Characterization of a low-phytate pea protein isolate obtained by electroacidification, and comparison with conventional pea protein extracts

Abstract

The composition, structure, and functional properties of pea protein ingredients are affected by changes in their ionic environment. Pea protein isolates were obtained from the same source (a dry-fractionated pea protein concentrate), initially extracted at pH 9. Precipitation was then carried out by electroacidification (EA) at pH 6 or 7, or by isoelectric precipitation (IEP) at pH 4.5 and redispersion at pH 7. The EA isolates were compared to the IEP isolate, as well as the initial protein extract at pH 9 and its corresponding isolate after dialysis (DL), focusing on differences in protein and ionic composition, solubility, and thermal properties. Among the methods, IEP resulted in the highest protein recovery for pea protein isolates. DL removed monovalent cations (Na⁺ and K⁺), while EA efficiently eliminated both monovalent and divalent cations (Ca²⁺ and Mg²⁺), as well as phytic acid. EA isolates contained 72– 75% crude protein (using a nitrogen conversion factor of 5.4), composed of globulins, and has a similar protein composition to IEP isolates, but with no lipoxygenase. Additionally, EA isolates demonstrated higher solubility than the corresponding IEP isolates at pH 3.5–6. The results of this study demonstrate the potential of EA as a viable and sustainable alternative to acid-induced isoelectric precipitation to obtain pea protein isolates. Additionally, this work serves as a proof of principle for applying EA to the preparation of other legume protein isolates.