Effect of CO2 on the preservation effectiveness of chilled fresh boneless beef knuckle in modified atmosphere packaging and microbial diversity analysis

To explore the effect of different concentrations of CO2 in modified atmosphere packaging (MAP) on the preservation shelf life of boneless beef knuckle (BBK), and to deeply study the changes in the bacterial community. In the controlled atmosphere combination, the proportion of O2 in each group is kept at 40%, CO2: 20%–45%, and N2: 15%–60%, the blank control group is set to 40%O2+0%CO2+60%N2. Sensory evaluation, headspace gas, total colony, and physicochemical indicators were measured at the 1st, 3rd, 5th, 7th, 9th, and 11th days of storage, respectively. The results showed that group 25%CO2+35%N2 had the longest shelf life is 9 days. In the analysis of the bacterial community, CO2 significantly inhibited the growth of Pseudomonas from the 3rd day onwards in the group 25%CO2+35%N2. After 4 days of storage, Lactobacillus was the main dominant bacterium, followed by Carnobacterium. Through KEGG metabolic pathway analysis, it was found that during the storage and preservation process, the expression levels of genes related to carbohydrate metabolism and amino acid metabolism in cold fresh BBK were higher than those in other metabolites.