Elaboration and characterization of pectin-gellan films added with concentrated supernatant of Streptococcus infantarius fermentations, and EDTA: effects on the growth of Escherichia coli, Staphylococcus aureus and Listeria monocytogenes in a Mexican cheese medium, and physical-mechanical properties

• Autor(a) principal: JIMÉNEZ-VILLEDA,Perla-Yesenia
• Data de Publicação: 2019
• Outros Autores: RODRÍGUEZ-HERNÁNDEZ,Adriana-Inés, LÓPEZ-CUELLAR,Ma.-del-Rocío, FRANCO-FERNÁNDEZ,Melitón-Jesús, CHAVARRÍA-HERNÁNDEZ,Norberto
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Food Science and Technology (Campinas)
• Texto Completo: http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0101-20612019000200436
• topic: lactic acid bacterium; bacteriocins; biopreservation; mechanical properties; gas permeability

Abstract Films were prepared with 0.2% (w/v) gellan gum, 1% (w/v) citric pectin, 0.5% (w/v) glycerol, 5 mM CaCl2, 0.05 M Ethylenediaminetetraacetic acid (EDTA), and different concentrations of an antimicrobial activity-concentrated supernatant (AMC) obtained from fermentations of Streptococcus infantarius, which produces bacteriocin-like inhibitory substances (i.e., treatments F1, F2 and F3 with 75, 90 and 120 arbitrary units (AU)/mL, respectively). The treatments were based on a minimum-inhibitory-concentration (i.e., AMC, 90 AU/mL, plus EDTA, 0.05 M) for Escherichia coli, Staphylococcus aureus and Listeria monocytogenes growing in brain-heart-infusion medium at 35 °C. The films hindered the bacterium growth in selective media: E. coli -MacConkey, S. aureus-Baird Parker and L. monocytogenes -Oxford, during 30 days at 25 °C. Moreover, the F2 films entirely inhibited the growth of the tested bacteria in a Mexican cheese medium, in 7-day cultures at 35 °C; contrariwise, controls with no film exhibited bacterial growths in the range 107 -109 CFU/g. The physical-mechanical properties of the films were changed by the addition of EDTA-AMC, being (F2 film)/(control-film with no AMC nor EDTA): Young’s modulus (MPa), 1,394/707; Elongation at break (%), 1.9/9.3; Stress at break (MPa), 5.7/12.6; Water Vapour Permeability (10-11 g m Pa-1 s-1 m -2), 3/20, and Oxygen Permeability (10-12 g m Pa-1 s -1 m-2), 1.9/1.2.