Effect of beeswax and carnauba wax addition on properties of gelatin films: A comparative study

Different levels of beeswax (B) or carnauba wax (C) were added into gelatin (G) at 5%, 10%, and 15% (w/w) to prepare films containing glycerol as a plasticizer. Although the wax addition increased the opacity and yellowness of gelatin films, both the UV/visible light and water vapor barriers were successfully improved gradually with increasing wax levels, and B was more effective than C. Addition of 10% and 15% wax significantly reduced the water solubility and WVP (P < 0.05). However, the mechanical properties of gelatin-wax films were not strengthened compared with control. As wax levels increased, the resulting films became more brittle, harder, and less stretchable. SEM showed GB films have more uniform surfaces and compact cross-sections compared with GC films. All films showed antioxidant activity against DPPH and hydroxyl radicals, and iron reducing; however, the effects obtained with the gelatin-wax films were not significantly different from the G films (P > 0.05). Based on FTIR analysis, all films showed amide absorption regions, but GB films showed higher intensity of absorption peaks for lipid functional groups than GC films. Wax addition improved thermal stability of films suggesting an interaction between wax and gelatin. The improved barrier properties and thermal stability of the gelatin-wax films suggest that they can be used to protect foods from deterioration, and B was found to be better than C when added in gelatin films.