Abstract
Solubilities of mixtures of soy protein isolate, calcium and phytate were determined as a function of pH and molar ratio of the components. Below the isoelectric point, phytate and protein solubility profiles paralleled each other, indicating some type of protein-phytate interaction. Addition of phytate shifted the isoelectric point and the minimum solubility to lower values. Between the isoelectric point and pH 6.5, the complex apparently dissociates; addition of phytate results in an increase in the maximum solubility of the phosphorus and the protein, as well as a shift in their solubility profiles. Calcium has no apparent effect on protein solubility in this pH region. Higher pH (>6.5) results in the formation of ternary protein-calcium-phytate complexes and a significant drop in calcium and phosphorus solubility, probably due to formation of insoluble calcium phytate salts.
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Grynspan, F., Cheryan, M. Phytate-calcium interactions with soy protein. J Am Oil Chem Soc 66, 93–97 (1989). https://doi.org/10.1007/BF02661792
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DOI: https://doi.org/10.1007/BF02661792