Effect of previous frozen storage on quality changes of grass carp (Ctenopharyngodon idellus) fillets during short-term chilled storage

The effect of chilled, frozen and freeze-chilled storage on quality of grass carp fillets and soups was evaluated by sensory score, total aerobic counts and biochemical quality. Fish fillets were stored at 4 °C for 6 days (T1), -40 °C for 12 h and then at -20 °C for 5 days (T2), -40 °C for 12 h and then at -20 °C for 5 days, followed by at 4 °C for 4 days (T3). T1 showed higher sensory score, salt-soluble protein content, better colour and texture qualities than T2 and T3 within 3 days. All fillets kept good quality based on the acceptable limit of sensory score, total volatile basic nitrogen and total aerobic count during storage time. According to the transportation and retail time, chilled storage is appropriate when it is within 3 days. If it extends for 5 days, freeze-chilling treatment keeps better quality, but later chilled fillets should be retailed within 4 days.