HVG Germany: Hopfen

Bitter substances in nature are usually poisonous. Bitterness is therefore a taste which is meant to warn us of poisoning. Very bitter substances can even cause one to retch. Over the course of time we can train the human body to accept bitterness in low concentrations - such as in coffee and beer.

For genetic reasons different people have varying sensitivity towards specific flavours. Especially the sensitivity towards bitterness is individually very different. In the perception threshold there are fluctuations around the factor 1,000. Newborn babies have an extreme aversion towards bitter substances.

Nowadays we know that the taste of the five different flavours occurs over the whole tongue and is not just limited to certain regions - as believed for many years. There are 3 kinds of papillae on the surface of the tongue, which have taste buds with chemo-sensorial cells.

What happens on the tongue when drinking beer, can be expressed scientifically as follows: The bitter impression occurs in the course of a metabotrop signal transduction.

The mechanisms of bitter taste are very complex. Various bitter substances also release different chemical reactions on the taste receptors. Substances such as quinine and caffeine (ionotropic signal transduction) are all bitter, but they are not tasted "equally" as bitter as beer because the mechanisms which they appeal to on the tongue vary.

This complexity makes it clear why not only hops can give the beer bitterness and astringency. Also a too strong lixiviation of grains, yeast autolysis, quality of the water, beer recovery from deposits or oxidation and aging can give the beer a quality which the drinker calls "bitter".

Moreover the quality of the beers, also called "beer matrix", is decisive for whether the bitterness stands "alone" as the taste or whether it is accompanied by other flavours and mouth-feels. The same chemical bitter level Is judged differently in a beer from unmalted cereals, a sweet beer or a strong ale.

Not only the intensity but also the quality of the bitterness can be rated. Tastings show that different hops can also cause different bitter tastes.

A week bitterness can be described as broad and astringent while a distinctive bitterness can be found to be soft and round. Also terms such as lasting, prolonged, recurring, intensive and scratchy are used to describe the bitter taste.