THE STUDY OF THE PROPERTIES AND RESISTANCE TO DEGRADATION OF MILK PROCESSED BY DIFFERENT TECHNIQUES

Abstract. In this paper we aimed to analyse and study the behaviour of 7 different varieties of milk, marketed in our region. They showed very similar parameters of pH, acidity and density, characteristics of fresh milk samples kept under appropriate conditions, during the shelf life mentioned by the manufacturer. The pH of the milk samples varied between 6.2 and 6.4, and the acidity varied between 1.7 °T for the 3.5% UHT milk and 2.4 °T for the 3.5% pasteurized milk. The small density variations in milk samples with 1.5% fat concentration compared to the same variety with 3.5% fat concentration did not follow a unique rule due to the complexity of the sample composition. Regarding milk casein concentration, the lowest concentrations were obtained for lactose-free milk, and the highest casein concentrations were obtained in samples with higher fat content, 3.5%. When storing milk samples for 4 days at room temperature, UHT milk proved to be the most stable. Heating the samples at different temperatures on the 4th day of storage at room temperature indicated that the 3.5% lactose-free milk was the most influenced.