Attenuated Total Reflectance–Fourier Transform Infrared (ATR–FTIR) Spectroscopy Combined with Chemometrics for Rapid Determination of Cold-Pressed Wheat Germ Oil Adulteration

Abstract

This paper describes the feasibility of attenuated total reflectance–Fourier transform infrared (ATR–FTIR) spectroscopy combined with multivariate data analyses for rapid determination of cold-pressed wheat germ oil (WGO) adulteration. Thirty-six pure edible oils, as well as 216 binary blends of WGO adulterated with cheaper refined oils, sunflower (SFO), and soybean oil (SBO) (1–50%) were analyzed by using ATR–FTIR spectroscopy in combination with PCA, LDA, SIMCA, and PLSR analyses. SIMCA models provide excellent classification for pure cold-pressed WGO and refined edible oil samples, with 95% significance level. The classification limits for detection of SFO and SBO adulterations in WGO were below 1%. Furthermore, a total of 100% of studied samples were correctly classified on the basis of their origin in calibration and in cross-validation by LDA models. Under the optimum conditions, the PLS–R plots of actual versus predicted values exhibited high linearity (R2 > 0.9990). The content of SFO and SBO adulterants has been successively quantified using PLSR at levels < 0.56% and < 0.99% in an unknown mixture. RMSEC and RMSECV values for the binary mixtures of WGO–SFO were between 0.56–1.98% and 0.68–4.46%, for the binary mixtures of WGO–SBO were between 0.99–1.77% and 1.09–5.12%, respectively.