title: Exploring the use of natural antimicrobial agents and pulsed electric fields to control spoilage bacteria during a beer production process.
abstract: Different natural antimicrobials affected viability of bacterial contaminants isolated at critical steps during a beer production process. In the presence of 1 mg/ml chitosan and 0.3 mg/ml hops, the viability of Escherichia coli in an all malt barley extract wort could be reduced to 0.7 and 0.1% respectively after 2 hour- incubation at 4 degrees C. The addition of 0.0002 mg/ml nisin, 0.1 mg/ml chitosan or 0.3 mg/ml hops, selectively inhibited growth of Pediococcus sp. in more than 10,000 times with respect to brewing yeast in a mixed culture. In the presence of 0.1 mg ml chitosan in beer, no viable cells of the thermoresistant strain Bacillus megaterium were detected. Nisin, chitosan and hops increased microbiological stability during storage of a local commercial beer inoculated with Lactobacillus plantarum or Pediococcus sp. isolated from wort. Pulsed Electric Field (PEF) (8 kV/cm, 3 pulses) application enhanced antibacterial activity of nisin and hops but not that of chitosan. The results herein obtained suggest that the use of these antimicrobial compounds in isolation or in combination with PEF would be effective to control bacterial contamination during beer production and storage.
authors.affiliation: Laboratorio de Microbiología Industrial, Departamento de Ingeniería Química, Facultad de Ingeniería, Pabellón de Industrias, Universidad de Buenos Aires, Ciudad Universitaria (1428), Buenos Aires, Argentina. mag@di.fcen.uba.ar
authors.forename: M A
authors.initials: MA
authors.lastname: Galvagno
authors.forename: G R
authors.initials: GR
authors.lastname: Gil
authors.forename: L J
authors.initials: LJ
authors.lastname: Iannone
authors.forename: P
authors.initials: P
authors.lastname: Cerrutti
mesh_terms: D001410:Bacillus megaterium / Q000187:drug effects / Q000254:growth & development / Q000302:isolation & purification* / Q000528:radiation effects; D001515:Beer / Q000382:microbiology*; D048271:Chitosan / Q000494:pharmacology*; D004574:Electromagnetic Fields; D004926:Escherichia coli / Q000187:drug effects / Q000254:growth & development / Q000302:isolation & purification* / Q000528:radiation effects; D005285:Fermentation; D005519:Food Preservation; D027582:Humulus; D007218:Industrial Microbiology / Q000379:methods*; D048191:Lactiplantibacillus plantarum / Q000187:drug effects / Q000254:growth & development / Q000302:isolation & purification* / Q000528:radiation effects; D008826:Microbial Sensitivity Tests; D009561:Nisin / Q000494:pharmacology*; D010376:Pediococcus / Q000187:drug effects / Q000254:growth & development / Q000302:isolation & purification* / Q000528:radiation effects; D010936:Plant Extracts / Q000494:pharmacology*; D013696:Temperature
chemical_list: D010936:Plant Extracts; D009561:Nisin; D048271:Chitosan