A Comprehensive Study on the Antimicrobial Activity of Polyhydroxybutyrate (PHB) Film Incorporated with Gallic Acid and Potassium Sorbate

Polyhydroxybutyrate (PHB) has gained attention as an excellent packaging material due to its high crystallinity, biodegradability, low interaction with food matrices, and favorable mechanical properties. This study explores the development of PHB films incorporated with potassium sorbate (KS) and gallic acid (GA) via solvent casting, followed by a 30-day biodegradation test in soil. The films are analyzed for physicochemical and microbiological properties using X-ray diffraction, tensile testing, and disk diffusion assays. The soil-buried PHB films demonstrate accelerated biodegradation, likely driven by increased microbial and fungal activity, as well as moisture absorption. Incorporating KS and GA significantly enhances the antimicrobial efficacy of the films against both Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus, with greater inhibition observed against S. aureus. This difference may stem from the additional lipopolysaccharide membrane in E. coli. Field emission scanning electron microscopy (FESEM) of the films, both pre- and post-biodegradation, provides further insights into their structural changes. These findings underscore the potential of PHB antimicrobial films in advancing sustainable food packaging applications.