Digestive Acceptability of Proteins as Measured by the Initial Rate of in Vitro Proteolysis

A study was undertaken to measure the initial rate of proteolysis with trypsin of some commonly used protein sources (sodium caseinate, defatted peanut flour, defatted cottonseed flour, FPC and isolated soy proteinate) as a simple in vitro means of measuring gastronomic acceptability. Although differences among proteolysis rates were found, in all products proteolysis occurred in the first few minutes and then remained constant. Sodium caseinate was by far the most easily digestible protein source evaluated; isolated soy proteinate was the least digestible followed by FPC, defatted cottonseed flour and peanut flour. Steaming resulted in faster hydrolysis rates. Concludes that although certain vegetable proteins may have high nutritional and biochemical values, their digestive acceptability may be quite poor since they are not rapidly hydrolyzed in the digestive system.