Adjusting the Hydrophobicity of Recombinant Microgels to Improve Interfacial Activity: Using a Promising Pickering Emulsion Stabilizer with a Dense Cubic Structure

Developing recombinant microgels (RMs) with high mechanical and anti-coalescence properties provides a safe and economical method for constructing uniform and stable Pickering emulsions. Previously, we prepared RMs based on polysaccharides using freeze–thaw cycles, displaying excellent stability. Because RMs can be formed between polysaccharides, we studied whether they can be formed between polysaccharides and proteins for preparing Pickering emulsions. Therefore, we report a heat-induced gelation method to generate RMs with bovine serum albumin (BSA) and κ-carrageenan (KC). Owing to heat-induced treatment (90 °C), the high hydrophilicity of KC could be regulated by the exposed hydrophobic groups of BSA, and the system rapidly gelated after cooling (−18 °C) to obtain a dense recombinant structure. The TPA and SEM results further demonstrated that the RMs with a BSA:KC ratio of 1:2 have a typical cubic structure (0.93 μm) and excellent gel strength. RMs adsorbed at the oil–water interface to form non-covalent binding layers, which improved interfacial activity and reduced interfacial tension (95.10°) to obtain more uniform and stable Pickering emulsions. The above results indicate that synthesizing RMs provides a feasible method for constructing uniform and stable Pickering emulsions with low oil content, these are similar to high internal phase emulsions with semi-solid rigid structures.