canada and the U.S.A.;
- increased demand for wheat for animal feed
to meet increased meat consumption in dev-
eloped countries;
- disappointingly slow implementation of the
potentialities of the so-called 'Green Revolu-
tion' in Asia - the use of new high-yielding
varieties (cf. p. 6);
- a series of natural disasters of which the most
far reaching was the Russian crop failure in
1972' The former Soviet Union bought l8
million tonnes of wheat (30% of world stocks)
to make good its shortfall. In the same year,
China and India also bought large quantities
of wheat.
degree of contamination with impurities, estimate
the moisture content, and investigate whether
The causes of the shortage in the 1970s were: the grain has suffered heat damage to the
protein during farm drying. Tests for heat
damage include estimates of the amount of
soluble, i.e. undenatured, protein (Every,1987),
the germination test, and the tetrazolium test (cf.
p. 113).
Quality
Besides these four aspects of condition -which
are dependent mainly upon the agricultural history
of the wheat before the miller received it - the
miller also wants the wheat to be of good milling
quality, that is, to perform well on the mill: to
give an adequate yield of flour, to process easily,
and to yield a product of satisfactory quality.
The quality of wheat on the mill is measured
by the yield and purity of the flour obtained from
it. Relatively more flour of lower mineral content
(ash yield) and lower grade colour (GC: cf. p. 184)
is obtained from good milling wheats, when
properly conditioned (cf. Ch. 5) and milled
under standard conditions, than from poor milling
wheats.
Purity of the flour (white flour) means relative
freedom from admixture with particles of bran.
Bran is dark coloured whereas the endosperm is
white: the Grade Colour (GC) of the flour is an
index of the degree of bran contamination (cf.
p. 184). Another measure of bran contamination
Wheat condition and quality - for the
miller
Condition
For the miller, wheat in good condition is:
1. Of good appearance: the grains are normal
in colour (not discoloured) and bright; un-
weathered, free from fungal and bacterial
diseases, unsprouted, and free from musty
odour.
2' Undamaged: the grains are not mechanically
damaged by the thresher, by insect infestation
is the yield of ash obtained upon incineration, as
bran yields mOre ash than endosperm does (,-f.
pp. 184 and 170).
The yield and purity of white flour are depen-
dent upon the way the endosperm separates from
the bran when the wheat is ground; on the
toughness of the bran, i.e. its resistance to
fragmentation; and on the friability of the endo-
sperm and the ease with which the flour is
sifted. All these characteristics are related to
grain texture and to the type of wheat (cf. p.
80).
Tests which measure baking strength and
flour for various purposes are described later (p.
184).
or by rodent attack, and have not been dam-
aged by over-heating during drying;
3. Clean: the grain is free from admixture with
an abnormal quantity of chaff, straw, stones,
soil, or with weed seeds and grains of other
cereals, or of other types or varieties of wheat;
the grains should be completely free from
admixture with ergot, garlic or wild onion,
bunt, rodent excreta and insects;
4. Fit for storage: the moisture content should
not exceed 16% for immediate milling, or 15%
Tests for grain condition therefore examine the
appearance and odour of the grain, measure the
'he wheat is to go into 'torage (but see P' lo4).
which give indication of the suitability of the
CEREALS OF THE WORLD 93
makes them unsuitable for malting (cf. p. 219),
but they are useful for food, having a higher
digestibility (94%) than the hulled types (83%).
In 1971,0.36 million tonnes of hulled barley and
in Japan, and approximately 0.17 million tonnes
of hulled and 0.14 million tonnes of hull-less were
used for food.
'Waxy' barley
is in the form of amylopectin (cf. p. 57), and
known as 'waxy' barley, is known. It was
of interest as a possible replacement for
success.
High amylose barley
A high amylose barley, in which about 40% of
the starch is in the form of amylose (as compared
genotypes), is also known: it would be useful
in the manufacture of malt whisky. The malt
enzymes digest amylose to glucose completely (cf.
p. 67) but digestion of amylopectin is incomplete,
of alcohol in the yeast fermentation of malted
barley is thus related to the amylose content of
the starch. The high amylose cultivar Glacier is
being hybridized with other barley cultivars in
order to introduce the high amylose factor into
mOre suitable cultivars.
US grades Of bar1eY
Barley, in the U.S.A., is defined as grain that,
before removal of dockage, consists of 50% or
more of kernels of cultivated barley (Hordeum
vulgare L. or H. distichum L.) and not more than
10% of other grains for which standards have
been established under the United States Grain
Standards Act. The term 'barley' as used in these
standards does not include hull-less barley (Federal
Register, 1985).
Barley grown in the U.S.A. is divided into
three subclasses, as follows:
Barley
Origin
11) reaches far back into history; it was known
to the ancient Egyptians, and grains of six-row
barley have been discovered in Egypt dating from
pre-dynastic and early dynastic periods. Barley is
mentioned in the Book of Exodus in connection
with the ten plagues.
Greeks and Romans. Hunter (1928) illustrates
Greek coins dating from 413 to 50 B.C. which
incorporate ears or grains of barley into their
gladiators who were known as the hordearii
(Percival, 1921). Calcined remains of cakes made
from coarsely ground grain of barley and Triticum
monococcum, dating from the Stone Age, have
been found in Switzerland.
Bread made from barley and rye flour formed
poorer people of England in the 15th century (cf.
p. 99, while nobles ate wheaten bread. As wheat
and oats became more generally available, and
with the cultivation of potatoes, barley ceased to
grain, however, in the Near East.
The cu1tivation Of bar1ey (Hordeum 'PP; cf* P*
0.14 million tonnes of naked barley were grown
Bar1ey was used as a bread grain by the ancient
A type of barley in which nearly all the starch
design* Bar1ey was the genera' food Of the Roman
tapioca starch, but has not been a commercial
the stap1e diet Of the country peasants and the
with a usual figure of 25-27% in mOSt cereal
be used for breadmaking* Bar1ey is sti11 a stap1e
being hindered near the cross linkages: the yield
Classification
There are three main types of barley: (a) hulled,
six-row; (b) hulled, two-row; and (c) hull-less,
all of which have been regarded as sub-groups of
one species, Hordeum sativum, or H. vulgare. The
characteristics of hulled barley are described in
Ch. 2, p. 41.
Hull-less barley
Hull-less or naked types of barley are cultivated
extensively in southeast Asia. The yield of grain
is lower than that of the hulled types, and the
spikelets have a tendency to shed grain when ripe,
thus further reducing the yield. Hull-less types
have weaker straw and are more liable to lodge
than are the hulled types. The absence of hull
94 TECHNOLOGY OF CEREALS
TABLE 4.12
US. Grades of Barley*
Minimum limits of Maximum limits of
Suitable Skinned
Test malting Sound Damaged Kernels Wild Foreign Other and broken Thin Black
Grade Wt type barley Total$ Heat oats
material grains kernels barley barley
No. (1 1bibu)t (“h) (Yo) (%) (Yo) (Yo) (Yo) (%) (%) (Yo) (Yo)
Sub-class Six-rowed Malting barley and Six-rowed Blue Malting barley
U.S. No. 1 47 95 97 2 0.2 1 2 4 7 0.5
U.S. No. 2 45 95 94 3 0.2 2 3 6 10 1
U.S. No. 3 43 95 90 4 0.2 3 5 8 15 2
U.S. No. 1 choice 50 97 98 0.2 1 0.5 5 5 0.5
U.S. No. 1 48 97 98 0.2 1 0.5 7 7 0.5
U.S. No. 2 48 95 96 0.2 2 1 10 10 1
U.S. No. 3 48 95 93 0.2 3 2 10 10 2
U.S. No. 1 47 97 2 0.2 1 4 10 0.5
U.S. No. 2 45 94 4 0.3 2 8 15 1
U.S. No. 3 43 90 6 0.5 3 12 25 2
U.S. No. 4 40 85 81 4 18 35 5
U.S. No. 5 36 75 10 3 5 28 75 10
* Source: U.S. Dept. Agric. (1989).
t 1 lbibu = 1.247 kgihl.
$ Includes heat-damaged kernels.
Sub-class Two-rowed Malting barley
Sub-class Six-rowed barley, Two-rowed barley and the class Barley
1. Malting barley: six-row or two-row barley,
which has 90% or more of the kernels with
white aleurone layer, and which is not semi-
steely in the mass;
2. Blue malting barley: six-row barley, which has
90% or more of the kernels with blue aleurone
layer, but otherwise as Malting barley;
3. Barley: barley that does not meet the require-
ments of the other sub-classes. Each sub-class
is graded into numerical grades. The grade
requirements are shown in Table 4.12.
The term ‘U.S. Sample Grade’ is applied to
barley which does not meet the requirements of
the numbered grades, which contains a quantity
of smut so great that one or more of the grade
requirements cannot be determined accurately,
or contains more than seven stones or more than
two crotolaria seeds (Crotolaria spp.) per kg, or
has a musty, sour or commercially objectionable
foreign odour except smut or garlic odour, or
contains the seeds of wild brome grasses, or is
heating or otherwise of distinctly low quality.
U.K. standards for intervention
Barley offered into Intervention in the U.K.
(i.e. offered for purchase by the government; cf.
p. 90) must attain the standards shown in Table
4.11.
In 1988/89 in the U.K. the winter varieties Igri
and Magic provided 22% of the total barley seed
certifications (H-GCA Cereal Statistics, 1989).
Oats
origin
Two species of oats, Avena sativa L. and A.
byzantina C. Koch, both hexaploids, are econ-
omically important since they provide the majority
of present-day cultivated varieties. In Europe,
types of A. sativa predominate. It is believed
(Coffman, 1946) that a wild hexaploid species,
A. sterilis L., is the progenitor of A. fatua L. (a
weed popularly known as the ‘wild oat’) and of
A. byzantina (red oat), and that A. sativa (white
CEREALS OF THE WORLD 95
25% of wild oats and other grains for which
standards have been established. Oats are classed
as White, Red, Grey, Black or Mixed; each class
is graded into four numerical grades and Sample
grade, as shown in Table 4.13.
The term ‘Sample grade’ is applied to oats
which do not meet the requirements of grades
1-4, or which contain more than 16% m.c., or
which contain more than 0.2% (by wt) of stones,
or are musty, sour, or heating, or which contain
objectionable foreign odour except that of smut
or garlic, or which are otherwise of distinctly low
quality.
oat) has been derived from the latter. In his
studies in 1916, the Russian botanist Vavilov
discovered plants of A. sativa in patches of
Emmer wheat (Triticum dicoccum; cf. p. 78) in
areas of the Middle East where oats are not
cultivated, and concluded that the spread of
common cultivated types of A. sativa from their
original centre, probably in the Mediterranean
basin, had been determined largely by the spread
of Emmer wheat, the oats being carried as a weed
as the Emmer spread northwards. Eventually, in
a harsher climate, the oats came to dominate the
wheat (Jones, 1956). The first oat crops seem to
have been grown in Europe at about 1000 B.C.
Oats as a crop reached America in A.D. 1602.
of oats which readily loses its husk during thresh-
ing. It is believed to have been derived from the
tetraploid species A. barbata. Naked oats has
considerable potential for food and feed use, since
the grains require no dehulling and have high
protein, oil and energy values. However, naked
oats are more susceptible than ordinary hulled
oats to mechanical damage during threshing, and
research is aimed at the breeding of types more
resistant to threshing damage. A. nuda is grown
principally in India, Tibet and China, and it is
currently being grown experimentally in Wales.
U.S. grading of oats
In the U.S.A., ‘oats’ is defined as grain consist-
ing of 50% or more of cultivated oats (A. sativa
and/or A. byzantina), containing not more than
TABLE 4.13
US. Grades of Oats*
Naked oats, A. nuda L. (hexaploid) is a type
We
Origin
Rye, Secale cereale, was domesticated in about
the 4th century B.C. in Germany, later in southern
Europe. According to Vavilov (1926), cultivated
rye has been derived from the rye grass that
occurred as a weed in wheat and barley crops.
In Roman times the chief cereal crop in the
south of Britain was probably wheat, but rye was
introduced by Teutonic invaders who used it for
making bread, and it was grown in East Anglia.
During the Middle Ages the poorer people in
England ate bread made from rye, or from a rye/
wheat mixture known as ‘maslin’ or ‘meslin’, or
from barley and rye (cf. p. 93). In 1764, according
to Ashley (1928), bread made in the north of
England contained 30% of rye, that in Wales 40%.
At this time, rye was still an important crop in
the north of the country and, in addition, was
regularly imported from Germany and Poland,
where it was plentifully grown.
The native rye grown in the U.K. until about
1945 was long-strawed, gave low yields, and had
Sound Heat high (10-13%) protein content. Since then, new
Test cu1tivated damaged Foreign Wi1d varieties have been introduced from Sweden and
Grade Wt oats kernels material oats
No. (Ibibu)? (%) (%) (yo) elo) Germany; they are short-strawed and suitable for
combine-harvesting, equal to wheat in yielding
ability on good land, and low (7-8%) in protein
U.S. No. 1 36 97 0.1 2
U.S. No. 2 33 94 0.3 3
U.S. No. 3 30 90 1 .o 4 5 content. Tetra Petkus, for example, is a tetraploid
U.S. No. 4 27 80 3.0 5 10 variety (i.e. with double the normal number of
chromosomes) produced in Germany by treating
Petkus rye with colchicine. The grain yield is
Minimum limits of Maximum limits of
i
* Source: U.S. Dept. Agric. (1987).
t 1 lbibu = 1.247 kgihl.
96 TECHNOLOGY OF CEREALS
TABLE 4.14
US. Grades of Rye*
Maximum limits for
Damaged kernels Foreign material
(rye and other grains)
Minimum Other than Thin
Grade test wt Total Heat damaged Total wheat rye
No. (Ib/bu)t ("1
(%) (Oh/.) (%I ("1
U.S. No. 1 56 2 0.2 3 1 10
U.S. No. 2 54 4 0.2 6 2 15
U.S. No. 3 52 7 0.5 10 4 25
US. No. 4 49 15 3.0 10 6
-
* Source: US. Dept. Agric. (1987).
t 1 lb/bu = 1.247 kg/hl.
reported to be 115% of that of Petkus., and the
variety is credited with superior winter hardiness,
test wt (bushel wt; cf. p. 82) and agronomic
characteristics. The open or cross pollination of
rye increases the difficulty of keeping the strain
pure, and therefore new seed must be raised in
isolation for this purpose.
U.S. grades of rye
Only one class of rye is recognized: it is defined
as any crop which, before removal of dockage
(cf. p. 93), consists of 50% or more of rye and
not more than 10% of other grains for which
standards have been established under provisions
of the U.S. Grain Standards Act.
The grades of rye recognized in the U.S.A.,
and their limiting characteristics, are shown in
Table 4.14. For all grades, the maximum permitted
content of ergot (cf. p. 15) is 0.3%. Sample grade
is defined in the same way as for Sample grade
barley (cf. p. 94).
University of Manitoba. The obiectives inmaking
the cross were to combine the grain quality,
productivity and disease resistance of wheat with
the vigour and hardiness of rye.
There are two types of triticale: durum wheat
x rye hybrid is an hexaploid (42 chromosomes),
and the usual kind of triticale; bread wheat x
rye hybrid is an octoploid (56 chromosomes).
Early varieties of triticale did not offer much
promise for milling and baking; they resembled
their rye parent more than their wheat parent,
particularly in a tendency towards undesirably
high activity of alpha-amylase. Moreover, the
early types were poor yielding, and generally had
shrivelled kernels. Grain yields of more recently
produced types are much increased, but triticale
is not yet equal to wheat on the basis of yield.
Thus, average yields in 1989 in Poland were: 33.3
qlha for triticale, 37.7 q/ha for wheat, and in
Germany: 52.0 q/ha for triticale, 62.1 q/ha for
wheat. Nevertheless, the world average yield of
triticale in 1989, 26.6 qlha, exceeded that of
wheat, 23.6 qlha. Further breeding will be neces-
sary to eliminate defects which include suscepti-
bility to lodging, low tillering capacity, endosperm
shrivelling, sprouting in the ear, susceptibility to
ergot (cf. p. 15) and lack of adaptability. Develop-
ment of types insensitive to day length will permit
the crops to be grown in lower latitudes. Types
with short, stiff straw have been developed recently
by introducing dwarfing genes from short-strawed
wheats.
Triticale
Origin
Triticale - an abbreviation of 'Triticosecale' -
is a polyploid hybrid cereal derived from a cross
between wheat (Triticum) and rye (Secale). It had
its beginnings in the late 19th century in Europe,
but intensive work began only in 1954, at the
CEREALS OF THE WORLD 97
TABLE 4.15
US. Grades of Triticale*
Maximum limits of
Damaged kernels Foreign material
Shrunken
Minimum Heat Other than and broken Defects
test wt damaged Total* wheat or rye Totals kernels (total)
Grade (Ib/bu)t (Oh) (”/.I (”/.I (Yo) (Oh) (Yo)
U.S. No. 1 48 0.2 2 1 2 5 5
U.S. No. 2 45 0.2 4 2 4 8 8
U.S. No. 3 43 0.5 8 3 7 12 12
U.S. No. 4 41 3.0 15 4 10 20 20
* Source: U.S. Dept. Agric. (1987).
t 1 lb/bu = 1.247 kg/hl.
$ includes heat-damaged kernels.
§ Includes material other than wheat or rye.
U.S. grades of triticale Asia, rice provides 68% of the total energy
contribution, wheat 10% and maize 2.5%; rice
Triticale) in the U.S.A., is defined as grain
also provides 69% of the total dietary protein
(Juliano, 1990, quoting CGIAR,TAC).
that, before removal of dockage, consists of 50%
or more of triticale (Triticosecale Wittmack) and
The peoples of various countries have varying
not more than 10% of other grains for which
preferences for types of rice: round-grain rice is
standards have been established under the United
preferred in Japan, Korea and Puerto-Rico, pos-
States Grain Standards Act, and that, after removal
sibly because the cooked grains are more adher-
ent, whereas long-grained rice (e.g. Patna rice)
of dockage, contains 50% or more of whole
is preferred in the U.S.A. People in most countries
triticale (Federal Register, 1986).
Triticale, in the U.S.A., is graded into four
prefer white rice, but in India and Pakistan the
numerical grades, of which the limiting character-
preference is for red, purple or blue strains.
istics are as shown in Table 4.15.
Classification of types of rice according to
cooking properties on the basis of the final
gelatinization temperature has been suggested
(Juliano et al., 1964). Grains of indica type soften
rapidly on cooking and become mushy, whereas
the cooked grains of japonica are non-sticky and
well separated.
Technological problems associated with the
Green Revolution concern quality of the new
varieties of rice. For example, the high yielding
dwarf varieties of rice contain starch of high
amylose content (cf. p. 6) which tends to lower
the cooking quality (Brown, 1972).
Ordinary rice is non-glutinous and has vitreous
endosperm. Another type, known as glutinous,
sweet or waxy rice (Oryza sativa L. glutinosa) has
a chalky, opaque endosperm) the cut surface of
which has the appearance of paraffin wax. The
starch of ordinary rice consists of amylose and
amylopectin (cf. p. 57) and gives a blue colour
Rice
Origin
Some authorities have traced the origin of rice,
Oryza sativa, to a plant grown in India in 3000
B.C., but the first mention of rice in history was
in 2800 B.C. when a Chinese emperor proclaimed
the establishment of a ceremonial ordinance for
the planting of rice. Rice culture gradually spread
westwards from northeastern Asia and was intro-
duced to southern Europe in medieval times by
the invading Saracens.
Classification
Rice provides up to 75% of the dietary energy
and protein for 2.5 billion people in Asia. In south
98 TECHNOLOGY OF CEREALS
with iodine. The starch from glutinous rice, how-
it contains 0.8-1.3% of amylose The amylose
1-2%; intermediate, 20-25% and high, >25% Rice form Long-grain Medium-grain Short-grain
(Juliano, 1979). Flour produced from waxy rice
is used as a thickener in processing foodstuffs as i;::! 3.4+ 2.3-3.3 2.2 and less
2.0 and less
it withstands the freezehhaw cycling well; it is Milled 3.0+ 2.G2.9 1.9 and less
also used for puddings and cakes.
* Source: Rice Inspection Handbook. Federal Grain
Inspection Service, U.S. Dept. Agric., Washington, D.C.,
1982.
US. grades of rice
Rough rice (paddy), brown rice and milled rice is no evidence - archaeological, linguistic, pic-
are classified as long-, medium- or short-grain torial, or historical - of the existence of maize
types according to length/width ratio of the in any part of the Old World before 1492, whereas
grains, as shown in Table 4.16. Six numerical cobs and ears of maize are frequently encountered
grades of rough rice (paddy) are recognized, with among archaeological remains in North and
requirements as shown in Table 4.17. ‘Sample South America. It is believed that maize origin-
grade’ is defined in a similar way to sample grade ated in Mexico, whence it spread northwards to
oats (cf. p. 99, except that the limiting m.c. is Canada and southwards to Argentina, and has
14%. Grades and grade requirements are also set subsequently been taken to Africa, India, Australia
out for Brown Rice and Milled Rice. and the warmer parts of Europe (Watson and
Ramstad, 1987).
TABLE 4.16
Ratio*
Lengthiwidth ratio
ever, gives a reddish-brown colour with iodine;
U.S. Classification of Rice (Paddy) According to LengthlWidth
content of milled rice may be classified as waxy,
2.1-3.0 3.1+
Maize
Types
The principal types of maize are listed in Table
Maize grains may be white, yellow or reddish
Origin
Maize or Indian corn (Zea mays, L.) is un-
doubtedly a plant of American origin, since there
2.3 (p. 46).
TABLE 4.17
US. Grades and Grade Requirements for Rough Rice* (Long-, Medium- and Short-grain types)
Maximum limits of
Seeds and heat-damaged grains
Heat Red rice, Chalky grains
damaged and Damaged
objectionable grains medium
(singly or Heat (singly or long- or short Other
Total combined) damaged combined) grained grained types Colour
Grade NoJ5OOg No.bOOg No./SOOg W) (“h) W) (YO) requirements
U.S. No. 1 4 3 1 0.5 1.0 2.0 1.0 white; creamy
U.S. No. 2 7 5 2 1.5 2.0 4.0 2.0 slightly grey
U.S. No. 3 10 8 5 2.5 4.0 6.0 3.0 light grey
U.S. No. 4 27 22 15 4.0 6.0 8.0 5.0 grey or
slightly rosy
US. No. 5 37 32 25 6.0 10.0 10.0 10.0 dark grey or
rosy
U.S. No. 6 75 75 75 15.0 15.0 15.0 10.0 dark grey or
rosy
* Source: U.S. Dept. Agric., 1991.
CEREALS OF THE WORLD 99
hybrid corn comprised less than 1% of the total
crop in the U.S.A. in 1933, but by 1945 it
accounted for about 90% (Watson and Ramstad,
1987).
Opaque2 maize
Maize mutants known as opaque-2 and floury-
2 contain the genes 02 and f12 which confer high
lysine content; floury-2 also has high methionine
content. The kernels of opaque-2 maize are soft,
chalky and non-transparent, and contain very
little hard, vitreous, horny endosperm. They are
also more liable to damage by kernel rot, insects,
rodents and harvesting machinery. Opaque-2 is
claimed to have 10-12% protein content (cf. 8%
for normal maize), 0.49% lysine content (cf.
0.24% in normal maize), a higher niacin content
and a lower leucine content than in normal maize.
In feeding trials with adult humans using opaque-
2 no improvement was obtained from individual
supplementation of the diets with lysine, trypto-
phan or methionine, indicating that the amino
acid composition of opaque-2 is well balanced for
humans.
The yield of early types of opaque-2 maize was
only 85-90% of that of normal maize, but has been
improved during the 1980s through selection. How-
ever, the use of opaque-2 in the U.S.A., though
nutritionally desirable, is restricted because the
yield is still less than that of normal dent maize.
US. grades of maize
In the U.S.A., maize is classified as White,
Yellow or Mixed, and is further qualified as Flint
or Flint and Dent. Five numerical grades are
recognized, with characteristics as shown in Table
4.18. ‘Sample grade’ is defined in a similar way to
sample grade oats (cf. p. 95).
Sorghum
in colour. White is preferred in western Europe,
but yellow is preferred for poultry feeds; the
reddish type is favoured in Japan.
The texture of the endosperm of maize is
variable, according to the type and the region of
the endosperm. The crown region of the endo-
sperm (at the opposite end from the germ), which
is light in colour, contains loosely packed starch
granules with little protein, whereas the horny
region (towards the base), which is more intensely
coloured in yellow varieties, has smaller starch
granules which are embedded in sheets of protein-
aceous material.
The yellow pigment in yellow varieties is
zeaxanthin, which contains 200-900 pg of beta-
carotene per 100 g. The oil and protein contents
of the horny endosperm are more than double
those in the crown region. In the more floury
types of maize the crown region predominates;
the endosperm is all soft with hardly any vitreous
endosperm. In some of these floury types the
crown region contracts during maturation, pro-
ducing a noticeable indentation. Such types,
varieties of Z.mays indentata, are called dent
maize (corn). Varieties of Z.mays indurata, in
which the horny region predominates, are called
flint maize (corn). The starches of dent corn and
flint corn comprise about 73% of amylopectin
and 27% of amylose.
The term ‘corn’ is frequently applied to the
predominant local cereal, viz. wheat in England,
oats in Scotland. In the U.S.A., ‘corn’ means
specifically maize.
The starch of waxy corn (Z.mays ceratina) is
10Oo/o amylopectin. A high amylose type of maize
is also known: its endosperm contains a mutant
amylose-extender (ae), which increases the amy-
lose content of the starch to 50-80%. Waxy and
high-amylose types of maize are used for wet-
milling (cf. p. 264); waxy maize is also used for
cattle feed.
Hybrid maize
Hybrid lines of maize have been developed that
give 15-20%, sometimes up to 50%, higher yields
than those of inbred lines, the use of which has
been almost superseded in the U.S.A. Thus,
Origin
Sorghum probably originated in North Africa
about 3000 B.C. and was certainly being culti-
vated in Egypt in 2200 B.C., as recorded in
100 TECHNOLOGY OF CEREALS
TABLE 4.18
US. Grades of Maize*
Maximum limits of
Damaged kernels
Minimum Broken corn
Grade Wt content material$ damaged Total
test Moisture and foreign Heat
No. (Ib/bu)t ("/.I ("1 ("/.I ("/.I
U.S. No. 1 56 14.0 2.0 0.1 3.0
U.S. No. 2 54 15.5 3.0 0.2 5.0
U.S. No. 3 52 17.5 4.0 0.5 7.0
U.S. No. 4 49 20.0 5.0 1 .o 10.0
U.S. No. 5 46 23.0 7.0 3.0 15.0
* Source: U.S. Dept. Agric (1987)
t 1 Ib/bu = 1.247 kg/hl.
$ Passing through a 12/64 in. (4.76 mm) round hole sieve.
wall paintings of that period. Thence it spread
throughout Africa and to India and the Middle
Bird-proof Sorghum
About one-third of the grain sorghum in South
tannins in the nucellar layer in this type of
sorghum are distasteful to birds and give the crops
some protection. Nevertheless, the presence of
tannins reduces protein digestibility; the available
methionine (by Streptococcus zymogenes assay) was
inversely related to tannin content (Hewitt and
Ford, 1982). As tannins are simply inherited,
they can be eliminated by breeding. Tannins in
existing high-tannin varieties can be inactivated,
e.g. by addition of absorbents such as polyethy-
leneglycol. The C.S.I.R. in South Africa has
developed a process which neutralizes the poly-
phenols in the intact grain without affecting
significantly its physiological properties.
U.S. Grades of Sorghum
Four grades of grain sorghum are recognized
in the U.S.A., with characteristics as shown in
Table 4.19. 'Sample grade' is defined in the same
way as for sample grade oats (cf. p. 95).
East. It reached China and America more recently.
Africa is Gbird-proof' sorghum. po~yphenols or
Classification
There are four main classes of sorghum that have
been bred for particular qualities: grain sorghum
for kernel quality and size; sweet sorghums for stem
sugar content and forage quality; broom corns for
length of panicle branches and suitability of the
panicle for use as brooms and brushes; grassy
sorghums for forage. All the cultivated sorghums
are generally known as Sorghum vulgare Pers.,
although the correct binomial terminology for
these types is Sorghum bicolor (Linn.) Moench.
Grain Sorghum
Grain sorghum is a coarse grass which bears loose
panicles containing up to 2000 seeds per panicle.
It is an hportant crop and the chief food grain in
Parts of Africa, Asia, Indiflakistan, and China,
where it forms a large part of the human diet.
Types of cultivated grain sorghum include
kaffir corn, milo and durra (Africa), feteritas
(Sudan), shallu, jowar, cholum and 'Indian millet'
(India), and kaoliang (China).
A waxy sorghum is known, in which the starch
orisin and Use
is composed almost entirely of amylopectin.
A sugary type of sorghum, sugary milo, is low The millets (cf. p. 25) have been used for food
in starch (31.5%) but contains 28.5% of a water- and for brewing since prehistoric times in Asia,
soluble polysaccharide resembling phytoglycogen Africa and Europe. Swiss Stone-age dwellers
from sweet maize. grew proso; finger millet (ragi) was cultivated from
Millet
CEREALS OF THE WORLD 101
TABLE 4.19
U.S. Grades of Grain Sorghum
Maximum limits of
Damaged kernels
Minimum
test Moisture Heat Broken Foreign
Grade Wt content damaged Total kernelsf material
No. (lb/bu)t (“h) (“/.I (%I (%) (Yo)
U.S. No. 1 57 13 0.2 2 3 1
U.S. No. 2 55 14 0.5 5 5 2
U.S. No. 3 53 15 1 .o 10 7 3
U.S. No. 4 51 18 3.0 15 9 4
* Source: U.S. Dept. Agric. (1991).
t 1 lb/bu = 1.247 kg/hl.
f Passing through a 5/64 in. (2.0 mm) triangular-hole sieve.
early times in India and Central Africa; pearl
fillet has similarly been used for thousands of
years in Africa and the Near East. Foxtail millet
is probably indigenous in China, although some
authorities believe that it originated in India. For
further information about the various types Of
millet, see Ch. 1 (p. 25).
GREENWELL, P., and SCHOFIELD, J. D. (1989) The chemical
basis of grain hardness and softness. Proc. zcc Symposium
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