AiF 20658 N - Aromahefe

The aroma of beer is characterized by the raw materials malt, hops, and yeast. The aroma-active substances from malt and hops contribute far less to the aroma of beer than the substances formed during fermentation by the yeast. In SMEs in the German brewing industry, however, the production of aroma-enhanced specialty beers is currently dominated by the use of new flavor hop varieties.The yeast used has so far played a minor role in increasing aroma diversity. The proposal is based on the working hypothesis that non-Saccharomyces yeasts can be used to produce beers with an aroma that is appreciated by consumers beyond the mainstream.

During preliminary work at research facility 2, an aromatic yeast had already emerged as a promising yeast for producing an aromatic yeast beer, with an “aroma-neutral” Kölsch yeast (Saccharomyces cerevisiae) serving as the reference strain.While beers produced with these two yeasts were available immediately after the start of the research project, two additional non-Saccharomyces yeasts with a beer aroma that was appreciated by consumers beyond the mainstream were to be selected. To this end, 110 non-Saccharomyces strains were subjected to a 96-well microtiter plate screening. In addition, odor tests were carried out to evaluate the sensory impression of the yeasts in beer wort. Promising yeast strains were then tested in small-scale fermentations with standard wort.
After testing 110 non-Saccharomyces yeasts, Torulaspora delbrueckii (T90) and Cyberlindnera saturnus (CSa1) proved to be particularly suitable. It should be emphasized that the yeast CSa1 can be used to produce non-alcoholic beers. In the aromatic yeast beer (T90), the fruity-smelling esters ethyl butanoate, ethyl 2-methylpropanoate, and ethyl propanoate were identified as the main odorants. In the aromatic yeast beer (CSa1), the banana-smelling 3-methylbutyl acetate was characterized as the main odorant. In addition, the influence of fermentation parameters on these essential odorants was investigated in order to optimize the brewing process with regard to ideal odorant yield. Finally, the transferability to practice was demonstrated for yeast CSa1 through large-scale fermentation in a brewery.

BMWK - IGF - AiF - WiFö

Industrielle Gemeinschaftsforschung (IGF)