Edible lactoferrin bacterial cellulose films as an effective and low-cost antimicrobial active packaging

摘要

Active packaging is an increasingly reliable technology for assuring the safety and maintenance/improvement of the organoleptic traits of theenclosed food products. Bio-based materials with a wide set of highly impressive characteristics were assembled through a simple and effectivemethodology to produce affordable edible antibacterial active films. Bacterial cellulose (BC) was used as film scaffold since it is an extremelypure polysaccharide that possesses noteworthy properties for food casing such as high toughness, shape retention and works as astabilizing agent. Functionalization of BC was achieved through absorption of lactoferrin (LF), a bilobar protein mainly extracted from milk thatpossess a numerous plethora of activities, such as broad spectrum antibacterial effect, immunoregulatory properties, and also promotesbifidobacteria and intestinal epithelium growth. These films were extensively characterized in terms of their physicochemical characteristics,bactericidal efficiency and cytotoxicity. The LF absorption and de-absorption profiles of the BC films were registered. Surface free energy, watervapour permeability, attenuated total reflection Fourier transform infrared spectroscopy, dynamic mechanical analysis (in water saturatedconditions) and swelling profile, and other critical characterization techniques were employed. The antibacterial properties were assessedthrough the determination of the specific growth rate impact, “live and dead” fluorescence, scanning electron microscopy and colony formingunits’ count; using two model microorganisms (Escherichia coli and Staphylococcus aureus). The contact killing properties were evaluated forstandalone films and for a specific case study (fresh sausage). Finally, the films cytotoxicity was determined after digestion in a dynamic mimeticartificial gastrointestinal digestive system. All attained results lead us to conclude that the obtained active edible films display an effectiveand significant antimicrobial activity against both Gram – and + and revealed no cytotoxicity, prior and after the gastrointestinal digestion.Thus, these new films present a high potential to safely functionalize the encased foods, while providing prophylactic properties.Acknowledgements: The authors acknowledge the Portuguese Foundation for Science and Technology (FCT, Portugal) for the financial supportprovided by the research grants SFRH/BD/64901/2009, SFRH/BD/63578/2009, SFRH/BPD/64958/2009, SFRH/BPD/64958/2009 forJorge Padrão, Sara Gonçalves, João P. Silva and Vitor Sencadas respectively, and also for FCT Strategic Project PEst-OE/EQB/LA0023/2013