INHIBITION OF PACIFIC WHITING SURIMI‐ASSOCIATED PROTEASE BY WHEY PROTEIN CONCENTRATE

Three whey protein concentrate (WPC) samples ranging in protein content from 34 to 95%, beef plasma protein (BPP) and bovine serum albumin (BSA) were analyzed for their effect on the autoproteolytic activity of Pacific whiting surimi. Autoproteolysis activity was determined in control and supplemented surimi containing up to 4% additive by measuring the amount of TCA‐soluble peptides produced under defined reaction conditions. The degradation of specific myofibrillar proteins was followed electrophoretically. The extent of inhibition by the WPCs showed a general correlation with their respective protein contents. Autoproteolysis was essentially undetectable in surimi samples supplemented at the 2% level with either the 80% or 95% protein WPCs. Autoproteolysis was decreased by 57% relative to the nonsupplemented control in surimi containing 2% of 34% protein WPC. No proteolytic activity could be detected in surimi samples supplemented at the 1% level with BPP. Supplementation of surimi with up to 4% BSA had no demonstrable effect on autoproteolysis. The extent of proteolytic degradation of the myosin and tropomyosin fractions within surimi samples were in general agreement with the measured rates of autoproteolysis.