Determination of sesame oil, rice bran oil and pumpkin seed oil in ternary mixtures using FTIR spectroscopy and multivariate calibrations

Pumpkin seed oil (PSO), rice bran oil (RBO), sesame oil (SEO) are considered as functional oils due to its biological activities which are beneficial to human health, as a consequence, these oils had the higher price. This attracted unethical players to blend these oils with lower price oils, therefore, its authentication by analysis of purity levels of oils is very important. This study highlighted the potential application of FTIR spectroscopy and multivariate calibrations for analysis of PSO, RBO, and SEO in ternary mixtures. Individual FTIR spectra of studied oils as well as in ternary mixtures with certain compositions were scanned and pre-processed. Two multivariate calibrations of principle component regression (PCR) and partial least square regression (PLSR) were compared and used to build the prediction models at optimized FTIR spectra regions. The selection of multivariate calibrations, wavenumbers region, and FTIR spectra modes was based on the statistical parameters of highest R² and lowest values of root mean square error of calibration (RMSEC) and root mean square error of prediction (RMSEP). The results showed that PLSR using second derivative FTIR spectra at wavenumbers region of 3100-2750 and 1500-663 cm^-1 was used to predict the levels of PSO in ternary mixtures with RBO and SEO with R² > 0.99 in calibration and validation models along with RMSEC value of 0.0054 and RMSEP of 0.0179. FTIR spectra using the second and first derivatives at wavenumbers of 3100-650 cm^-1 were used for prediction of RBO and SEO in ternary mixture with PSO, respectively. It can be concluded that FTIR spectra combined with PLSR at certain wavenumbers region are accurate as indicated by high R² values and precise as indicated by low values of RMSEC and RMSEP for analysis of PSO, RBO and SEO in ternary mixtures. © 2019 Elsevier B.V., All rights reserved.