Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: January 20, 2009
Publication Date: N/A
Technical Abstract: Hydrolysate production is a low-cost method of preservation that could be employed to decrease the amount of fish byproducts discarded by Alaska’s salmon industry. However, endogenous enzymes within salmon vary with spawning maturity, and must be controlled in the raw material to ensure a consistent hydrolysate. Both male and female adult Pink Salmon (Onchorhynchus gorbuscha) were harvested at three different levels of maturity. Crude extracts of four different tissue groups (fillets, heads, livers, and viscera) were tested for proteolytic activity (pH 3.5, 6.5, and 7.3) using a spectrophotometric method hydrolyzing either casein or hemoglobin as a substrate. Corresponding protein, fat, moisture, and ash levels were also determined. Endogenous proteases were found to vary in different tissues as pink salmon moved from ocean to river environments prior to spawning. Ocean salmon (premium quality with silver scales and no watermark) generally displayed increasing proteolytic activity (per mg of soluble protein) in fillets and liver tissues during spawning migration. Protease content in viscera decreased as salmon moved into freshwater. No differences in proteolytic activity were observed in salmon heads regardless of spawning maturity or pH level tested. This study demonstrated that significant changes can occur in proteolytic activity levels within individual tissues when salmon are harvested at different spawning maturities. Variation in the quantity of active proteases will have implications for reduced-heat processing of hydrolysates when salmon byproducts of different maturity levels are used.