Abstract: Air-packaged and nitrogen-packaged Pelteobagrus fulvidraco were evaluated for changes in freshness indices, microbial flora and volatile flavor substances during cold storage at 4 ℃. The results showed that nitrogen gas packaging slowed down the growth rate of total bacterial count (TBC), total volatile basic nitrogen (TVB-N) value and pH, effectively maintained the color, hardness and sensory quality, and prolonged the shelf-life of P. fulvidraco by two days. Nitrogen gas packaging affected the changes in the microfloral structure of P. fulvidraco during cold storage, and prevented Pseudomonas from becoming the dominant spoilage bacteria. Notably, it had a significant inhibitory effect on Acinetobacter on the 3rd day of cold storage (P < 0.01). Compared with the non-nitrogen group, nitrogen gas packaging reduced the types and contents of alcohols, aldehydes, ketones and esters in P. fulvidraco during the refrigeration process. The results of redundancy analysis (RDA) performed on microbial communities and volatile flavor substances showed that Pseudomonas aeruginosa and Bacillus immobilis played an important role in the flavor changes, and were positively correlated with the production of spoilage markers such as n-octanal, 3-hydroxy-2-butanone, 3-methylbutanol and 1-octanol. Therefore, nitrogen gas packaging could slow down the growth of dominant spoilage bacteria for a short period, thus delaying the deterioration of the freshness and flavor of P. fulvidraco, which could be a simple and effective method to prolong the shelf-life of P. fulvidraco.

Key words: nitrogen gas packaging; Pelteobagrus fulvidraco; freshness; microbial community; volatile flavor compounds