High- and Low-Protein Pea Genotypes: A Comparative Study of the Physicochemical, Functional, and Quality Properties of Protein Isolates

Background and Objectives

This study evaluated the effect of seed protein content on the composition, physicochemical, functional, and quality properties of pea protein isolates recovered through alkaline extraction/isoelectric precipitation. Samples were divided into three high-protein lines (HPL), three low-protein lines (LPL), and one control (medium protein).

Findings

Isolates derived from HPLs had higher protein (92.4%–94.5%) compared to LPLs (79.9%–88.7%) and the control (~92%). The protein content was significantly correlated to the legumin/vicilin ratio (1.0–1.8), surface charge (−38 to −23 mV), and surface tension (49–52.7 mN/m). No significant correlation was observed between protein content and functionality. Minor variation was observed for emulsifying (17.7–22.1 m²/g) and foaming (160%–215%) properties. LPLs presented higher amino acid score (0.83), and In Vitro protein digestibility corrected amino acid score (~0.72) than HPLs (~0.72 and ~0.64, respectively). Protein digestibility was in the range of ~87% for all lines.

Conclusions

Seed protein concentration impacted the pea protein isolates' proximate composition, quality, and physicochemical/surface properties. HPLs presented higher total protein content and LPLs presenting overall higher protein quality, whereas functionality did not differ significantly between HPLs versus LPLs.

Significance and Novelty

Our findings highlight the importance of sourcing and selecting pea lines tailored to specific applications, with a trade-off between protein quantity versus quality.