Colorimetric method for estimating the intensity of heat load during milk pasteurization

The authors proposed a method for determining the intensity of heat load during milk pasteurization based on the transformation of the products of the initial stage of the Maillard reaction (lactosylated amino acids) contained in milk into intensely colored products of the final stage of the Maillard reaction (melanodes). The color intensity of products is measured by the colorimetric method. To carry out the analysis, a casein preparation purified from free lactose is made from milk, dried and crushed into particles with a size of 500–800 microns. The casein preparation is kept at 100°C for 5 hours to form melanoids. The color intensity of casein preparations is measured on the CIE L* a* b* color scale and the criterion of total color difference ΔE is calculated by the value of the L* a* b* color criteria before and after heat treatment of casein preparations. The conducted studies of pasteurized milk samples confirmed the physical nature of the coloration of casein powders, consisting in the presence of melanoids in them, the content of which was proportional to the intensity of pasteurization of milk sample.