Metagenomic Analysis of the Spoilage Microbiota of MAP Packaged and Air Packaged Cooked Meat

Introduction: Different packaging may well lead to a different dominant flora in cooked spoiled meat, like hams and hot dogs. Several reports on identification of cooked meat spoilers are present in literature, but it is difficult to extract a general picture in terms of variation in dominance, the influence of packaging, region, etc. Application of metagenomics enables us to analyze more samples, with more depth and less effort, eventually leading to a more comprehensive overview.

Purpose: In the current study we analyzed sliced, cooked meat and looked at the influence of modified atmosphere packaging (MAP) and air packaging on the microbiota.

Methods:   Multiple samples (22 in total) of sliced cooked ham and chicken breast, MAP and air packaged, from two different supermarkets, were incubated at 4°C. The samples were analyzed, on the expiry date and two days later, with regard to the CFU, the gas composition, and microflora via 16 S rDNA metagenomics.

 Results: The samples (11) taken at the expiry date contained between 106 and 107 bacteria and all samples (11 samples) taken two days later contained between 107 and 108. In literature, a CFU count above 107 is usually considered spoiled. We can conclude that all samples were at or just below the spoilage point at the expiry date. Looking at the microflora, some frequent spoilers of VP cooked meat were present in both MAP and air packaged samples, especially Leuconostoc carnosum. Compared to vacuum packaged meat, we saw more Brochotrix spp. in MAP.

 Significance: A better understanding of the dominant spoilage flora will lead to better and specific interventions to elongate shelf life.