Retrofit Process Development for Phytate Extraction from Corn-Ethanol Coproducts Using Industrial Anion-Exchange Resins

Phytate, the principal storage form of phosphorus in corn, is found to remain as a significant portion of phosphorus in the corn-ethanol coproducts streams. This poses concerns over poor digestion of these coproducts by monogastric animals and subsequent environmental issues on phosphorus. An ion-exchange-based process was developed to extract the phytate from thin stillage, which was selected as the influent based on the inositol phosphate distribution conducted on different corn-ethanol coproducts. Commercial industrial resins (IRA-93, IRA-68, IRA-900, IRA-400, and IRA-402) were characterized and screened for the phytate adsorption, specificity and capacity. Different types of eluents (NaOH, NaCl, NaHCO₃, HCl, and NH₄OH) were tested to evaluate the desorption capacity in all the six resins. Phytate-P isotherms and kinetics of the adsorption process, breakthrough profile on IRA-900 column and phytate elution curves were presented. This process yields a phytate-rich solution (11 g L^-1), which is 25-fold concentrated compared to the concentration in thin stillage. The results show that the proposed retrofit process allows to leverage the existing corn-ethanol plants for high-value phytate production.