Chromatographic Study of Mineral–phytate and Protein–phytate Interactions in Soymilk

Abstract

While many studies have examined the binding of phytate to proteins and/or minerals, little information is available on the number of complex types and combinations of binding molecules. In this study, interactions of phytate with proteins and divalent ions in the soluble fraction of soymilk obtained from the soybean cultivar Tachinagaha were examined using a Sephacryl S-400 HR column. Phosphorus and divalent ions were detected using inductively coupled plasma atomic emission spectroscopy. Phytate was identified as the phosphorus peak digested by phytase. Three phytate peaks were detected in fractions 21, 49, and 53. The phytate in fraction 21, indicating the presence of the largest complex, was co-eluted with proteins and disappeared after proteinase K treatment. The phytate in fraction 49 was co-eluted with iron, while that in fraction 53 was co-eluted with calcium. Our methods have potential applicability for detecting mineral-phytate and protein-phytate interactions.