Effect of microwave extraction temperature on the chemical structure and oil-water interface properties of fish skin gelatin

Abstract

This study investigated the effect of microwave extraction temperature on the chemical structure and oil-water interface properties of fish skin gelatin. Results showed that increasing microwave extraction temperature from 55 to 75 °C led to the degradation of α subunits and breaking of the triple helical structure of gelatin, consequently exposing more hydrophobic groups and showing an improvement of amphiphilicity (58.35°-81.65°). Correspondingly, the interface pressure and adsorption also respectively increased from 8.00 to 8.90 mN/m and 43.70% to 93.66% due to its enhanced amphiphilicity. Furthermore, the volume-mean diameter and creaming index (CI) of emulsion obviously decreased, but the water holding capacity significantly increased, implying an improvement of emulsifying property. The rheological results showed the emulsion displayed a typical shear thinning behavior, and the apparent viscosity increased from 230 to 1339.4 Pa·s with the increase of microwave extraction temperature (55–75 °C) and concentration (1.0–3.0 wt%) at 0.1 s−1. The possible reason is that more gelatin molecules participated in the formation of dense network structure of continuous phase due to the higher amphiphilicity. This work would provide guiding significance for green extraction of fish skin gelatin and its application in stabilizing emulsion.