Bacteriophage IBB-PF7A loaded on sodium alginate-based films to prevent microbial meat spoilage

Despite the recent advances achieved in food industries to fulfil the growing consumer demand for high quality and food safety, microbial contamination remains a serious issue. This study aimed to incorporate IBB-PF7A bacteriophage (phage) onto sodium alginate-based films crosslinked with calcium chloride, to prevent poultry spoilage caused by Pseudomonas fluorescens. Films were prepared by casting and characterized in terms of phage loading, distribution, stability, release profile and antimicrobial performance. Results showed that phages were successfully incorporated as evidenced by their viability and homogeneous distribution within the films as assessed by microscopy. A decrease in phage viability was only detected after 8 weeks when stored under refrigerated conditions. Antimicrobial activity demonstrated that incorporated phages significantly impaired P. fluorescens growth. Films' antimicrobial efficacy was further demonstrated on chicken breast fillets artificially inoculated, decreasing 2Log P. fluorescens viable cell counts in the first two days and reductions were maintained up to 5 days of exposure (1 Log). These results highlight that phage incorporation onto sodium-alginate-based films constitutes a simple approach of preserving the antimicrobial activity of phages in a dried and insoluble format, that can further be applied in food industry for the prevention of microbial spoilage.AM, CM, MC acknowledge the Portuguese Foundation for Science and Technology (FCT) grants SFRH/BD/132911/2017, SFRH/BD/ 94434/2013, and SFRH/BD/122897/2016. SS is an Investigador FCT (IF/01413/2013). This study was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UID/BIO/04469/2013 unit and COMPETE 2020 (POCI-01-0145-FEDER-006684) and BioTecNorte operation (NORTE01-0145-FEDER-000004) funded by the European Regional Development Fund under the scope of Norte2020 - Programa Operacional Regional do Norte and the Project RECI/BBB-EBI/0179/ 2012 (FCOMP-01-0124-FEDER-027462).