NIR based quality control of frying fat samples by means of Polar Qualification System

NIR spectroscopy based monitoring of quality changes of culinary fats and oils was aimed during prolonged heating (4 types, 36 h, 7 heating temperatures, n = 252). “Heat-sum” value was defined as heating temperature × heating time. Samples were sub-ordered into four heat-sum classes, representing deterioration during commercial use. Polar Qualification System was utilized for the identification of fat or oil types and heat-sum classes by the recorded NIR spectra. After fat and oil types were classified precisely with a polar sensitivity value over 4.5, optimization was run on heat-sum classes by fat and oil types, respectively. Sensitivity values were between 0.75 and 3.42 for animal fats when different heat-sum classes were identified. These values were between 1.39 and 6.86 for vegetable oils, indicating that classification was more effective from the early stage of heating, as compared to animal fats. Lower sensitivity values obtained for animal fats show that vegetable oils underwent a more expressed degradation during heating.