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Inactivation of Cronobacter sakazakii in reconstituted infant formula by combination of thymoquinone and mild heat
Author(s) -
Shi C.,
Jia Z.,
Chen Y.,
Yang M.,
Liu X.,
Sun Y.,
Zheng Z.,
Zhang X.,
Song K.,
Cui L.,
Baloch A.B.,
Xia X.
Publication year - 2015
Publication title -
journal of applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.889
H-Index - 156
eISSN - 1365-2672
pISSN - 1364-5072
DOI - 10.1111/jam.12964
Subject(s) - cronobacter sakazakii , infant formula , thymoquinone , scalding , microbiology and biotechnology , population , cronobacter , food science , chemistry , gram , biology , bacteria , enterobacter , medicine , biochemistry , escherichia coli , genetics , environmental health , gene , antioxidant
Aims The objective of this study was to determine the combined effect of thymoquinone ( TQ ) and mild heat on Cronobacter sakazakii in reconstituted infant formula. Methods and 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 ® Bac Light ™ 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. Significance and Impact of the Study 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.