Quantitative analysis of extra virgin olive oil adulterated with pressed rapeseed oil based on PCA-SVM and confocal Raman spectroscopy
To promote the healthy development of the domestic olive oil market,a study was conducted on quantitatively identifying extra virgin olive oil adulterated with low-temperature pressed rapeseed oil containing natural carotenoids.The confocal Raman spectroscopy technology was used to test oil samples with different adulteration amounts.Theoretical analysis was conducted on attributing Raman spectral peaks of different oil samples based on density functional theory.Principal component analysis(PCA)was performed on the Raman spectral data,and then the support vector machine(SVM)was used to construct a PCA-SVM model.In addition,the detection limit of the PCA-SVM model was studied.The results showed that there was difference in the Raman spectra of extra virgin olive oil and low-temperature pressed rapeseed oil,and the most apparent spectral differences mainly concentrated in the spectral peaks 1008,1161,1528 cm-1 and spectral bands 2800-3000 cm-1,which was consistent with the analysis of Raman spectral peaks of different oil samples using density functional theory.The PCA-SVM model established without considering the characteristic signals of carotenoids had a coefficient of determination greater than 0.989,and the root mean square error was lower than 2.990%,and the detection limit was 2%(volume fraction of low-temperature pressed rapeseed oil).In the quantitative analysis of extra virgin olive oil adulteration,considering the characteristic signals of carotenoids could help to improve the prediction accuracy of the model,but it was only limited to the absence of carotenoids in adulterated low-price vegetable oils.The PCA-SVMmodel still had good quantitative prediction performance even when the characteristic signals of carotenoids were not considered.In summary,the established PCA-SVM model can be used to quantitatively identify extra virgin olive oil adulterated with over 2%low-temperature pressed rapeseed oil.
extra virgin olive oillow-temperature pressed rapeseed oilPCA-SVMRaman spectroscopydensity functional theory
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