Moist-heat induced interfacial co-assembly of κ-carrageenan and soy lecithin: A chemical-crosslinker-free paradigm for physically stable Pickering emulsion

Pickering emulsions stabilized by biopolymer-based particles have attracted considerable interest, yet fabricating eco-friendly stabilizers with simplified processes remains challenging. This study developed lipid-based particles via moist-heat treatment, a one-step preparation strategy without chemical crosslinkers, using κ-carrageenan (KC) and soy lecithin (SL) as a synergistic interfacial system. SL gradually enriches at the lipid-based particle interface and transforms the surface into a more hydrophobic structure, mainly through non-covalent interactions. The lipid-based particles exhibit good cooperative assembly behavior (minimum particle size: approximately 279.43 nm). The corresponding microgels show improved wettability for Pickering stabilization (maximum contact angle: 86.1°). The optimized Pickering emulsion prepared with 1.5% microgel and 30% oil has a relatively uniform droplet distribution (approximately 6.80 μm) and a high negative zeta potential (−106.67 mV), indicating enhanced colloidal stability. Mechanistically, SL likely serves as both a bridging and filling component within the KC gel network, while a possible change in the dominant stabilization mechanism evolves from hydrogen bonding and hydrophobic interactions into electrostatic repulsion as the SL content increases. Overall, this study proposes a novel chemical-crosslinker-free strategy for constructing physically stable food-grade Pickering emulsions by tailoring interfacial composition and molecular interactions via moist-heat treatment.