History of Sour Beer
For thousands of years, beer was fermented and aged on wood, with mixed cultures of yeast and souring bacteria. Pasteur’s discovery of yeast in 1857 allowed brewers to understand the advantages of collecting and isolating brewing yeast. Thus, some modern traditions and practices of mixed culture fermentation: lambics and guezes hail from the Lambeek region of Belgium, while the sometimes herbed and salted goses of Leipzig and the delicate citrus flavored berlinerweiss of Berlin hail from Germany. The advent of glass allowed brewers to ‘bottle condition’ their beers. They simply allowed the beers residual sugar to form CO2, which carbonated and further aged the relatively still beers. This aging not only increased the amount of CO2, but also the overall sourness and wild character of the beer.
Liquids were held in clay pots prior to the invention of closed wooden barrels during the Iron Age. (900 BC). The profession of cooper was born, and continued to grow proportionally with trade over generations.
Benefits of Wood Barrels:
- Ease of Transport
- Flavor and Texture Contribution
Why Oak Barrels:
- Water Tight
- Resistant to decay and leakage
- Flavor and texture contribution
When an oak barrel ceases to contribute flavor and texture, it’s called a ‘neutral barrel’ and is longer useful for wine production. At this point it is perfect for beer acidification. French oak is tighter and less dense than American oak, making it an ideal, workable wood for coopers.
These large wooden barrel-vats, called foeders (and pronounced food-er) are used by breweries like New Belgium, Deschutes, Epic and others for their sour beer production. Once these barrels are liquid-tight, they are inoculated with sour beer from an older foeder and then filled with beer. Preparation and maintenance includes:
- Sealing doors with beeswax
- Stopping leaks with reeds, spiles, and oaken wedges
- Hammering hoops with drivers and pounders
- Ensuring external hydration by spraying foeders with water
- Keeping foeder temperature within key range
Minimal oxygen diffusion in the foeders allow these flavor-positive souring bacteria to thrive – lactobacillus and pediococcus are the fermenting bacteria that make lactic acid. The Wild Yeast: Brettanomyces produces the sour flavors. Sour beer starts with beer production. Fully finished beer feeds the souring bacteria and wild yeast that reside inside of the foeder. The beer does not ferment in foeders, it acidifies. The beers serve as food (sugar) for the yeast, and the souring activity thrives by creating lactic acid (bacteria) and funky flavors (yeast!)The beer will sit in the foeder for its aging period (1-3 years) and is pumped out slowly & bottled, and the foeder is filled again.
There are six primary forms of sour beers: American Wild Ale, Berliner Weisse, Flanders Red Ale, Gose, Lambic and Oud Bruin.
Info / Photos from: New Belgium Brewery