Properties of gelatin-based films with added ethanol-propolis extract

Considering the possibility of using propolis as a natural bioactive compound, and the growing interest in active and biodegradable packaging materials, gelatin-based films plasticized with sorbitol and added of ethanol-propolis extract (EPE) were produced. Four different concentrations of EPE (0, 5, 40 or 200 g/100 g of gelatin) were analyzed. The effect of concentrations of EPE were evaluated on: mechanical properties, solubility, moisture content, water vapor permeability, scanning electron microscopy and infrared spectroscopy characteristics, stability of polyphenol concentrations, and antimicrobial activity against Staphylococcus aureus. EPE incorporation to the films promoted reduction in rupture tension and water vapor permeability, besides other microstructural changes, when compared with the control films (0 g of EPE/100 g of gelatin). Activity against S. aureus was observed in films with 40 and 200 g of EPE/100 g of gelatin. These films kept their antimicrobial activity and polyphenol concentration for 177 days of storage.

► Effect of different concentrations of ethanol-propolis extract on gelatin films. ► Extract incorporation practically did not change the properties of films. ► Films with ethanol-propolis extract were effective against Staphylococcus aureus. ► The antimicrobial effect of ethanol-propolis extract continued for 177 days.