Effect of temperature, ionic strength and 11S ratio on the rheological properties of heat-induced soy protein gels in relation to network proteins content and aggregates size

The effects of heating temperature, ionic strength and 11S ratio on the rheological properties of heat induced soy protein gels, particularly in relation to network proteins content and aggregates size were investigated. Results revealed that non-network proteins consisted of undenatured glycinin (11S) AB subunits, high levels of A and A(3) polypeptides but low levels of beta-conglycinin (7S) alpha and alpha' subunits. Results further showed that a positive correlation between storage modulus (G') and network proteins ratio of gels that were formed at different temperatures. Additionally, the G' values of gels initially increased with increasing NaCl concentration from 0 to 0.25 M, but decreased with further increasing ionic strength from 0.25 to 0.50 M. This trend was consistent with the variation of heat-induced protein aggregates size in soy protein solution at the same ionic strength. Higher 11S/7S ratio resulted in higher storage modulus values of soy protein gels due to the formation of larger and compacter aggregates mainly by B polypeptides via hydrophobic bonds. (C) 2016 Elsevier Ltd. All rights reserved.