Performance evaluation of protein recovery from Argentinian soybean extruded-expelled meals under different operating conditions

Abstract

The soybean extruded-expelled (EE) meals are the byproduct of the process commonly used by small or medium-sized Argentinian companies for obtaining soy oil. In this work, the performance of the pH-shifting process for obtaining a protein product from the EE meals was evaluated as a strategy for on-site value-adding.The EE meals were subjected to the proposed pH-shifting process under different operating parameters at the alkaline extraction stage (2 and 3 cycles at 55, 60 and 65 ºC with and without sodium sulfite) and isoelectric precipitation stage (0 ºC and 20 ºC with hydrochloric and phosphoric acids), which constitute the controlling steps in an industrial scaling of the process. The pH-shifting process consisting of 3 alkaline extraction cycles at 60 ºC followed by isoelectric precipitation at low temperature using hydrochloric acid was found to be well suited for obtaining a final product with a protein content upwards of 75%.