Studies on the odorant concentrations and their time dependencies during dry-hopping of alcohol-free beer

Both the market for alcohol-free beer and the number of craft beer breweries increased in the past years. Thus, dry-hopping as a possibility to compensate/mask aroma deficiencies of alcohol-free beers is gaining more and more interest. To better understand the transfer of odorants from hops into alcohol-free beer during dry-hopping, their concentrations were monitored over a period of 7 days in a laboratory-scale experiment simulating the dry-hopping process. Thereby, a main transfer occurred during the first 2-3 days. However, the relevance of the transferred odorants to the overall aroma can only be evaluated by taking their sensory properties into consideration. Therefore, orthonasal odour thresholds and sensorial dose-response relationships were investigated in an alcohol-free beer matrix. Sensory tests showed a nearly linear increase in the odour intensities of different esters, whereas further typical hop odorants, such as linalool, geraniol, and myrcene, showed a multistage increase. Overall, the present study clearly corroborated that dry-hopping of alcohol-free beers can be optimised regarding the hop dosage and the contact time, depending on the desired flavour of the final product.