Quenching mechanism and kinetics of ascorbyl palmitate for the reduction of the gamma irradiation-induced oxidation of oils

The effects of 0, 250, 500, and 1000 ppm (wt/vol) ascorbyl palmitate (AP) o n the gamma irradiation-induced oxidation of soybean oil,cottonseed oil, co rn oil, tallow, lard, or linoleic acid either in a solvent mixture (benzene /methanol, 4:1 vol/vol) or in methanol, was studied immediately after gamma irradiation with a dose of 1-5 kGy. Steady-state kinetic approximation was used to determine a quenching mechanism and quenching rate constant of AP on the gamma irradiation-induced oxidation of purified soybean oil in a sol vent mixture (benzene/methanol, 4:1 vol/vol). Irradiation greatly increased oxidation of all oils, as was expected. AP was extremely effective at mini mizing oxidation in all oils, and its effectiveness was concentration depen dent. AP showed significantly greater antioxidative activity than alpha-toc opherol for the reduction of oxidation in all oils (P < 0.05). The steady-s tate kinetic studies indicated that AP quenched oxygen only to minimize the oxidation of oils. The calculated total quenching rate of AP was 7.51 x 10 (7) M(-1)s(-1). The present results clearly show the effective oxygen quenc hing ability of AP for the reduction of gamma irradiation-induced oxidation of oils.