title: Inactivation of Cronobacter sakazakii in reconstituted infant formula by combination of thymoquinone and mild heat.
abstract: OBJECTIVE
  The objective of this study was to determine the combined effect of thymoquinone (TQ) and mild heat on Cronobacter sakazakii in reconstituted infant formula.
  
  
  RESULTS
  Reconstituted infant formula samples inoculated with a mixture of four C. sakazakii strains (approx. 6·5 log CFU ml(-1) ) were prepared with various concentrations of TQ (0, 5, 10, 20 and 30 mmol l(-1) ) and were heated to 45, 50 and 55°C for 0, 10, 20, 30, 60 and 120 min, and the surviving populations of C. sakazakii at each sampling time were enumerated. To elucidate the mode of action of TQ, membrane integrity and changes in cell morphology were examined by LIVE/DEAD(®) BacLight(™) bacterial viability kit and field emission scanning electron microscope respectively. TQ at 30 mmol l(-1) reduced the pathogen to undetectable level in between 60 and 120 min at 45°C, 60 min at 50°C and 10 min at 55°C respectively.
  
  
  CONCLUSIONS
  Our results demonstrated that the combined treatments significantly reduced (P < 0·05) the population of C. sakazakii, compared to the control. Cronobacter sakazakii numbers were reduced much more rapidly with higher temperatures and increased concentrations of TQ. And combined treatment inactivated pathogen partly by causing cell membrane disruption.
  
  
  CONCLUSIONS
  These findings suggested that TQ, together with mild heat, may have potential application in infant formula to control C. sakazakii before consumption and therefore is a possible way to prevent infections associated with C. sakazakii in infant formula.
authors.affiliation: College of Food Science and Engineering, Northwest A&F University, Yangling, Shaanxi, China.
authors.forename: C
authors.initials: C
authors.lastname: Shi
authors.affiliation: College of Food Science and Engineering, Northwest A&F University, Yangling, Shaanxi, China.
authors.forename: Z
authors.initials: Z
authors.lastname: Jia
authors.affiliation: College of Food Science and Engineering, Northwest A&F University, Yangling, Shaanxi, China.
authors.forename: Y
authors.initials: Y
authors.lastname: Chen
authors.affiliation: College of Food Science and Engineering, Northwest A&F University, Yangling, Shaanxi, China.
authors.forename: M
authors.initials: M
authors.lastname: Yang
authors.affiliation: College of Food Science and Engineering, Northwest A&F University, Yangling, Shaanxi, China.
authors.forename: X
authors.initials: X
authors.lastname: Liu
authors.affiliation: College of Food Science and Engineering, Northwest A&F University, Yangling, Shaanxi, China.
authors.forename: Y
authors.initials: Y
authors.lastname: Sun
authors.affiliation: College of Food Science and Engineering, Northwest A&F University, Yangling, Shaanxi, China.
authors.forename: Z
authors.initials: Z
authors.lastname: Zheng
authors.affiliation: College of Food Science and Engineering, Northwest A&F University, Yangling, Shaanxi, China.
authors.forename: X
authors.initials: X
authors.lastname: Zhang
authors.affiliation: College of Food Science and Engineering, Northwest A&F University, Yangling, Shaanxi, China.
authors.forename: K
authors.initials: K
authors.lastname: Song
authors.affiliation: College of Food Science and Engineering, Northwest A&F University, Yangling, Shaanxi, China.
authors.forename: L
authors.initials: L
authors.lastname: Cui
authors.affiliation: College of Food Science and Engineering, Northwest A&F University, Yangling, Shaanxi, China.
authors.forename: A B
authors.initials: AB
authors.lastname: Baloch
authors.affiliation: College of Food Science and Engineering, Northwest A&F University, Yangling, Shaanxi, China.
authors.forename: X
authors.initials: X
authors.lastname: Xia
mesh_terms: D016227:Benzoquinones / Q000494:pharmacology*; D044083:Cronobacter sakazakii / Q000187:drug effects / Q000528:radiation effects; D005516:Food Microbiology; D006358:Hot Temperature; D006801:Humans; D007223:Infant; D041943:Infant Formula / Q000382:microbiology*; D050296:Microbial Viability / Q000187:drug effects / Q000528:radiation effects
chemical_list: D016227:Benzoquinones; C003466:thymoquinone
keywords: Cronobacter sakazakii; cell membrane; mild heat; reconstituted infant formula; thymoquinone