German Purity Law
Traditional German Brewing Practices
Followed by Gilde
Before the invention of thermometers and advances in malting technology, decoction mashing was widely used in continental Europe to regulate mash temperatures and convert under-modified malt. Modern malting technology has led many brewers to abandon the time-consuming practice of boiling a portion of the mash to breakdown starch for conversion to sugar. However, decoction still adds depth to the malt character of beer because the chemical reaction that occurs when sugar and protein are combined with heat forms powerful flavor compounds called melanoidins. Melanoidins are the same rich flavors found in caramel candy, roasted nuts, baked bread, and roasted meats. Gilde decocts most of our biers to produce these subtle, but flavorful melanoidins.
Two Stage Fermentation & Maturation
Over eighty percent of the bier we produce is cold-fermenting lager bier. “Lagern” in German means “to store”, and it is the extended time in the lager tank that mellows the character of lager bier and lets the bier naturally clarify during long, cold conditioning periods. Because most craft breweries brew warm-fermenting ales that ferment quickly, they ferment and condition their bier in the same tank. We follow the old-world practice of fermenting in one tank and then transferring the bier to a specifically dimensioned conditioning tank for the long, cold maturation period.
We carbonate our bier with natural carbon dioxide that is produced by yeast during fermentation. Not only is naturally produced CO2 required under the Reinheitsgebot, but natural CO2 is also 100% pure and, therefore, free of odors and flavor-staling oxygen.
Gilde Bier and the Reinheitsgebot of 1516
Gilde follows the primary basis of the Reinheitsgebot of 1516 because we only use the four permitted ingredients – malt, hops, water, and yeast. However, from a strict interpretation of modern German law that regulates more than ingredients, there are areas where we do not always comply, either because American suppliers do not meet the German Purity Law standards, or because Gilde chooses to brew a bier that is not Reinheitsgebot compliant.
Although the Reinheitsgebot has been in force since 1516, German officials have had to judge whether modern brewing methods are consistent with the intent of the original 1516 law. The modern brewing law (Vorläufiges Biergesetz), addresses what a brewer can and cannot do to brew a beverage called “Bier” and place on the label, “Brewed According to the German Purity Law of 1516”.
Gilde practices compared to the modern interpretation of the Reinheitsgebot:
While lager bier in Germany can only be brewed with barley malt, it is permitted to brew ales (e.g., wheat ales) with other malted grains like wheat or rye. Gilde uses only malted barley in our lager biers, and only malted wheat and barley in our Hefeweizen. We do not add any adjuncts, that is, no sugar or unmalted grains.
Germany permits only whole hops, hop powder pellets, or un-isomerized hop extracts in beer. The addition of aromatic hop oils to the conditioning tank, which occurs in some hoppy IPAs, is not permitted in Germany. Gilde uses only Reinheitsbgebot permitted hop pellets in our bier. We don’t add botanicals or spices other than hops (see “Oak-Aged Bier” below).
Germany allows brewing water to be treated according to public water safety guidelines (Trinkwasserverordnung), which includes adding chlorine to control pathogens. Because chlorine causes off flavors in bier, charcoal water filters are allowed in Germany to remove the chlorine. The addition of naturally occurring water salts like calcium chloride and gypsum are allowable in treating brewing water (water hardness in the form of calcium is an important yeast nutrient).
Alkaline water is not well suited for brewing a slightly acidic beverage like beer. Alkalinity can be neutralized by adding acids. It is common outside Germany for brewers to add industrial acids, like phosphoric or lactic acid, to control alkalinity. In contrast, only biologically produced lactic acid from bacteria that are found naturally on malt is allowed in Germany under the Purity Law.
Gilde complies with Reinheitsgebot requirements for water treatment. We use charcoal filtration to remove chlorine, and we only add calcium chloride and gypsum as additions to our brewing water. Biologically produced lactic acid from sour malt (Sauermalz) is the only means we use to counteract water alkalinity and lower the pH in our bier.
In Germany, yeast can only be propagated with wort produced from malt. Because we bank our yeast in a domestic, non-Reinheitsgebot compliant country where yeast labs add sugar and yeast nutrients like zinc and amino nitrogen to constitute their propagation wort, our yeast is not compliant. Until we bank and propagate our own yeast, our yeast will technically violate the Reinheitsgebot.
While Germans can only carbonate their bier with CO2 that has been produced by fermentation, they can use non-fermentation derived CO2 to purge and pressurize tanks and bier lines. Gilde also carbonates its bier naturally with CO2 from fermentation. And, perhaps we have occasionally corrected an under carbonated bier by similar means as our German brothers.
Germans still fill bier in oak barrels, but the wood is covered with pitch so the bier does not acquire flavor through contact with the wood. Gilde occasionally ages its bier on oak, which is not specifically addressed in the Vorlaeufiges Biergesetz. However, oak-aging probably violates the intent of the law, since toasted oak adds vanilla and caramel flavors like those found in bourbon. Reinheitsgebot Verbrecher!