Abstract
A qualitative and quantitative analysis of trans fatty acids (TFAs), conjugated linoleic acids (CLAs) and linoleic acid/α-linolenic acid (ω6/ω3) in eleven different brands of fresh and heated corn oil was investigated. Corn oil was subjected to thermal treatment at 180, 210 and 230 °C for 4, 8 and 12 h. The kinds of fatty acids were almost the same in all eleven brands of corn oil, but there were differences in the quantities of TFAs, CLAs and ω6/ω3 among the brands. The formation of TFAs in different brands of corn oil increased slowly at 180 °C and rapidly at 230 °C with the maximum increase of 28 and 374%, respectively. The formation of CLAs also increased during the heating with the amount of 0.00-0.32 g/100 g in fresh corn oil and 0.71-1.12 g/100 g in corn oil heated at 230 °C for 12 h. The value of ω6/ω3 was high in corn oil and increased with heating temperature and time. The largest rise of ω6/ω3 can reach upwards of 239:1. The results showed that temperature control was essential for maintaining the quality and nutritional value of corn oil.