(by my son Christopher Palm, 3rd quarter Honors Chemistry essay)
In the Middle Ages, many European
towns had their own brewery, each with its own particular style of beer. Over
time certain locations became famous for their unique brew. For example, Dublin became distinguished for its dark
Guinness stouts, Pilsen was noted for
its pale lagers, and Burton-on-Trent was renowned for its pale ales. Brewers
did not know then what we know now — that the mineral content of the water used
in zymurgy greatly affects the outcome of the beer. Today, brewers take these
chemicals into account when they brew beer.
Several
ions, including calcium, magnesium, carbonate, sulfate, and chloride, typically
found in water affect beer in important ways. Metal ions tend to aid enzyme
activity, while anions directly influence the flavor. Water either naturally
has a lot of these ions in it – this is considered hard water – or it has few
minerals dissolved in it – this is considered soft water
Calcium
ions (Ca2+) and magnesium ions (Mg2+) ions protect the
enzyme amylase (also found in human saliva) that breaks down the starches into
simple sugars. Without these, the yeasts would not be able to break down enough
starches to eat and the flavor of the beer would be substantially different.
This enzyme is all-important for this reason, as the malts used in beer are
roasted specifically to obtain certain sugars in them. “High levels [of Mg2+] taste
sour/bitter” (Palmer 38), however. Besides these useful metallic ions, there
can also be dissolved iron in the water, which has no useful purpose. It must
be removed, or it will give the beer a bad taste.
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Sulfate
ions (SO42-), which are also often paired with Ca2+
in calcium sulfate, are a third important ion present in water in some
locations. This compound, gypsum, is often added to hard water (water that has
carbonates in it) to cancel some of the basicity of the water. It also enhances
the hops' bitterness, so it is a perfect ion to include in hoppy, light beers.
But, as Donald Gajewski, former assistant brewmaster at City Brewery in La
Crosse, Wisconsin, warns, “Too low a pH gives a beer an astringent, harsh
taste” (Gajewski 3/07/12). This happens if too many sulfate ions are added.
Another
fairly common ion is the chloride (Cl-) ion. (This is not the
chlorine added to water to disinfect it – that chlorine has a bad taste and
must be removed if present.) It can be added as either NaCl or CaCl2.
If calcium chloride is added, it boosts the calcium level (which is not
necessarily needed if the calcium level is already adequate). If sodium
chloride is added, the sodium does not have quite the same effect: it “acts
like salt to accentuate the malt flavor at moderate levels” (Palmer 38) – or in
too large a quantity, it imparts a salty flavor to the brew (not too
surprisingly). The Cl- ion has similar effects, and it also helps
give a beer a smoother taste. Some people actually use a salt shaker when they
drink highly bitter beers!
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Works
Cited
Foster, Terry. Pale Ale.
Brewers Publications. 1999. Print
Gajewski, Donald. Former
Assistant Brewmaster at the City Brewing Company, La Crosse. Interview.
Palmer, John J. How to Brew.
Brewers Publications. 2006. Print.
The Practical Brewer.
Edited by Broderick, Harold M. Master Brewers Association of the Americas.
Madison, Wisconsin. 1977. Print.