Berliner Weisse beer
Berliner Weisse is a generally acidic beer, but it is not the yeast that brings this taste.
The yeasts used assimilate much more complex sugars than the others. During this transformation lactic acid bacteria are released, and they are the ones that will give a more or less tart taste depending on their quantity.
These reactions have been known for centuries but their scientific understandings are rather recent. The mastery of lactic yeasts has actually existed since humans transformed milk into cheese. And it is not uncommon to feel an aftertaste of cheese, yogurt or whey (residual layer during cheese making) when tasting a brett beer.
The yeast brings a fruity, barn like and woody taste to the beer. It is quite common to believe that Berliner Weisse beers are brewed with fruit, which happens, but usually it is the yeast that gives the taste, and even a color ranging from pink to light purple to yellow.
Today the demand for Berliner Weisse is increasing sharply among informed consumers. Many new generation breweries are doing this tricky exercise.
The production is not necessarily more complicated than for other style of beers. There is a risk for breweing the next beer because the yeasts could infect future brews.
Therefore it is necessary either to brew only this style, or to clean the brewing tools from top to bottom, which takes a lot of time. Some brewers sometimes organize themselves to produce Berliner Weisse just before the big spring cleaning.