Development and characterization of antimicrobial bilayer biodegradable films from wheat flour and biopolymers for food packaging

Abstract

This study focuses on the development and characterization of biodegradable bilayer films with antimicrobial properties (against Bacillus cereus) formed from wheat flour (WF) monolayers assembled with polycaprolactone (PCL) or Mater-Bi (MB). Monolayer films were made by compression molding, and bilayer films were obtained by bonding a wheat flour layer with a PCL or Mater- Bilayer, incorporating potassium sorbate (PS) and citric acid (CA) as antimicrobial agents at the interface. Film properties were evaluated, including color, gloss, thickness, opacity, internal transmittance, moisture content, water solubility, water absorption capacity, water contact angle, water vapor permeability, mechanical properties, and antimicrobial activity. The results showed that the bilayers with PCL and Mater-Bi offer a better barrier and lower solubility than the wheat flour monolayers and, in turn, show moderate stresses and deformations, with higher elastic moduli, especially in the BWF-CA-MB bilayer, which has the highest elastic modulus (174.5 MPa). Also, the inclusion of antimicrobial agents and the combination of varied materials significantly influence the properties of the films, highlighting the antimicrobial effectiveness against Bacillus cereus. The study concludes the films offer a sustainable alternative to conventional plastics, improving food safety and extending shelf life in food packaging combining sustainability with functionality. However, additional studies using real food matrices are required to confirm their impact on food safety and product shelf-life extension.