The influence of heat treatment on the activity of lipo- and hydrophilic components of oat grain

Lipids in oat grains are protected against oxidation by various chemical co mpounds with antioxidant properties. Biologically active compounds such as tocopherols, L-ascorbic acid, thiol, phenolic amino acids and phenol compou nds feature such properties. Phenolic compounds inhibit lipase activity, pr otect lipids against oxidation and, as a consequence, protect plant cells a gainst the destructive activity of free radicals. The disadvantage of natur al antioxidants is their low resistance to high temperatures since heating over 80C destroys their antioxidant properties. Operation such as drying, b lanching, roasting or extrusion destroy the protective system of plant lipi ds. The paper is an attempt to explain to what degree extrusion conditions infl uence activity of natural antioxidants. Oaf flour possessing the largest am ount of lipids and biologically active compounds compared to other cereal f lour was used in the model system. It has been found that oat phenolic comp ounds are a mixture of free phenolic acids, esters and phenolic acid glycos ides as well as flavonols and polyphenols. It has been established that alc oholic extracts produced from oat great and flour had strong antioxidant pr operties, whereas the extracts front extruded substances did not reveal suc h properties. During extrusion about 50% degradation of phenolic compounds was observed. Phenolic compounds were the main group of organic compounds e nabling enzyme activity and playing an antioxidant role.