Abstract The hop isomerization reaction during the brewing process is interfered by many factors such as wort composition and time resulting in significant bitter substance losses. A novel mash filtration system provides new possibilities, as four wort flows (instead of one) are separated in parallel and thus different wort characteristics are available for enhancing the hop isomerization rate. A laboratory-scale screening experiment was performed to investigate the different effects of the wort parameters beyond the conventional brewhouse range. Based on previous industrial field trials, the boundary parameters (minimum and maximum) of the laboratory-scale wort fractions, corresponding to filter modules 1 and 4, were adjusted accordingly to the pH value (pH 5.6 or 7.0) and original gravity (17.0 or 2.0°P). The parameters boiling time and dosing quantity of α-acids were adapted to conventional brewhouse standards as well as to the novel system. Additionally, the influence of magnesium (0.0 or 40.0 mg/L) dosed to the wort on the isomerization reaction was tested. The results showed that the boiling time at a pH value of 5.6 had more influence on the inversion to iso-α-acids than with a wort pH of 7.0. Even with a high original gravity of 17.0°P, an extension of the boiling time showed no significant effect on the isomerization rate.

中文翻译：

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啤酒花异构化超出常规范围的影响因素

摘要 啤酒花在酿造过程中的异构化反应受到麦汁成分、时间等多种因素的干扰，导致苦味物质大量损失。一种新型的麦芽汁过滤系统提供了新的可能性，因为四个麦汁流（而不是一个）平行分离，因此不同的麦汁特性可用于提高啤酒花异构化率。进行了实验室规模的筛选实验，以研究超出常规啤酒厂范围的麦汁参数的不同影响。根据之前的工业现场试验，对应于过滤器模块 1 和 4 的实验室规模麦汁部分的边界参数（最小值和最大值）根据 pH 值（pH 5.6 或 7.0）和原始重力（17.0 或2.0°P)。α-酸的煮沸时间和投加量参数适应于传统的啤酒厂标准以及新系统。此外，还测试了添加到麦芽汁中的镁（0.0 或 40.0 mg/L）对异构化反应的影响。结果表明，与麦芽汁 pH 值为 7.0 时相比，pH 值为 5.6 时煮沸时间对异α-酸转化的影响更大。即使具有 17.0°P 的高原始重力，延长沸腾时间对异构化速率也没有显着影响。与麦芽汁 pH 值 7.0 相比，6 对异α-酸转化的影响更大。即使具有 17.0°P 的高原始重力，延长沸腾时间对异构化速率也没有显着影响。与麦芽汁 pH 值 7.0 相比，6 对异α-酸转化的影响更大。即使具有 17.0°P 的高原始重力，延长沸腾时间对异构化速率也没有显着影响。