Properties, digestion and peptide release of heat-induced duck egg white

In this study, moisture content, textural properties, microstructure, free sulfhydryl group content, the secondary structure of heat-induced duck egg white gels (DEWG) under different heating temperatures of 80 °C, 90 °C, 100 °C and times of 10, 15, 20, and 25 min were investigated. Enzymolysis efficiency and peptide mapping were determined to clarify the linkage mechanism in gel properties, digestion behavior and peptide release of DEWG. Results indicated that with the increasing temperature and time, a gel with harder texture and less moisture was formed. Related gel exhibited a more compact form of aggregation in the environmental scanning electron microscopy (ESEM) and transmission electron microscope (TEM), as well as an increase in the amount of free sulfhydryl group and β-sheet. The in vitro digestibility and the number of peptides produced were affected by protein aggregation morphology. The gel with low induction temperature and shorter induction time showed a loose structure, resulting in a higher digestibility and more quantity of peptides released. In conclusion, heat induced changes in gelation behavior of duck egg white protein, and thus exhibited critical effects on protein digestion and peptide released.