Development of antimicrobial edible film containing antagonistic bacteria

The microbial spoilage of food products causes significant economic losses. In this study, Bacillus clausii (O/C, T, SIN, and N/R) as an antagonistic bacterium was incorporated into an edible film solution based on whey protein concentrate (WPC) and fermented for 24 h to produce antimicrobials and create an antimicrobial edible film. Taguchi test trial (3x3) was used to analyze the optimum condition for the growth of B. clausii and its antimicrobial production in the film solution. Nine different growth parameters including temperature (33, 35, and 37°C), pH (8.5, 9.0, and 9.5), and protein concentration in the film (6, 8, and 10%) were chosen for that purpose. The optimum growth of B. clausii and the maximum antimicrobial production were observed when protein concentration was 10% (w/v) and pH was 8.5 and 9.0. The film solutions showed antimicrobial effects against Aspergillus niger, Penicillium expansum, Staphylococcus aureus, and Escherichia coli. The 86% and 87% of B. clausii cells survived in the dry film for 14 days at 4 and 25°C, respectively. The highest TS and % E of the film containing B. clausii was measured as 3.14 MPa and 27.63%, respectively. Taguchi test trial results showed that the protein content of the film was the most important parameter affecting water solubility (WS) and water vapor permeability (WVP). In conclusion, the present work showed that B. clausii with their spores could be used to prepare WPC films with antimicrobial properties against spoilage of food products.