Document Detail

Inhibitory effect of caprylic acid and mild heat on Cronobacter spp. (Enterobacter sakazakii) in reconstituted infant formula and determination of injury by flow cytometry.
MedLine Citation:
PMID:  19500867     Owner:  NLM     Status:  MEDLINE    
The combined effects of caprylic acid and mild heat were investigated to ascertain their impact on Cronobacter spp. (E. sakazakii) in reconstituted infant formula. Samples containing a mixture of 3 strains of Cronobacter spp. (10(7) to 10(8) CFU/ml) were prepared with various concentrations of caprylic acid (5, 10, 20, and 30 mM) and were then heated to 45, 50, and 55 degrees C. The inhibitory effect of the combined treatment resulted in a synergistic effect, in which Cronobacter spp. numbers were reduced much more rapidly with increased temperatures and concentrations of caprylic acid. When samples were treated with 30 mM caprylic acid, the time required to reduce Cronobacter spp. cell numbers to an approximate reduction of 7.8 log CFU/ml was 60 min at 45 degrees C, 20 min at 50 degrees C, and 10 min at 55 degrees C. In the validation assay using a low population of Cronobacter spp. (approximately 10(3) log CFU/ml), no recovery of injured cells was observed after samples were treated with 10 mM caprylic acid for 20 min at 55 degrees C, 20 mM caprylic acid for 10 min at 50 degrees C and 55 degrees C, and 30 mM caprylic acid for 10 min at 45 degrees C to 55 degrees C. To determine the bactericidal mechanism of caprylic acid, membrane integrity was examined by fluorescent staining followed by flow cytometry and confocal microscopy. Increased cellular inactivation was associated with increased propidium iodide staining, indicating damage to the cell membrane of Cronobacter spp.. Overall, these data indicate that the addition of this natural antimicrobial agent to infant formula may have potential use for controlling microbes prior to consumption at lower heating temperatures. The study also provides a complementary understanding of the mode of action of caprylic acid on Cronobacter spp.
Hye In Jang; Min Suk Rhee
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2009-05-13
Journal Detail:
Title:  International journal of food microbiology     Volume:  133     ISSN:  1879-3460     ISO Abbreviation:  Int. J. Food Microbiol.     Publication Date:  2009 Jul 
Date Detail:
Created Date:  2009-06-29     Completed Date:  2009-12-02     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8412849     Medline TA:  Int J Food Microbiol     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  113-20     Citation Subset:  IM    
Korea University, Anam-dong, Sungbuk-gu, Seoul, South Korea.
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MeSH Terms
Anti-Bacterial Agents / pharmacology*
Cell Membrane / ultrastructure
Colony Count, Microbial
Enterobacter sakazakii / drug effects*,  ultrastructure
Flow Cytometry
Food Contamination / prevention & control
Food Microbiology*
Hot Temperature*
Infant Formula*
Microscopy, Confocal
Milk / microbiology
Octanoic Acids / pharmacology*
Reg. No./Substance:
0/Anti-Bacterial Agents; 0/Octanoic Acids; 124-07-2/caprylic acid

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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