Laureys David, Leroy Frédéric, Hauffman Tom, Raes Marc, Aerts Maarten, Vandamme Peter, De Vuyst Luc
Research Group of Industrial Microbiology and Food Biotechnology, Faculty of Sciences and Bioengineering Sciences, Vrije Universiteit Brussel, Brussels, Belgium.
Research Group of Electrochemical and Surface Engineering, Faculty of Engineering Sciences, Vrije Universiteit Brussel, Brussels, Belgium.
Front Microbiol. 2021 Feb 11;12:628599. doi: 10.3389/fmicb.2021.628599. eCollection 2021.
Eleven series of water kefir fermentation processes differing in the presence of oxygen and the type and concentration of inoculum and substrate, were followed as a function of time to quantify the impact of these parameters on the kinetics of this process a modeling approach. Increasing concentrations of the water kefir grain inoculum increased the water kefir fermentation rate, so that the metabolic activity during water kefir fermentation was mainly associated with the grains. Water kefir liquor could also be used as an alternative means of inoculation, but the resulting fermentation process progressed slower than the one inoculated with water kefir grains, and the production of water kefir grain mass was absent. Substitution of sucrose with glucose and/or fructose reduced the water kefir grain growth, whereby glucose was fermented faster than fructose. (formerly known as ), (formerly known as ), (formerly known as ), , and were the main microorganisms present. Acetic acid bacteria were present in low abundances under anaerobic conditions and only proliferated under aerobic conditions. Visualization of the water kefir grains through scanning electron microscopy revealed that the majority of the microorganisms was attached onto their surface. Lactic acid bacteria and yeasts were predominantly associated with the grains, whereas acetic acid bacteria were predominantly associated with the liquor.
研究了11组不同氧气存在情况、接种物和底物类型及浓度的水开菲尔发酵过程，并将其作为时间的函数进行跟踪，以通过建模方法量化这些参数对该过程动力学的影响。水开菲尔粒接种物浓度的增加提高了水开菲尔的发酵速率，因此水开菲尔发酵过程中的代谢活性主要与这些颗粒有关。水开菲尔液也可作为一种替代接种方式，但由此产生的发酵过程比用水开菲尔粒接种的过程进展更慢，且没有水开菲尔粒团的产生。用葡萄糖和/或果糖替代蔗糖会减少水开菲尔粒的生长，其中葡萄糖的发酵速度比果糖快。（原名 ）、（原名 ）、（原名 ）、 和 是主要存在的微生物。在厌氧条件下，醋酸菌数量较少，仅在有氧条件下增殖。通过扫描电子显微镜对水开菲尔粒进行观察发现，大多数微生物附着在其表面。乳酸菌和酵母菌主要与颗粒相关，而醋酸菌主要与液体相关。
