In a flour mill, wheat and spelt are processed into flour. The grain is, before it is milled, carefully cleaned and dampened with water, that the water can penetrate into the shell (bran), which then better can be separated from the endosperm. The grain is then milled with roller mills, afterwards sifted in a plansifter. The flour will be screened and the grits are transferred back and milled again until all the flour has been removed.
Oat seeds are first dehulled. The vitamins and fiber in the outer layer of the grain are preserved. Then grains are kilned for several hours. Kilning disables the fat-decomposing enzymes in oats and reduces the moisture content. Thus, flakes get not rancid. Oat groats, resulting in splitting of oat kernels into small pieces. Groats is raw material for many other products. Big leafed flakes arise from whole Oat kernels which are moistened and then rolled on flaking mill. Then they are dried again. For small leafed flakes grits are flaked. For oatmeal and oat bran, grits are finally ground.
In the Preconditioner, the dry raw materials – e.g. flours or premixes - are mixed with water or hot steam and other ingredients such as salt or even cocoa powder and are pre-cooked. In the extruder itself, the ingredients are modified by the influences of temperature, mechanical impact, and time. The speed of the two screws in the extruder and the shear forces determine temperature, degree of starch gelatinisation and hence the texture and quality of the finished product. But also the composition of the raw material has an influence. At the end of the extruder, the dough is pressed through a defined opening, shaped and cut. This is followed by a drying process. Depending on further processing steps, shapes, granulates or flours are produced.