Removal of Phenolic Compounds from Soy Protein Extracts Using Activated Carbon

ABSTRACT

Soy protein extracts were subjected to activated carbon and ion exchange process treatments to remove phenolic compounds that have been reported as being responsible for adverse color and flavor characteristics of soy protein products. Minimum equilibrium contact time, adsorption rate, and adsorption isotherm data were established for syringic, ferulic and p-coumaric acids. HPLC data confirmed that both activated carbon and ion exchange processes effectively removed phenolic compounds from soy protein isolates and improved their flavor and color. Activated carbon treatment re- sulted in soy protein isolates with superior overall odor and flavor, but no improvement in bitter and astringent flavor descriptions. Both activated carbon and ion exchange treated laboratory soy protein isolates exhibited lower color intensity values than those for conventional laboratory isolate, but higher than those of commercial soy protein isolates. Ion exchange processing was more effective than activated carbon for improving the color of soy protein isolates.