Bacterial cellulose-lactoferrin as an antimicrobial edible packaging
Bacterial cellulose (BC) films from two distinct sources (obtained by static culture with Gluconacetobacter xylinus ATCC 53582 (BC1) and from a commercial source (BC2)) were modified by bovine lactoferrin (bLF) adsorption. The functionalized films (BC + bLF) were assessed as edible antimicrobial packaging, for use in direct contact with highly perishable foods, specifically fresh sausage as a model of meat products. BC + bLF films and sausage casings were characterized regarding their water vapour permeability (WVP), mechanical properties, and bactericidal efficiency against two food pathogens, Escherichia coli and Staphylococcus aureus. Considering their edibility, an in vitro gastrointestinal tract model was used to study the changes occurring in the BC films during passage through the gastrointestinal tract. Moreover, the cytotoxicity of the BC films against 3T3 mouse embryo fibroblasts was evaluated.BC1 and BC2 showed equivalent density, WVP and maximum tensile strength. The percentage of bactericidal efficiency of BC1 and BC2 with adsorbed bLF (BC1. +. bLF and BC2. +. bLF, respectively) in the standalone films and in inoculated fresh sausages, was similar against E. coli (mean reduction 69% in the films per se versus 94% in the sausages) and S. aureus (mean reduction 97% in the films per se versus 36% in the case sausages). Moreover, the BC1. +. bLF and BC2. +. bLF films significantly hindered the specific growth rate of both bacteria. Finally, no relevant cytotoxicity against 3T3 fibroblasts was found for the films before and after the simulated digestion. BC films with adsorbed bLF may constitute an approach in the development of bio-based edible antimicrobial packaging systems.
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