|Contributed by Hubert Hanghofer|
|May 24, 2005 at 01:36 PM|
Page 1 of 2
The composition of a brewing water has a big influence on the quality of your brew. Brewing water chemistry is rather complex and unfortunately the deep insight given in many brewing texts is very complicated and confusing. But that needn't be so. I'm water chemist and could make big efforts but I've learned that an easy approach will do to adjust almost all waters to any beerstyle.
Let's focus on the essential elements first. Depending on the underground formation the water arises from, it takes up more or less mineral salts. When this salts are dissolved, they form ions -- positive or negative charged elementar particles. Ions of primary concern for the brewer are Hydrogencarbonat (HCO3+), Calcium (Ca++), Magnesium (Mg++), Chlorid (Cl-), Sulfat (SO4--) and Hydrogen (H+, acidity -- given as pH-value).
Carbonate Hardness = Alkalinity = Temporary Hardness
HCO3- + H+ --> H2O + CO2
As can be seen from the equation hydrogencarbonates are binding acid and thus have the potential to rise pH-level. This leads to some negative effects:
Calcium- and Magnesium- ions together form the total hardness. Due to precipitation of alkaline Phosphates in the mash these ions have an acidifying effect. Brewing scientist Kolbach has found, that the alkalinity of 1 equivalent Hydrogencarbonat can be neutralized with 3.5 equivalents Calcium or 7 equivalents Magnesium. Unfortunately such a high surplus can only be found seldom in natural well waters.
Residual alkalinity according to Kolbach
The residual alkalinity (RA) is a measure, that describes what remains of the Carbonate-based alkalinity after Calcium and Magnesium have reacted in the mash. RA is the most important parameter for brewing water. Today for pale lagers a balanced RA in the range of 0°dH (deg. German Hardness) is strived for, Pils brewers even go down to minus 5°dH. Melanoidines -- the coloring substances of dark Malts act acidifying -- dark beers go with higher RA's up to 10°dH, but balancing the RA will do no harm to the flavor quality either!
Chlorid adds to the fullness and creates a soft, mild flavor. In the mash Chlorid aids activity of a-Amylase.
Sulfat helps creating hop flavor and aroma. It also adds a somewhat dry bitterness, that however can get incompatible (harsh) with some beerstyles at levels higher than 180mg SO42-/L.
|Last Updated ( Feb 14, 2013 at 09:43 PM )|