Structural characterization of the exopolysaccharides from water kefir

• Published in: Carbohydrate polymers Vol. 189; pp. 296 - 303
• Main Authors: Fels, Lea, Jakob, Frank, Vogel, Rudi F., Wefers, Daniel
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.06.2018
• Subjects: Dextran; Exopolysaccharides; Levan; NMR spectroscopy; Structure; Water kefir; HMBC; HPAEC-PAD; COSY; TFA; Dextran; Levan; Exopolysaccharides; Water kefir; RI; PMAA; HSQC; Structure; NMR spectroscopy
• ISSN: 0144-8617; 1879-1344
• DOI: 10.1016/j.carbpol.2018.02.037

[Display omitted] •Dextrans are the predominant exopolysaccharides in the water kefir beverage.•Levans occur in the analyzed water kefir beverage.•Water kefir grains are mainly composed of O3-branched dextrans.•Different fine structures are present in the water kefir beverage and grains. Water kefir is a beverage which is produced by initiating fermentation of a fruit extract/sucrose solution with insoluble kefir grains. Exopolysaccharides that are formed from sucrose play a major role in the kefir grain formation, but the exopolysaccharides in the kefir beverage and the detailed structural composition of the whole kefir grains have not been studied yet. Therefore, kefir grains and the corresponding kefir beverage were analyzed for exopolysaccharides by multiple chromatographic approaches and two-dimensional NMR spectroscopy. Furthermore, different fractionation techniques were applied to obtain further information about the exopolysaccharides. The exopolysaccharide-fraction of the investigated kefir beverage was predominantly composed of O3- and O2-branched dextrans as well as lower amounts of levans. The insoluble dextrans from the kefir grains were mostly O3-branched and contained an elevated portion of 1,3-linked glucose units compared to the soluble dextrans. The structurally different exopolysaccharides in water kefir suggest the involvement of multiple bacteria.