Changes in fatty acids and formation of carbonyl compounds during frying of rice cakes and hairtails

This study investigated the effects of frying of foods on the fatty acids and formation of carbonyl compounds in frying soybean oils. Rice cakes and hairtails were selected as typical starch/protein-based foods for frying using soybean oil. In this study, fifteen carbonyl compounds were detected by an efficient high performance liquid chromatography (HPLC) developed by this paper. During frying with rice cakes or hairtails, the linolenic acid in frying oils was reduced by approximately 20 % compared with that in the no-food frying system. Fewer types of carbonyl compounds (frying without food: 11; frying of rice cakes: 9; frying of hairtails: 6) were detected, and the levels of some carbonyl compounds such as trans-2-nonenal were decreased. Results suggested that frying rice cakes or hairtails can substantially influence the contents of fatty acids and the formation of carbonyl compounds in frying oils. This study provides references for evaluating the quality of fried oil and food.