Fabrication of gel-like sorbents derived from pomelo (Citrus grandis L.) peel powder via an immediate setting emulsion approach†

Abstract

This study developed emulsion gel-like sorbents by valorising pomelo peel (Citrus grandis L.) powder enriched with fibres (52.11–59.59%) and antioxidants. The process utilized an emulsion-based gelation approach, where an immiscible oil–water mixture with various oil-to-water ratios (1 : 3, 1 : 1, and 3 : 1) was first blended with a pre-emulsion using high-shear mixing. PP powder (10–40% w/w) with two particle sizes (125 and 250 μm) was then incorporated into the pre-emulsion, where its amphiphilic nature enabled interactions with both the oil and water phases, stabilising the emulsion and promoting gelation. Upon mixing, the PP powder rapidly absorbed the oil and water phases, forming self-sustaining gel-like sorbents within 2 min at room temperature. Comprehensive analyses of their chemical composition, antioxidant properties, texture, rheology, microstructure, and oxidative stability showed that increasing the water phase reduced the amount of PP powder required, softened the sorbents, and enhanced their cohesiveness. Conversely, higher PP concentrations and oil phases increased the gel strength and textural hardness by forming denser structures and altering oil droplet sizes. Stability testing revealed that oil-rich sorbents (3 : 1 oil-to-water ratio) maintained a peroxide value below 4 meq kg⁻¹, attributed to their low water content and the antioxidant-rich properties of PP powder. This research provides a robust and eco-friendly approach to developing functional and stable PP-based sorbents, with potential applications as fat replacers for creating low-fat food products.