Comparison of Carbon Stable Isotope and Fatty Acid Analyses for the Authentication of Perilla Oil

Abstract

Perilla oils distributed in Korea are authenticated by analyzing their C-13/C-12 isotope ratios (expressed as C-13) or fatty acid compositions. No significant differences are found in the C-13 values of authentic (n=27) and adulterated (n=10) perilla oils, whereas the distributions of 11 fatty acids (FAs) are significantly different in these oils. By using orthogonal projections for latent structures discriminant analysis (OPLS-DA) technique, the 18:2n-6, and 18:3n-3 content levels are determined to be the best variables for authenticating perilla oil. The authenticity of 7 out of 76 blind samples are identified through C-13 values, whereas using the 18:2n-6 and 18:3n-3 content levels can identify the authenticity of 66 blind samples. These results suggest that fatty acid analysis is a more useful procedure for determining the perilla oil authenticity. A blind trial shows that perilla oils adulterated with corn, soybean, or perilla-flavored oil at concentrations 5 vol% can be distinguished.Practical applications: Public concern about economically motivated adulteration (EMA) of food is growing worldwide. Perilla oil is a targeted product for EMA in Korea due to its high retail price. This study provides the first evidence showing that 18:2n-6 and 18:3n-3 content levels can become new specifications and standards for perilla oils distributed in Korea. The present study develops a procedure for authenticating perilla oils on the basis of the range of linoleic and -linolenic acid content levels. The procedure can correctly identify perilla oils adulterated with corn, soybean, or perilla-flavored oil at concentrations 5 vol%.