Examination of the functional properties, protein quality, and iron bioavailability of low-phytate pea protein ingredients

The effect of seed phytate content (regular and low) on the composition (protein and mineral content), protein quality [in vitro protein digestibility-corrected amino acid score (IVPDCAAS)], iron bioavailability, and functionality (solubility, oil/water holding capacity, foaming capacity and stability, and emulsion stability) of pea flours and extracted protein isolates was investigated. There was 37-45% less phytate in the flours of the low-phytate varieties compared to the regular varieties and approximately 39% less for the isolates. Upon extraction of protein, phytate increased over threefold, but for the mineral ions, this was selective in that Fe2+ ions increased more than threefold, while Ca2+ content halved. The phytate content did not influence the IVPDCAAS of the flours or isolates. The functional properties of the isolates and flours were largely similar between the low and regular phytate varieties. For each variety, iron was more bioavailable in the flours (10.5-22.0 ng ferritin/mg protein) than in the isolates (2.9-16.5 ng/mg). The low-phytate flours (20.6 ng/mg) had overall higher iron bioavailability than the regular phytate pea flours (10.7 ng/mg). For the isolates, this trend was not significant, possibly due to high intra-variety variation and the limited number of samples; however, the mean iron bioavailability value of the three low-phytate isolates was three times greater than that of the two regular phytate isolates. In conclusion, protein isolates extracted from low-phytate varieties did not show deleterious or positive impacts on the functional characteristics or protein quality; more evidence is required for iron bioavailability.

Automated summary

The study investigated the effect of seed phytate content on the composition, protein quality, iron bioavailability, and functionality of pea flours and extracted protein isolates. Low-phytate varieties had lower phytate content and similar functional properties compared to regular-phytate varieties. Phytate had a selective effect on mineral ions, with an increase in Fe2+ and decrease in Ca2+ content. Iron bioavailability was higher in flours compared to isolates, and low-phytate flours had overall higher bioavailability than regular-phytate flours. More evidence is needed for iron bioavailability in protein isolates.