Characterization and film-forming mechanism of egg white/pullulan blend film

Edible films based on pullulan (Pu) and egg white (EW) were prepared in this study. As the egg white proportion increased, the mechanical properties of the blend films initially increased and then decreased. The best mechanical properties occurred at the optimal proportion of Pu:EW = 1:1. The blend films with a higher content of egg white showed a lower degradation speed of moisture and polymers. FTIR spectroscopy illustrated peak displacement, X-ray diffraction patterns showed noticeable changes, and the secondary structure of egg white was altered. These results indicated that pullulan and egg white interacted extensively. The total a-helix and beta-sheet content increased with the increment of pullulan content. The decrease of free amino content indicated that the degree of glycosylation increased with the addition of pullulan, which is associated with the Maillard reaction. The apparent color and the scanning electron microscopy images were also assessed in this study.