Determination of free fatty acids in crude palm oil and refined-bleached-deodorized palm olein using Fourier transform infrared spectroscopy

A rapid direct Fourier transform infrared (FTIR) spectroscopic method using a 100 mu BaF2 transmission cell was developed for the determination of fre e fatty acid (FFA) in crude palm oil (CPO) and refined-bleached-deodorized (RBD) palm olein, covering an analytical range of 3.0-6.5% and 0.07-0.6% FF A, respectively. The samples were prepared by hydrolyzing oil with enzyme i n an incubator. The optimal calibration models were constructed based on pa rtial least squares (PLS) analysis using the FTIR carboxyl region (C=O) fro m 1722 to 1690 cm(-1). The resulting PLS calibrations were linear over the range tested. The standard errors of calibration (SEC) obtained were 0.08% FFA for CPO with correlation coefficient (R-2) of 0.992 and 0.01% FFA for R ED palm olein with R-2 of 0.994. The standard errors of performance (SEP) w ere 0.04% FFA for CPO with R-2 of 0.998 and 0.006% FFA for RED palm olein w ith R-2 of 0.998, respectively. In terms of reproducibility (r) and accurac y (a), both FTIR and chemical methods showed comparable results. Because of its simpler and more rapid analysis, which is less than 2 min per sample, as well as the minimum use of solvents and labor, FTIR has an advantage ove r the wet chemical method.