Biochemistry

aldehydes, ketones, esters, aromatic and heteroaromatic compounds. In addition, heated fat contains acrolein (acrylic aldehyde, "kitchen gas"), which is a product of thermal dehydration of glycerol. Many products of thermal oxidation of fats are toxic, they cause irritation of the human digestive tract. The most pronounced damaging effect causes oxidized fatty acids, which contain during oxidation oxygen-containing functional groups (ОН, С = O, etc.). A sign of polymerization is an increase in viscosity and molecular weight of fat during prolonged heating. The non-volatile products of thermal oxidation and thermopolymerization include cyclic fatty acids. When assessing the quality of heated fats, an indicator - frying resistance is used, i.e. time (in hours) during which 1% of oxidized fatty acids accumulate in the heated fat. Fat is considered absolutely spoiled if in its mass at least 1% is oxidized fatty acids. This indicator depends on the degree of fat contact with oxygen, the type of fat, the degree of hydrolysis and the content of hydroperoxides in the original fat. Auto-oxidation of lipids inhibits compounds that can quickly bind free radicals. They are called antioxidants (antioxygen) and are used to slow down oxidation. Antioxidant activity has a number of natural compounds: phosphatides, some vitamins (E, С, P). They oxidize more easily to fats, bind free radicals and slow down the oxidation of fats. So, tocopherols stabilize various fats, as well as dry milk cream. Antioxidant properties are inherent with substances released from oily raw materials, cereals, mature olives and their juice. They retain their activity in the processed products, so that is why the raw soybean, cottonseed, palm, sesame oils, flax, soybean, peanut, finely ground roasted and defatted cocoa beans, fat extracts of soybeans, peanuts, cocoa have antioxidant effects. Antioxidants are also isolated from cocoa peel, sunflower seeds . Melanoidins, which are formed as a result of the interaction of reducing sugars with amino acids and other nitrogen-containing compounds, also have antioxidant activity. Spices in the amount of 0.2% by weight of lard or fat in mayonnaise delay the oxidation of fats. Along with natural antioxidants, artificial foods are also used in the food industry. These include phenols and their derivatives (cresols, naphthols, alkyl derivatives of phenol, etc.). The most common antioxidants of this group are butylhydroxytoluene-butyloxytoluene (ВОТ) and butylhydroxyanisole- butyloxyanisole (BOA), which are used to slow down the oxidation of lipids in baked goods, confectionery mass, etc. Effective antioxidants are also gossypol, a dye-ware of raw cotton oil; 2,4,5- trihydro-oxyphenols, aromatic acids with two to three hydroxyls in the ring 209