Cereals processing technology

16 Cereals processing technology
of Brewing until they have been subjected to commercial scale malting. Tworow
barley varieties are preferred to six-row varieties because of the evenness of
the grain, whilst varietal admixtures are not acceptable for malting.
The characteristics of a good malting variety are that it readily takes up water
on steeping, germinates readily and evenly and produces high levels of
hydrolytic enzymes for the conversion of the starch to soluble sugars. The
malting process is effectively a process of controlled germination and every
effort must therefore be made to retain a high germination capacity. Poor
germination can result from careless threshing damaging the embryo, from
drying at too high a temperature, or from heating caused by storage at too high a
moisture content. Furthermore, uniform, complete germination can only be
achieved by avoiding crop lodging and harvesting the grain when it is fully ripe.
The physical appearance of the grain is also important; maltsters prefer samples
where the grain is uniformly plump. This is usually measured by passing the
grain through a sieve and determining the percentage grain retained on the sieve.
Screening standards vary slightly between England and Scotland. Samples
should also have a low husk and high endosperm content, free from broken
grains and damaged husk.
There is a very good correlation between grain nitrogen and the amount of
malt extract achieved, low grain nitrogen giving more fermentable extract.
During the past decade the swing from traditional cask conditioned draught ale
towards light lager beers has reduced the demand for very low nitrogen grain.
For the former a nitrogen content of 1.5 to 1.65% is required whereas for lager
beer a grain nitrogen content of 1.8% is acceptable. Traditionally the lowest
grain nitrogen samples have been obtained from crops grown on light sandy
soils along the eastern coast of Britain. These soils have low residual levels of
organic nitrogen which allows better control of plant nitrogen supply from
annual fertiliser nitrogen applications. The amount of nitrogen applied to a
malting barley crop will be less than that applied to a crop destined for the feed
market, thereby sacrificing some yield potential for low nitrogen grain.
Applications of spring nitrogen to both the winter and spring sown crops
should also be completed at an early stage of crop development.
About a half of the UK oat crop is used for human consumption, whilst the
remainder is used for animal feeding. Food products containing oats include
oatmeal for porridge, oatcake, muesli and other breakfast cereal products. In
many of these products it is necessary to remove the fibrous husk surrounding
the kernel mechanically, although in recent years the introduction of naked or
huskless oats has been a major breeding achievement. Husk content has also
been found to differ between varieties and consequently some varieties are more
likely to attract a premium.
Traditionally oats were regarded as a low input crop; however, if a high
quality product is required for human consumption then more careful
management of inputs is required. Foremost amongst these is the need to avoid
the crop lodging with careful attention to the time and rate of nitrogen
application, coupled with the use of plant growth regulators. Maintaining the