Beer can develop an unpleasant, bitter aftertaste as it ages. Unlike wine, scotch whiskey, and bourbon, beer tastes best when consumed fresh. Experts estimate that the average beer goes bad after 6 to 12 months of storage.
Past studies have identified dozens of bitter-tasting substances formed during beer manufacturing -- the "prenylated polyketides" derived from hops. But, until now, there was no solid information about the bitter substances in aged beer.
Now, a team, led by Thomas Hofmann at the Technical University of Munich, has identified the main substances that cause the bitter and harsh aftertaste of aged beer, and also suggests preventing the formation of these substances could help extend its freshness.
The researchers, in fact, have identified some 56 substances that contribute to beer`s bitter taste, including five which appear to be largely responsible for its harsh flavour after ageing.
They have based their findings on an analysis of a variety of commercial beers both before and after storage.
"The present study offers the scientific basis for a knowledge-based extension of the shelf life of the desirable beer`s bitter taste and the delay of the onset of the less preferred harsh bitter aftertaste by controlling the initial pH value of the beer and by keeping the temperature as low as possible during storage of the final beverage," they said.
The findings have been published in the latest edition of the `Journal of Agricultural and Food Chemistry`.