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Sour beer: Origins and Styles

Updated: Aug 11, 2021

On our last beer tour we had a very pleasant experience, one we are hoping to have on every tour and for all of our guests. Those two ladies found a new type of beer that they had never heard of before and that they were absolutely fascinated by: #sourbeer. This shows how little people actually know about the wide range and tradition of #goses, #lambics and so on. As #zurichbeertour we want to change this, on tour and online. So let's talk about sours!


Origins of sour beer

People who approach sour beers for the first time may have controversial thoughts about it. Some may like it, but most people will be a bit confused by the #acidity. Also most people think that this is some kind of modern interpretation of beer. And that last one is far from the truth. Before yeast was discovered and cultivated, beer was fermented by wild #yeasts and was often infected by wild #bacteria. This means that most beers back then were at least slightly sour. Some regions even specialized in producing sour beers, for example lambic brewers in #Belgium, those beers were first mentioned in 1794 as "allambique".

What makes beer sour?

How is sour beer actually made? The most common way to make a beer sour is to use #microbes such as the bacterias lactobacillus, pediococcus and brettanomyces. Those are added to the beer by the brewer. There is also a way to make beer sour without adding microbes yourself. Some beers are fermented by wild yeasts and bacteria by leaving them in open #fermentation vessels and letting microbes from the surrounding environment fly in. Another way to trigger spontaneous fermentation is to put beer in barrels (check our blog about barrel ageing) or put fruit in the beer, as it carries wild microbes which will also ferment the beer.

Sour beer styles

There are many different styles of sour beers, so let's give you a small overview on the most common ones with some examples.


Lambics are spontaneously fermented beers that can only be brewed in the region of #Pajottenland in Belgium. The beer is left to cool in the so called "koelschip" and later put in barrels to ferment and mature. The beers are often blended (e.g. Gueuze) or secondarily fermented over different types of fruit (e.g. cherries in "Kriek").

One of our favorite Gueuzes is this fantastic "Golden Blend" by 3 Fonteinen. This is a blend of one-, two-, three- and at least four-year old lambics matured in oak barrels.

Flanders Red Ale

The Flanders red ale is a beer brewed in West Flanders, Belgium. It is fermented with brewers yeast and also lactobacillus that gives it its acidity. They are also getting aged for a longer period, mostly in oak barrels, and later blended with younger beer. The name comes from the region and the red malt that is used to brew it.

One of our favorite Flanders red ales is the Rodenbach Classic by Rodenbach Brewery, a blend of 25% aged and 75% young ale.


Gose is German sour beer that originates in the city of Goslar. This particular sour beer is characterized by the use of coriander and salt and is made sour by inoculating the wort with lactic acid bacteria like lactobacillus for example.

One of our favorite Goses is a pretty new take on this classic beer style by the freaks of Omnipollo in Sweden. This is Bianca, to be exact this is the Double Peanut Butter Jelly Lassi Gose. Brewed with rock salt, lactose, peanut butter, strawberry and raspberry jam. Weirdly delicious.

American Wild Ale

An American wild ale is a sour beer produced in the United States. And can be almost any kind of sour beer. They tend not to have specific parameters or guidelines for brewing, but instead simply refer to the use of unusual yeasts. That means any kind of sour beer produced in the US could be called an American wild ale, no matter how many times and in what type of vessels they are fermented in or if the used microbes are cultured or acquired spontaneously. As long as there is more then normal brewers yeast in use.

One of our favorite American wild ales is the Rueuze (2016) from The Bruery Terreux. This beer is an American take on the traditional lambic style beer. The base beer, a sour blonde ale, is aged in oak barrels for up to several years and is then blended to perfection.

Berliner Weisse

This sour wheat beer was once the most popular alcoholic beverage in Berlin, it mostly has a lower ABV than other sour beers (around 3%). In Berlin they used to add sweet syrups to it, to balance out the acidity.

One of our Favorite Berliner Weisse is one of the newest brews by Lost Grain from Zurich. Their new Berliner "I like sloths" is cold steeped with naturally fermented coffee from Miró Cofferoasters also from Zurich.


This is our beginners guide to sour beer but there is still so much more to discover. The best thing to do, and this is what we will do now, is to grab a delicious sour and try to find out even more about those really complex beer styles. And hopefully soon you are going to be as much a sour fan as our two guests from the last tour.

Cheers, Your Zurich Beer Tour Guides

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