SHORT-CHAIN FATTY-ACID FORMATION DURING THERMOXIDATION AND FRYING

Formation and evolution of the short-chain fatty acids originated by o xidation and remaining bound to the parent triglyceride, specifically heptanoate and octanoate, mere studied during thermoxidation of palm o lein, conventional sunflower oil and high-oleic sunflower oil at 180 d egrees C, as well as in real used frying oils of unknown history colle cted by Food Inspection Services. Fatty acids were quantified by gas-l iquid chromatography following transesterification of samples and usin g methyl nonanoate and methyl heptadecanoate as internal standards. Al teration level was determined through analyses of polar compounds and polar fatty acids. Results showed high correlation coefficients betwee n short-chain fatty acids and polar compounds or polar fatty acids, th us suggesting that quantification of short-chain fatty acids is a good indication of the total alteration level in used frying oils.