Changes in the physicochemical properties of whey and cottage cheese produced from the milk of Ukrainian black-and-white dairy cows with different genotypes of kappa-casein during storage

Abstract

The article presents experimental materials on the study of changes in the whey and cottage cheese physicochemical properties which are made from the milk of Ukrainian black-and-white dairy cows with different kappa-casein genotypes during storage. The experimental part of the work was carried out in the conditions of a pedigree plant for breeding Ukrainian black-and-white dairy breed of the «Profintern» unit of the State Enterprise «Gontarivka» in the Institute of Animal Science of the National Academy of Agrarian Sciences (NAAS). Based on the analysis results of the chemical composition, there were no significant differences between the groups for most indicators during storage in the period from the first to the 15th day, although in absolute values they can be placed in the following order: cottage cheese made from milk of cows with the BB genotype, AB and AA. It was found that the concentration of active acidity, similar to most quality indicators of cottage cheese, was determined at the beginning of storage by a higher value in cows with genotype BB by 0.9 and 0.5% compared to animals with genotypes AA and AB. With the extension of the shelf life, the rate of acid formation tended to decrease and on the 15-th day was 3.8–3.1%, compared the initial values. In contrast, the difference between the samples from the representatives with the BB and AA genotype in terms of the activity of hydrogen ions during this period was 1.6% and the AB genotype – 0.9%. Despite the fact that the duration of storage had a negative effect on the hydrogen ions’ concentration in cottage cheese, made from cow’s milk with different genotypes of kappa-casein, its moisture-retaining properties, on the contrary, have improved. It was found that cottage cheese and whey, regardless of the cows’ genotype at the kappa-casein locus, during storage have a relatively stable composition and meet the requirements of the current DSTU. The recommended shelf life is 15 days. The best combination of the studied parameters in the production of BB genotype cows reflects the higher course of metabolic processes in the body, which led to an improvement in its quality.