Frozen Storage and Thawing Methods Affect Biochemical and Sensory Attributes of Rainbow Trout

Rainbow trout were subjected to four thawing treatments after being stored at −18°C and ‐40°C for 0, 3, 7, 13 and 18 mo. Membrane integrity was estimated as the volume of centrifuged tissue fluid (CTF) and by lysosomal β‐N‐acetylglucosaminidase (NAG) activity in CTF. Slow thawing, in air at 5°C resulted in higher NAG activity in CTF and a larger volume of CTF than fast thawing, at 25°C in water, independent of storage time. After 3 or more months storage, a higher NAG activity in CTF and a larger volume of CTF were found in all ‐18°C stored samples compared to that at ‐40°C. Sensory evaluation confirmed differences between trout stored at ‐18°C and at ‐40°C for 18 mo.