Document Detail


Milk acidification by Lactococcus lactis is improved by decreasing the level of dissolved oxygen rather than decreasing redox potential in the milk prior to inoculation.
MedLine Citation:
PMID:  18986723     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Although redox potential is very rarely taken into account in food fermentation it could be as influential as pH on bacterial activities. Lactococcus lactis is already known to exhibit a powerful reducing activity in milk but its reduction activity was shown to occur prior to its acidification activity with a potential interaction between these two lactococcal activities. Therefore, acidification lag-type phase could be shortened by decreasing the redox potential of milk before inoculation. As the redox potential is highly dependent on the dissolved oxygen level, our objective was to study their separate and combined influences on acidification and growth kinetics of pure L. lactis strains in milk. Results showed that high level of dissolved oxygen is significantly more influential on growth, and even more on acidification kinetics, than initial decreased redox potential of milk. Reduction of milk was drastic and mostly due to bacterial activity. The redox potential of milk only dropped when dissolved oxygen was entirely consumed. When there was no dissolved oxygen from the beginning, L. lactis immediately decreased the redox potential of milk and acidified afterwards. When the level of dissolved oxygen was initially high, acidification and reduction of milk occurred at the same time. Acidification kinetics was then biphasic with a slower rate during the aerobic stage and a faster rate during the anaerobic stage. The seven strains tested demonstrated diversity in both their acidification kinetics and their adaptation to high level of dissolved oxygen, independent of their growth kinetics. To conclude, we have shown that the level of dissolved oxygen in milk has a dramatic influence on acidification kinetics and could be used to control acidification kinetics in dairy industries.
Authors:
Sophie Jeanson; Nadine Hilgert; Marie-Odile Coquillard; Céline Seukpanya; Marc Faiveley; Pascal Neveu; Christophe Abraham; Véra Georgescu; Pascal Fourcassié; Eric Beuvier
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2008-10-07
Journal Detail:
Title:  International journal of food microbiology     Volume:  131     ISSN:  1879-3460     ISO Abbreviation:  Int. J. Food Microbiol.     Publication Date:  2009 Apr 
Date Detail:
Created Date:  2009-04-20     Completed Date:  2009-08-10     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8412849     Medline TA:  Int J Food Microbiol     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  75-81     Citation Subset:  IM    
Affiliation:
INRA, UR 342 Technologie et Analyses Laitières, Poligny, France. Sophie.Jeanson@rennes.inra.fr
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MeSH Terms
Descriptor/Qualifier:
Animals
Fermentation / physiology*
Food Microbiology*
Hydrogen-Ion Concentration
Kinetics
Lactococcus lactis / growth & development,  metabolism*
Milk / microbiology*
Oxidation-Reduction
Oxygen / metabolism*
Chemical
Reg. No./Substance:
7782-44-7/Oxygen

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


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