Evaluation of Edible Oils Oxidation by Raman Spectroscopy

Abstract:

Lipid is the main raw material of food industry，and its quality and oxidation stability directly affect the food quality. Therefore，it is highly necessary to develop a fast，reliable and sensitive technology to evaluate the quality of edible oil. In this paper，linseed oil，fish oil and camellia-seed oil were analyzed by Raman spectroscopy and surface-enhanced Raman spectroscopy. The results indicated that during the process of oxidation，the characteristic peak at 974 cm-1 which on behalf of the trans structure gradually increased，resulting in increase of relative intensity of I974/I1442，and the characteristic peak at 1 265 cm-1 which on behalf of the cis double bond gradually decreased，resulting in decrease of relative intensity I1265/I1442. With silver nanosubstrate，the highest analytical enhancement factor was achieved for linseed oil diluted 50 times with hexane by SERS analysis. The changes of intensity for the same characteristic peaks were similar between SERS and Raman spectroscopy，indicating similar structure information for fatty acids was obtained，and SERS analysis was more sensitive.