Geology of Beer

There were some major changes on this blog latterly - not only now it displays a very professional layout, but more importantly "History of Geology" is now part of the awesome "Field of Science Blog Network" - many thanks to Edward Michaud for the invitation and the possibility to join.

This event has to be celebrated by combing two of the most important topics dear to geologists, one of them also appreciated by all non-geologists and essential for almost all celebrations.

It is considered one of the oldest foods and most appreciated beverages of the world - chemical remains were found on fragments of a more than 4.000 old jar, the Mesopotamians guaranteed its purity with a law that threatened with death whoever manipulated the traditional recipes and the old Egyptian considered it an essential part of the afterlife, it was the beverage of the gods of the Vikings - and today of geologist - known also as beer.



The quality of a beer, produced by the fermentation of an extract of cereal grains, comprises five factors: the flavour, alcohol content, colour, head retention, and clarity. These factors depend strongly from the used ingredients - one of the most important is water and the quality of water depends strongly from the geology and hydrology of the tapped spring.

"The enjoyment of a glass of beer may be received by many senses: the sight may be attracted first by the clarity of a pale ale or the rich creamy head of a stout.
As the glass is raised to the lips the aroma of the bever age, possibly the bouquet of the essential oils of the hops, may excite the nostrils. Then, as the liquid flows over the taste buds at the back of the mouth, and further volatile products diffuse into the back of the nose, the flavour of the beverage is perceived. Finally, the beer enters the body, where the alcohol is rapidly absorbed into the bloodstream and exerts its well known physiological and psychological effects."
Anonymous source

The brewing process involves great quantities of water and many breweries possess or profit from private springs or wells, referring even to the water quality or purity in their advertisements. In medieval times beer was a more trusted beverage than river water.

Natural waters contain mainly four cations particularly significant for the brewing process, calcium, magnesium, sodium and potassium.
Calcium stabilize the enzymes used by the yeast to breakdown the starch, it also precipitates phosphate - also present in water - correcting the acidity of the water and supporting microbial activity.
Magnesium has a similar effect and also controls the phosphate content of the mash - however to much Magnesium will give the beer a bitter taste.
Sodium and potassium in to great concentration can ruin the taste of the beer, and more importantly have a laxative effect on the heavy drinker.

In areas dominated by Carbonate rocks - with springs high in content of calcium and magnesium - the control of the pH of the water and mash is one of the major problems. The low pH resulting makes only relatively sweet beers possible, even if by selecting carefully other ingredients still variation is possible - one bad luck of the Irish, with an island dominated by Carboniferous limestone. However the chemistry of the water made it possible to brew a particular porter and a well-known stout of Dublin

Also the content of anions of the water influence the final product.
Sulphate, deriving from evaporitic rocks, can give a beer a desired bitter flavour by supporting the release of bitter oils from the used hops and reacting with magnesium to produce magnesium sulphate - a bitter tasting salt.
Also springs with high contents of chloride and sodium (deriving from salt deposits) give a salty to bitter flavour - however in the correct proportions the sweetness of the chloride ion can prevail - causing the taste of the unique classic ale.

Regions dominated by sandstone and Palaeozoic or Precambrian metamorphic rocks have waters with low contents of dissolved minerals and ions, this causes often a less distinct flavour, therefore the beer has to be ferment for longer time, this also increments the alcoholic content of a beer.
Pils and lager, classic beers from Central Europe, received their name from the traditional storage and fermentation of the beer in cold caves.

Today, with the advent of effective water pumps and transfer of water over long distances, the role of local geologic conditions is less important than in the past. Many wells or springs - especially in industrialized areas or regions with intense agriculture, are today also contaminated with pollutants or overexploit. Some modern breweries are using water that was previously deionized and subsequently customized to a desired chemical composition- with the advantage of hygiene and better quality control.

So in the end - enjoy your beer like a geologist and remember: Now that you know how complicated it is to brew a good beer, do not waste it and drink with moderation - especially don't Drink and Drive!

Bibliography:

CRIBB, S.J. (2005): Geology of Beer. In Selley, R.C.; COCKS, L.R.M. & PLIMER, I.R.: Encyclopedia of Geology: Elsevier Academic Press: 78-81