title: Effect of vanillin, ethyl vanillin, and vanillic acid on the growth and heat resistance of Cronobacter species.
abstract: Preservatives could be part of an effective intervention strategy for the control of Cronobacter species in foods, but few compounds with the desired antimicrobial properties have been identified to date. We examined the antibacterial activity of vanillin, ethyl vanillin, and  vanillic acid against seven Cronobacter spp. in quarter-strength tryptic soy broth with 5 g/liter yeast extract (TSBYE) adjusted to pH 5.0, 6.0, and 7.0 at 10, 21, and 37°C. All compounds exhibited pH- and temperature-dependant bacteriostatic and bactericidal activity. MICs of vanillin  and ethyl vanillin consistently increased with decreasing pH and temperature, but vanillic acid had little activity at pH values of 6.0 and 7.0. The MICs for all temperatures, pH values, and bacterial strains tested were 2 mg/ml ethyl vanillin, 3 mg/ml vanillin, and >8 mg/ml vanillic acid.  MBCs also were influenced by pH, although significantly higher concentrations were needed to inactivate the bacteria at 21°C than at 10 or 37°C. Survivor curves for Cronobacter sakazakii strains at the MBCs of each compound revealed that all treatments resulted in immediate  loss of cell viability at 37°C. Measurements of propidium iodide uptake indicated that the cell membranes were damaged by exposure to all three compounds. The thermal resistance of C. sakazakii was examined at 58°C in TSBYE supplemented with MBCs of each compound at pH 5.0 and  6.0. D-values at pH 5.0 were reduced from 14.56 ± 0.60 min to 0.93 ± 0.01, 0.63 ± 0.01, and 0.98 ± 0.02 min for vanillin, ethyl vanillin, and vanillic acid, respectively. These results suggest that vanillin, ethyl vanillin, and vanillic acid may be useful  for the control of Cronobacter spp. in food during preparation and storage.
authors.affiliation: Department of Food Engineering, Ankara University, Diskapi Campus, Ankara, Turkey 06110.
authors.forename: Gökçe Polat
authors.initials: GP
authors.lastname: Yemiş
authors.forename: Franco
authors.initials: F
authors.lastname: Pagotto
authors.forename: Susan
authors.initials: S
authors.lastname: Bach
authors.forename: Pascal
authors.initials: P
authors.lastname: Delaquis
mesh_terms: D001547:Benzaldehydes / Q000494:pharmacology; D015169:Colony Count, Microbial; D003257:Consumer Product Safety; D059126:Cronobacter / Q000187:drug effects* / Q000254:growth & development; D004305:Dose-Response Relationship, Drug; D005421:Flavoring Agents / Q000494:pharmacology*; D005511:Food Handling / Q000379:methods*; D005520:Food Preservatives / Q000494:pharmacology*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D045730:Soy Foods / Q000382:microbiology*; D013696:Temperature; D014641:Vanillic Acid / Q000494:pharmacology
chemical_list: D001547:Benzaldehydes; D005421:Flavoring Agents; D005520:Food Preservatives; C100058:vanillin; D014641:Vanillic Acid; C045941:ethyl vanillin