The following two fry tests were carried out to investigate the synergistic antioxidant effects of tocopherol (Toc) and citric acid (CA), monoacylglyceryl citrate (MGC), L-ascorbic (AA) or erythorbic acid (EA) on fried foods. In Fry Test I, potato chips were fried once at 160°C with lard systems consisting of a mixture of d-Tocs and one of each of the synergists. Five fryings at 30 min intervals were carried out at 170°C for Fry Test II. Stability of the chips toward oxidation was evaluated primarily on the basis of changes in the POV of the chip lipid fraction during a storage at 60°C.
1) All the tested synergists contributed enhanced the antioxidant effects of Toe on potato chips. The time required to attain POV 30 and for a perceivable odor to occur during storage at 60°C of EA CA>AA>MGC.
2) Potato chips stored at 60°C showed a tendency such that the remaining Toc was higher with increased oxidative stability.
3) In Fry Test II, there was little difference in POV, carbonyl value or total Toc content of lard containing CA or EA in the initial and final fryings. Also, the oxidative stability of chips fried in each lard system hardly varied with an increase in fry times, when stored at 60°C. Notably, the synergistic antioxidant effect of EA with Toc on potate chips was still maintained provided the lard system was heated at 170°C for 2h.
