Microencapsulation of gallic acid through the complex of whey protein concentrate-pectic polysaccharide extracted from Ulmus davidiana

The objectives of this study were to (1) prepare gallic acid loaded microcapsules coated with single whey protein concentrate (WPC) and complexes of WPC-pectic polysaccharide extracted from Ulmus davidiana (UDP) using spray dryer and (2) evaluate structural, physicochemical, and storage properties of these microcapsules. To produce complexes of WPC-UDP, three different concentrations (1.0, 1.5, and 2.0 g UDP per 30 g WPC) of UDP were used. Results showed that microcapsules coated with WPC-UDP had significantly higher encapsulation efficiency than microcapsules coated with WPC. The moisture contents of microcapsules ranged from 0.30 to 2.64% and decreased with an increase in UDP concentration in wall materials. The particle morphology of each microcapsule became smoother and more spherical, when the concentration of UDP was increased. The increased particle sizes of microcapsules coated with complex of WPC-UDP were indicated by creating a thicker layer by the formation of electrostatic interactions between anionic reactive sites of UDP and small cationic reactive sites of WPC. The electrostatic interactions between wall materials were confirmed by Fourier Transform Infrared spectroscopy spectra analysis. Microcapsules coated with WPC-UDP complexes showed higher stability with lower release of encapsulated compounds when they were stored at different temperatures (4, 20, and 40 degrees C) for 20 days than microcapsules coated with WPC. The release profiles of gallilc acid showed that microcapsules coated with WPC-UDP complexes released less amounts of gallic acid than microcapsules coated with single WPC in gastrointestinal conditions (pH = 1.2).