Abstract：
Kombucha is prepared by fermenting sugared green or black tea with a symbiotic culture of bacteria and yeast (SCOBY). Some of the bacteria within the SCOBY are known to form exopolysaccharides (EPS) from sucrose. However, it is yet unknown whether water-soluble EPS are formed in kombucha, and if so, which specific EPS are present. Therefore, different kombucha samples were prepared by fermentation of green and black tea with SCOBYs from different manufacturers. Subsequently, the EPS were isolated and characterized by using various chromatographic methods, partial enzymatic hydrolyses and NMR spectroscopy. It was demonstrated that levans with a varying degree of branching at position O1 (4.3-7.9 %) are present, while only trace amounts of glucans were detected. Furthermore, levans isolated from kombucha had a comparably low molecular weight and the content of levan within the kombucha samples varied from 33 to 562 mg levan/L kombucha. Therefore, our study demonstrated that levans are the main EPS type in kombucha and that levan amounts and structures varied when different starter cultures and ingredients were used. Furthermore, we provide a comprehensive data set on the structural variability of levans from kombucha.
摘要：
红茶菌是通过用细菌和酵母的共生培养物（SCOBY）发酵含糖的绿茶或红茶来制备的。已知SCOBY内的一些细菌从蔗糖形成胞外多糖(EPS)。然而,目前尚不清楚红茶菌是否形成EPS，如果是这样,哪些具体的每股收益存在。因此,用不同制造商的SCOBY对绿茶和红茶进行发酵，制备了不同的红茶菌样品。随后，使用各种色谱方法分离和表征EPS，部分酶水解和NMR光谱。已经证明，在位置O1（4.3-7.9％）存在不同程度的分支的levans，而只检测到痕量的葡聚糖。此外，从红茶菌中分离出的果聚糖具有相对较低的分子量，并且红茶菌样品中的果聚糖含量从33到562mg果聚糖/L红茶菌不等。因此,我们的研究表明，levans是红茶菌中主要的EPS类型，当使用不同的发酵剂和成分时，levan的数量和结构会有所不同。此外，我们提供了一个关于康普茶果聚糖结构变异性的全面数据集。
