A rapid method to authenticate vegetable oils through surface-enhanced Raman scattering.

Ming Yang Lv,Xin Zhang,Zheng Wang,Li Min Liu,Luo Liu,Hai Jun Xu,Yong Mei Zhao,Hai Rui Ren,Zheng Long Wu

doi:10.1038/srep23405

Abstract

Vegetable oils are essential in our daily diet. Among various vegetable oils, the major difference lies in the composition of fatty acids, including unsaturated fatty acids (USFA) and saturated fatty acids (SFA). USFA include oleic acid (OA), linoleic acid (LA), and α-linolenic acid (ALA), while SFA are mainly palmitic acid (PA). In this study, the most typical and abundant USFA present with PA in vegetable oils were quantified. More importantly, certain proportional relationships between the integrated intensities of peaks centered at 1656 cm−1 (S1656) in the surface-enhanced Raman scattering spectra of different USFA were confirmed. Therefore, the LA or ALA content could be converted into an equivalent virtual OA content enabling the characterization of the USFA content in vegetable oils using the equivalent total OA content. In combination with the S1656 of pure OA and using peanut, sesame, and soybean oils as examples, the ranges of S1656 corresponding to the National Standards of China were established to allow the rapid authentication of vegetable oils. Gas chromatograph-mass spectrometer analyses verified the accuracy of the method, with relative errors of less than 5%. Moreover, this method can be extended to other detection fields, such as diseases.

Highlights

Low-cost, and rapid, may overcome these disadvantages
In combination with principal component analysis (PCA), partial least-squares, least squares support vector machines (LS-SVM), or neural network techniques[19,20,21,22], Raman spectroscopy has been successfully used to authenticate oils: Zou et al detected olive oil adulteration using the Raman spectrum combined with two-dimensional figure and PCA23; and Dong et al predicted the fatty acid composition of vegetable oils based on Raman spectroscopy and the LS-SVM technique[20]
The present study aims to establish a novel and universal analysis system based on surface-enhanced Raman scattering (SERS) to authenticate whether the USFA content of vegetable oils conforms to certain quality control specifications, such as those of the National Standard of China (GB)

Summary

Introduction

In combination with principal component analysis (PCA), partial least-squares, least squares support vector machines (LS-SVM), or neural network techniques[19,20,21,22], Raman spectroscopy has been successfully used to authenticate oils: Zou et al detected olive oil adulteration using the Raman spectrum combined with two-dimensional figure and PCA23; and Dong et al predicted the fatty acid composition of vegetable oils based on Raman spectroscopy and the LS-SVM technique[20] These detection methods can establish standards to authenticate oils with a high level of accuracy, they require knowledge of chemometrics and sophisticated data processing, which limits their widespread application. The silver/silicon (Ag/Si) substrate will be used for the SERS test

Methods

Results

Conclusion