Vol 106, No 5 (2017)

In view of Montreal, Kyoto and Paris climate agreements the refrigerants corresponding to the main tradition of these documents that is the greenhouse gases impact lowering are examined. The hydrofluoroolefins (HFO) produced today, their properties, qualities and defects as well as the principal of technical designation are examined in detail; they are compared with R134а that is the most used now HFC. Also the mixtures of HFO with other refrigerants mainly with HFC are described. The plan of consecutive phase out of HFC refrigerants used today depending on their greenhouse potential is given. The increase of СО2 emissions of refrigerants, when calculating these emissions using the LCCP index instead of TEWI, was estimated. It was shown that natural refrigerants that are not the universal panacea may be considered today as the most reliable alternative to synthetic ones.

This work covers the problem of keeping of stability and survival rate of Lactococcus lactis lactis and Lactococcus lactis cremoris lactobacilli. The influence of the suspension density of lactobacilli on their survival rate, on cryogranules as well as on cryogranules that were subject to cool dehumidification was studied. The factors influencing the survival rate and lactobacilli’s activity were revealed. The investigations resulted in accumulation of experimental data on the lactobacilli survival rate and activity at cryogranulation and their using in cryogranulating form. It was specified that the suspension density of lactobacilli before cryogranulation impacts on the survival rate to a very little degree after cryogranulation, but it impacts greatly on the granules state, particularly after cool dehumidification. Also the suspension density impacts on the granule colour: the higher the density, the darker the colour of the granule. It was noted that the cryogranules when granulating without additional components have a high level of survival rate, but to make further cool dehumidification it was necessary to use sucrose or maltose solutions. An acidforming capability of cryogranulated lactobacilli didn’t change during the cryogranulation process. So, it was shown that the Lactococcus lactis lactis and Lactococcus lactis cremoris cultures yielded well to cryogranulation in liquid nitrogen and had a high survival rate and kept an acidforming capability as well.