Effects of different freezing treatments on physicochemical responses and microbial characteristics of Japanese sea bass (Lateolabrax japonicas) fillets during refrigerated storage

•Effect of various freezing treatments on quality of Japanese sea bass fillets were evaluated.•A new freezing method for preservation of Japanese sea bass was established.•Freezing at −55 °C 24 h and then −18 °C kept a good quality of fish fillets.

In order to establish an effective freezing method for quality control, the present research evaluated the effects of the different freezing treatments on the quality of Japanese sea bass (Lateolabrax japonicas) over a period of 20 days storage at 0 ± 1 °C. Fish pH value, total volatile basic nitrogen (TVB-N), K-value, trimethylamine nitrogen (TMA-N), drip loss, hardness, color, biogenic amines, microbiological characteristics were measured. Sea bass fillets were stored at −18 °C (T1), −55 °C for 24 h and then −18 °C (T2), −55 °C (T3) for 3 months prior to refrigerated storage. T2 showed lower TVB-N, pH value, biogenic amines and drip loss than T3 and T1 did. Significant lower value of bacterial loads, b* value and hardness were observed in T1, T2 and T3 than those of control group. No significant differences were observed among T1, T2 and T3 for TMA-N and a* value. The study demonstrated that Japanese sea bass fillets treated with −55 °C for 24 h and then −18 °C up to 3 months maintain better quality during refrigerated storage.