2009_Book_FoodChemistry

15 Cereals and Cereal Products
15.1 Foreword
15.1.1 Introduction
Cereal products are amongst the most important
staple foods of mankind. Nutrients provided by
bread consumption in industrial countries meet
close to 50% of the daily requirement of carbohydrates,
one third of the proteins and 50–60%
of vitamin B. Moreover, cereal products are also
a source of minerals and trace elements.
The major cereals are wheat, rye, rice, barley, millet
and oats. Wheat and rye have a special role
since only they are suitable for bread-making.
15.1.2 Origin
The genealogy of the cereals begins with wild
grasses (Poaceae), as shown in Fig. 15.1. Barley
(Hordeum vulgare), probably one of the first
cereals grown systematically, was known as early
as 5000 B.C. in Egypt and Babylon. Also, the
bearded wheat cultivars from the groups Einkorn
(Triticum monococcum) and Emmer (T. dicoccum),
with diploid (genome formula: AA,
2n = 14) and tetraploid (AABB, 2n = 28) sets of
chromosomes, (the chromosome number of the
wheat genome is n = 7), were found among cultivated
plants that were widely spread in temperate
zones of Euroasia during the neolithic period.
These cultivars are becoming extinct. Only the
durum form of Emmer (T. turgidum durum, hard
wheat, AABB), at 10% of the total wheat grown,
has a significant role. The hexaploid (AABBDD,
2n = 42) wheats derived from spelt are grown
worldwide as bread cereals. The A genome of
the spelts is closely related to that of Einkorn
(T. monococcum). The origin of the B genome is
unknown. It probably comes from species of the
genus Aegilops and the D genome from Aegilops
squarrosa.
Two varieties are derived from the spelts, bare
wheat (soft wheat, T. aestivum) and bearded spelt
(T. spelta). The low yield and the additional dehusking
procedure led to the fact that soft wheat
(called “wheat” below) gained more acceptance
than spelt. As late as the middle of the 19th
century, 15–20 times more spelt than wheat was
grown in Southern Germany. Since the 1980s,
however, demand for spelt has increased, especially
in the natural food market. To compensate
for the disadvantages with respect to the yield
and the baking properties, wheat cultivars are
crossed with the spelt. Such varieties differ from
pure spelt in their gliadin pattern, which can be
determined by HPLC (cf. 15.2.1.3.1).
Rice (Oryza sativa) andcorn(Zea mays) have
been cultivated for 5000 years, first in tropical
Southeast Asia and then in Central and South
Fig. 15.1. Evolutionary development (phylogeny) of cereals
H.-D. Belitz · W. Grosch · P. Schieberle, Food Chemistry 670
© Springer 2009