复热食用植物油结构变化的红外吸收光谱分析

Structural Transformation Analysis of Reheated Edible Vegetable Oil by Infrared Spectrophotometry

利用衰减全反射(ATR)傅立叶红外光谱(FTIRS)法对市售优质品牌的8种植物油(转基因豆油、非转基因豆油、葵花籽油、花生油、玉米油、红花籽油、调和油、橄榄油)未加热及反复高温加热后的红外二阶导数光谱进行比较,发现复热食用油在反复高温加热下会使不饱和脂肪酸亚油酸、亚麻酸的含量降低,饱和脂肪酸棕榈酸和硬脂酸的含量增加;顺式脂肪酸的含量下降,反式脂肪酸的含量明显增加。确定以二阶导数光谱中3 009、988、966 cm-13处特征吸收峰的峰高判定是否为反复加热用油。此方法样品用量少、分析速度快,可从整体上了解油品的质量及成分,并可作为市场复热食用油的快速筛查方法,也可为地沟油检测方法的建立提供理论依据。

Eight kinds of reheated oils （genetically modified soybean oil, non-genetically modified soybean oil, sunflower oil, peanut oil, corn oil, safflower oil, cooking oil, olive oil） were identi- fied by fourier transform infrared spectroscopy （FT - IR）. Unsaturated degree of unsaturated fatty acids（ e. g, linoleic acid and linolenic acid） in cooking oil decreased and saturated fatty acids （e. g. palmitic acid and stearic acid） increased under the condition of high temperature reheating, while the cis fatty acids were also changed to be trans fatty acids. The absorption of the peak at 3 009, 988, 966 cm 1 were selected as characteristic absorption peak of the alkene and trans structure by second order derivative spectrophotometry. This method, with the advantages of simplicity, small dosage and rapidness for quality analysis of reheated oil in market screening, could be used as the theoretical evidence for determination of waste oil.