Influence of mixing ratio of blending oil (rice bran oil : RBD palm olein = 1 : 1, 1 : 4 mixture: w/w) and natural tocopherol, citric acid, and sodium polyphosphate on enhancement of oxidation stability of blending oil under the condition of tap water infulx(1 ml/min/200g oil) were compared by AOM test after heating these system at l80℃. In addition, the effects of tocopherol, and synergist on oxidition stability were also tested with potato chips fried with blending oil(1 : 4 mixture). The result obtained were as followes; 1. The test of RBD palm olein addition of 50% and 80% against rice bran oil on oxidation stability showed that the higher the palm olein contents in blending oil, the higher the oxidation stability. 2. The test of oxidation stability, adding l00ppm, 200ppm and 400ppm of natural tocopherol in two different types of blending oils, A(1 : 1 mixture) and B(1 : 4 mixture), disclosed that blending oil B was more positively effective, and this trend was superior at 200ppm level particularly, Furthermore, oxidation stability was enhanced remarkably upon addition of 100ppm of natural tocopherol, and 50ppm of citric acid together with 50ppm, 100ppm and 200ppm of sodium polyphosphate in general. Especially, 200ppm of sodium polyphosphate addition induced the most synergetic effect on oxidation stability showing as much as 3 times compare to control. 3. The results of oxidation stability obtained by peroxide value on potato chips fried with blending oil (1:4 mixture added tocopherol, citric acid and sodium polyphosphate and preserved at 60℃ revealed that addition of tocopherol and 50ppm of citric acid together with 200ppm of sodium polyphosphate treatment was the most synergistic coinciding with AOM test results.

The oxidative stability of palm oil with moisture addition during heationg was investigated and the antioxidant effects of tocopherol, citric acid and sodium polyphosphate were evaluated. The addition of natural tocopherol up to 200 ppm level did not improve the oxidative stability of palm oil with moisture (1m1 H2O additive to 200g of oil at 180℃). The maximum antioxidant effect was observed at the Concentration of 400 ppm. Addition of citirc acid did not influence the effective concentration of tocopherol. Whereas addition of sodium polyphosphate and citric acid increased the antioxidant effect of tocopherol. The maximum synergistice effect was observed at the concentrations of 50 ppm citric acid and 50 ppm of sodium polyphosphate. Addition of 50 ppm citric acid and 50 ppm sodium polyphosphate to 100 ppm of tocopherol exceeded the antioxidant effect of 400 ppm tocopherol alone.