Sour and funky beer is on the rise with some breweries only specialising in beers with these very different flavour profiles to what we would normally expect from beer. I'm a big fan of sour beer and have previously brewed some in the UK and now I'm starting my US sour beer program. This post goes through how I have gone about brewing a beer with mixed fermentation and where you can learn more.

There is probably no more unusual style of beer than sour beers, the flavours present in these beers are normally considered off flavours and undesirable. However, for some beer drinkers and brewers the pursuit of sour and funk is something of a life long journey. What is a sour beer? How do you get these flavours into a beer? Where can I learn more? I hope to answer most of these in this post.

What is sour beer?
Sour beer can be broken down into several sub categories:
Mixed Fermentation - fermentation and flavour comes from a mixed culture of yeast and bacteria. The most common organisms are Saccharomyces, Brettanomyces and Lactobacillus and Pediococcus.
Wild Fermentation - fermentation takes place with either brettanomyces on its own or a mixture of Brettanomyces and Saccharomyces. Very similar to spontaneous fermentation. 
Spontaneous Fermentation - takes place when ales are fermented with organisms that are present on the raw ingredients or from the air.

The most common place you will find these types of beers are in the European beer styles such as lambic, gueuze, flanders, gose, berliner weisse and bier de garde.

What do these organisms do to the flavour of the beer?
Saccharomyces - The normal yeast brewers use for fermentation, so big on flavour compounds such as esters depending on the strain but no sourness or funk.
Brettanomyces - A wild yeast which is often described as funky, farmyard and horsey. 
Lactobacillus - A bacteria that produces lactic acid to give the acidity associated with a number of these styles and carbon dioxide.
Pediococcus - A bacteria that produces lactic acid and diacetyl, so it is associated with acidity and butterscotch/buttered popcorn flavours.
Acetobacter - A bacteria that produces acetic acid which is what gives vinegar its flavour.

Where can I learn more?
I'm a keen reader of all things craft beer and sour beer most definitely fits in this style. I've learnt pretty much everything I know from the following sources.

Books

Websites

  • http://www.themadfermentationist.com
  • http://sourbeerblog.com
  • http://www.milkthefunk.com
  • http://www.thebrewingnetwork.com/category/shows/sourhour/ - also a podcast in iTunes and hosted by sour brewer Jay Goodwin of The Rare Barrel

Homebrew
As I mentioned earlier I recently started my own US sour beer program and to do this I used the extract lambic recipe from http://www.themadfermentationist.com/2015/11/extract-lambic-recipe.html I did modify this a little and doubled the amount of maltodextrin as I wanted a more Brett forward character to the beer. I also used bottle dregs from two of my favourite sour beers  Bruery Terreux - Sour in the Rye and Firestone Walker - Bretta Rosé and White labs WLP650 Brettanomyces Bruxellensis which is is normally used in secondary but I pitched it in primary as I want a more assertive funk character to my beer and a normal Saccharomyces strain for primary fermentation instead of The Yeast Bay Melangé - sour blend. I think the mixture of bacteria and different yeast strains should make for a fun and complex mixed fermentation and I will update with flavours in a few months time to let you know how it progresses.

Update 10 June 2017

I took a sneak peak at the brew to see how it was coming along and to my amazement there was a beast of a pellicle (biofilm produced from Brett fermentations) on it. This is pretty typical to see from mixed fermentations and is no cause for concern. My plan is to now leave this for a few more months to mellow out before blending with some clean beer to get the flavour profile I am after.

Pellicle from the Brett fermentation

Pellicle from the Brett fermentation

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