Films based on Pectin, Gellan, EDTA, and bacteriocin‐like compounds produced by Streptococcus infantarius for the bacterial control in fish packaging

A fish‐packaging film was prepared with 0.4% gellan gum (GG), 2% citrus pectin (CP), 0.75% glycerol, EDTA 1 mM, and 50 arbitrary‐units (AU)/ml of antimicrobial‐activity supernatants (AS) from Streptococcus infantarius cultures containing bacteriocin‐like compounds of 5–10 kDa. The formulation was based on a minimum inhibitory condition (AS, 50 AU/ml; EDTA, 1 mM; CP, 0.1%; GG, 0.05%) for 10 5  CFU/well of Escherichia coli , Staphylococcus aureus or Listeria monocytogenes growing in BHI at 35°C, 24 hr. The films entirely inhibited the growth of the three bacteria in two model fish media, containing trout or tilapia, at two incubation‐conditions: 9°C, 90% RH, 30‐day; and 35°C, 35% RH, 7‐day. Furthermore, wrapped fresh‐fillets of trout or tilapia exhibited the lowest total‐aerobes counts, 8 × 10 6 –1 × 10 7  CFU/g, after 7‐day‐incubation at accelerated conditions (25 ± 2°C, 60 ± 10% RH), showing the film‐potential. The film‐physical‐mechanical properties (Young’s modulus; elongation and stress at break; oxygen and water vapor permeability) were slightly affected by the EDTA‐AS contents. Practical applications Development of a biodegradable‐film based on citrus pectin, and gellan gum, enriched with EDTA and antimicrobial substances produced by Streptococcus infantarius , for hindering the growth of pathogen bacteria (i.e., Escherichia coli , Staphylococcus aureus, and Listeria monocytogenes ) and total aerobes that would contaminate and/or deteriorate fresh fish, like trout and tilapia.