Microbial species diversity, community dynamics, and metabolite kinetics of water kefir fermentation

Water kefir is a sour, alcoholic, and fruity fermented beverage of which the fermentation is started with water kefir grains. These water kefir grains consist of polysaccharide and contain the microorganisms responsible for the water kefir fermentation. In this work, a water kefir fermentation proce...

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Bibliographic Details
Published in:Applied and Environmental Microbiology 2014-04, Vol.80 (8), p.2564-2572
Main Authors: Laureys, David, De Vuyst, Luc
Format: Article
Language:English
Subjects:
Acetic Acid - metabolism
Bacteria
Bacteria - classification
Bacteria - metabolism
Bifidobacterium
Biodiversity
Biota
Cultured Milk Products - microbiology
Dekkera
Ethanol - metabolism
Fermentation
Food Microbiology
Fungi - classification
Fungi - metabolism
Glycerol - metabolism
Hydrogen-Ion Concentration
Lactobacillus casei
Lactobacillus hilgardii
Mannitol - metabolism
Metabolites
Microbiology
Nonnative species
Saccharomyces cerevisiae
Sucrose - metabolism
Time Factors
Volatile Organic Compounds - metabolism
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Summary:Water kefir is a sour, alcoholic, and fruity fermented beverage of which the fermentation is started with water kefir grains. These water kefir grains consist of polysaccharide and contain the microorganisms responsible for the water kefir fermentation. In this work, a water kefir fermentation process was followed as a function of time during 192 h to unravel the community dynamics, the species diversity, and the kinetics of substrate consumption and metabolite production. The majority of the water kefir ecosystem was found to be present on the water kefir grains. The most important microbial species present were Lactobacillus casei/paracasei, Lactobacillus harbinensis, Lactobacillus hilgardii, Bifidobacterium psychraerophilum/crudilactis, Saccharomyces cerevisiae, and Dekkera bruxellensis. The microbial species diversities in the water kefir liquor and on the water kefir grains were similar and remained stable during the whole fermentation process. The major substrate, sucrose, was completely converted after 24 h of fermentation, which coincided with the production of the major part of the water kefir grain polysaccharide. The main metabolites of the fermentation were ethanol and lactic acid. Glycerol, acetic acid, and mannitol were produced in low concentrations. The major part of these metabolites was produced during the first 72 h of fermentation, during which the pH decreased from 4.26 to 3.45. The most prevalent volatile aroma compounds were ethyl acetate, isoamyl acetate, ethyl hexanoate, ethyl octanoate, and ethyl decanoate, which might be of significance with respect to the aroma of the end product.
ISSN:0099-2240
1098-5336
1098-6596
DOI:10.1128/aem.03978-13