On this day, before a committee consisting of gentry and knights in Ingolstadt, William IV, Duke of Bavaria, issued his famous purity regulation for the brewing of Bavarian Beer, stating that only barley, hops, and water could be used. The text does not mention yeast as an ingredient, although yeast was at the time knowingly used in the brewing process. It is likely that brewers of the time preferred to see yeast as a fixture of the brewing process. The new regulation also set the price of beer (depending on the time of year and type of beer), limited the profits made by innkeepers, and made confiscation the penalty for making impure beer. This regulation remained in force until it was abolished as a binding obligation in 1986 by Paneuropean regulations of the European Union.
