title: Effect of immersion solutions containing enterocin AS-48 on Listeria monocytogenes in vegetable foods.
abstract: The effect of immersion solutions containing enterocin AS-48 alone or in combination with chemical preservatives on survival and proliferation of Listeria monocytogenes CECT 4032 inoculated on fresh alfalfa sprouts, soybean sprouts, and green asparagus was tested. Immersion treatments (5 min at room temperature) with AS-48 solutions (25 microg/ml) reduced listeria counts of artificially contaminated alfalfa and soybean sprouts by approximately 2.0 to 2.4 log CFU/g compared to a control immersion treatment in distilled water. The same bacteriocin immersion treatment applied on green asparagus had a very limited effect. During storage of vegetable samples treated with immersion solutions of 12.5 and 25 microg of AS-48/ml, viable listeria counts were reduced below detection limits at days 1 to 7 for alfalfa and soybean sprouts at 6 and 15 degrees C, as well as green asparagus at 15 degrees C. Only a limited inhibition of listeria proliferation was detected during storage of bacteriocin-treated alfalfa sprouts and green asparagus at 22 degrees C. Treatment with solutions containing AS-48 plus lactic acid, sodium lactate, sodium nitrite, sodium nitrate, trisodium phosphate, trisodium trimetaphosphate, sodium thiosulphate, n-propyl p-hydroxybenzoate, p-hydoxybenzoic acid methyl ester, hexadecylpyridinium chloride, peracetic acid, or sodium hypochlorite reduced viable counts of listeria below detection limits (by approximately 2.6 to 2.7 log CFU/g) upon application of the immersion treatment and/or further storage for 24 h, depending of the chemical preservative concentration. Significant increases of antimicrobial activity were also detected for AS-48 plus potassium permanganate and in some combinations with acetic acid, citric acid, sodium propionate, and potassium sorbate.
authors.affiliation: Area de Microbiología, Departamento de Ciencias de la Salud, Facultad de Ciencias Experimentales, Universidad de Jaén, Campus Las Lagunillas s/n, 23071-Jaén, Spain. agalvez@ujaen.es.
authors.forename: Antonio Cobo
authors.initials: AC
authors.lastname: Molinos
authors.forename: Hikmate
authors.initials: H
authors.lastname: Abriouel
authors.forename: Nabil
authors.initials: N
authors.lastname: Ben Omar
authors.forename: Eva
authors.initials: E
authors.lastname: Valdivia
authors.forename: Rosario Lucas
authors.initials: RL
authors.lastname: López
authors.forename: Mercedes
authors.initials: M
authors.lastname: Maqueda
authors.forename: Magdalena Martínez
authors.initials: MM
authors.lastname: Cañamero
authors.forename: Antonio
authors.initials: A
authors.lastname: Gálvez
mesh_terms: D001430:Bacteriocins / Q000633:toxicity*; D005516:Food Microbiology; D005519:Food Preservation; D008089:Listeria monocytogenes / Q000187:drug effects / Q000254:growth & development*; D000455:Medicago sativa / Q000382:microbiology; D012996:Solutions; D013025:Glycine max / Q000382:microbiology; D014675:Vegetables / Q000382:microbiology*
chemical_list: D001430:Bacteriocins; D012996:Solutions; C466236:enterocin AS-48, Enterococcus faecalis