Structural Characteristics of Binary Biopolymers-Based Emulsion-Filled Gels: A Case of Mixed Sodium Casein/Methyl Cellulose Emulsion Gels

Sodium casein (NaCN) and methyl cellulose (MC) were used as emulsifiers and structure-modifying agents to prepare composite emulsion gels at 10% of oil phase fraction ( v/v ). Microscopy and rheological studies were performed to reveal the effect of emulsifier types on the microscopic structures of the emulsion gels. The results showed that at a fixed NaCN concentration (8.0%, w/v ), with increasing MC addition (from 0-1.0%, w/v ), the composite emulsion gels exhibited a structural transition from NaCN-dominant single phase to “water-in-water” emulsion structure, suggesting pronounced segregative phase separation. Moreover, when NaCN was used to prepare emulsion, the oil droplets located into the NaCN-dominant phase, whereas in the case of MC as the emulsifier, the oil droplets existed as the third phase, indicating that the emulsifier types affected the location of the oil droplets in the emulsion gels. These results are important to understanding the structural characteristics of polysaccharide-protein based composite emulsion gels.