Effect of drying methods on the solubility and amphiphilicity of room temperature soluble gelatin extracted by microwave-rapid freezing-thawing coupling.

The effect of three drying methods (hot air, freeze and spray drying) on the solubility and amphiphilicity of gelatin were investigated and compared. Results showed spray drying gelatin (SDG) and hot air drying gelatin (HDG) showed the lowest and best solubility, respectively. This phenomenon was attributed to the degree of subunits degradation and hydrophobicity. The HDG showed an obvious degradation during the hot air drying and displayed the strongest hydrophilicity, while SDG showed a slight degradation and strongest hydrophobicity. The results of wettability showed that SDG had a better amphiphilicity (92.48°) in comparison with HDG (57.7°) and freeze drying gelatin (VDG, 77.53°), which can effectively reduce the interfacial tension of gelatin, thus significantly improving the stability of foam and emulsion (p < 0.05). These results suggested the drying methods can adjust the amphiphilicity of gelatin, and the SDG displayed a better amphiphilicity, showing good potential applications in foam and emulsion.