Effect of oleic/linoleic acid ratio on simultaneous formation of epoxy fatty acids and polar compounds in deep frying oils

This study investigated the effect of oleic/linoleic acid ratio (2:1, 1:1, and 1:2) on the simultaneous formation of epoxy fatty acids and polar compounds (TPC) in fried edible oil. The findings revealed that oleic acid resulted in higher levels of epoxy fatty acids, while linoleic acid contributed to higher TPC levels. After 24 h of frying, two oils (C18:1/C18:2 = 2:1 and 1:2) were criticized due to their respective contents of 7.19 mg/g epoxy fatty acids and 30.0 g/100 g TPC. When the TPC index reached 25 g/100 g (discarding point in most countries), the contents of epoxy fatty acids were 7.58 mg/g (at 23.4 h), 4.59 mg/g (at 27.2 h), and 2.74 mg/g (at 20.2 h) for the oils with different ratios. It is important to note that a higher content of oleic acid in the oil does not necessarily indicate better frying stability. Considering the balance of epoxy fatty acids, TPC, and frying time, our results supported the oil (C18:1/C18:2 = 1:1) to be a suitable option for frying applications.