Effect of storage time under home refrigeration conditions on the quality of opened drinking milk

Abstract

Aim of the study was to determine the effect of the duration of storage of opened drinking milk (pasteurized, micro-filtered and UHT) under home refrigeration conditions on indicators of its freshness (acidity and TBC), nutritional value (contents of fat, protein, lactose, dry matter, non-denatured whey proteins and free fatty acids) and organoleptic characteristics. Refrigeration was found to ensure that opened micro-filtered and pasteurized milk was suitable for consumption for 4 days and UHT milk for at least 7 days. Significant changes in the quality characteristics of protein and fat fractions were not observed until the 7th day of storage. The greatest changes in the content of whey proteins were observed in micro-filtered milk, expressed as decrease of individual proteins of about 20 % each. Pasteurized milk was the most susceptible to lipolysis that resulted in the greatest quantity of saturated free fatty acids. Lipolytic changes affected the acidity of product and thereby led to slight changes in its odor and flavor.