A simple and rapid method for the determination of free fatty acid (FFA) content in brown rice using Fourier
transform infrared spectroscopy (FTIR) in conjunction with second-derivative treatment was proposed.
Ground brown rice (10 g) was soaked in toluene (20 mL) for 30 min, and the filtrate of the
extract was placed in a 1 mm CaF2 liquid cell. The transmittance spectrum of the filtrate was recorded
using toluene for the background spectrum. The absorption band due to the C@O stretching mode of FFAs
was detected at 1710 cm1, and the Savitzky–Golay second-derivative treatment was performed for band
separation. A single linear regression model for FFA was developed using the 1710 cm1 band in the second-
derivative spectra of oleic acid in toluene (0.25–2.50 g L1), and the model displayed high prediction
accuracy with a determination coefficient of 0.998 and a root mean square error of 0.03 g L1.
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