Culture-dependent and culture-independent evaluation of the effect of protective cultures on spoilage-related bacteria in vacuum-packaged beef mince

This study investigated the effects of two commercial protective cultures, one containing Lactobacillus sakei (now Latilactobacillus sakei) and the other containing Staphylococcus carnosus and L. sakei, in vacuum-packaged minced beef (ground beef) to advance the understanding of this biopreservation approach for fresh meat shelf-life extension. The protective cultures’ effects on spoilage-related bacterial profiles over time were evaluated using both culture-dependent and culture- independent methods in premium (containing 7.7% fat) and standard (containing 19.2% fat) beef mince stored at 4 °C for 12 days. The culture-dependent method showed that in premium mince, the mixed culture containing S. carnosus and L. sakei significantly suppressed the growth of Enterobacteriaceae and Pseudomonas spp. The culture containing only L. sakei exhibited a slight inhibitory effect against these spoilage bacteria. In contrast, neither protective culture inhibited the spoilage bacteria in standard mince. The 16S rRNA gene sequencing indicated bacterial community changes by protective cultures. Photobacterium spp., a potentially important group of meat spoilage bacteria that were usually undetected in culture- dependent studies, were found to be abundant in this study. The protective cultures’ impact on other meat quality aspects was also assessed. The culture containing S. carnosus and L. sakei lowered the pH of both premium and standard mince more than the culture containing only L. sakei, and the mixed culture slightly decreased the redness of premium mince. These findings support the use of protective cultures for bacterial spoilage control and shelf-life extension of fresh red meat, but limited to lean or low-fat products.