title: Environmental and biological factors influencing the UV-C resistance of Listeria monocytogenes.
abstract: In this investigation, the effect of microbiological factors (strain, growth phase, exposition to sublethal stresses, and photorepair ability), treatment medium characteristics (pH, water activity, and absorption coefficient), and processing parameters (dose and temperature) on the UV resistance of Listeria monocytogenes was studied. The dose to inactivate 99.99% of the initial population of the five strains tested ranged from 21.84 J/mL (STCC 5672) to 14.66 J/mL (STCC 4031). The UV inactivation of the most resistant strain did not change in different growth phases and after exposure to sublethal heat, acid, basic, and oxidative shocks. The pH and water activity of the treatment medium did not affect the UV resistance of L. monocytogenes, whereas the inactivation rate decreased exponentially with the absorption coefficient. The lethal effect of UV radiation increased synergistically with temperature between 50 and 60 °C (UV-H treatment). A UV-H treatment of 27.10 J/mL at 55 °C reached 2.99 and 3.69 Log10 inactivation cycles of L. monocytogenes in orange juice and vegetable broth, and more than 5 Log10 cycles in apple juice and chicken broth. This synergistic effect opens the possibility to design UV combined processes for the pasteurization of liquid foods with high absorptivity.
authors.affiliation: Tecnología de los Alimentos, Universidad de Zaragoza, Facultad de Veterinaria, C/ Miguel Servet 177, CP 50013 Zaragoza, Spain.
authors.forename: E
authors.initials: E
authors.lastname: Gayán
authors.affiliation: Tecnología de los Alimentos, Universidad de Zaragoza, Facultad de Veterinaria, C/ Miguel Servet 177, CP 50013 Zaragoza, Spain.
authors.forename: M J
authors.initials: MJ
authors.lastname: Serrano
authors.affiliation: Tecnología de los Alimentos, Universidad de Zaragoza, Facultad de Veterinaria, C/ Miguel Servet 177, CP 50013 Zaragoza, Spain.
authors.forename: R
authors.initials: R
authors.lastname: Pagán
authors.affiliation: Tecnología de los Alimentos, Universidad de Zaragoza, Facultad de Veterinaria, C/ Miguel Servet 177, CP 50013 Zaragoza, Spain.
authors.forename: I
authors.initials: I
authors.lastname: Álvarez
authors.affiliation: Tecnología de los Alimentos, Universidad de Zaragoza, Facultad de Veterinaria, C/ Miguel Servet 177, CP 50013 Zaragoza, Spain. Electronic address: scondon@unizar.es.
authors.forename: S
authors.initials: S
authors.lastname: Condón
mesh_terms: D001628:Beverages / Q000382:microbiology*; D003470:Culture Media / Q000737:chemistry; D005514:Food Irradiation / Q000379:methods*; D006863:Hydrogen-Ion Concentration; D008089:Listeria monocytogenes / Q000254:growth & development / Q000528:radiation effects*; D050296:Microbial Viability / Q000528:radiation effects; D013696:Temperature; D014466:Ultraviolet Rays; D014675:Vegetables / Q000737:chemistry*
chemical_list: D003470:Culture Media
keywords: Absorption coefficient; Combined processes; Food pasteurization; Listeria monocytogenes; Ultraviolet radiation