Hacker-Pschorr brews its beer according to the Bavarian Reinheitsgebot or Beer Purity Law, one of the strictest food regulations in the world. Barley, hops and water are the only ingredients allowed in beer.
On 23 April 1516, the two dukes William IV and Ludwig X issued the Bavarian States Regulation, which also contained the Beer Purity Law. An excerpt from the law states:
We especially wish that henceforth everywhere in our cities, market towns and in the countryside, no other ingredients are to be used in beer other than barley, hops and water.
They were hoping for a better quality of beer. They especially no longer wanted beer to contain psychoactive additives such as henbane, belladonna or opium. Even extract of the fly agaric mushroom or “magic mushrooms” used to hide a lack of fermentation was banned as an intoxicating component from use in beer.
And the yeast? To start the fermentation process requires yeast. But that was probably not common knowledge in 1516. So people hoped and prayed that the good Lord would make it work. The divine intervention now has a simple scientific explanation: The air contains yeast spores that can randomly land on the beer foam, thus triggering the fermentation process. For those who did not want to rely on just the good Lord, there were other ways. For example, brewers liked to add the remains of a previous brewing batch, whose contents also included yeast particles. That helped, even if they did not really understand why.
But unlike today, brewers were not always so strict in their choice of beer ingredients, even if they claimed to be. Ingredients such as coriander, juniper, cumin and salt were allowed for brief periods. However, during the 19th Century, all exemptions were gradually revoked and there was a return to barley, hops and water. Only for Weißbier or wheat beer do the Bavarians look the other way for centuries now, adding malted wheat to the malted barley.