Effect of phytate-removal and deamidation of soybean proteins on calcium absorption in the in situ rats

Soybean proteins were deamidated by cation‐exchange resins after phytate, the inhibitor for calcium absorption from the small intestine, was removed in order to provide the enhancement function of calcium absorption to soybean proteins. About 92% of the phosphorus was removed from the soybean proteins by anion‐exchange‐resin treatment, indicating that most of the phytate was removed. About 70% of the acid amide was deamidated by cation‐exchange‐resin treatment, and phytate‐removed and deamidated soybean proteins (PrDS) having high calcium binding properties were obtained. PrDS were hydrolyzed by digestive enzymes and their calcium‐binding properties and the enhancement function of the calcium absorption from the small intestine of rats were examined. As a result, PrDS retained their high calcium binding properties even after hydrolysis by digestive enzymes. in situ experiments showed that PrDS and their hydrolysates enhanced the calcium absorption from the intestine.