Preparation, characterization, and in vitro antioxidant activities of natural selenium-enriched peanut protein fractions

In this work, the content of selenium (Se), physicochemical properties, and antioxidant capacity of Se-enriched peanut proteins isolate (S-PPI) and its fractions arachin (S-Arachin) and conarachin (S-Conarachin) were investigated. The S-PPI, S-Arachin, and S-Conarachin were prepared using natural Se-enriched peanut with alkali extraction, acid precipitation, and sedimentation coefficients method. The Se content of S-PPI (420.83 μg/kg) was two times compared to ordinary peanut protein isolate (O-PPI, 203.10 μg/kg). Besides, the Se is more likely to bind with conarachin than arachin. The solubility curves of these peanut proteins at different pH were similar. The emulsifying activities and the emulsion stability of S-Arachin was relatively low, as well as its foaming activity and the foam stability was the lowest. The DPPH scavenging activity of peanut proteins were decreased in order of S-Conarachin, S-PPI, S-Arachin, and O-PPI, as well as reducing power and the superoxide radical scavenging activity. The antioxidant activity trend was similar to Se content distribution trend, suggesting that the content of Se is related to antioxidant activity. The finding may indicate that Se content played a positive role in promoting the antioxidant activity of peanut protein. • Se-enriched peanut is a good raw for economic natural Se-enriched food supplements. • The abilities of S-Conarachin to enrich Se are higher than that of S-Arachin. • Se enrichment can change the structure and functionality of the proteins. • Se can significantly increase antioxidant activity of peanut protein isolates.