Formation and Functional Attributes of Canola Protein Isolate—Gum Arabic Electrostatic Complexes

Abstract

The formation of electrostatic complexes within mixtures of canola protein isolates (CPI) and gum Arabic (GA) was investigated by turbidity during an acid pH titration (7.00–1.50) as a function of mixing ratio (1:1 to 8:1 CPI: GA), and the resulting functional properties (e.g., flow behavior, solubility, foaming and emulsification) of formed complexes were studied. Complexation typically follows two pH-dependent structure forming events associated with the formation of soluble (pHc) and insoluble complexes (pHϕ1). Both pHc and pHϕ1, was found to shift to higher pHs with increasing mixing ratio until reaching a plateau at a 4:1 CPI-GA ratio. Maximum coacervation occurred at pH 4.20 at a ratio of 2:1 CPI-GA, prior to complete dissolution at pH 2.20. The coacervate phase was pseudoplastic in nature, with some evidence of elastic-like behavior associated with a weakly interconnected network or entangled polymer solution. Solubility of CPI and CPI-GA was found to be pH-dependent with minimum solubility occurring at pH 4.00 and 3.00, respectively. Foaming and emulsifying properties of CPI-GA remained unaffected relative to CPI alone, except foaming capacity which was reduced for the mixed system.