Microflora in water kefir grains

Foodinfo Online FSTA Reports -->13 November 2003

Water kefir grains are a unique starter culture community commonly used to produce home-made sparkling acidic beverages with low-alcohol content.

The white to grey coloured, irregularly shaped grains comprise a backbone of a polysaccharide matrix such as dextran. The microflora of water kefir grains differs significantly from that of dairy kefir grains, which, unlike water kefir grains, have been widely studied. The grains can be simply inoculated under non-sterile conditions using sucrose-containing tap water in the presence of dried figs. They are also known as Tibi grains, sugary kefir grains, gingerbeer plants or Californian bees.

These different grains are all thought to have a similar complex microbial community comprising yeasts and lactic acid bacteria. The addition of figs is essential for the optimal fermentation and production of lactic acid and acetic acid. Figs also contain growth-promoting substances, which can be extracted with cold water. Water kefir grains utilize a nutritionally simple environment compared with the complex milk medium for dairy kefir grains. It is therefore of interest to compare the microflora of these two types of kefir grains.

In a study by Neve and Heller,1 the composition of the microflora of water kefir grains, obtained from a domestic household, was analysed. The diversity and distribution of the microbial population of the grains were also studied by scanning electron microscopy.

Water kefir grains were found to comprise a complex biofilm of yeasts and bacteria of various shapes on the grains surfaces embedded in the dextran matrix. There were high numbers of bacterial cocci in water kefir grains, compared with the scarcity reported in dairy kefir grains. Both types had a predominance of specific yeast populations.

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1 Neve, H; Heller, KJ (2003).

The microflora of water kefir: a glance by scanning electron microscopy.

Kieler Milchwirtschaftliche Forschungsberichte 54 (4) 337-349.

Página de WEB referencia del artículo

AN: 2003-07-Hs1624
TI:
The microflora of water kefir: a glance by scanning electron microscopy.
DA:
5-Jul-2003
DT:
Journal Article
AU:
Neve, H.; Heller, K. J.
PY:
2002
AD:
Inst. for Microbiol., Fed. Dairy Res. Cent., PO Box 6069, D-24121 Kiel, Germany
SO:
Kieler Milchwirtschaftliche Forschungsberichte 54 (4) 337–349
RF:
32 ref.
LA:
English with French, German summaries
SN:
0023-1347
AB:
Water kefir grains comprise a unique starter culture community used for production of home-made sparkling acidic beverages. Composition of water kefir grains obtained from a private household and preserved in the laboratory for several years was investigated by SEM. A complex and tightly packed biofilm was observed on the exterior of the grains, while the interior mainly comprised unstructured (dextran) material. Microflora was dominated by lemon-shaped or long filamentous yeast cells growing in close association with bacterial cocci and short or long rod shaped bacteria (lactobacilli, responsible for polymer production). Cocci grew preferentially on the surfaces of the yeast cells, while the rod-shaped bacteria were mainly found between the yeast cells. Results are discussed in relation to microflora of dairy kefir grains.
SC:
Alcoholic and non-alcoholic beverages
KW: BEVERAGES; ELECTRON MICROSCOPY; FERMENTED MILK; KEFIR GRAINS; MICROFLORA; MICROORGANISMS; SEM; STRUCTURE