No abstract

One of the ways to ensure safety, preserve quality and increase the shelf life of meat with minimum technological processing of raw materials is the use of supercooling and storage technologies at sub-cryoscopic temperatures. Supercooling is a process of refrigeration processing, which provides the meat temperature decrease (by 1-2°C) below the cryoscopic temperature without phase conversion of water into ice (supercooling) or with partial ice formation (freezing). Subcooling ensures better quality preservation and longer shelf life of raw meat and finished meat products compared to cooling. Phase transformation of water into ice during freezing and freezing of food products causes irreversible changes in them as a result of crystal formation in muscle fibers and denaturation of sarcoplasmic and myofibrillar proteins. The article presents the results of research to justify the temperature regime of storage, which provides a stable hypothermal state of meat and meat products. It is shown that the limit temperature of subcooling is a fixed individual characteristic of the beginning of ice formation in meat and certain types of meat products and can be used as an indicator to justify the temperature of the cooling medium, providing the stability of products in the subcooled state.

Changes in the state of meat during freezing are determined by the phase transition of water into ice and an increase in the concentration of substances dissolved in the liquid phase. The process of crystal formation leads to a change in the physical characteristics of the meat and may be accompanied by changes in its structural properties. The effect of the proportion of frozen water on the permeability of the membranes of muscle fibers of frostbitten and frozen meat has been established. The ratio of optical densities at wavelengths of 270 nm and 290 nm (R) can be used to judge the thermal state of the meat. It is shown that the value of R after defrosting frozen meat is 2 times higher than for frostbitten meat.

The article provides data on the weight growth of bulls of different types of productivity. The growth and development of Black-and-white, Simmental and Aberdeen-Angus bulls were studied during the period of their rearing and feeding. The change in live weight was established, the dynamics and growth rate of the studied bulls were calculated depending on the breed and type of productivity. The research results showed that the Aberdeen-Angus bulls had the highest live weight during fattening - 485.2 kg, which was significantly higher than that of the Black-and-White and Simmental breeds by 68.7 kg (p <0.001) or 14.0% and 19.7 kg (p <0.01), or 4.1% respectively. The average daily gain in live weight from birth to 15 months of age in bulls of Black-and-white, Simmental and Aberdeen Angus breeds amounted to 860.0; 965.1 and 1022.7 grams respectively. In the Aberdeen-Angus cattle, in comparison with the Black-and- White and Simmental breeds, the value of this indicator was significantly higher, by 162.7 g, or 15.9% (p <0.001) and 57,6 g, or 5.6% (p <0.01) respectively. It was found that the type of productivity had a certain effect on the dynamics of live weight, the intensity of growth and development of animals.

Improving the safety and quality of meat raw materials from animals of special-purpose beef cattle helps to meet the demand for foods at high nutritional value. In the Russian Federation, the Aberdeen-Angus breed is one of the leading beef cattle, from which high quality marbled beef is obtained. Investigations have been carried out to study the qualitative indices of beef from this breed at storage under temperature conditions of cooling medium of 1 ± 0.5 ° C and minus 2.5 ± 0.5 ° C in cold chambers during 12 and 24 days. A decrease in the content of free amino acids in meat during storage was noted. It was found that after 24 days of storage, the biological value of the product (ratio of essential amino acids to nonessential ones) at minus 2.5±0.5 ° C was 1.14 times higher as compared with storage at 1.0±0.5 ° C temperature. After 12 days of storage at 1.0±0.5 ° C temperature, the values of acid and peroxide numbers increased about 3 times in comparison with the initial values, while at minus 2.5±0.5 ° C two times only. After 24 days of storage, the increase of acid number in chilled meat was 42% higher than in super-cooled meat; the values of the peroxide number in meat at 1.0±0.5 ° C was 1.3 times higher than in meat at minus 2.5±0.5 ° C. The researches resulted in recommendations of the temperature conditions providing the storage of super-cooled vacuum-packed meat without phase transition of water into ice as well as ensuring better preservation of biologically relevant components and nutritional value of meat.