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.
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.
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.
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.
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 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.