Cereal Chem 52:263 - 271.  |  VIEW ARTICLE
Preparation of Low-Phytate Soybean Protein Isolate and Concentrate by Ultrafiltration.

K. Okubo, A. B. Waldrop, G. A. Iacobucci, and D. V. Myers. Copyright 1975 by the American Association of Cereal Chemists, Inc. 

A process is described for removal of phytate from defatted soybean meal and meal extracts to produce low-phytate protein concentrates and isolates. The process consists of two steps: 1) dissociation of phytate from protein; 2) removal of the dissociated phytate from the protein by ultrafiltration using a membrane permeable to phytate but impermeable to protein. Conditions for phytate dissociation were established above, below, and at the isoelectric point of soybean globulins (pI 4.9). At pH 8.5 where multivalent cations such as calcium ion appear essential for the integrity of the protein-phytate complexes, ethylenediamine tetraacetic acid (EDTA) effected dissociation. At pH 3 calcium ion resulted in phytate dissociation. At pH 5 to 5.5 and 65 C the indigenous phytase present in the meal and meal extract promoted continuing dissociation of the complex by enzymatic hydrolysis of the dissociated phytate. Subsequent removal of phytate and other low-molecular-weight impurities by ultrafiltration thus afforded low-phytate soybean isolates and concentrates of high-protein content.