A novel biodegradable active packaging based on PHB/PCL for controlling Listeria monocytogenes in fresh salmon

Our study was focused on developing a novel active packaging material with antibacterial properties to ensure food safety, especially against Listeria monocytogenes . For this purpose, blends formed by a mixture of biodegradable polymers, polyhydroxybutyrate (PHB) and polycaprolactone (PCL), and different ε-poly-L-lysine (EPL) concentrations, were produced by extrusion. Then, active laminates were prepared by thermoforming and characterized by TGA, DSC and FT-IR. Besides, an EPL release assay into food simulants was performed and a sustained release was observed. Laminates activity was evaluated against Listeria monocytogenes and Salmonella enterica , both in liquid and solid media, where they exhibited high antibacterial activities, especially in the case of Listeria . To further study whether the developed materials maintained their active properties when in contact with contaminated food, a challenge test was performed on Listeria monocytogenes -inoculated fresh salmon. For that purpose, tray packaging prototypes containing 3 and 5 % EPL were produced by injection moulding and used to store salmon for 12 days. Microbial counts ( Listeria monocytogenes, Lactic Acid Bacteria, Pseudomonas spp. and Total Viable Counts), and total volatile basic nitrogen (TVB-N) were determined over time. Results showed that active tray prototypes did not affect the quality of the stored salmon in terms of TVB-N. Moreover, they yielded significant reductions on microbial counts for all bacterial groups when compared to control samples. Thus, biodegradable antimicrobial developed trays effectively controlled Listeria monocytogenes and other spoilage bacteria present in fresh salmon. • PCL/PHB blends containing EPL were produced by scalable industrial process • Active materials were effective against L. monocytogenes and S. enterica in vitro • A sustained release of the EPL into food simulants was observed • Active tray prototypes effectively controlled L.m. and other bacteria in salmon • Active tray prototypes did not affect the quality of salmon