EFFECTS OF SUCROSE, STARCH AND OIL ON THE IN VITRO DETERMINATION OF PROTEIN DIGESTIBILITY USING THE IMMOBILIZED DIGESTIVE ENZYME ASSAY (IDEA) SYSTEM

The effects of various food components on the in vitro digestibility of proteins, measured by the immobilized digestive enzyme assay (IDEA) system, were investigated. The digestibility of unprocessed and processed sodium caseinate and soybean protein was examined. Varying concentrations of sucrose (0, 5, 10 and 20%) or starch (0, 0.5, 1 and 2%) had no significant effects on digestibility of protein. Similarly, the presence of emulsified (1% lecithin) vegetable oil (0, 0.5, 1 and 2%) did not affect digestibility. Therefore, these common ingredients of foods did not affect the extent of hydrolysis of the protein samples under the conditions of the IDEA method, suggesting that this assay is suitable for use with complex foods.