Effects of dry ice freezing on ice crystal and quality of large yellow croaker (Pseudosciaena crocea) during frozen storage

Abstract

Objective: The effects of freezing method and storage temperature on the quality of large yellow croaker during storage were investigated. Methods: Fresh large yellow croaker fillets were frozen with dry ice and air freezing (-40 ℃) to the central temperature of -18 ℃, and then stored at -40 ℃ and -18 ℃, respectively. Physical and chemical indexes such as freezing curve, ice crystal morphology, pH value, volatile base nitrogen, K value, Ca2+-ATPase activity, total sulfhydryl group, carbonyl group, protein degradation and texture characteristics of large yellow croaks were determined after freezing and during freezing storage. Results: The time of dry ice freezing through the maximum ice crystal formation zone was 40 min, which is 1/6 of that of air freezing at -40 ℃. The initial ice crystal cross-section area and equivalent diameter of dry ice frozen fish samples were (96.12±1.61) μm2 and (11.06±1.43) μm, respectively, which is significantly lower than that of air frozen fish samples. Conclusion: The effect of freezing temperature on fish myofibrillator protein was greater than that of freezing temperature, and a lower freezing temperature can result in a lower degradation degree of fish myofibrillator protein. Storage at -40 ℃ after dry ice freezing is beneficial to maintain freshness and quality stability of large yellow croaker.

Keywords

• dry ice freezing
• large yellow croaker
• frozen storage
• ice crystal
• quality