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

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 edibleoils, as wellas 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 (R-2>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.