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