Microbial Species Diversity, Community Dynamics, and Metabolite Kinetics of Water Kefir Fermentation

Abstract

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.

Chemical composition and hypocholesterolemic effect of milk kefir and water kefir in Wistar rats

“…They produce a fermented beverage [2,3] that has the anti-inflammatory, antineoplastic, antioxidant, antibacterial, antifungal, immunomodulatory, and hypocholesterolemic properties [4]. The "water kefir" or "Tibico" grains are brownish color and produce a slightly acidic, refreshing beverage with medicinal properties also described in the literature [5,6].…”

Bifidobacterium aquikefiri sp. nov., isolated from water kefir

“…They are generally obligately anaerobic but some species can also grow aerobically (Simpson et al, 2004;Delcenserie et al, 2007;Watanabe et al, 2009). Bifidobacteria are considered to be non-pathogenic (Borriello et al, 2003) and some species occur in fermented foods and beverages (Delcenserie et al, 2007;Watanabe et al, 2009;Hsieh et al, 2012;Gulitz et al, 2013;Laureys & De Vuyst, 2014). Sometimes, bifidobacteria are added to foods and beverages because their consumption is associated with positive health effects (Tojo et al, 2014).…”

“…Sometimes, bifidobacteria are added to foods and beverages because their consumption is associated with positive health effects (Tojo et al, 2014). Recently, an unknown Bifidobacterium species was detected in several water kefirs from different origins via PCR denaturing gradient gel electrophoresis community fingerprinting with both the universal prokaryotic primer pair 357f-GC/518r and the Bifidobacterium-specific primer pair bif164f/bif662r-GC (Laureys & De Vuyst, 2014; D. Laureys & L. De Vuyst, unpublished results). The 0.5 kb partial 16S rRNA gene sequences, obtained with the latter primer pair, were 100 % identical to the 16S rRNA gene sequence of an unknown Bifidobacterium species detected in a water kefir fermentation process in Germany (Gulitz et al, 2013), but were only 98 % identical to the 16S rRNA gene sequence of the closest relative Bifidobacterium psychraerophilum.…”

“…A water kefir fermentation process was carried out as described by Laureys & De Vuyst (2014). Strain R 54638 T (5LMG 28769 T ) was isolated from the water kefir liquor by plating on mTY agar medium (Gulitz et al, 2013) NaCl (Merck), 0.3 g cysteine hydrochloride (SigmaAldrich), 5.0 g glucose (Merck) and 15.0 g agar (Oxoid)] and DNA was obtained via alkaline lysis of the cells, as described previously (Niemann et al, 1997).…”

Fermented beverages with health-promoting potential: Past and future perspectives

“…They ferment sweetened water, to which figs and lemon are traditionally added for 237 additional flavour and nutrients. The composition of water kefir can vary, but is known to 238 contain LAB, including Lactobacillus, and Bifidobacterium (Laureys & De Vuyst, 2014). Hardaliye 239 is a non-alcoholic, Turkish, fermented beverage made from red grapes, black mustard seeds, 240 cherry leaf and benzoic acid.…”