Edible microbial cellulose-based antimicrobial coatings and films containing clove extract

Abstract

Abstract Recently, microbial cellulose-based coatings and films have attracted substantial attention because of their promising uses in numerous fields, such as food packaging. The present work was designed to synthesize active microbial cellulose-based coatings and films with a comprehensive investigation of their antimicrobial and structural properties. Microbial cellulose was synthesized by using a gram-negative bacterium called Acetobacter aceti. The produced microbial cellulose was mixed with sodium alginate, chitosan and starch to obtain two different composite solutions, i.e., microbial cellulose + starch + chitosan (MSC) and microbial cellulose + starch + sodium alginate (MSS). The antimicrobial properties were achieved by incorporating four different concentrations of clove extract into the composite solutions. The resulting composite solutions were tested against S. aureus, Shigella, Salmonella, and E. coli through the agar diffusion assay method. The clove extract was found to be effective in inhibiting the growth of these pathogens, as a clear zone of inhibition was observed at all clove extract concentrations, with a maximum zone of inhibition of 4.0 ± 0.05 cm on E. coli for the MSC solution incorporated with 4% clove extract. The best antimicrobial solutions found were then casted into films by pouring the solutions into petri dishes and drying at 50 °C in a tray drier. The antimicrobial activity was again evaluated for the films. The results indicated that MSC 3% showed a greater zone of inhibition against all pathogens (1.7 ± 0.18 cm). Furthermore, structural and thermal analyses of the formed films were conducted. The results indicated distinctive antimicrobial and structural characteristics of the films. Graphical Abstract

Keywords

• Polysaccharide
• Clove extract
• Antimicrobial
• Microbial cellulose
• Coating
• Edible films