Emulsion gels as delivery systems for phenolic compounds: Nutritional, technological and structural properties

•Emulsion gels were formulated with olive oil, polyphenol extracts and soy protein.•Composition, technological and structural properties were evaluated in emulsion gels.•Emulsion gels provide hydroxytyrosol, gallic acid, flavanol monomers and procyanidins.•Phenolic compounds appear to become trapped in the emulsion gel matrix network.•Textural behaviour of emulsion gels may relate with their structural features. Polyphenols have interesting antioxidant properties and could help prevent certain diseases. Emulsion gels (EGs) have characteristics that make them a promising alternative system for supplying several bioactive compounds simultaneously, among them polyphenols. We produced four EGs containing olive oil, soy protein and a cold gelling agent based on alginate. One basic formulation (ES) contained only these ingredients and was used as a reference, while the other three also contained different solid polyphenol extracts from grape seed (G), grape seed and olive (O) or grape total (T), called ESG, ESO and EST, respectively. The corresponding EGs were prepared by mixing soy protein, alginate, water and one of these types of polyphenol extract (G, O or T), using a homogenizer. Then, the olive oil was gradually added to the mixture and finally, each mixture was placed in a metal container under pressure and chilled for 24 h until they formed an EG. The composition (including concentrations of phenolic metabolites), and technological and structural properties of these EGs were evaluated. Hydroxytyrosol was identified in all the EGs, but ESO showed the highest (P