Effect of κ-carrageenan/milk protein interaction on rheology and microstructure in dairy emulsion systems with different milk protein types and κ-carrageenan concentrations

We investigated the effect of κ-carrageenan (κ-CG) addition and supplementation with Na-CN, WPI, and MPI on the rheological properties, microstructure, fat globule size distribution, and stability of low-fat cream (LFC) emulsions containing 19% milk fat. Rheological parameter (η_a,10, K, and G′) values of LFCs increased with κ-CG addition. At 0.1% κ-CG concentration, MPI-stabilized LFC had higher G′ value (64.8 Pa) than those of WPI-stabilized LFC (51.3 Pa) and Na-CN-stabilized LFC (34.8 Pa), indicating the strong interaction between MPI and κ-CG. Cryo-SEM images showed the protein layers on milk fat globule membrane in dairy emulsions and revealed that κ-CG led to depletion-flocculation of milk fat globules and promoted clustering of globules. The creaming index values of LFCs with 0.10% κ-CG were lower than those of LFCs with 0.05% κ-CG. Thus, high κ-CG concentrations can contribute to the physical stability in dairy emulsions stabilized by milk proteins. Practical applications: Milk proteins are widely used as emulsifiers, and κ-carrageenan (κ-CG) is added to dairy emulsion products to improve their physical properties and stability. Therefore, in this study, the effect of κ-CG addition on physical properties and stability of low-fat creams (LFCs) supplemented with different milk protein types (Na-CN, WPI, and MPI) was investigated. The strong synergistic interaction between proteins and κ-CG was observed in MPI-stabilized LFCs when compared to Na-CN- and WPI-stabilized LFCs. We found that the presence of κ-CG in MPI-stabilized LFCs improved the stability of LFCs by inhibiting the phase separation due to the high viscosity of the continuous phase. These findings suggest that dairy cream-based food products with desirable physical properties can be realized through κ-CG addition to LFC emulsions with milk proteins such as ice cream mix, coffee creamer, and light cream.