Near and mid infrared spectroscopy and multivariate data analysis in studies of oxidation of edible oils

Infrared spectroscopic techniques and chemometric methods were used to study oxidation of olive, sunflower and rapeseed oils. Accelerated oxidative degradation of oils at 60 °C was monitored using peroxide values and FT-MIR ATR and FT-NIR transmittance spectroscopy. Principal component analysis (PCA) facilitated visualization and interpretation of spectral changes occurring during oxidation. Multivariate curve resolution (MCR) method found three spectral components in the NIR and MIR spectral matrix, corresponding to the oxidation products, and saturated and unsaturated structures. Good quantitative relation was found between peroxide value and contribution of oxidation products evaluated using MCR - based on NIR (R2 = 0.890), MIR (R2 = 0.707) and combined NIR and MIR (R2 = 0.747) data. Calibration models for prediction peroxide value established using partial least squares (PLS) regression were characterized for MIR (R2 = 0.701, RPD = 1.7), NIR (R2 = 0.970, RPD = 5.3), and combined NIR and MIR data (R2 = 0.954, RPD = 3.1).