Yummie .... Michael Granvogl investigates promising brewing technology [01.09.20]
Beer is known to be Germany's favorite beverage. But what about the non-alcoholic version? Even though the sale rates for non-alcoholic beer are increasing worldwide, beer lovers in Germany often dismiss it for its taste. The difference in taste is a result of the dealcoholization process. In thermal dealcoholization, alcohol is evaporated by heat, which also causes important aromatic substances to disappear. Alternatively, the fermentation can be stopped prematurely so that no alcohol is produced in the first place. However, such beer also contains higher amounts of unfermented sugar and fewer aroma-active fermentation products. So what's the solution for that dilemma? Scientists from the University of Hohenheim and the Technical University of Munich have been investigating dry-hopping. This technique adds hops to the beer after its main fermentation and is typical for craft beer brewing. It can bring characteristic beer flavors to non-alcoholic beer, that's the claim at least.
Picture Credit: https://pixabay.com/de/photos/glas-bier-bier-glas-alkohol-3444480/
Publication
Brendel, S., Hofmann, T., Granvogl, M., 2020. Dry-Hopping to Modify the Aroma of Alcohol-Free Beer on a Molecular Level—Loss and Transfer of Odor-Active Compounds. J. Agric. Food Chem. 68, 8602–8612. doi.org/10.1021/acs.jafc.0c01907
Abstract
There are mainly two options for the dealcoholization of beer: evaporation of ethanol by heat treatment, whereby desired aroma-active compounds are also removed, and stopped fermentation that leads to beers still containing high amounts of unfermented sugar in parallel with lower amounts of aroma-active fermentation products. Thus, dry-hopping could be an opportunity to compensate for these aroma deficiencies. Therefore, following the sensomics approach, odorants were characterized in dry-hopped (Hallertauer Mandarina Bavaria, Hallertauer Cascade, or Hallertauer Mittelfrüh) top- and bottom-fermented alcohol-free beers either after thermal dealcoholization or stopped fermentation. Twenty-three odorants were quantitated via stable isotope dilution analysis, and odor activity values (OAVs; ratio of concentration to odor threshold) were calculated. Thermally dealcoholized samples showed high losses (up to 100%) of key odorants like 3-methyl-1-butanol or 3-methylbutyl acetate. During stopped fermentation, aroma compounds like ethyl butanoate or 2-phenylethanol were formed in relevant concentrations, leading to OAVs ≥ 1, but the amounts were significantly lower compared to beers with normal alcohol contents. For hop-derived odorants (linalool, geraniol, myrcene, and esters), transfer rates between 20 and 90% were found, leading to OAVs ≥ 1 in beer. Furthermore, hop addition apparently induced the formation of ethyl esters of hop-derived monocarboxylic acids.
 | More research of Prof. Granvogel and the Institute of Food Chemistry you'll find here.ResearchGate |
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