Oxidative Stability and Microbial Ecology of Fresh Beef with Extremely Long Shelf-Life

Abstract

This study was aimed at assessing the pigment and lipid stability and characterising the microbial ecology by classical methods and metagenetics in beef with an extremely long shelf-life. Bovine longissimus thoracis et lumborum subprimals from different origins (Australia, Brazil, Ireland, and United Kingdom), displaying a shelf-life from 35 to 140 days in vacuum packaging, were aged at −1 (subzero storage) or a −1/+4°C two-level stepwise scheme. At different times, samples were repackaged under a high-oxygen atmosphere (70/30% O2/CO2) and stored at 4°C for two days and then 8°C for five days to simulate retail distribution. Subzero storage inhibited the growth of total aerobic mesophilic flora and Enterobacteriaceae during ageing in vacuum ( $p<0.001$ ). During simulated retail distribution, the shelf-life was limited by metmyoglobin formation and excessive lactic acid bacteria growth. Classical microbiological methods underestimated the lactic acid bacteria count. Nonetheless, metagenetics evidenced, specifically in Australian samples, high proportions of Carnobacterium maltaromaticum, a lactic acid bacterium that may have contributed to the extremely long shelf-life of Australian beef.