Effects of pH on Calcium, Zinc, and Phytate Solubilities and Complexes Following In Vitro Digestions of Soy Protein Isolate

High intraluminal gastric pH values in young infants could affect the bioavailability of zinc in soy protein isolate formula. This investigation examined the effects of pH on the solubilities and complexes of calcium, zinc and phytate following in vitro pepsin and pepsin‐pan‐creatin digestions of soy protein isolate. The results of these in vitro studies suggested that (1) high intraluminal gastric pH values could lead to the formation of insoluble calcium‐zinc‐phytate complexes in the stomach following ingestion of soy protein isolate and (2) high intraluminal gastric pH values would only affect resultant soy zinc solubility in the small intestine in the absence of exogenous calcium or zinc but not in the presence of same.