Antimicrobial effects of edible gluten films incorporated with vanillin

This research aimed to evaluate the antibacterial effect of vanillin on Escherichia coli and Staphylococcus aureus using agar diffusion technique. For this reason, edible films were manufactured from wheat gluten containing 0.5%, 1%, 2% and 4% w/w. The inhibitory effect of the films was assessed based on the surface area of inhibition zone. According to the results, 0.5% of vanillin had no inhibitory effect neither on E. coli nor S. aureus. However, vanillin concentrations higher than 1% could have antibacterial effect on E. coli and S. aureus. Results revealed that with the increasing of vanillin concentration, the surface area of inhibition zone was increased. Moreover, the increasing of vanillin concentration could lead to an increase in the extensibility and elongation of the gluten film. Interpenetrating network cross-linking mechanisms might account for the Schiff base reaction between gluten and vanillin. Although significantly different inhibitory effect was observed between E. coli and S. aureus, the vanillin films were effective on both bacteria.