Encapsulation of bacteriophages in whey protein films for extended storage and release

Abstract The overall motivation of this study was to enable development of pathogen specific antimicrobial packaging materials. These materials are expected to have a significant impact in improving efficacy of antimicrobial treatment and retention of commensal and probiotic microbes on food materials. To achieve these goals, this study was aimed at encapsulation of a model bacteriophage, T4 bacteriophage, in WPI based edible protein films. Phage encapsulated WPI films were characterized for stability and release of encapsulated phages. Antimicrobial efficacy of phage encapsulating edible films was characterized using a microbial growth inhibition assay. Distribution of phages in edible film was measured using a confocal fluorescence microscopy. The results demonstrate that the WPI films are able to stabilize phages at ambient (22 °c and light) and refrigerated (4 °C and dark) conditions without significant loss in phage infectivity over a period of one month. Additionally, the WPI films are able to release a significant concentration of phages in an aqueous environment and leaf surface within 3 h of incubation. Antimicrobial activity measurements demonstrate that the phage encapsulating WPI film can effectively inhibit the microbial growth. The results of microbial growth analysis showed an approximately 5 log difference in microbial levels between the control and the treatment samples. Confocal imaging measurements show that fluorescently labeled phages are homogenously distributed within the WPI film matrix. Overall, this study demonstrates integration of phages with edible packaging materials to develop novel active packaging materials for biocontrol applications.