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Wheat Milling Part 3 (Dampening and Tempering, The Second Cleaning Section)

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By : Novozymes and Buhler
5. Dampening and Tempering
Dampening and tempering of wheat helps : Make the bran tough and elasticMellow the endospermAchieve the correct flour moisture contentMaintain constant grinding conditions
During dampening, the grain enters the dampener through the front-end inlet. Together with the separately added  water, the grain undergoes an intensive intermixing and water penetration by the bi-rotor whirling system. The thoroughly dampened grain is discharged from the machine through the tangential outlet to the tempering bins. Selection of the moisture content of wheat at the 1st break depends on various factors. If we have to produce flour with low ash content, it would be better to run with higher moistures. This is especially the case with the hard wheat varieties. Here, we have a rather brittle bran layer and a harder endosperm and it is rather difficult to avoid too much bran breakage. By increasing the moisture content of the wheat, this problem can be s…
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Dough and Gluten Strength Tests

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1.Glutomatic Wet gluten content is determined by washing the flour or ground wheat sample with a salt solution to remove the starch and other solubles from the sample. The residue remaining after washing is the wet gluten. During centrifugation, the gluten is forced through a sieve. The percentage of gluten remaining on the sieve is defined as the Gluten Index, which is an indication of gluten strength. A high gluten index indicates strong gluten. Wet gluten content results are expressed as a percentage on a 14% moisture basis; for example, 35% for high protein, strong gluten wheat or 23% for low protein, weak gluten wheat.
The wet gluten test provides information on the quantity and estimates the quality of gluten in wheat or flour samples. Gluten is responsible for the elasticity and extensibility characteristics of flour dough. Wet gluten reflects protein content and is a common flour specification required by end-users in the food industry.
2.Farinograph The farinograph determines …
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Strucuture of a Wheat Kernel and its Chemical Composition

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Picture above give an idea of the structure of a wheat kernel and its various constituents, as well as its % mineral matter (ash content on dry matter basis). The amount of each constituent in the whole kernel is also given in percent.
The flour cells (endosperm) are mainly filled with starch and protein, and represent a dry reserve for the germ. The sprouting germ derives its first nourishment from this part. The thickness of the whole bran varies with the varying thickness (0.048 – 0.066 mm) of the longitudinal cells (pericarp). The colorless aleurone cells do not cover the germ. The ash content of these cells is more than 20 times higher than that of the white flour (endosperm). This layer is approx. 0.05 mm. thick and contains up to 30% protein (but no gluten protein), lipids (another 30%), vitamins and enzymes. A toxic substance has been found in the aleurone fat of the rye kernel which is of importance in animal feeding.
The nuccelar epidermis is situated between the aleurone c…
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