Optimal Conditions for the Distribution of Cryoprotectant into the Intact Fish Muscle of Oncorhynchus mykiss during Freeze/Thaw Cycling

摘要

Conditions for sufficient and rapid distribution of a cryoprotectant (sorbitol solution) into intact fish muscle (Oncorhynchus mykiss) were studied as changing in the residual Ca~(2+) ATPase activity during freeze/thaw cycling. Chunks of the fish muscle were immersed in 4 concentrations of sorbitol solutions (20%, 30%, 45%, and 60%) by a shaker mechanism at 5°C. Whole immersion samples (W) showed a higher value of the residual Ca~(2+) ATPase activity than those in the untreated controls (C), exceptin the treated controls (TC), while less effect of immersion concentration could be found. Comparing the extent of penetration of sorbitol into the surface layer to inner layer of immersed fish chunks, outer portion samples achieved excellent cryoprotection with 100% of the residual ATPase activity values or more. For the inner portion samples, 30% and 45% sorbitol solution treatments indicated ahigher ATPase activity than 60% treatment. At high concentrations, mass transfer rates during osmotic dehydration might berapid and it causes faster surface drying by dewatering at surface solute layer. Periodically immersed and relaxed samples, W (5-3-1), led to good cryoprotection effect: W (5-3-1) indicated high residual Ca~(2+) ATPase activity values and the residual ATPase activity values excess 100% in immersion of 30% and 45% sorbitol solutions.