傅里叶变换红外光谱法鉴别纯核桃油并定量检测掺伪含量

应用傅里叶变换红外光谱(FT—IR)法测定纯核桃油和分别混合大豆油、普洱茶籽油和葵花籽油的掺伪核桃油的红外光谱,结合主成分分析法(PCA)以及马氏距离判别法对核桃油的纯度进行判别,3个判别模型的准确率均达到100%;同时对验证集样品的类归属进行判别,判别准确率达均为100%。结合偏最小二乘法(PLS)定量检测核桃油纯度,建立的PLS校正集模型中核桃油的真实含量与FT—IR预测含量的相关系数R2分别为0.990 8、0.994 4和0.995 5,校正集均方根误差分别为0.032 7、0.023 5和0.019 6。试验结果证明,该方法可以作为核桃油质量监控的快速检测方法。

Application of Fourier transform infrared (FT-IR) spectroscopy for detection and quantification of adulteration in virgin walnut oil

Fourier transform infrared (FT-IR) spectrometer was used to collect infrared spectra of pure virgin walnut oil (VWO) and VWOs adulterated with soybean oil (SO), puer tea seed oil (PO) and sunflower oil (SFO). FT-IR spectroscopy combined with principal component analysis (PCA) and mahalanobis distance were developed for determining the authenticity of VWO, and all the accuracy rates of three models are 100%; Meanwhile, validation samples were used to predict the results by the models, and all the prediction accuracy rates are 100%. The partial least square (PLS) model was further used to predict the levels of these vegetable oils in independent samples for validation purpose. PLS models correlate the actual and FT-IR estimated values of oil adulterants (SO, PO and SFO) with coefficient of determination (R₂) of 0.9908, 0.9944, 0.9955 respectively. The RMSEC values of SO, PO and SFO in VWO obtained are 0.0327, 0.0235 and 0.0196, respectively. The method, therefore, has potential as a rapid method for detection and quantification of VWO adulteration.