Abstract: This study aimed to investigate the effect of plasma-activated lactic acid (PALA) treatment on the quality and microbial community structure of rainbow trout during refrigerated storage. First, the physicochemical properties of PALA were characterized. Next, the effects of PALA treatment on the total viable count (TVC), total volatile basic nitrogen (TVB-N) content, texture, color, and sensory evaluation of rainbow trout during storage were examined. Based on the changes in TVC during refrigerated storage, the shelf life of the control group was determined to be 4 days, while that of the PALA-treated group was 8 days. Subsequently, high-throughput sequencing was used to analyze the changes in microbial community structure in the PALA and control groups during storage, and the isolated single colonies were identified by 16S rRNA sequencing. Finally, the spoilage enzyme production capacity of the isolates was analyzed, and their spoilage potentials were evaluated by inoculation into rainbow trout. The results showed that PALA treatment improved the storage quality of rainbow trout. The dominant spoilage bacterial genus at the early storage stage was Acinetobacter, while Pseudomonas became dominant in the middle and late stages. PALA treatment reduced the microbial diversity of rainbow trout. Among the isolated strains, C3 (Pseudomonas), C13 (Bacillus), C14 (Rahnella), C18 (Rahnella), P5 (Leclercia), and P6 (Pseudomonas) were each capable of producing at least two spoilage enzymes, with C13 exhibiting the strongest spoilage capacity. In conclusion, PALA treatment effectively improved the quality of rainbow trout, inhibited microbial growth during refrigerated storage, and reduced microbial diversity. This study provides a scientific basis for the application of PALA in the preservation of rainbow trout.

Key words: rainbow trout; plasma-activated lactic acid; high-throughput sequencing; enzyme production capability; spoilage ability