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

This study focuses on the development of new bio-active protein-based bioplastics through a thermo-mechanical 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.

► Albumen and wheat proteins as renewable raw materials in the development of bioplastics by thermo-mechanical processing.
► Use of oregano essential oil as natural substance which demonstrates suitable antimicrobial activity.
► Antimicrobial activity, active substance releasing rate and mechanical properties controlled by formulation and processing.