The specific feature of the oat is its high hull content, reaching 25…30%. The shells do not grow tightly together with the kernel. The oat kernel has relatively thin coat and aleurone layer, making up 9…11% grain weight. Besides, the kernel is covered with short fuzz, whose presence makes oat processing special. Oat products feature higher caloric value compared to other grain products, quite high protein and fat content. Moreover, owing to the availability of considerable glair content oat products are dietary. They contain many vitamins – thiamine, riboflavin, niacin and a number of mineral elements.
The process offered by our company is different from that offered by Buhler in the fact that we use grain hydrothermal treatment before its hulling, and then, similarly to Buhler, oat hydrothermal treatment before flattening.
Based on the scientific research and practical experience, specialists of Research and Production Company Agro-Simo-Mashbud proved that grain hydrothermal treatment before its hulling is beneficial for the grain processing properties, its food value and useful qualities.
For example, one of the drawbacks of all crops, processed into groats, is their fragility, which entails lower output of the whole kernel. The only way to decrease kernel damaging is grain hydrothermal treatment, which includes grain preheating (to reduce steam condensation on the grain), grain steaming that «cements» the kernel and further drying.
Steaming and drying change the grain structural - mechanical and physicochemical properties, improve the grain processing characteristics. Owing to starch gelatinization and protein denaturation swollen starch grains have «closed and glued» cracks in the kernel. Grain colour depends on the steaming modes, which is connected with generation of the products, capable of reacting with each other – reducing sugars, their split products and amino groups (proteins and amino acids), determining sugar amino reaction, or the Maillard reaction. It should be mentioned that the reaction of sugars interaction may involve not only amino acids, but also ammonia, peptides and proteins. The intensity of the Maillard reaction is influenced by the rigidity of steaming modes and the degree of kernel heating. The higher the temperature, the more intensive kernel colour change, which is related to the heat hydrolysis of the above substances and their quantitative increase.
The next important process operation is drying. After drying the kernel becomes glassy and hard. Its mechanical strength rises greatly, and the dried shells become brittle and easily removable. As a result, hulling factor increases, damaged kernel content decreases, huller capacity rises thus enabling to save hulling specific energy costs.
Consequently, the total groats output after the hydrothermal treatment is higher by 4-8% compared to the grain that does not undergo this treatment, whereas the damaged kernel output rate falls 6-10%. This applies to oats as well as to the other glumaceous crops.
Furthermore, hydrothermal treatment considerably increases grain biological value, since vitamins and minerals contained in the outer layers of the kernel are preserved in contrast to conventional hulling and polishing during which they are usually lost. Treating grain hydrothermally, the significant part of vitamins, minerals and aromatic substances dissolves and migrates with steam from the peripheral shells deeper into the kernel due to the overpressure. Oat processing properties improve, specific bitter off-flavour disappears, groats storage properties enhance (oats are rich in fat that is quite easily hydrolyzed and oxidized).
This technique allows for notable improvement of useful qualities and food value of the oat and other cereals.
Centrifugal huller SIMO TsShS-3 developed by Research and Production Company Agro-Simo-Mashbud is designed for high performance sunflower seed and oat grain hulling alongside with simultaneous shaking and winnowing a part of fuzz and hull, corn crushing to remove corcules. Rotor operating surfaces and huller decks are made of high-duty chilled cast iron. To hull other cereals the operating deck surfaces may be made of abrasive or polymer materials.
The use of our hullers TsShS-3, centrifugal sieves TsS-1 and screening machine MSH at oat processing mills enables to obtain the whole grain groats output os 58…62% at the bushel weight of 490-510 kg/m³; and the output of 62…64% at the bushel weight of over 520 kg/m³. The hulling factor per passage is 90…93%.
At present there are no analogues to centrifugal huller SIMO TsShS-3 in terms of its hulling factor preserving the maximum undamaged kernel rate.
