This study aimed at improving the mechanical properties and water solubility of peanut protein isolate (PPI) films by glycosylating with xylose (X). The modification process of glycosylation was optimized by using response surface methodology (RSM). The effects of pH, temperature and time on degrees of glycosylation (DG), tensile strength (TS), elongation (E), solubility and microstructure of xylose glycosylated PPI films (PPI-XF) were determined. The changes of DG in different conditions indicated that crosslinking should occur between PPI and xylose during the modification. Optimum glycosylation conditions were found to be pH 9.5, 91.5 °C and 95 min. Under these conditions, TS and E values of PPI-XF were 10.37 MPa and 96.47 %, respectively. Due to glycosylation, solubility of PPI-XF decreased from 96.64 to 35.94 % and these films remained intact in water for 24 h. The microstructure of PPI-XF was denser and more compact than the unmodified PPI films. These results suggest that the xylose glycosylated PPI films have potentiality of being used as biodegradable films in food packaging application.
Keywords: Biodegradable film; Glycosylation; Peanut protein isolate; Properties; RSM; Xylose.