Reinheitsgebot
Medieval brewers had used many problematic ingredients to preserve beers, including, for example soot and fly agaric mushrooms. More commonly, other “gruit” herbs had been used, such as stinging nettle and henbane. Indeed, the German name of the latter, Bilsenkraut, may originally mean “Plzeň herb”, indicating that this region was a major centre of beer brewing long before the invention of (Reinheitsgebot-compliant) Pilsener.