Effect of Lectins and the Mixing of Proteins on Rate of Protein Digestibility

The rate of digestibility of protein in raw bean extract (RBE), heat-treated bean extract (HBE), casein and bovine serum albumin (BSA) was determined. The pepsin and/or pancreatin hydrolysis of RBE which contains lectins or hemagglutinins was less than that of other proteins. Addition of lectins at the same concentration present in RBE decreased the rate of digestion of HBE, casein and BSA to levels close to that of RBE. In comparison with the respective single proteins, mixtures of RBE or HBE with casein have lower digestibilities while a mixture of casein and BSA, higher digestibilities. The results suggest that lectins can affect the activity of digestive enzymes and that mixing of proteins has an effect on digestibility which is unpredicted by amino acid composition.