Effect of Liquid Nitrogen Frozen Treatment on Fresh-keeping Quality and Colony Structure of Cultured Large Yellow Croaker

To study the effect of liquid nitrogen frozen treatment on fresh-keeping quality and colony structure of cultured large yellow croaker,large yellow croaker were managed by liquid nitrogen freezing treatment,the TBA,TMA,TVB-N,K and the total number of colonies were taken as indexes. The untreated samples were used as blank control,analyze the freshness quality of samples under low temperature storage conditions. The effect of liquid nitrogen freezing on the colony structure of cultured large yellow croaker was studied by high throughput sequencing. The results showed that the indexes of liquid nitrogen group and blank group increased with the time of storage,and the TBA value of liquid nitrogen group was(1.71±0.08) mg/100 g on the 14th day after storage,the TBA of the blank group was(2.10±0.43) mg/100 g. At the 14th day,the TMA of the liquid nitrogen group and the blank group were(5.46±0.037) mg/100 g and(6.99±0.008) mg/100 g,respectively. In the blank group,the TVB-N value reached(14.7±0.16) mg/100 g on the second day of storage,while the TVB-N value reached(15.6±0.34) mg/100 g on the fourth day of storage. At the 14th day the K values of the liquid nitrogen group and the blank group were 45.1% and 55.6%,respectively. Compared with the blank group,the total number of colonies decreased by 98.21% after liquid nitrogen treatment,indicating that liquid nitrogen freezing had better bacteriostasis. The results showed that liquid nitrogen freezing treatment had some influence on the colony structure of cultured large yellow croaker. The total change rate of the indexes in the liquid nitrogen group was lower than that in the blank group. Indicating that liquid nitrogen freezing treatment could delay the process of corruption of large yellow croaker,allow large yellow croakers to be kept for longer.