Encapsulation of grape seed phenolic-rich extract within W/O/W emulsions stabilized with complexed biopolymers: Evaluation of their stability and release.

The ability of electrostatic complexes made up of sodium caseinate (NaCAS) and a polysaccharide, carboxymethyl cellulose (CMC) or gum Arabic (GA), to retain polyphenols from grape seed extract when encapsulated in W/O/W emulsions was compared to that of the single NaCAS (1%). Both electrostatic complexes (0.5% NaCAS - 0.375% CMC and 0.5% NaCAS - 0.5%GA at pH 5.6) used as hydrophilic emulsifiers in W/O/W were able to stabilize the O/W interface for 14 days, even though their protein content was reduced by a 50% regarding that of the emulsions only stabilized with NaCAS. Moreover, interfacial adsorption did not show significant differences between NaCAS-polysaccharide electrostatic complexes and the single NaCAS. In terms of interfacial barrier properties, the rate of polyphenol release during storage was not affected by the type of hydrophilic emulsifier. Since polyphenol transport in W/O/W emulsions was diffusion controlled, interfacial adsorption was considered the main factor limiting polyphenol retention.