Effect of immersion freezing with edible solution on freezing efficiency and physical properties of obscure pufferfish (Takifugu Obscurus) fillets

The impact of immersion freezing (IF) with edible solution (ethanol, NaCl, dextran, active protein, chrysin and naringenin) on physical properties of obscure pufferfish (Takifugu Obscurus) was compared with air freezing (AF) and liquid nitrogen freezing (LNF). Freezing process, microstructure, texture characteristics, water holding capacity, and cell integrity were investigated. Results showed that IF(-30 °C) rate was 11.5/4.7-fold quicker than AF(-18/-50 °C) rate. As for microstructure, ice crystals in IF(-30 °C) fish were much smaller than that in AF. Referring to texture characteristics and water holding capacity, shear force and hardness of IF(-30 °C) fish were 12.9% and 16.7% higher, and drip and cooking loss were 44.1% and 8% lower, than that of AF(-50 °C) fish after 24 weeks storage. Besides, IF led to higher integrity of muscle fibers than AF. For all physical indexes, IF fish had similar quality as LNF fish. Principal component analysis (PCA) further proved these results. In conclusion, edible IF(-30 °C) could retard physical properties deterioration of frozen fish in a better way than AF and have potential to replace LNF. •AF, IF and LNF were shown freezing curves and rates.•Microstructure, texture, water holding capacity and cell integrity were compared.•Edible IF(-30 °C) rate was 11.5-fold quicker than AF(-18 °C).•Physical properties and PCA showed edible IF(-30 °C) had similar aspects as LNF.