Fabrication and characterization of curcumin-loaded pea protein isolate-surfactant complexes at neutral pH

Abstract

The purpose of this study was to fabricate the binary complexes as novel delivery systems for curcumin (Cur) using pea protein isolate (PPI) and individual surfactants (rhamnolipid (Rha), tea saponin (TS) and ethyl lauroyl arginate hydrochloride (ELA)) by a pH-driven method. The effects of type and concentration of surfactants on the functional attributes of the complexes were investigated. The optimum mass ratio of PPI to Rha, TS, and ELA was 1:3, 1:2, and 1:5, respectively. The PPI-Cur-Rha1:3, PPI-Cur-TS1:2, and PPI-Cur-ELA1:5 complexes with the particle sizes of 176.53, 160.23 and 191.20 nm exhibited the highest encapsulation efficiencies of 93.69, 91.66, and 89.91% among different PPI to surfactant mass ratios. Both hydrogen bonds and hydrophobic effects were dominant forces for the formation of PPI-Cur-surfactant complexes. Apart from this, the electrostatic interactions also played an important role in the formation of PPI-Cur-ELA complexes. The XRD results verified that curcumin was successfully entrapped in the complex and transformed into an amorphous state. The curcumin in the PPI-Cur-Rha1:3 complex exhibited higher photo- and thermal stability. Moreover, the PPI-Cur-Rha1:3 complex possessed a controlled release of curcumin and higher acid stability in gastric juice during the in vitro digestion.