Characteristics of the composition of the psychrotrophic microflora of frozen beef in the process of storage
Authors: Salata V. 
Published: June 2018

In the technological process of obtaining raw materials and food products, the main task is to ensure their safety. During the curing of beef meat, the risks are most often associated with microbial contamination. The purpose of the work was to investigate the dynamics of quantitative content and generic composition of psychrotrophic microflora in the process of storage of frozen beef with different initial microbial sowing. The investigated samples were divided into four groups, depending on the initial content of the psychrotrophic microflora. The first group of psychrotrophic microorganisms was up to 103 CFU/cm3 from the surface; second group of 103 to 104 CFU/cm3 of washed away; the third – from 104 to 105 CFU/cm3 of washed away; the fourth is more than 105 CFU/cm3 of washed away. It was established that during the storage of beef in the frozen state, the rate of development of the psychrotrophic microflora is 3,0-32,6 times faster than the mesophilic microflora. Also it was found the higher the initial microbial sowing of beef, the faster the pace of development of the microflora in the process of storing meat in the frozen state. Therefore, when choosing meat storage conditions (temperature, term), the initial microbial contamination of the carcass surface with a psychrotrophic microflora is important. It was found that from beef with low microbial sowing it is allocated three classes of psychrotrophic bacteria: Acinetobacter, Alcaligenes i Pseudomonas. The largest part of the cooled meat was 56.2 ± 2.4% of the genus Acinetobacter, and the smallest 12.5 ± 0.8% Pseudomonas. After 20 days of storage of beef in the frozen state, the growth of bacteria of the genus Pseudomonas was 1,4 times (P ≤ 0.05) due to the reduction of the Acinetobacter species of microorganisms. At the same time, the bacteria of the genus Alcaligenes were stably high in both frosty and frozen meat – 31.2–32.7%, respectively. Identification of psychrotrophic microflora with an initial content of mesophilic and psychrotrophic microorganisms 6.5 ± 0.5×103 and 4.2 ± 0.2×103 CFU/cm3 of the washed away, has established an increase in the number of identified genera. Among the already identified three genera in the washed away from beef of this group, bacteria of the genus Flavobacterium i Aeromonas are isolated, both in frozen meat and after storage in a frozen state. When identifying a psychrotrophic microflora with a significant initial microbial sowing  (the number of mesophilic bacteria is greater than 5.9 ± 0.4 × 104 and psychrotrophic 3.7 ± 0.2×104 CFU/cm3 washed away the surface) was established an increase in generic composition. Thus, in the psychrotrophic microflora, 5 to 10% of bacteria of the Enterobacteriaceae genus, gram-positive sticks and cow's bacterial forms began to stand out from 3 to 5%. Consequently, the conducted searches have found that with an increase in the initial microbial contamination of beef, the quantitative genetic composition of the psychrotrophic microflora increases. As a result, the storage period of frozen beef and the hygienic and technological quality of meat is reduced.