Immature and Frost Damaged
Kernels
These kernels are usually found in Manitoba wheat No. 5. This normally
ground for disqualification . they are a cause of poor flour yield and dark
flour color, but they promote gas production in the dough in yeast
fermentation. Frost damaged kernels are usually blistered on the outside.
Sprout-Damaged Kernels
These are wheat kernels that have begun to sprout or germinate in the
wheat ear out in the field as a result of continuous high moisture. These kernels
are similar to malting-barley kernels. The internal break-down has already
begun, thanks to the activity of strong enzymes. Dough made from sprouted wheat
flour are sticky, due to excessive amounts of alpha-amylase.
Heat-Damaged Kernels
These are kernels with a brownish endosperm, caused by spontaneous
heating during wheat storage and strong respiration. A dark colored flour is
the result. Really burnt (carbonized) kernels are occasionally found. These are
produced by over-heating in grain driers operated on the direct flame
principle. In cases where only the germ under the bran is dark, this is due to
fungi.
Bug Wheat
The kernel is punctured in the field by a flat bug (8-13 mm in length)
during the actual growth stage. A liquid (an enzyme) is introduced into the
kernel as the bug sucks out the contents of the kernel. In any case this liquid
dissolves the gluten around the point of puncture, which is easily recognized
externally by a small red spot, with a yellowish halo around it. Doughs made
from flour from bug damaged wheat have a tendency to flow and are difficult to
bake. 2% bug punctured kernels are sufficient to cause trouble.
Antidote : Many of the suggestions are of practically no use (addition
of acids, formaline, large amounts of kitchen salt). The best results are
obtained with :
a.conditioning of the wheat at higher temperature
b. additions of higher doses of bromate, ammonium persulfate, ascorbic
acid, and so forth, to the flour.
A certain improvement can be achieved with the above mentioned means,
but a complete elimination of the damage is not possible.
Detection : yellow colored areas on the kernel with a clearly visible
red spot (point of puncture) in the middle. The gluten is sticky and extensible
to an unlimited extent after 24 hours. Dough reach a flowing stage within 1-2 hours. Flour
derived from sound kernels. Bug damaged wheat is mostly found in wheats from Russia
and the Balkan Countries, practically never in American and seldom in western
European domestic wheats.
Grain Desease
Smutty kernels : the interior of the smut balls consists of a black
powder, nothing but fungi spores with a herring-like smell. Such wheat is
called smutty wheat and must be cleaned very carefully.
Weevily kernels : kernels damaged by the grain weevil and other pests.
This damage is likely to increase through rapid reproduction during storage. Weevils
in grain to be milled increase the insect fragment count in the flour (filth
test) that could cause difficulty in marketing the flour in certain supply
areas (export, large scale consumers).
Broken kernels : these kernels are mainly produced during threshing and
during the transport of grain. Such kernels will give a dark flour of
objectionable odor, as the break surfaces are dirty. If these kernels are
scoured carefully by centrifugal action, the dirt will be rubbed off the break
surfaces. It is thus possible to mill the broken kernels together with the
sound ones. Broken kernels are excellent food for microorganisms.
Pesticides
Pesticides are used to eliminate insects in grain and granary products
in silos. Mills and bakeries. These are products that easily develop toxic
gases, which can be eliminated by aeration and in any case leave little or no
residue.
The word sanitation is used to cover the work necessary to keep
machinery, buildings, and finally all products, free from insects. The trend is
towards through gassing of a mill to exterminate all signs of life including
insects eggs, followed by periodical spot fumigation. The most comprehensive
work on the subject is no doubt the book of Kurtz & Harris.
The filth test enables one to distinguish between grain infestation
and later infection of grain products. Since this method is not yet very easy
to find in journals.
A promising new solution is irradiation with Gamma Rays, which are
even shorter than X-rays, but do not penetrate very deeply, so that only thin
layers of product can be treated. Gamma rays have the great advantage of not
leaving any chemical residue and of the treatment not being strong enough to
form radioactive products. Actually experimental work is going on in the USA
(Savannah, Ga. ) and in various European countries, including Switzerland. It needs
higher doses per gram to kill bacteria and insect eggs than man. Since the
Cobalt-60 source used emanates rays day and night, a plant must be fed
continuously. Thus the future may lie in mobile plants. Cost of plant and
operation are still quite prohibitive, but the future will surely see a reduction
in these prices.
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