Protein-polysaccharide complex coated W/O/W emulsion as secondary microcapsule for hydrophilic arbutin and hydrophobic coumaric acid.

This study aimed to examine the modification effect of whey protein concentrate (WPC), WPC-gum arabic (WPC-GA) or WPC-high methoxyl pectin (WPC-PEC) complex to tailor-modify W/O/W emulsion for secondary microencapsulation of hydrophilic arbutin and hydrophobic coumaric acid. The stability and rheological properties of coated emulsions, encapsulation yield, release and degradation kinetics of arbutin and coumaric acid were investigated. Results revealed that WPC-PEC complex (at the ratio of 1:3) coating W/O/W emulsion exhibited the highest viscosity and stability, with the highest encapsulation yield of 91.08% for arbutin and 80.92% for coumaric acid, respectively. Tighter coating structure of the WPC-PEC complex (1:3) forming a stronger gel network structure was confirmed, accounting for the larger mean particle size of 569.67 nm. Moreover, the WPC-PEC (1:3) coating W/O/W emulsion also showed controlled release of arbutin and coumaric acid in simulated conditions. The k value of degradation kinetics for arbutin (7.99 × 10-4 at pH = 1.2, 4.19 × 10-4 at 90 °C and 7.52 × 10-4 at UV-C treatment) and coumaric acid (5.18 × 10-4 at pH = 1.2, 3.24 × 10-4 at 90 °C and 6.90 × 10-4 at UV-C treatment) indicated low degradation rate. The present study revealed that the WPC-PEC (1:3) coating W/O/W emulsion could provide a better synergistic effect on higher encapsulation yield and stability of arbutin and coumaric acid.