Encapsulation of polyphenolic grape seed extract in polymer-coated liposomes

Polyphenolic grape seed extract (0.1 w/v%) was encapsulated in liposomes (1% soy lecithin) by high pressure homogenization at 22 500 psi. Liposomes containing grape extract had mean particle diameters of <100 nm compared to control liposomes that contained no extract and that had mean particle diameters of <40 nm. Liposomes with grape seed extract were long-term oxidatively stable, e.g. significantly less hexanal (<15 μmol L(-1)) was formed during storage for 150 days compared to liposomes without extract (>717 μmol L(-1)). Over 80% of the polyphenolic compounds in grape seed extract were incorporated into the liposomal membrane rather than into their interior and compounds remained integrated even if the system pH was changed. Coated liposomes were prepared by alternately adding a cationic polymer (chitosan) and an anionic polymer (citrus pectin). Up to 4 coats could be deposited onto the liposomes without incurring aggregation, i.e. dispersions were physically stable during storage for up to 150 days. Deposition of multiple biopolymer coats onto liposomes decreased the amount of polyphenols that reacted with the Folin-Ciocalteu reagent, suggesting that the polyphenols were no longer exposed to the aqueous phase. Our results hence indicate that polymer-coated liposomes are highly capable carrier systems for polyphenols that may have reduced interactions with ingredients in complex media such as foods.