Grinding process

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Modern roller mill in a flour mill

Grinding process , also known as milling referred to are technological processes for the production of powdered (mealy) products from coarse solids, in the accepted sense, only the processing of grain to flour , semolina , mist and shot in a flour mill .

Procedure

Common procedures are as follows:

  • Flat milling,
  • High milling,
  • Half-high meal,
  • Combined grinding process and
  • Peeling .

The grinding takes place in principle with the processes of comminuting (grinding), sieving (sifting) and mixing the various intermediate products. Milling used to take place in the grinding mill (millstones), but today on roller mills in which the grain is cut and ground.

Low grinding ( Flachmahlverfahren ) means a few (approximately three to four) passages ( passages ) the grain quickly to grind into flour and meals and ground oversize material together. It is a grinding process that is mainly used for rye . In contrast to high milling, a narrow roller spacing (flat roller guide) causes the grain to be severely torn immediately, resulting in a high flour yield with a low number of passes. In the process, more ingredients from the outer layers of the ground cereal grain get into the flour, making it darker and richer in minerals.

The high milling ( high milling process) is a milling process in which, in contrast to flat milling, the rollers (formerly stones) are initially guided with a relatively large, gradually decreasing distance. After each grinding, the fine material (flour) is sieved off and the coarse fractions ( meal , semolina , fumes ) are returned to the rolling mill. The gentle high-milling process allows the flour to be sorted as far as possible according to grain size and the extraction of semolina and haze. It encompasses extensive grinding with up to thirty passes for wheat , which enables the white flours produced to be of high quality. The process is today mostly durum wheat used mills for which it in Austria-Hungary was also developed primarily in the 19th century.

The (German) Halbhochmahlverfahren is a combination of the two aforementioned processes. It takes into account the varietal characteristics of the softer German wheat varieties and is primarily intended for flour production.

Combined mills process rye and wheat on a common grinding system ( combined grinding process ). These mills always represent a compromise between flat grinding and half-high grinding methods.

Larger mills work in an automatic cycle. This means that each grinding machine or passage is only used once. The flow of the (intermediate) products is determined by various flap settings. This also allows certain quality fluctuations to be absorbed in a targeted manner.

The husk is a separate milling process and is mainly used for the processing of barley , oats , rice and spelled adopted in which it comes to shelling and / or the husking of the grain. For this purpose, the grain can be peeled intensively several times with a normal peeling machine or a special peeling cycle is introduced in which the grains are processed with specially designed friction surfaces for a specific, adjustable peeling time. Since this always results in a fraction of broken grain, a subsequent sifting is inevitable. The terms used are the pearl barley mill ( pearl barley is practically the white peeled endosperm of winter barley) and the oat mill (oat is a husk grain that has to be subjected to additional heat treatment during processing).

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