A Second Derivative Fourier-Transform Infrared Spectroscopy Method to Discriminate Perilla Oil Authenticity

Abstract

The aim of this study was to discriminate the authenticity of perilla oils distributed in Korea using their Fourier-Transform infrared spectroscopy (FT-IR) spectra with attenuated total reflectance accessory. By using orthogonal projections for latent structures discriminant analysis (OPLS-DA) technique, the =C-H cis-double bond, -C-H asymmetric and -C-H symmetric stretching are determined to be the best variables for discriminating the perilla oil authenticity. Comparing the integral and the second derivative methods between authentic and adulterated perilla oil samples, the most obvious and significant differences among the three variables is =C-H cis-double bond stretching. The procedure for applying the second derivative range of variables found in authentic perilla oil samples correctly discriminated between the adulterated samples of perilla oils with soybean oils and/or corn oils added at concentrations of ≥ 5 vol%. These results showed that the second derivative FT-IR analysis can be used as a simple and alternative method for discriminating the authenticity of perilla oil.