Encapsulation of resveratrol in biopolymer particles produced using liquid antisolvent precipitation. Part 1: Preparation and characterization

Several health-promoting effects have been ascribed to resveratrol, a polyphenol extracted from grape skins and other sources. Its utilization as a functional food ingredient, however, is compromised by its low water solubility, poor UV stability, and low oral bioavailability. The purpose of this study was to examine the possibility of encapsulating resveratrol in biopolymer particles to overcome these issues. The particles were produced by antisolvent precipitation of hydrophobic biopolymers (gliadin or zein) in the absence or presence of hydrophilic biopolymers (pectin or sodium caseinate). Bare gliadin and zein particles had mean particle diameters of 260 and 120 nm, respectively. Pectin was the best hydrophilic biopolymer for coating gliadin particles [0.1% (w/v) pectin on 0.5% (w/v) gliadin], whereas caseinate was the best for coating zein particles [1.0% (w/v) sodium caseinate on 0.5% (w/v) zein]. Resveratrol was encapsulated at a concentration of 250 mg/l with encapsulation efficiencies of 53% and 86% in coated gliadin and zein particles, respectively. Encapsulation efficiencies were higher for coated than bare particles. No covalent bonds were detected by FTIR between resveratrol and the proteins within the particles. Electron microscopy showed that bare particles had smooth surfaces with some evidence of aggregation, whereas coated particles had rougher surfaces surrounded by filaments or films, suggesting the presence of non-absorbed hydrophilic biopolymers. In conclusion, these particles seem promising encapsulation systems to enrich functional foods with resveratrol.