Covalent conjugation of hemp protein isolates with curcumin via ultrasound to improve its structural and functional properties

Abstract

This study investigated the covalent conjugation of hemp protein isolate (HPI) with curcumin induced by ultrasound-generated free radicals and its impact on HPI's structural and functional properties. Ultrasound treatment unfolded the protein structure, increased free amino and sulfhydryl groups, and altered the secondary structure. Curcumin addition enhanced free radical scavenging capacity. Conjugation with curcumin significantly improved emulsifying activity index (+ 2.6-fold), foam stability (+ 1.8-fold), and solubility (+ 0.9-fold) and further enhanced free radical scavenging capability (+ 2.4 or 2.7-fold). Conjugation with curcumin also enabled gel formation, as evidenced by a continuous increase in the storage modulus of HPI during heating and cooling. These findings highlight the potential of HPI-curcumin conjugates as healthy ingredients in functional food applications.