Apart from many factors, quality of both plant and animal raw materials plays a crucial role in quality of food products as early as the beginning of the manufacturing process. It is clearly visible in plant raw materials in which quality at least at a certain stage can not be controlled by man. A sudden change in weather conditions can cause a big difference in technological parameters of the same variety of corn grown in different regions of the country during the harvest time. The criteria of purchase of the already mentioned corns are very simple and in case of oat very limited. It concerns some parameters pertaining to the science of commodities and that is all. Yet a grain does not only consist of shape, mass, density and colour. It mainly contains protein, starch, fat, cellulose and recently very popular β-glucans. Mixing corns of different varieties, or the same variety, but of different parameters contributes to an average value of chemical properties, and consequently to obtaining commercial oat of general (poor) quality. A high health quality of oat due to its specific chemical composition should make technologists point out which varieties are to be used to either manufacture diet products, or fodder.