Changes in Physicochemical Properties and Microstructure of Channel Catfish (Ietalurus punetaus) Fillets Quick Frozen with Liquid Nitrogen or Liquid Ammonia
LI Xin, WANG Lan, DING Anzi, QIAO Yu, SHI Liu, WU Wenjin, XIONG Guangquan
Hubei Innovation Center of Agricultural Science and Technology, Institute of Agro-Products Processing and Nuclear-Agricultural Technology, Hubei Academy of Agricultural Sciences, Wuhan 430064, China
Abstract：The effect of liquid nitrogen versus liquid ammonia quick freezing on the quality of channel catfish was investigated. Fresh fillets were frozen by tunnel liquid nitrogen spraying freezing (?90 ℃/35 min) or tunnel liquid ammonia freezing (?35 ℃/90 min), and then stored at ?18 ℃ for up to 90 days. The thawing loss, cooking loss, pressurized water loss, shear force, pH value, K value, volatile base nitrogen (TVB-N) content, trimethylamine (TMA) content and thiobarbituric acid reactive substance (TBARs) value of fresh and freeze-stored fish were analyzed. The microstructure of fish tissue was observed by fluorescence microscope. Results showed that compared with fresh fish, the cooking loss of frozen fillets increased, the pressurized water loss, shear force and pH value decreased, and the K value, TVB-N, TMA content and TBARs value showed an increasing trend. The physicochemical properties of frozen fish deteriorated during frozen storage. It was observed that the area of muscle cells decreased and the intercellular space increased after quick freezing. Compared to liquid ammonia quick freezing, liquid nitrogen quick freezing was more beneficial to maintain the water-holding capacity, freshness and structural integrity of fish meat, thereby effectively restraining quality deterioration during frozen storage. It was conducted that the quality of fish fillets treated by liquid nitrogen quick freezing was close to fresh fish during frozen storage for 30 days.
2020, Vol. 34 
