Cryogenic and air blast freezing techniques and their effect on the quality of catfish fillets

- Catfish fillets were frozen approximately three times faster by cryogenic freezing than by blast freezing.
- Cryogenic frozen fillets had best overall quality as compared to the fillets frozen by air blast freezing.
- Low lipid oxidation found in cryogenically frozen fillets after 6-months storage.

The effects of cryogenic and air blast freezing techniques on catfish fillet quality during frozen storage was evaluated. Fresh channel catfish fillets were cryogenically frozen by liquid carbon-dioxide using a pilot plant size cabinet type cryogenic freezer (CF) and by air blast (BF) frozen to −21 °C, separately. Freezing time (FT), freezing rate (FR), and energy removal rate (ERR) for freezing depend on the freezing techniques, which affect energy consumption and frozen seafood quality. The frozen fillets were stored at −20 °C and analyzed for weight loss, relative moisture loss, color, and lipid oxidation (Thiobarbituric acid; TBA) after 1-day, 1-month, 3-months, and 6-months of storage. Triplicate experiments were conducted and data were statistically analyzed at α = 0.05. FT for cryogenic freezing and air blast freezing were 19.3, and 55.1 min, respectively. Cryogenic freezing had higher FR (1.29 °C/min) and ERR (10.62 J/s) than BF (0.46 °C/min and 3.38 J/s, respectively). The cryogenically frozen catfish fillets had a lower freezing loss than fillets frozen by air blast freezing. TBA (mg MDA/kg sample) of the fillets frozen by CF was 0.94 which was lower than BF (1.25). The study demonstrated that catfish fillets cryogenically frozen had better quality characteristics than blast frozen catfish fillets after 6-months of storage.