Writing in the Journal of Agricultural and Food Chemistry, Thomas Hofmann and colleagues at the Technical University of Munich sought to identify what causes the bitter, off-taste in old beer.
The research uncovered 56 substances that contribute to the bitter taste of beer. These are mostly "prenylated polyketides" derived from hops.
From this list, the study authors pinpointed five substances that appear to be largely responsible for the harsh taste of ageing beer.
The scientists claim that this is the first time that anyone has built up solid information about the bitter substances that form in beer as it ages. They claim that the knowledge could be a significant aid for brewers looking to make their products stay fresh for longer.
“The present study offers the scientific basis for a knowledge-based extension of the shelf life,” concluded the authors.
What next?
Explaining what needs to be done to achieve this aim, lead author Thomas Hofmann told BeverageDaily.com: “The next step is to use these compounds as analytical marker molecules in order to monitor taste development during industrial brewing processes or aging studies on a molecular level.
The chair of Food Chemistry and Molecular Sensory Science at the Technical University of Munich added: “The aim is to control and tailor industrial processes based on kowledge rather than on trail and error.”
Giving examples of ways that shelf life could be extended, Hoffman cited controlling of the initial pH of the beer or the maintenance of low temperatures during storage. In addition, he said use of iso-hops which contain only the stable cis-iso-alpha acids instead of the instable trans-iso-alpha acids could help extend shelf life significantly.
Source: Journal of Agricultural and Food Chemistry
dx.doi.org/10.1021/jf104392y
Comprehensive Sensomics Analysis of Hop-Derived Bitter Compounds during Storage of Beer
Authors: Daniel Intelmann, Gesa Haseleu, Andreas Dunces, Annika Lagemann, Andreas Stephan, and Thomas Hofmann