Production and characterization of emulsion filled gels based on inulin and extra virgin olive oil

Emulsion filled gels (EFG) can help food producers to reduce fat content in foods. The present study evaluated the physical, chemical, sensorial and microbiological properties of emulsion filled gels based on inulin, a gel-forming prebiotic carbohydrate, and extra virgin olive oil (EVOO), well-known for its high nutritional value and phenolic antioxidant content. EFG based on inulin and EVOO were produced by means of both mechanical shearing and ultrasound homogenization. Three different ingredient ratios lead to high, medium and low oil content EFG (H, M, L respectively). H EFG had also lower inulin/water ratio. The resulting gels could be considered as a healthy alternative to spreads, rich in fiber, unsaturated fatty acids and phenolic antioxidants. Compared to mechanical shearing, ultrasound homogenization gave more consistent EFG, characterized by lower lightness respect to mechanical processing. Lower coarseness and fusion-like behavior and higher greasiness, perceived by panelists, confirmed the structural and textural differences conferred by ultrasound. Higher inulin content and inulin/water ratios determined consistency increase. The EFG with the best sensory profile (melting, less coarse texture, higher consistency, greasy mouthfeel) was submitted to consumer test and liked by over 70% consumers (n = 80). The volatile pattern was characterized by compounds found in fresh oils, mainly 2-hexenal. Oxidized triacylglycerols showed a slight increase in the EFG oil fraction respect to the fresh oil, particularly when using ultrasound homogenization. The residual phenolic compounds were in the range 50-76%, with losses minimized in mechanically sheared EFG. Ultrasound improved the microbiological stability of EFG.