Functional and structural properties and in vitro digestibility of acylated hemp (Cannabis sativa L.) protein isolates

Abstract

SummaryThe effects of succinylation and acetylation on some functional, structural properties and in vitro trypsin digestibility of hemp protein isolate (HPI) were investigated. The extent of acylation gradually increased from 0 to 60–70%, with the anhydride‐to‐protein ratio increasing from 0 to 1.0 g g−1. Size exclusion chromatography showed that succinylation led to formation of more soluble protein aggregate than acetylation, especially at anhydride levels higher than 0.1 g g−1. Succinylation led to gradual increase in protein solubility (PS) from 30 to 85–90%, while in the acetylation case, the PS was improved only at low anhydride levels, increasing from 30 to about 50% with anhydride‐to‐protein ratio increasing from 0 to 0.2 g g−1. At neutral pH, the emulsifying activity indexes (EAI) of HPI was 22.1 m2 g−1, and the EAI linearly and significantly increased with the extent of acylation. The EAIs of succinylated and acetylated HPI (1.0 g g−1) were 119.0 and 54.4 m2 g−1, respectively. Differential scanning calorimetry (DSC) and intrinsic fluorescence spectrum analyses indicated gradual structural unfolding of proteins, or exposure of hydrophobic clusters to the solvent, especially at higher anhydride levels. Additionally, the in vitro trypsin digestibility was significantly improved by the succinylation. The results indicated that the chemical acylation treatment (especially succinylation) could be applied to modify some selected functional properties of hemp proteins, especially PS and emulsifying ability.