Succinylated nori protein-alginate complex particles prepared using temperature-controlled ultrasonication for the formation of high internal phase Pickering emulsion gels as plant-based fat analogues.

In this study, succinylated nori protein (SNP), sodium alginate (SA), and flaxseed oil were used to develop novel high-internal-phase Pickering emulsion (HIPPE) gels with potential application as plant-based fat analogues. Stable composite particles were successfully fabricated through ultrasonication combined with temperature control. The ultrasonic treatment condition was identified as 450 W for 30 min, under which the Pickering particles exhibited the smallest particle size and superior emulsifying ability. The optimal formulation parameters were identified as an SNP-to-SA ratio of 1:5, an SNP-SA complex particle concentration of 3%, and an oil-phase fraction of 75%, which resulted in optimal oil retention and emulsion stability. Confocal laser scanning microscopy and cryo-scanning electron microscopy revealed that the SNP-based emulsion produced smaller droplets (23.08 ± 0.09 μm) and a more compact core-shell interfacial structure than the emulsion prepared with native nori protein. These structural improvements were associated with enhanced adsorption kinetics and wettability, with a contact angle approaching 90°, indicating optimal amphiphilicity. Rheological analysis further demonstrated that the emulsion exhibited more solid-like viscoelastic behavior, with a greater difference between G' and G″ than that prepared with native nori protein. Moreover, microscopic observations showed that the dense packing of lipid droplets within the gel network resembled the cellular architecture of animal fat tissue. The thermal behavior of the HIPPE gels in the range of 200-500 °C was similar to the two downward endothermic peaks observed for pork fat during cooking. Sensory and texture analyses of meat patties revealed that 25% and 50% fat substitution levels could closely mimic full-fat meat patties. Overall, the proposed material provides an environmentally friendly and healthy strategy for developing fat analogues from marine-derived protein resources and flaxseed oil, while mimicking animal fat tissue in terms of texture, microstructure, thermal behavior, and sensory properties.