The employment of FTIR spectroscopy and chemometrics for authentication ofpumpkin seed oil from sesame oil

Abstract

The adulteration practice of high price oils such as pumpkin seed oils (PSO) with lower ones could be motivated by economic gains. The objective of this study was to apply FTIR spectroscopy in combination with chemometrics of multivariate calibrations and discriminant analysis for the authentication of PSO. A total of fifteen oils were scanned using FTIR spectrophotometer at mid-infrared regions (4000-650 cm-1 ) and subjected to principal component analysis (PCA) using absorbance values at whole mid-IR regions to know oil having a close similarity to PSO in terms of FTIR spectra. Two multivariate calibrations namely principle component regression (PCR) and partial least square regression (PLSR) along with FTIR spectra modes (normal, derivative-1, and derivative2) were optimized to get the best prediction models. In addition, discriminant analysis (DA) was used for classification of PSO and PSO adulterated with oil adulterant. The results showed that among 15 oils, sesame oil (SeO) had the closer score plot in terms of the first principle component and second principle components with that of PSO. Based on the statistical parameters selected (higher R2 and lowest errors), FTIR spectra in derivative -1 mode at wavenumbers of 1800-663 cm-1 were selected for quantification of PSO in SeO with coefficient of determination (R) values of 0.9998 and 0.9994 in calibration and validation models, respectively. The values of root mean square error of calibration (RMSEC) and root mean square error of prediction obtained were 0.003% and 0.006%, respectively. DA using 10 principle components could clearly discriminate PSO and PSO adulterated with SeO with accuracy levels of 100%. FTIR spectroscopy in combination with chemometrics could be an effective means to detect the adulteration of PSO with SeO.