In order to be able to discuss about the Reinheitsgebot, we shall first establish what the law text originally says, in its original language, and what it means in modern language.
The 1516 Reinheitsgebot is rooted in the Bayerische Landesordnung of 1516, a law enacted in that year to harmonize the different local Bavarian laws in all kinds of different legal matters, be it policing, milling, building, trading, fishing, or brewing. This law contains one passage that regulates the allowed beer ingredients, and originally says (in Early New High German):
Wir wöllen auch sonderlichen / das füran allenthalben in unsern Stetten / Märckthen / unn auf dem Lannde / zu kainem Pier / merer stückh / dann allain Gersten / Hopfen / unn wasser / genommen unn gepraucht sölle werdn.
Translated to Modern Standard German it says:
Ganz besonders wollen wir, dass forthin allenthalben in unseren Städten, Märkten und auf dem Lande zu keinem Bier mehr Stücke als allein Gerste, Hopfen und Wasser verwendet und gebraucht werden sollen.
Translated to Modern English, this means:
Exceptionally so we want that henceforth, everywhere in our cities, market towns and on the countryside for no beer more pieces than alone barley, hops and water shall be used.
So, the language is very clear: no matter where in Bavaria you’re brewing, all you’re allowed to use is barley, hops and water. A common question here is: but what about yeast? Well, the nature of yeast was not fully understand until several hundred years later. This ingredient being left out is usually interpreted that the use of yeast is implied, that is if you’re not relying on spontaneous fermentation.
Another detail is also quite interesting: it specifically mentions barley, not malt in general or barley malt, but only barley. This is apparently based on the Munich purity law that had been enacted a few decades earlier, while other purity laws, such as the Landshut purity law, does mention malt, without a limitation to a specific grain. As I said before, the 1516 purity law was implemented as a harmonization, and thus overruled both the Munich and the Landshut purity law. Its emphasis on barley, and not malt, is quite a crucial detail here. I’ll discuss that in a later article.