Associative phase separation involving canola protein isolate with both sulphated and carboxylated polysaccharides

Associative phase separation within admixtures of canola protein isolate (CPI) and anionic polysaccharides (alginate and ι-carrageenan) was investigated as a function of pH (1.50–7.00) and biopolymer weight mixing ratio (1:1–50:1, w/w) by turbidimetric analysis. Solubility of formed complexes was also studied vs. protein alone as a function of pH. In both CPI–polysaccharide systems, critical pH, associated with the onset of soluble and insoluble complexes, shifted to higher pHs as the mixing ratios increased to a 20:1 CPI–polysaccharide ratio, and then became constant. Complexes formed primarily through electrostatic attractive forces with secondary stabilisation by hydrogen bonding. Solubility of the CPI–alginate system was significantly enhanced relative to CPI alone or CPI–ι-carrageenan.