Abstract Changes to industrial fermentation processes are rare, largely due to the impact on viability for Saccharomyces spp., related to environmental stresses during the process such as: osmotic pressure, ethanol concentration, dissolved CO2. This research studied yeast behavior during a High Gravity (HG) fermentation under partial vacuum pressure during standard brewing operations. This was accomplished by controlling the temperature and pressure of 30 L pilot fermentations. An experimental lager wort recipe with “Diamond” lager yeast (Saccharomyces pastorianus) was used in this study. The modified process conducted at 24.1 kPa of pressure in the headspace was compared to a control process at standard atmospheric pressure (101.3 kPa). This research showed that at 15 °C, lager fermentations (14–15°P) fermented up to 30% faster under vacuum, with an increase in the number of yeast cells in suspension of up to 100%. The rate of sugar consumption under vacuum was greater compared to the control, thus increasing the rate of ethanol production. The removal of volatile CO2 is one hypothesized mechanism for these results. The total ethanol production, pH and yeast viability did not differ significantly between the control and modified process. The application of vacuum during brewing resulted in an increased fermentation rate and number of yeast cells in suspension during fermentation.

中文翻译：

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快速啤酒发酵：真空压力对中试规模啤酒发酵的影响

摘要 工业发酵过程很少发生变化，主要是由于对酵母菌生存力的影响，与过程中的环境压力有关，例如：渗透压、乙醇浓度、溶解的 CO2。本研究研究了标准酿造操作期间在部分真空压力下的高重力 (HG) 发酵过程中酵母的行为。这是通过控制 30 L 中试发酵的温度和压力来实现的。本研究使用了一种含有“钻石”啤酒酵母（Saccharomyces pastorianus）的实验性啤酒麦芽汁配方。将顶空压力为 24.1 kPa 的改进过程与标准大气压 (101.3 kPa) 下的对照过程进行了比较。这项研究表明，在 15 °C 下，贮藏啤酒发酵 (14–15°P) 在真空下的发酵速度提高了 30%，悬浮液中酵母细胞的数量增加了 100%。与对照相比，真空下的糖消耗率更高，从而提高了乙醇生产率。去除挥发性 CO2 是这些结果的一种假设机制。总乙醇产量、pH 值和酵母活力在对照工艺和改进工艺之间没有显着差异。在酿造过程中应用真空可提高发酵速度和发酵过程中悬浮的酵母细胞数量。pH 值和酵母活力在对照和改良工艺之间没有显着差异。在酿造过程中应用真空可提高发酵速度和发酵过程中悬浮的酵母细胞数量。pH 值和酵母活力在对照和改良工艺之间没有显着差异。在酿造过程中应用真空可提高发酵速度和发酵过程中悬浮的酵母细胞数量。