Rapeseed oil, sunflower oil, pig (mangalica breed) and goose fat were heated (36 h, 4 h sampling intervals) at seven temperatures (140, 150, 160, 165, 170, 175 and 180C; n = 256) to follow quality alterations. Acid value (AV) increased permanently, while the increase of peroxide value (PV) was followed by a drop. Carbonyl number tended to increase, while p-anisidine value (pAV) showed two-peaked alterations. Total polar material (TPM) and dimeric and polymeric triacylglycerol content of oils increased up to over 60 and 25%, while by animal fats, these reached 45 and 19%, respectively. Near-infrared spectroscopy (0.1 mm layer, transflectance mode, 800-2,400 nm wavelength, second derivative, modified partial least squares regression) was used for quantitative calibrations. Estimation accuracy of sampling event, heat-sum (heating hours × temperature) exceeded R2 = 0.94, with over 0.9 cross-validation values, analyzing fats separately. Calibrations for AV, PV, pAV and TPM reached practical application levels.
ASJC Scopus subject areas
- Food Science
- Safety, Risk, Reliability and Quality