title: Investigation of the instability and low water kefir grain growth during an industrial water kefir fermentation process.
abstract: A poorly performing industrial water kefir production process consisting of a first fermentation process, a rest period at low temperature, and a second fermentation process was characterized to elucidate the causes of its low water kefir grain growth and instability. The frozen-stored water kefir grain inoculum was thawed and reactivated during three consecutive prefermentations before the water kefir production process was started. Freezing and thawing damaged the water kefir grains irreversibly, as their structure did not restore during the prefermentations nor the production process. The viable counts of the lactic acid bacteria and yeasts on the water kefir grains and in the liquors were as expected, whereas those of the acetic acid bacteria were high, due to the aerobic fermentation conditions. Nevertheless, the fermentations progressed slowly, which was caused by excessive substrate concentrations resulting in a high osmotic stress. Lactobacillus nagelii, Lactobacillus paracasei, Lactobacillus hilgardii, Leuconostoc mesenteroides, Bifidobacterium aquikefiri, Gluconobacter roseus/oxydans, Gluconobacter cerinus, Saccharomyces cerevisiae, and Zygotorulaspora florentina were the most prevalent microorganisms. Lb. hilgardii, the microorganism thought to be responsible for water kefir grain growth, was not found culture-dependently, which could explain the low water kefir grain growth of this industrial process.
authors.affiliation: Research Group of Industrial Microbiology and Food Biotechnology, Faculty of Sciences and Bioengineering Sciences, Vrije Universiteit Brussel, Pleinlaan 2, B-1050, Brussels, Belgium.
authors.forename: David
authors.initials: D
authors.lastname: Laureys
authors.affiliation: Research Group of Industrial Microbiology and Food Biotechnology, Faculty of Sciences and Bioengineering Sciences, Vrije Universiteit Brussel, Pleinlaan 2, B-1050, Brussels, Belgium.
authors.forename: Amandine
authors.initials: A
authors.lastname: Van Jean
authors.affiliation: Kaskade bvba, Rotselaar, Belgium.
authors.forename: Jean
authors.initials: J
authors.lastname: Dumont
authors.affiliation: Research Group of Industrial Microbiology and Food Biotechnology, Faculty of Sciences and Bioengineering Sciences, Vrije Universiteit Brussel, Pleinlaan 2, B-1050, Brussels, Belgium. ldvuyst@vub.ac.be.
authors.forename: Luc
authors.initials: L
authors.lastname: De Vuyst
mesh_terms: D001419:Bacteria / Q000254:growth & development / Q000302:isolation & purification / Q000378:metabolism; D001644:Bifidobacterium / Q000254:growth & development / Q000378:metabolism; D044822:Biodiversity; D005285:Fermentation; D006863:Hydrogen-Ion Concentration; D000070716:Kefir / Q000382:microbiology*; D007778:Lactobacillus / Q000254:growth & development* / Q000378:metabolism; D050296:Microbial Viability; D014867:Water / Q000032:analysis*; D015003:Yeasts / Q000254:growth & development* / Q000378:metabolism
chemical_list: D014867:Water
keywords: Bifidobacteria; Exopolysaccharide; Kefir grain; Lactic acid bacteria; Water kefir; Yeast