Koch Elisabeth, Löwen Ariane, Nikolay Sharline, Willenberg Ina, Schebb Nils Helge
Chair of Food Chemistry, Faculty of Mathematics and Natural Sciences, University of Wuppertal, Gaussstrasse 20, 42119 Wuppertal, Germany.
Department of Safety and Quality of Cereals, Max Rubner-Institut (MRI)─Federal Research Institute of Nutrition and Food, Schützenberg 12, 32756 Detmold, Germany.
J Agric Food Chem. 2023 May 17;71(19):7508-7513. doi: 10.1021/acs.jafc.3c00964. Epub 2023 May 4.
Deep-frying of food is a common cooking technique causing thermal oxidation of fatty acids (FA). Here, we investigated for the first time the formation of hydroxy-, epoxy- and dihydroxy-FA derived from oleic, linoleic (LA), and α-linolenic acid (ALA) during frying. Potato chips were fried in high-oleic sunflower oil for 4 × 5 cycles on 2 days, and the oil was comprehensively analyzed by liquid chromatography-tandem mass spectrometry. During frying, the ,-9- and ,-13-hydroperoxy-LA and -ALA concentrations decrease while their corresponding hydroxy-FA remain constant. The concentrations of both ,-9-/13-hydroperoxy-LA and ,-9-/13-hydroxy-LA increase with the frying cycles, which is also found for the concentration of -epoxy-FA. The increase in -epoxy-FA is more pronounced than that of the corresponding -epoxy-FA, exceeding their concentrations on the second day of frying. This selective change in the -/-epoxy-FA ratio is also observed for their hydrolysis products: concentrations of -dihydroxy-FA, derived from -epoxy-FA, increase during frying stronger than -dihydroxy-FA derived from -epoxy-FA. Based on these data, we suggest that the ratio of ,-/,Z-hydroxy-FA, in combination with the -/-epoxy-FA ratio, as well as the -/-dihydroxy-FA ratio are promising new parameters to evaluate the heating of edible oils and to characterize the status of frying oils.
食物的油炸是一种常见的烹饪技术，会导致脂肪酸（FA）发生热氧化。在此，我们首次研究了油炸过程中源自油酸、亚油酸（LA）和α-亚麻酸（ALA）的羟基脂肪酸、环氧脂肪酸和二羟基脂肪酸的形成情况。将薯片在高油酸葵花籽油中油炸4×5个周期，分两天进行，并用液相色谱-串联质谱法对油进行全面分析。在油炸过程中，9-和13-氢过氧-LA和-ALA的浓度降低，而它们相应的羟基脂肪酸保持恒定。9-/13-氢过氧-LA和9-/13-羟基-LA的浓度均随油炸周期增加，环氧脂肪酸的浓度也有此现象。环氧脂肪酸的增加比相应的环氧脂肪酸更明显，超过了油炸第二天它们的浓度。在它们的水解产物中也观察到了环氧脂肪酸比例的这种选择性变化：源自环氧脂肪酸的二羟基脂肪酸的浓度在油炸过程中的增加比源自环氧脂肪酸的二羟基脂肪酸更强。基于这些数据，我们认为9-/13-羟基脂肪酸的比例，与环氧脂肪酸比例以及二羟基脂肪酸比例相结合，有望成为评估食用油加热情况和表征油炸油状态的新参数。
