Reinheitsgebot! No, it’s not a German swear word and you don’t have to reply, “Bless you.”The Reinheitsgebot (Gebot) is the 1516 German Beer Purity Law that limits Bavarian beer to three ingredients: water, malt, and hops. Yeast wasn’t one of the original, permissible ingredients because it wasn’t discovered until 1857. The modern version of the law now includes yeast.
Water makes up about 95% of beer so its characterization is crucial – elements and minerals can affect the fermentation, giving the beer a fingerprint of where it was brewed. Many homebrewers will try to mimic beer styles from around the world by making small additions of minerals to the water.
Malted barley is the grain used in beer and it was a major reason for The Gebot. There was competition between bakers and brewers for wheat and rye. Limiting brewers to barley meant there would be ample supply of wheat and rye for bakers. Barley must be malted, which is the process of partially germinating the grain to activate naturally occurring enzymes, followed by kilning, or the drying process that stops the germination. The malted barley provides the required starches which are converted into sugar during the brewing process.
Hops, flowers from the hop plant,were originally added to beer as a preservative because they kill microorganisms, allowing the transport of beer overseas (ex. India, giving rise to the India Pale Ale, or IPA). Hops act as a preservative and impart bitterness to the beer. The more hops added to beer, the more bitter it will taste. Brewers can impart additional flavors and aromas based on when hops are added during the brewing process.
Yeast is responsible for the chemical process of converting the sugar derived from the mashing or steeping process into ethanol (alcohol). There are thousands of yeast strains available to brewers, not to mention wild varieties that can impart local flavor. Although wild yeast strains can impart new and interesting flavors, they’re not as alcohol tolerant as purified strains. In order to achieve the alcohol levels found in most craft beers, brewers rely on commercially available strains.
Prost! (That’s German for cheers.)