تخمین پایداری نسبی روغنهای نباتی بر حسب آزمونهای تسریع شده

In this research, the relative stability of canola, soybean, olive and corn oils in terms of the accelerated tests of rancimat at 120 ºC and carbonyl at 160 ºC was compared. The highest and lowest amount of the ratio between polyunsaturated fatty acids (PUFA) and saturated fatty acids (SFA) belonged to the corn (4.74) and olive (1.03) oils, respectively. The canola (3.16) and soybean (3.38) oils, with an intermediary position, had no significant difference between their PUFA/SFA ratios. The highest amount of phenolic compounds with no significant difference was observed in the canola and soybean oils (48.19 and 45.80 ppm, respectively). Its lesser amount was found in the corn (30.80 ppm) and olive (15.27 ppm) oils, respectively. The order of the oxidative stability for the oils studied in terms of the accelerated carbonyl test (tΔCV=30) was (104.93, 77.67, 61.23, and 50.29, respectively), and the difference between the olive and corn oils here was statistically significant. The oxidative stability order of the oil samples in terms of the rancimat test was similar that of the carbonyl test (9.26, 6.89, 5.65, and 4.82 h, respectively). The comparative investigations on the ratio between the two stability indices of the carbonyl and rancimat showed more obvious differences between the oils studied in terms of the carbonyl value (1.35, 1.27, and 1.22) than in terms of the rancimat value (1.34, 1.22, and 1.17).