Mikyška Alexandr, Štěrba Karel
Research Institute of Brewing and Malting, Lípová 511/15, 120 00 Prague, Czech Republic.
Faculty of Agrobiology, Food and Natural Resources, Czech University of Life Sciences Prague, Kamýcká 129, 165 00 Prague, Czech Republic.
Foods. 2023 Aug 18;12(16):3111. doi: 10.3390/foods12163111.
The main factor responsible for the sensory aging of beer is the increase in off-flavor aldehydes during beer storage. In pilot brews (200 L) of pale lager beer with different hopping regimes and wort boiling systems, 15 carbonyls were monitored using the GC-MS method. Factor analysis revealed several groups of aldehydes with similar behavior during wort boiling. The concentration of most of them decreased with atmospheric wort boiling and increased with the time and energy-saving pressurized boiling system. Wort clarification was a critical step because of the increase in carbonyl concentration, with the level of most carbonyls being higher in the final wort compared to sweet wort. The hopping regimes only affected the level of 3-methylbutan-2-one in the wort. The concentration of carbonyls decreased significantly (30-90%) during fermentation, except for trans-2-butenal, which increased by 59% on average, likely due to the release from imine complex. The concentration of free aldehydes in the fresh beers was similar for all variants used, but the pressurized wort boiling system could result in lower sensory stability of the beer due to the release of aldehydes from inactive complexes formed during fermentation. This aspect requires further investigation.
导致啤酒感官老化的主要因素是啤酒储存期间不良风味醛类物质的增加。在采用不同啤酒花添加方式和麦汁煮沸系统的200升淡色贮藏啤酒中试酿造中，使用气相色谱 - 质谱联用（GC - MS）方法监测了15种羰基化合物。因子分析揭示了几组在麦汁煮沸过程中行为相似的醛类物质。其中大多数醛类物质的浓度在常压麦汁煮沸时降低，而在节能加压煮沸系统中随时间增加。由于羰基化合物浓度的增加，麦汁澄清是一个关键步骤，与甜麦汁相比，大多数羰基化合物在最终麦汁中的含量更高。啤酒花添加方式仅影响麦汁中3 - 甲基丁 - 2 - 酮的含量。除反式 - 2 - 丁烯醛外，发酵过程中羰基化合物的浓度显著降低（30 - 90%），反式 - 2 - 丁烯醛平均增加了59%，这可能是由于亚胺络合物的释放。所有使用的变体新鲜啤酒中游离醛的浓度相似，但由于发酵过程中形成的非活性络合物释放醛类物质，加压麦汁煮沸系统可能导致啤酒的感官稳定性较低。这方面需要进一步研究。
