Sour Beer Brewing

Notes from 2017 meeting topic …

Click here to see the info:

Sour Brewing for Us Home Brewers
There are various ways and techniques to process sour brew at home. Each method have pros and cons, do’s and don’ts and varying outcomes. The best part is there is no one way better than the other.

Sour Mashing
Sour mashing is a process that is typically regarded as the lesser of the different methods due to it’s lack of ability to control the outcome and to measure the progress throughout. But yet it is a way to produce a sour beer none the less.

Sour mashing starts out just as any other all grain mash would but is allowed to keep warm for several days after the introduction of a lactic acid producing bacteria, typically lactobacillus. The inoculation can come from various sources
such as; a pure pitch of a commercial culture of lactobacillus, a small amount of un-mashed base grain (the husks of grains have one or more wild strains of lactobacillus on them) or alternative sources of lactic acid producing bacteria.

After a certain level of souring and pH drop is achieved, the mash is then sparged as normal, followed up by the boil, chilling of the wort and then cold side “clean” fermentation takes place. A benefit of this method is that that lactobacillus, and any other wild or non-wild bacteria that was in the mash, will be killed off in the boil and only “clean” beer will go into your fermentation and serving equipment.

Steps Are:

  • Mash either a single infusion, step infusion, turbid mash or decoction mash – Whatever your recipe calls for, or what you are familiar with.
  • After saccharification rest is completed perform a mash out, raise mash temp to 168°, to stop enzymatic activity.
  • Next pre-acidify your mash. Drop the mash pH to 4.5 by adding lactic acid or phosphoric acid. You can also add acidulated malt AFTER the saccharification rest but the amount of total weight vs total gist weight is too high.
  • Cool the mash to around 110° to 120° and add your source of lactic acid produce bacteria.
  • Seal and removing oxygen from the vessel is the best practice. If you have a way to flush with CO2 this is ideal, but impractical at the home brewer level. The most important thing is to seal the vessel off and not allow oxygen into the vessel during the process. This needs to be an anaerobic process, absent of oxygen, during the souring.
  • Keep the vessel and mash above 100° if possible. Checking the pH during the process every 12 to 24 hours.
  • Typical desired pH levels are: 3.6 for a tartness of a Berliner Weisse or Gose, 3.3 would be a strong younger lambic style and even lower to your liking. Typically the 3.6 to 3.0 level is where you will fall. Be mindful though that Saccharomyces yeast strains will have difficulty with pH levels below 3.4. And mixed culture strain or Brettanomyces pitch for primary fermentation maybe need for your lower pH beers. Brettanomyces can ferment way below a pH of 3.0.
  • Once the desired pH level is achieve that you want, heat the mash to 170° and then sparge as normal.
  • Then follow your recipe for a standard boil, hop additions, chill and pitch your saccharomyces yeast or brettanomyces for a standard alcohol fermentation.

This process is obviously for all-grain brewers but the next processes can be used for extract brewers. I have not tried
the process of sour mashing nor will I probably try either.

Kettle Souring
Then there is kettle souring, This is another process where lactic acid producing bacteria, again typically lactobacillus, is used to inoculate the runnings of a typical mash and sparge procedure or even an extract brew. It is also kept warm for several days to allow the bacteria to lower the pH in the kettle and then gives you the choice to either boil or not boil the wort.

The “no boil method” will keep the lactic acid bacteria alive through fermentation and will survive in the final product.

The “boil method” will kill the bacteria before fermentation and will be a “clean” beer going into your fermentation and serving equipment, just like in sour mashing. I have done both methods and both have the benefits.

Steps Are:

  • If you go with the “boil method” A good practice to do is before pre acidifying your wort is to bring the wort to at least 180°, or even a low boil, for 2 to 3 minutes to kill off any unwanted wild bacteria. Basically pasteurize the runnings. For you extract brewers you need to steep your specialty grains, dissolve your DME and/or LME and bring to 180° to thoroughly mix the extracts and kill off any unwanteds.
  • If you are going the “no boil method” follow your recipe for boil but keep you hop additions low, like >10 IBU, or lower, to none at all. The higher IBU, alpha acid and hop oils will inhibit the lactobacillus and will not sour and
  • lower the pH during fermentation.
  • Chill the wort, for either method, to below 120° then pre-acidify your wort. Drop the pH of your wort to 4.5 by adding lactic acid or phosphoric acid before pitching your source of lactobacillus to the kettle. Again a pure pitch of a commercial culture of lactobacillus, a small amount of un-mashed base grain or alternative sources of lactic acid producing bacteria.
  • Seal and removing oxygen from the kettle is the best practice. If you have a way to flush with CO2 this is ideal. You can bubble CO2 into and through the wort for several minutes to scrub the oxygen from the wort pre-say. The idea is to omit the O2 to maintain an anaerobic condition.
  • Just like with sour mashing, keep the kettle and wort above 100° if possible. Checking the pH during the souring process every 12 to 24 hours. The ideal temperate range is typically between 90° and 120° and takes between 5 to 7 days to reach the desired power pH levels.
  • Now with the “no boil method”, where the bacteria is not killed off, cool the wort to the proper fermentation temperature and pitch lager or ale saccharomyces yeast or brettanomyces for a standard alcohol fermentation.
  • The “boil method”, where the bacteria is killed off, you would now follow your recipe and boil as normal, chill and pitch your saccharomyces yeast or brettanomyces for a standard alcohol fermentation.
  • You can dose the wort with a hefty amount of oxygen prior to aid with alcohol fermentation, the lactobacillus bacteria at this point would not be negatively affected by introduction of O2. The use of yeast nutrient, Go-Ferm, FermAid-K is wise too.

Traditional Souring: Spontaneous Fermentation, Mixed Fermentation, Dregs, Coolships and Soleras
There are other traditional and non-traditional brewing techniques that deal with sour beer brewing. I will just touch on a few. And these are often used in different combinations as well. That can create interesting results.

  • Spontaneous Fermentation: Is the use the yeast and bacteria from naturally in the air, on fruit, the surroundings
  • for examples. The inoculation of these microbes traditional occurs in a coolship.
    • Coolship: A coolship is a fermentation vessel that is used in traditional lambic production. It’s a wide and swallow, open top vessel where the hot wort is cooled and exposed to the air over night.
  • Mixed Fermentation: This is a beer that contains more than just saccharomyces yeast to ferment it. Or lack of Saccharomyces. Use of Brettanomyces, Saccharomyces, Lactobacillus, and Pediococcus. There are numerous species or strains of each to pick from.
  • Dregs: The use of commercial bottle’s last 1/2″ sediment is the “Bottle Dregs” that is typically discarded by most. The microbes left in the beer are built up in a starter. These microbes are typically stronger and more aggressive from commercial breweries. Some breweries pasteurize their beers to stop this from happening or use champagne or wine yeast to bottle condition killing the original microbes in suspension in the beer.
  • Solera: A sour beer solera is process of taking about a third of the beer out for packaging out of a single large fermenter every 6-12 months. Then is replaced with new beer or wort. The beer will continue to develop and change over time but can be steered by changing the recipe. The blending of new and old provides everlasting sour beer, similar to sourdough beard and it’s mother dough.

Microbes and Alternative Sources of Lactic Acid Producing Bacteria

  • Saccharomyces: Typically it’s called “Sacch” – Considered a yeast, is actually a genus of fungus. Different species are used to ferment beer, wine, sake, and an agent in bread.
  • Lactobacillus: Typically it’s called “Lacto” – A lactic acid bacteria. There are over 100 species and many found in your gastrointestinal track. Used to ferment cheese, yogurt, sauerkraut, pickles and kimchi.
  • Brettanomyces: Typically it’s called “Brett” – Is a yeast usually thought as a spoilage yeast and is unwelcome to most breweries and wineries. It can breakdown dextrins (chains of too long for Sacch to ferment) and can add a wide range of complexity beers. From pineapple, apple, and pear; to horse blanket, farmhouse and funk.
  • Pediococcus: Typically it’s called “Pedio” – Is a lactic acid bacteria that often takes several months to really get working. Note; never use pedio without the use of brett. Brett is needed to clean up the mess pedio causes. Strains can cause your beer to become “sick” and “ropey” but generally goes away and the brett is there to help.
  • Alternative Sources: There are many sources for lactic acid bacteria, typically various strains of lacto. Sources include; yogurt, unmashed grains, Kefir (Ke-feer), sauerkraut, probiotics and dietary supplements.

Various Sources and the book American Sour Beers

This entry was posted in Uncategorized. Bookmark the permalink.