Müller Magdalena, Becker Thomas, Gastl Martina
Research Group Raw Material Based Brewing and Beverage Technology, Institute of Brewing and Beverage Technology, Technical University of Munich, 85354 Freising, Germany.
Foods. 2021 Jul 10;10(7):1602. doi: 10.3390/foods10071602.
Dealcoholisation of beer has gained prominence over the last decade. A well-known procedure involves the combination of a rectification column for thermal dealcoholisation and a downstream column for aroma recovery. However, the recovery of valuable fermentation by-products is rarely performed due to limited data about the enrichment and depletion of ethanol and aromatic compounds. The influence of operating conditions on the transfer of ethanol and aroma compounds to the recovery fluid, henceforth, 'aromawater', has not yet been fully explored. Therefore, this study involved examining how ethanol concentration and aroma compounds in the aromawater are affected by the condenser temperature and reflux rate during thermal dealcoholisation. The aim was to obtain an aromawater having a maximum level of valuable aroma substances and a minimum level of ethanol for re-blending with non-alcoholic beer, hypothetically causing aroma intensification. An industrial system was used for sample production. Ethanol as well as higher alcohols and ester concentrations were analysed in the different material flows, and mass balances were thus compiled. Sensory analysis was performed to evaluate the beer aroma's intensification as a sustainable industrial application. The obtained results indicate that increased condenser temperature was associated with increased aroma concentrations in the aromawater. If the temperature of the condenser's coolant exceeded 15 °C, dealcoholisation < 0.05% abv could not be guaranteed. A higher reflux rate led to higher concentrations of fermentation by-products in the aromawater. Finally, the aroma profile of three non-alcoholic beers (0.0% abv, 0.5% abv after blending with original beer, and 0.5% abv after blending with aromawater) were evaluated. By blending, the attributes 'estery' and 'flowery' were assessed as dominant. The effect was more pronounced with aromawater than with the original beer.
在过去十年中，啤酒脱醇变得越来越重要。一种广为人知的方法是将用于热脱醇的精馏塔与用于香气回收的下游塔相结合。然而，由于关于乙醇和芳香化合物的富集和消耗的数据有限，有价值的发酵副产物的回收很少进行。操作条件对乙醇和香气化合物转移到回收液（即“香液水”）中的影响尚未得到充分研究。因此，本研究考察了热脱醇过程中冷凝器温度和回流率如何影响香液水中的乙醇浓度和香气化合物。目的是获得一种香液水，其具有最高水平的有价值香气物质和最低水平的乙醇，以便与无醇啤酒重新混合，理论上可增强香气。使用工业系统进行样品制备。分析了不同物料流中的乙醇以及高级醇和酯的浓度，并据此编制了质量平衡。进行感官分析以评估啤酒香气增强作为一种可持续工业应用的情况。所得结果表明，冷凝器温度升高与香液水中香气浓度增加有关。如果冷凝器冷却剂的温度超过15°C，则无法保证脱醇度低于0.05%（体积分数）。较高的回流率导致香液水中发酵副产物的浓度更高。最后，评估了三种无醇啤酒（0.0%（体积分数）、与原啤酒混合后为0.5%（体积分数）以及与香液水混合后为0.5%（体积分数））的香气特征。通过混合，“酯香”和“花香”属性被评估为主要特征。与原啤酒相比，香液水的效果更明显。
