Authentication of adulterated edible oil using coherent anti-Stokes Raman scattering spectroscopy

Abstract

A comparative analysis on five edible oils with the same chemical composition but different composition ratios was performed by using coherent anti-Stokes Raman scattering spectroscopy in the wavenumber 2400-3200 cm(-1) corresponding to C-H vibration band. Intensity ratio (I=C-H/IC-H) in C-H stretching region was obtained according to the mixing ratio of the two types of edible oil, and the fitting curves were obtained from the fact that the intensity ratio is proportional to the square of N=(C-H)/NC-H where N-k is the expectation value of k bonds of the edible oil. N=C-H and NC-H of the edible oils obtained from the fitting curves were well matched with the referred values. And finally, we showed that the coherent anti-Stokes Raman scattering spectroscopy can be used as a method of authentication of adulterated edible oil by demonstrating a method to determine the type and the amount of unknown mixed oil.