低场核磁技术检测芝麻油掺假

Application of LF-NMR for Detection of Sesame Oil Adulteration

为评价低场核磁检测油脂掺假的能力,先用低场核磁结合主成分分方法区分大豆油和3种芝麻油(分别为精炼、冷榨和热榨工艺)样品,然后用偏最小二乘法分析不同掺兑比例的模拟掺假样品数据。结果表明,大豆油和芝麻油样品的特征信号区域在0~900 ms弛豫时间段,低场核磁能够较好地区分芝麻油和大豆油样品;低场芝麻油中掺入大豆油的最低检测比例为体积分数5%~10%,精炼芝麻油中掺入冷榨或热榨芝麻油的最低检测比例为体积分数10%~20%。因此低场核磁技术可以作为油脂掺假的快速初筛检测方法之一。

To evaluate the ability of low field nuclear magnetic resonance(LF-NMR) in detecting oil adulteration, LF-NMR and principal component analysis(PCA) were applied jointly to discriminate pure soybean oil from pure sesame oils(refined, cold pressed and hot pressed), and partial least squares(PLS) regression was applied to analyze three sesame oils adulterated with soybean oil and mixtures of two different sesame oils. The results showed that transverse relaxation time(0 to 900 ms) was an important signal region for discrimination of oil samples. LF-NMR could completely distinguish four different pure oil samples. The limit of detection(LOD) for sesame oil adulteration with soybean oil was 5% to 10%, and the LOD for refined sesame oil adulteration with cold or hot pressed sesame oil was 10% to 20%. Therefore, LF-NMR can be used as a rapid screening method to detect adulteration of oil.