DOSE-DEPENDENT OXIDATION-KINETICS OF LIPIDS IN FISH DURING IRRADIATION PROCESSING

Kinetic aspects of the development of lipid oxidation in complex foods as fish in the course of irradiation were analyzed with respect to th e associated formation of malonaldehyde (MA) through the reactions mod ified so as to be consistent with those in complex foods as fish. Air- packed anchovy (Engraulis encrasicholus) samples in polyethylene pouch es were irradiated at the doses of 1, 2, 5, 10, 15, 20 and 25 kGy at 2 0 degrees C in st Cs-137 gamma irradiator of 1,806 kGy/h dose rate. Im mediately after each irradiation, MA contents of irradiated and unirra diated samples were determined by thiobarbituric acid test. Based on t he MA formation, a kinetic model to simulate the apparent oxidation of lipid in fish as a function of irradiation dose was derived from the rate equations consistent with modified reactions. Kinetic parameters and simulation were related to conditions of lipid oxidation, and asso ciated rancidity state of fish with respect to the doses applied in di fferent irradiation-preservation processes. Numerical values of kineti c parameters based on the MA formation were found as a threshold dose of 0.375 kGy, an apparent yield of 1.871 mu mol/kg kGy, and a maximum attainable concentration of 15.853 mu mol/kg which may be used for pro cess control and dosimetry. (C) 1997 Elsevier Science Ltd.