Phytic acid in soybeans

Phytic acid, the hexaphosphate of myo-inositol, is the most important phosphate reserve compound in many plant seeds, but many of its salts are poorly digested by animals. It can form complexes with seed proteins, some of which sequester metal ions, making them unavailable for the animal organism. Soya protein isolates may be higher in phytate content than the soya flour from which they are obtained. Zinc is the mineral of most concern because its bioavailability from some soya products is quite low and because of its marginal levels in some human diets. The availability of iron from soya flour and soya isolates is higher than that from some other plant foods with lower phytate contents. Processes for removing the larger part of the tightly bound phytates from soya protein isolates are described.