Analysis of corn and soybean oils in red fruit oil using FTIR spectroscopy in combination with partial least square

The study highlighted the application of Fourier transform infrared (FTIR) spectroscopy as a non destructive and fast technique in the determination of red fruit oil (RFO) authenticity. RFO was made in binary mixture with corn oil (CO) and soybean oil (SO). Multivariate calibration method, partial least square (PLS), was used to construct the calibration model that correlate between actual and predicted values of RFO contents in the mixture at the FTIR spectral frequencies of 1800 – 1600 and 1200 – 800 cm^-1. Attenuated total reflectance (ATR) measurements were made on pure RFO and that adulterated with varying concentrations of CO and SO (1– 50% v/v). PLS at these frequencies showed the best calibration model, in terms of the highest coefficient of determination (R2) and the lowest of root mean square error of calibration (RMSEC), with R2 of 0.999 and RMSEC of 0.987% (v/v), respectively for analysis of CO in the mixture with RFO. Meanwhile, the R² and RMSEC values obtained for the quantification of SO were of 0.997 and 1.195%. In general, FTIR spectroscopy serves as a suitable technique for determination of CO and SO in RFO for authenticity studies.