Soybean oil organogelled emulsions as oral delivery systems of hydroxytyrosol and hydroxytyrosol alkyl esters

Water-in-soybean oil organogelled emulsions (OGEs) were formulated as fat replacers and evaluated as delivery systems of hydroxytyrosol (HT, hydrophilic compound), hydroxytyrosol octanoate (HTC18, hydrophobic compound) and hydroxytyrosol decanoate (HTC10, with intermediate hydrophobicity and the highest antioxidant activity measured by conjugated autoxidizable triene assay). OGEs formulated with 55% of water and a ternary blend of candelilla wax, fully hydrogenated palm oil and monoacylglycerols showed mechanical properties similar to lard and solid-like behavior. The increase in the water content, together with a higher concentration of structuring agents in the oil phase, led to an increase in oil retention capacity and texture parameters. A slight desesterification of HTC10 and HTC18 was found during in vitro gastrointestinal digestion. The three bioactive compounds loaded in OGEs showed high bioaccessibility values (∼84%) at the end of digestion, regardless their chain length and hydrophobicity. These OGEs designed as fat replacers showed a great potential for vehiculation of both hydrophilic and lipophilic compounds.