Oxidation kinetics of polyunsaturated fatty acids esterified into triacylglycerol and phospholipid in dried scallop (Argopecten irradians) adductor muscle during storage
The difference between oxidative susceptibility of polyunsaturated fatty acids (PUFAs) esterified into triacylglycerol (TAG) and phospholipid (PL) and the effects of polyphenolic antioxidant on such susceptibility in dried seafood were investigated. Lipid fractions containing TAG and PL were extracted from dried scallops stored for various times, and their fatty acids contents were determined. The changes in contents of four representative PUFAs, including α-linolenic acid (ALA), arachidonic acid (AA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) esterified into TAG or PL, were used to fit kinetic models to obtain the reaction rate constant (k), which reflects the oxidation rates of different lipid classes. The results indicated that the oxidation of PUFAs (ALA, AA, EPA, and DHA) esterified into TAG or PL at two storage temperatures (15 °C and 25 °C) followed the first-order kinetic model, and TAG had a greater oxidation rate than PL under the experimental conditions. The results further showed that natural phenolics could effectively inhibit the oxidation of PUFAs esterified into PL and TAG, while retain the nutritional value of dried scallop during long term storage. Furthermore, PL could better be protected by the polar polyphenolic antioxidant than TAG. This study shows that monitoring substrate loss and using kinetic models of PUFAs esterified into different lipid classes can provide insights into further studies on chemical and nutrition of foods containing complex lipid class compositions.