Rheology, physicochemical properties, and microstructure of fish gelatin emulsion gel modified by γ-polyglutamic acid

In this work, the effect of the addition of gamma-polyglutamic acid (gamma-PGA) on the rheology, physicochemical properties, and microstructure of fish gelatin (FG) emulsion gel was investigated. Samples of the emulsion gel were evaluated for rheological behavior and stability prior to gelation. The mechanical properties and water-holding capacity (WHC) of the emulsion were determined after gelation. The microstructure of the emulsion gel was further examined using confocal laser scanning microscopy (CLSM). The results indicated a gradual increase in the apparent viscosity and gelation temperature of the emulsion at a higher concentration of gamma-PGA. Additionally, frequency scan results revealed that on the addition of gamma-PGA, FG emulsion exhibited a stronger structure. The emulsion containing 0.1% gamma-PGA exhibited higher stability than that of the control samples. The WHC and gel strength of the emulsion gel increased on increasing the gamma-PGA concentration. CLSM images showed that the addition of gamma-PGA modified the structure of the emulsion gel, and the droplets containing 0.1% gamma-PGA were evenly distributed. Moreover, gamma-PGA could regulate the droplet size of the FG emulsion and its size distribution. These findings suggest that the viscoelasticity and structure of FG emulsion gels could be regulated by adjusting the gamma-PGA concentration. The gamma-PGA-modified FG emulsion gel also exhibited improved rheology and physicochemical properties. The results showed that gamma-PGA-modified FG emulsion gel may find potential applications in food, medicine, cosmetics, and other industries.