Protein Hydrolysis in Coho and Sockeye Salmon During Partially Frozen Storage

Coho ( Oncorhynchus kisutch ) and sockeye salmon ( O. nerka ) were held at O°, −1°, −2°, −3°, and −20°C for up to 25 days. Hydrolysis of individual soluble proteins was analyzed by SDS‐PAGE. The highest rates of Hydrolysis were in fish held at −2° and −3°C. Several proteins were present in nearly constant ratios. Significant changes were observed in nine other protein bands. A 35,000 dalton protein was present only in coho salmon. This protein appeared with a half‐time of five days and then disappeared. Major changes were observed in 34,000 and 36,000 dalton proteins; half of which were hydrolysed in 7 to 20 days. A 32,000 dalton protein was half‐hydrolyzed in 14–23 days in sockeye but very slowly in coho salmon.