应用脂肪酸甲酯快速筛选植物油中掺假地沟油

Rapid Screening for Gutter Oil Adulteration in Vegetable Oil Based on Fatty Acid Methyl Esters

根据植物油和地沟油中脂肪酸酯存在方式的不同,建立植物油中地沟油掺假的快速筛选方法。植物油中脂肪酸是以甘油三酯的形式存在,地沟油中脂肪酸以脂肪酸甲酯的形式存在,利用气相色谱-质谱的全扫描模式,结合NIST 05标准谱库检索功能,对37种脂肪酸甲酯进行测定。样品采用直接稀释-气相色谱-质谱全扫描分析脂肪酸甲酯,100个植物油样品中均未检出脂肪酸甲酯;20个地沟油样品中13个检出肉豆蔻酸甲酯(C14:0)、棕榈酸甲酯(C16:0)和硬脂酸甲酯(C18:0)等14种脂肪酸甲酯,检出率为65%,且70%的检出脂肪酸甲酯的地沟油样品中脂肪酸甲酯种类多、含量较高。因此,若植物油样品脂肪酸甲酯种类多、含量高,则可判定为有地沟油掺假;若脂肪酸甲酯含量低或没有脂肪酸甲酯,则可以进一步用其他指标和方法进行检测,脂肪酸甲酯的检测方法可以作为地沟油掺假的快速粗筛方法。

A rapid screening method for adulteration of gutter oil in vegetable oils based on different forms of fatty acid esters detected in samples was developed. The major forms of fatty acids were triglycerides in vegetable oils and fatty acid methyl esters(FAMEs) in gutter oil. Using gas chromatography-mass spectrometry(GC-MS) in a full-scanning detection mode, 37 kinds of fatty acid methyl esters were determined by searching against the NIST 05 standardmass spectral library. The fatty acid methyl esters of samples were determined by direct dilution with n-hexane and GC-MS with full-scanning analysis. Fatty acid methyl esters were not detected in 100 vegetable oil samples. Meanwhile, 14 kinds of fatty acid methyl esters were detected in 13(65%) out of 20 gutter oil samples, mainly including methyl myristate(C14:0), methyl palmitate(C16:0) and methyl stearate(C18:0). In addition, 70% of the 13 gutter samples were detected to simultaneously contain many kinds of fatty acid methyl esters at higher levels. Thus, vegetable oil sample detected to contain more fatty acid methyl esters at higher contents can be confirmed to be adulterated with gutter oil. In the case of lower or undetectable levels of fatty acid methyl esters, other indicators or methods are needed. In conclusion, fatty acid methyl esters can be used an indicator for rapid screening for gutter oil adulteration in vegetable oils.