Chitosan/hydroxypropyl guar gum/fucoidan composite-stabilized Pickering emulsions for enhanced surimi gel quality

In this study, emulsifiers were prepared using chitosan (CS), hydroxypropyl guar gum (HGG), and fucoidan (FU) at various ratios, and their properties were characterized using various indicators. The results demonstrated that a CS/HGG/FU ratio of 1/2/1 yielded the most favorable emulsifying performance, characterized by optimal particle size, amphiphilicity, and stability. Based on this optimized formulation, Pickering emulsions with a 50% oil phase volume fraction were subsequently produced. These emulsions exhibited desirable attributes, including appropriate particle size, well-defined interfacial structures, and excellent storage stability. Building on this, we further examined the effects of these emulsions on the gelling characteristics of surimi. The addition of 5% emulsion improved the overall quality of the surimi gel. Specifically, water-holding capacity increased to 85.34%, hardness rose to 3404.81 ± 81.25 gf, and gel strength increased to 1744.07 g∙mm. The improvement resulted from an optimized secondary structure of surimi proteins, with the β-sheet content rising to 44.57%, which contributed to a tighter and better-organized gel network. However, excessive emulsion addition occupied the spatial domains necessary for protein cross-linking, increased the intermolecular distances, and thereby impaired the development of a dense 3D network. As a result, the overall gel quality was adversely affected. In conclusion, CS/HGG/FU composite emulsions significantly enhanced the gelling properties of surimi, demonstrating their potential as an effective emulsion-based strategy for improving the quality of surimi products.