Fabrication of soy protein - pea protein composite fibril/κ-carrageenan emulsion gels through thermal fibrillation for application as fat replacers in ice cream.

Growing interest in reduced-fat frozen desserts has created a need for plant-based fat replacers capable of reproducing the structural and sensory functions of milk fat. In this study, soy protein isolate (SPI) and pea protein isolate (PPI) were co-fibrillated by acid-heat treatment to produce composite protein fibrils (SPI/PPI-F), which were then combined with κ-carrageenan (KG) to construct emulsion gels. SPI/PPI-F exhibited a total β-sheet content of 60.49% and, among the fibrillar emulsifier systems tested, produced an emulsion with a near-zero creaming index. These results indicated that co-fibrillation promoted the formation of a more ordered fibrillar structure and improved emulsion stability. Increasing the KG concentration progressively enhanced the apparent viscosity, viscoelasticity, water-holding capacity, and mechanical strength of the emulsion gels. The emulsion gel containing 0.8% KG (KG-0.8%) exhibited a hardness of 6.30 N and a springiness of 0.87, whereas the gel containing 1.0% KG reached a higher hardness of 7.34 N but showed a similar springiness of 0.84, reflecting a more rigid and deformation-resistant network. KG-0.8% was therefore selected because it provided a more suitable balance between structural integrity and deformability. When this formulation replaced 75% of the whipping cream by mass, the resulting ice cream (R-75%) showed a reduction in theoretical total fat content from 21.65% to 10.40%, corresponding to a 51.96% decrease, while retaining favorable melting resistance, overrun, texture, and preliminary sensory acceptability. These findings demonstrate that SPI/PPI-F-KG emulsion gels have potential as plant-based fat replacers for reduced-fat frozen desserts.