Dynamics of microbiota in the imported beef primal cuts during storage at different chilled temperatures.

Primal cuts of Australian beef transported by sea were stored under different chilled temperatures (0, 2, and 4 °C) for 6 weeks in different packaging conditions (aerobic or anaerobic packaging). The number of microorganisms and the transition of the microbiota were investigated using culture methods and amplicon sequencing. After 6 weeks of storage, the beef tended to show a high total viable count under aerobic packaging conditions and a high lactic acid bacteria count under anaerobic packaging conditions. The result of amplicon sequencing analysis showed that different beef samples had different predominant bacterial groups. Moreover, at high storage temperatures, Serratia sp. having high putrefactive activity showed increased abundance, while at low storage temperatures, Lactobacillus sp. showed increased abundance. Thus, differences in the packaging conditions and distribution temperatures after import affect the number of bacteria and the type of microorganisms in the Australian beef primal cuts, which may affect their quality.

Dynamics of microbiota in Japanese Black beef stored for a long time under chilled conditions.

In this study, changes in the microbiota of Japanese Black beef carcasses, which are expected to be transported for a long time in chilled temperatures, were investigated. Three Japanese Black beef samples (carcasses A, B, and C) immediately after slaughter were stored at 0 °C for 15 weeks under aerobic and vacuum conditions. The initial bacterial counts were 50 CFU/g for carcass A and less than the reliable quantitative detection limit for carcasses B and C. Under aerobic storage conditions, the bacterial count increased to 8.0 log CFU/g or higher, which is a measure of putrefaction, at 6-9 weeks. Under anaerobic storage conditions, the bacterial counts of carcasses A and C reached 3.5-6.5 log CFU/g, but carcass B showed no bacterial growth during the 15-week storage period. The predominant group was Pseudomonas spp. under aerobic conditions and Serratia spp. under anaerobic conditions. To the best of our knowledge, there is no previous study investigating the transition of microbiota when Japanese Black beef is stored at low temperatures for a long period of time, and the results of this study are considered very important findings for the expansion of international trade of Japanese Beef in the future.