Cold-tolerant Clostridium spp. in beef and in the beef production chain in Austria - occurrence and species identification.

The discussion surrounding cold-tolerant clostridia regarding spoilage of vacuum-packed beef has been going on for years. However, there is a lack of investigations in the beef production chain. This study aims to identify the contamination sites of these bacteria in abattoirs and cutting plants and their occurrence in beef. For this purpose, 815 swab and 85 beef samples from a cattle abattoir and a beef cutting plant, and 71 vacuum-packed beef samples from retail in Vienna (Austria), were analyzed. Three qPCR systems, 16S rRNA sequencing, and cultivation methods were applied. The occurrence of clostridia was high on hides and in the stunning and dehiding sites. Overall, 35.3 % and 31.0 % of the beef from the cutting plant and the retail tested positive. The main species detected in beef samples were C. algidicarnis, C. frigoriphilum, C. estertheticum and C. tagluense-like. These species were also found on cattle hides or surfaces of the abattoir. After storing beef samples at 4 °C for up to 1 to 2 weeks past the use-by date, 73.1 % and 34.6 % of positive beef samples exhibited off-odor and high gas production, respectively. These spoilage signs were found in only 38.5 % and 20.2 % of the negative samples. This confirms that a contamination with cold-tolerant clostridia leads to a shorter shelf life of vacuum-packed meat. To reduce carcass contamination with these bacteria, hygiene protocols for dehiding and effective surface disinfection of equipment and processing surfaces with sporicidal disinfectants authorized for the food industry, and corresponding monitoring plans, should be drawn up.