Formation and functionality of canola protein isolate with both high- and low-methoxyl pectin under associative conditions

Electrostatic interactions within mixtures of a canola protein isolate (CPI) and both low (LMP) and high-methoxyl (HMP) pectin were investigated as a function of mixing ratio (1:1 to 30:1; CPI-pectin) and pH (8.0-1.5) using turbidity and electrophoretic mobility measurements during an acid titration. The rheological (flow behavior) and functional (solubility, foaming, and emulsifying properties) attributes of CPI-pectin complexes were also studied. Increasing biopolymer mixing ratios shifted critical pH values associated with formation of soluble and insoluble complexes to higher values until plateauing at approximately 10:1. Maximum coacervation of CPI-HMP and CPI-LMP mixtures occurred at pH values of 5.3 and 4.8, respectively, and at a 10:1 mixing ratio. The functionality of formed complexes was similar to CPI alone, except for a slight increase in solubility for the CPI-HMP system and a reduction in foaming capacity for CPI-LMP mixtures. For both mixed systems, viscosity was enhanced relative to CPI alone, showing greater pseudoplastic behavior.