Köhler Sarah, Schmacht Maximilian, Troubounis Aktino H L, Ludszuweit Marie, Rettberg Nils, Senz Martin
Department Bioprocess Engineering and Applied Microbiology, Research and Teaching Institute for Brewing (VLB) in Berlin, Berlin, Germany.
Technische Universität Berlin, Faculty III Process Sciences, Chair of Bioprocess Engineering, Institute of Biotechnology, Berlin, Germany.
Front Microbiol. 2021 Nov 4;12:732019. doi: 10.3389/fmicb.2021.732019. eCollection 2021.
A process development from a traditional grain-based fermentation to a defined water kefir fermentation using a co-culture of one lactic acid bacterium and one yeast was elaborated as a prerequisite for an industrially scalable, controllable, and reproducible process. Further, to meet a healthy lifestyle, a low ethanol-containing product was aimed for. Five microbial strains-, , , , and -were used in pairs in order to examine their influence on the fermentation progress and the properties of the resulting water kefir products against grains as a control. Thereby, the combination of and provided the best-rated water kefir beverage in terms of taste and low ethanol concentrations at the same time. As a further contribution to harmonization and reduction of complexity, the usage of dried figs in the medium was replaced by fig syrup, which could have been proven as an adequate substitute. However, nutritional limitations were faced afterward, and thus, an appropriate supplementation strategy for yeast extract was established. Finally, comparative trials in 5-L scale applying grains as well as a defined microbial consortium showed both water kefir beverages characterized by a pH of 3.14, and lactic acid and aromatic sensory properties. The product resulting from co-culturing outperformed the grain-based one, as the ethanol level was considerably lower in favor of an increased amount of lactic acid. The possibility of achieving a water kefir product by using only two species shows high potential for further detailed research of microbial interactions and thus functionality of water kefir.
阐述了从传统谷物发酵到使用一种乳酸菌和一种酵母的共培养进行特定的水开菲尔发酵的工艺开发，这是实现工业规模可扩展、可控且可重复工艺的前提条件。此外，为了符合健康的生活方式，目标是生产一种低乙醇含量的产品。将五种微生物菌株——、、、和——两两配对使用，以研究它们对发酵进程的影响以及所得水开菲尔产品相对于作为对照的谷物的特性。由此，和的组合在口感和低乙醇浓度方面提供了评分最高的水开菲尔饮料。作为进一步促进协调和降低复杂性的举措，培养基中干无花果的使用被无花果糖浆所取代，事实证明无花果糖浆是一种合适的替代品。然而，随后面临营养限制，因此建立了酵母提取物的适当补充策略。最后，在5升规模下使用谷物以及特定微生物群落进行的对比试验表明，两种水开菲尔饮料的pH值均为3.14，且具有乳酸和芳香感官特性。共培养产生的产品优于基于谷物的产品，因为乙醇含量显著更低，有利于乳酸含量的增加。仅使用两种菌种就能生产出水开菲尔产品，这为进一步详细研究微生物相互作用以及水开菲尔的功能特性显示出了巨大潜力。
