Effect of Pretreatment on Preservation Quality of Cultured Large Yellow Croaker (Pseudosciaena crocea) in the Process of Logistics

The influence of pre-treatment methods of tea polyphenols, cold brine immersion and liquid nitrogen freezing on the logistics process of cultured large yellow croaker was investigated to keep fresh quality. By changing the temperature and time to change the logistics conditions and the temperature were 2, 4, -18, 35℃ and the time was 25 d. The changes of pH, TVB-N, the total number of colonies, K value and TBA in cultured large yellow croaker were determined. Results showed that tea polyphenols solution brewing was well to keep fresh quality. With the passage of storage until the end, the tea polyphenols group had a pH of 6.48, which was 0.09 lower than that of liquid nitrogen group in the whole process;The tea polyphenols TVB-N was 30.07 mg/100 g, which was 7.73 mg/100 g lower than the lowest cold saline group. The total number of colonies in the tea polyphenols group gradually increased to 3.48 log (cfu/g), which was 0.19 log (cfu/g) lower than that in the liquid nitrogen group. K value was taken as the indicator of the freshness of the early stage, when the 15th day, the K value of the tea polyphenols group was 25.2%, which was 3.2% lower than that of the control group. Tea polyphenols group TBA was 0.68 mg/100 g, which was 0.23 mg/100 g lower than liquid nitrogen group. From the perspective of the whole logistics process model, it was not ideal to the fresh-keeping effect of cultured large yellow croaker in liquid nitrogen brewing and cold saline brewing, in contrast, tea polyphenols solution brewing was better than others.