Development of protein-based bioplastics with antimicrobial activity by thermo-mechanical processing

Abstract

This study focuses on the development of new bio-active protein-based bioplastics through a thermomechanical processing, which involves a first compounding step followed by compression-moulding of the resulting material into the desired shape. Two types of proteins, wheat gluten and egg-white albumen, and two different bioactive agents, formic acid and oregano essential oil, were selected. The effect of biocide addition on the material rheological response, its antimicrobial activity and biocide release behaviour have been assessed. Rheological tests demonstrated that formulation and processing may exert a notable effect on the material linear viscoelasticity. Kirby–Bauer tests carried out on four selected types of microorganisms revealed that oregano essential oil into a wheat gluten-based matrix may be suitable for applications where the active agent must be progressively delivered (for up to 7 days). Moreover, this biocide can inhibit microorganisms’ growth even if the bioplastic is not in direct contact with the substrate.