During deep-fat frying of chicken muscle in sunflower seed oil the content of thermolabile hydroperoxides reaches a value of about 5 mmoleikg while the amount of benzidine-active substances depends on the original amount of hydroperoxides in frying oil. Oxidation products in frying oil deteriorate the quality of odour, flavour and of the overall sensory value of fried chicken muscle. The flavour quality is mainly affected by increasing intensity of rancid, oily, and fishy off-flavours by interaction of lipid oxidation products with the fried substrate. Breast muscle is more affected by the oxidation products present in frying oil than thigh muscle.

During cold storage of fried poultry muscle the peroxide value of the fat fraction increased after a short induction period. The benzidine value increased during the induction period, and then decreased. The overall sensory quality slowly (insignificantly) deteriorated during the induction period, relatively rapidly afterwards. Changes of odour and especially those of the flavour were more pronounced than changes of other organoleptic properties. Greater changes took place in fried duck muscle than in fried chicken muscle. Changes of the flavour profile were characterized by increasing intensity of the following partial flavours: gluey, fishy. rancid, stale, old (stored) meat, both in duck and in chicken muscle. The oxidative changes were almost the same in fried breast muscle as in fried thigh muscle but the sensory quality changed more in case of breast muscle. In the flavour profile the intensity of rancid flavour increased more distinctly in thigh muscle while the intensity of stale flavour rose more rapidly in fried breast muscle. The deterioration of sensory quality was partly due to peroxids decomposition products and their interaction with amino acids and proteins.