Physical, antioxidant and antimicrobial properties of modified peanut protein isolate based films incorporating thymol

An active film made from modified peanut protein isolate (PPI) and incorporating thymol (TML) was developed. The physical, antioxidant and antimicrobial properties of modified PPI based films containing TML at 0.5, 1, 1.5, and 2% (w/v) were examined. Incorporation of TML decreased the water vapor permeability, tensile strength (TS) and percentage of elongation at break (E) of the film. TML incorporation decreased the transparency and made the film darker, but increased the total phenolic content and antioxidant capacity. Antimicrobial activity was significantly increased by adding TML; Staphylococcus aureus and Lactobacillus plantarum were more susceptible than Escherichia coli and Pseudomonas aeruginosa. These results suggest that edible, modified PPI films incorporating an appropriate amount of TML have the potential to preserve food products, which offers a way to use PPI in active food packaging.