Potentially active spoilage bacteria community during the storage of vacuum packaged beefsteaks treated with aqueous ozone and electrolyzed water

The microbial contamination that occurs during the slaughtering process and during handling of the meat results in a shortening of the shelf-life of meat. In this study, which has had the aim of extending the shelf life of beefsteaks, pilot-scale treatments were carried out with aqueous ozone (AO) and electrolyzed water (EW) before vacuum packaging (VP). The development of the potentially active microbiota and the associated volatilome were followed over 15days of storage under refrigerated conditions (4°C), in order to define the potential long-term effects of the treatments and storage condition on microbiota. The targeted RNA-based amplicon sequencing identified Pseudomonas fragi as the most frequent species before and after the treatments with AO and EW, as well as in the untreated control. The tested treatments did not reduce the overall presence of this species, but they affected the intra-species distribution of its oligotypes, albeit slightly. With the progression of the refrigerated storage and the reduction of the oxygen availability, Lactobacillus sakei, Leuconostoc gasicomitatum and Lactococcus piscium became the dominant, potentially active, beef microbiota, as confirmed by microbiological data. When the OTU abundances and volatilome were coupled, a significant association was observed between the organic acids, esters and aldehydes and these lactic acid bacteria species. In spite of the limited effectiveness of the treatments over the short and long term, this study has provided a detailed view of beef spoilage using RNA as the sequencing target, strengthening and confirming the current knowledge based on DNA-amplicon sequencing. •Aqueous ozone (AO) and electrolyzed water (EW) were applied in beefsteaks to extend their shelf life;•An inefficacy of the EW and AO treatments in reducing the initial microbial contaminations of the beefsteaks was recorded;•Lactobacilli were the most potentially active OTUs at the end of the storage period;•Molecular analysis demonstrated that Pseudomonas fragi was the dominant species before and after the treatments;•The RNA-based analysis has helped to unravel the complexity of potentially active microbiota, in vacuum packaged beef meat.