title: The combined effect of nisin, moderate heating and high hydrostatic pressure on the inactivation of Bacillus sporothermodurans spores.
abstract: OBJECTIVE
  To investigate the combined effect of hydrostatic pressure (HP), moderate temperature and nisin on the inactivation of Bacillus sporothermodurans spores which are known to be contaminant of dairy products and to be extremely heat-resistant.
  
  
  RESULTS
  A central composite experimental design with three factors, using response surface methodology, was used. By analysing the response surfaces and their corresponding contour plots, an interesting interaction with the three factors was observed. The inactivation observed was shown to be well fitted with values predicted by the quadratic equation, since the adjusted determination coefficient (R(adj)(2)) was 0·979. The optimum process parameters for a 5-log spores ml(-1) reduction of B. sporothermodurans spores were obtained, 472 MPa/53°C for 5 min in presence of 121 UI ml(-1) of nisin.
  
  
  CONCLUSIONS
  Nisin and temperature treatments improve the effectiveness of pressure in the inactivation of highly heat-resistant spores of B. sporothermodurans.
  
  
  CONCLUSIONS
  This study shows the potential of using high HP for a short time (5 min) in combination with moderate temperature and nisin to inactivate B. sporothermodurans spores in milk. Such treatments could be applied by the dairy industry to ensure the commercial sterility of UHT milk.
authors.affiliation: Laboratory of Epidemiology and Veterinary Microbiology, Bacteriology and Biotechnology Development Groups, Pasteur Institute of Tunisia (IPT), University Manar, Tunis, Tunisia. chediaaouadhi@yahoo.fr
authors.forename: C
authors.initials: C
authors.lastname: Aouadhi
authors.forename: H
authors.initials: H
authors.lastname: Simonin
authors.forename: S
authors.initials: S
authors.lastname: Mejri
authors.forename: A
authors.initials: A
authors.lastname: Maaroufi
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001407:Bacillus / Q000187:drug effects*; D006358:Hot Temperature; D006874:Hydrostatic Pressure; D050296:Microbial Viability / Q000187:drug effects; D009561:Nisin / Q000494:pharmacology*; D013171:Spores, Bacterial / Q000187:drug effects
chemical_list: D000900:Anti-Bacterial Agents; D009561:Nisin