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Native high methoxy citrus pectin (NP) was de-esterified by pectin methyl esterase to produce modified pectins [MP (42, 37, and 33)] having different degrees of esterification. Complex coacervation between a pea protein isolate (PPI) and each pectin was investigated as a function of pH (8.0–1.5) and mixing ratio (1:1–30:1, PPI-pectin). Complex formation was found to be optimal for biopolymer-mixing ratios of 8:1, 8:1, 25:1 and 25:1 for PPI complexed with NP, MP42, MP37 and MP33, respectively, at pHs 3.6, 3.5, 3.9 and 3.9. And, the critical pHs associated with complex formation (accessed by turbidity) was found to shift significantly to higher pHs as the degree of esterification of the pectin decreased, whereas the shift in the pH corresponding to their initial interactions was minimal with degree of esterification. Complexation of PPI with NP and MP42 greatly improved the protein solubility. • Pectin was enzymatically modified to have degrees of esterification of 33–42%. • Interactions between pea protein isolate and modified pectin were examined. • Optimal protein-pectin mixing ratios increased as DE values increased. • Protein solubility was enhanced with the addition of pectin (DE 42%). [ABSTRACT FROM AUTHOR]