Evaluation of Physico-mechanical and Antifungal Properties Of Gluten-based Film Incorporated with Vanillin, Salicylic Acid, and Montmorillonite (Cloisite 15A)

A novel wheat gluten (WG) film was developed by adding vanillin, salicylic acid, and montmorillonite cloisite 15A (MMT). Some physico-mechanical properties, including thickness, tensile strength (TS), elongation at break (E), yellowness index (YI), whiteness index (WI), and water solubility (SWF) of the film were investigated using response surface methodology. Results revealed that maximum tensile strength occurred at the highest level of MMT and salicylic acid, and that the effect of MMT on elongation at break was considerable. The YI and WI of the composite films increased respectively, while the WI value and increment of MMT reduced. Moreover, the water solubility was raised with an increasing amount of MMT, vanillin, and salicylic content in the films. The optimum level of the variables obtained by the software was 0.92% vanillin, 0.94% salicylic acid, and 1.92% MMT (% w/w). The intensity and shifting of some absorption peaks in the FTIR spectra pattern confirmed the interaction of functional groups of additive and gluten chain. SEM images revealed an even distribution of the particles with no evidence of particle agglomeration in WG/vanillin/salicylic acid/MMT. Inhibition zone around the nanocomposite films against Aspergillus niger and Alternaria alternate strains indicated antifungal activity of WG nanocomposite films, which was more considerably observed for Aspergillus niger.