Preparation and Characterization of Pullulan-Soy Protein Concentrate Blended Film Incorporated With Zataria multiflora and Artemisia biennis Essential Oils

Abstract

Background: Adding antimicrobial agents to biodegradable packaging can make a coating that can protect foods and drugs against microbial contamination. Objectives: To evaluate the physical and mechanical properties and antimicrobial activity of soy protein concentrate (SPC) and pullulan films incorporated with Zataria multiflora (ZM) and Artemisia biennis (AB) essential oils (Eos). Methods: In this study, the pullulan and SPC solutions were mixed in a 50:50 ratio and EOs from ZM or AB were incorporated into the film solution at various concentrations. The casting/solvent evaporation method was used for film formation. Physical and mechanical characterization was determined, and the antimicrobial activities of the films were evaluated against Staphylococcus aureus, Lactobacillus plantarum, and Escherichia coli by agar diffusion method. The minimum inhibitory concentration (MIC) was also identified. Results: The prepared films were flexible without pores and homogeneous. The addition of EOs significantly increased the thickness and elongation at break but reduced the tensile strength, water vapor permeability, and solubility in water of the films (P < 0.05). Unlike in the control film, the addition of EOs resulted in a dark and yellow film appearance as evidenced by the lower L and greater ΔE and b. In all concentrations, the intensity of the antimicrobial activity of AB was significantly lower than that of ZM (P < 0.05). E. coli and S. aureus had the highest and the lowest resistance to the antimicrobial effect of Eos, respectively. Conclusions: These findings may lead to the utilization of this new antibacterial film that has the potential to be used as packaging material.