What Is Wild Fermented Sour Beer?

Historically all beer would have been sour beer. This was due to the lack of sterility in the brewing process and the fact that standardized pure yeasts weren’t available. So all beers would have contained wild yeasts and bacteria, which inevitably led to unpredictable results and sour flavored beer.

In contrast, modern sour beers are brewed with specific cultures for unique and delicious flavors. I wanted to learn more about this style of brewing, so I went to visit Ali Kocho-Williams in Wales.

Seren Brewing claimed to be the smallest brewery in the UK, operating from a family home out in the Welsh countryside. A single small room with a bit of extra storage stashed away under the stairs housed most of the brewing equipment. However, it was the yeasts and the brewing process that primarily piqued my interest in the nano-brewer.

Seren Brewing proudly used wild yeasts, collected in a manner that would be familiar to most fermentation foodies. Ali, Seren’s Master Brewer, set out mason jars filled with a starter solution in various parts of his land to collect different strains of yeast and bacteria.

Precision Brewing

The thought of mason jars protected only by a piece of gauze to keep the flies out caused me to ask whether he had many failures. <I know that I’ve certainly had my share.> However, Ali never had a large-scale failure.

After collecting the culture, he would look at it under a microscope to determine exactly which microbes were in his ferment. Then he would produce small test batches to determine their flavor profiles and viability, while carefully monitoring the pH levels.

It’s all of this sort of attention to detail that gives modern sour beers a flavor profile that is worth searching for.

What do you think? Are you a fan of sour beer?