Refrigeration technology evaluation in extending cheese shelf life

The goal is to study the refrigeration and long-term storage of cheeses of various species groups to ensure product safety and microbiological safety. Research was carried out to substantiate the shelf life and biological safety of cheeses using rational modes of their refrigeration treatment in developed models of devices with two types of refrigerants. The influence of rapid freezing regimes on the physicochemical, water-binding, organoleptic properties of semi-hard cheeses was studied with further justification, based on thermoeconomic analysis, of the best conditions for carrying out refrigeration treatment using cryogenic and air freezing. For research, a wide range of low temperatures of heat exchange between the environment and the object of freezing was selected. Rational conditions for organizing the experiment were set: in the ultra-low temperature range from -50 to -90 °C at the first stage of freezing and from -20 to -40 °C at the second. The air speed was maintained stationary at 5 m/s. The developed modes largely retained all the original properties of the product at low energy costs. The end of the process was determined by establishing the average volumetric temperature across all layers of the product to -20 °C, which was subsequently used for low-temperature storage. In the studies, cheeses were considered as objects of low-temperature processing from the perspective of phase changes in the water content and the consequences that these changes can lead to. Particular attention in the work was given to the consideration of the preservation of the structure of the product under the influence of various freezing and storage temperatures; accordingly, conclusions were drawn about the identified patterns with further recommendations for practical use. The value of active acidity pH was studied, which influenced the hydration of proteins, regulating the water-binding properties and consistency of cheese. Frozen cheeses showed the best performance in terms of chemical composition, properties and quality preservation when stored at -20 °C for 15-18 months. The obtained patterns of changes in the properties of frozen cheeses showed the possibility of regulating the effect of freezing from the position of increasing the storage capacity of objects.