Improvement of the quality of surimi gels by high internal-phase emulsions prepared with fish oil and Zein peptide nanoparticles

This graphical abstract depicts a technical route for preparing stable high internal phase emulsions (ZPNHIPE) from corn protein and applying them in surimi processing. The procedure commences with trypsin catalysed hydrolysis of corn protein under optimised conditions; the resulting supernatant, collected by centrifugation, is then lyophilised to yield modified corn protein nanoparticles, designated as ZPN. Owing to their amphiphilic nature, these nanoparticles exhibit strong surface activity, which is essential for effective adsorption at the oil–water interface. The ZPN are re dispersed in an aqueous phase and mixed with a lipid phase (FO) at a volume ratio of 1:1. Rotary evaporation is employed to remove any residual organic solvent, followed by high shear homogenisation to generate a gel like HIPE with finely distributed droplets and excellent stability against coalescence and creaming. Subsequently, a water bath heating step is applied to induce controlled protein unfolding and disulphide cross linking, further reinforcing the interfacial film around the droplets. The resulting ZPNHIPE is then incorporated into raw fish chunks or comminuted surimi paste. During thermal processing, the emulsion acts as both a fat replacer and a texture modifier; it interacts with myofibrillar proteins, promoting a more densely cross linked gel network. This leads to significant improvements in gel strength, water holding capacity, springiness, and hardness, while reducing oil loss.