Cereal Chem 56:58 - 62.  |  VIEW ARTICLE
Low-Phytate, Full-Fat Soy Protein Product by Ultrafiltration of Aqueous Extracts of Whole Soybeans.

O. Omosaiye and M. Cheryan. Copyright 1979 by the American Association of Cereal Chemists, Inc. 

The feasibility of using ultrafiltration (UF) to eliminate phytic acid from aqueous extracts of soybeans was studied. Soybeans were cleaned, soaked, blanched, and ground, and the slurry was filtered through a plate- and-frame filter press to obtain the water extract. After adjustment to the appropriate pH and temperature, the extract containing 3.5-3.9% total solids was processed in a pilot-scale hollow-fiber UF unit by discontinuous and continuous diafiltration techniques. Elimination of phytic acid from the soy concentrate was governed by the environment and state of binding of phytate to rejected species and did not follow expected behavior for a nonrejected solute that is freely permeable through the membrane. UF to a volume concentration ratio of 5 resulted in 65, 43, and 27% elimination of phytic acid at pH 6.7, 8, and 10, respectively. Dilution at the same pH and reultrafiltration eliminated about 92% of phytic acid at pH 6.7 and more than 80% at pH 8 and 10. The final product assayed 60% protein, 35% fat, and 0.64 mg phytic acid per gram of solids (dry basis).