Lard is a preferred frying fat in the Hungarian culinary routine. Our study aimed at measuring conventional fat quality indices and performing NIR-based calibrations of those indices. during prolonged heating. Lard was heated for 4 days at 8 different temperatures (160. 170. 175. 180. 185. 190. 200 and 230 °C) for 8 h a day (n=32+1. i.e. the original sample). Acid value (AV) and carbonyl value (CON) increased in parallel with the duration of heating and heating intensity. Peroxide value (PV) increased in the first 8 h. and decreased back during further treatment. p-Anisidine value (pAV) increased at each heating temperature below 200 °C. while temperatures above 200 °C decreased it. NIR analysis (NIRSystems 6500) was performed on original samples in transflectance mode (400-2500 nm wavelength range. 0.1 mm layer thickness. aluminium-plated reflector). Treatment characteristics (temperature. heat-sum. sampling event) could be estimated effectively. Calibration for AV was robust: R2=0.927; 1-VR=0.786. Weak relationship was found for PV (R 2=0.48) and CON (R2=0.109). For pAV. good calibration was gained. expressly below 200 °C. in the 2000-2500 nm wavelength interval (R2=0.912; 1-VR=0.772). Based on calibration and cross-validation results. NIR technique may be a rapid. solvent-free alternative for the estimation of acid value and p-anisidine value of lard below 200 °C.
ASJC Scopus subject areas
- Food Science