Sour Beer

Sour brewing, wild brewing, brett brewing and blending all of the above is a significant part of my homebrewing experience. I've broken these beers out coarsely into different projects or topics. Most of my mixed fermentation brewing these days involves the sour blending project, spontaneous fermentation and mixed fermentation saison/farmhouse. However, some of these older posts may present good starting points for homebrewers looking to get their feet wet in sour or brett beers.


Lambic Solera | Spontaneous Beer | Sour Mash/Wort | Sour Blending Project | Other Mixed Fermentation Recipes

Lambic Solera Project


Solera is a method of aging alcoholic beverages and vinegar in a series of vessels by transporting the liquid through the series over a period of time so when bottled each bottle will be filled with liquid that has traveled through each vessel and the liquid is a blend of vintages accumulated from each vessel. The solera process is commonly associates with sherry but is also used with vinegar, rum, brandy, wine, whisky and beer. 

In a true solera system the initial barrel or group of barrels are filled and at a designated point in time the initial filling will be partially drained and transferred to another barrel or barrels and then the first barrel/barrels are refilled with fresh liquid. The same aging period then occurs and part of the content from the second round of barrels are moved to a new set of barrels, a portion of the contents of the first round of barrels moves to the second and the first round of barrels are topped up with fresh liquid. This continues each aging period until a terminal set of barrels are filled. At the end of the next aging period part of the contents of the terminal set of barrels is packaged and the barrels are filled by the same partial transfer. The end result is a liquid that is a blend of all the barrels and all of the vintages that have ever been inside the barrels in a continuous blend rather than blending multiple independent vintages of the liquid. It is a unique and different form of blending.

Some beer is brewed in these mult-vessel solera systems while other brewers, both commercial and hobby, have adapted the solera process in a single vessel. In this process a single vessel is filled on the initial fill and then partially drained and refilled at the end of each aging period. The single vessel solera process has a similar effect of the continuous blending but misses the benefit of multiple vessels that can imprint their individual identity on the liquid along the aging process. However, it is more manageable for those of us brewing at home with minimal space. 

I began a single vessel solera using a lambic base recipe in December 2010 and have kept it running with a partial draining and filling each December. The posts below document the solera's journey.

Introductory Post - Discussion of initial plans and brewday
Update 1 - A quick update into fermentation
Update 2 - 2 months into fermentation
Update 3 - 6 months
Update 4 - 8 months
Update 5 - 1 year; first refill and second brewday
Update 6 - Review of how Year One was divided up and plans for Year Two
Update 7 - 13 months and a taste of Year One
Update 8 - 18 months and bottling raspberry Year One
Update 9 - 19 months and tasting raspberry Year One
Update 10 - 21 months
Update 11 - 22 months
Update 12 - 2 years; bottling Year Two and brewing Year Three
Update 13 - 2 years and 1 week
Update 14 - 26 months and a tasting of Year Two
Update 15 - 2.5 years and bottling blackberry lambic
Update 16 - 32 months and tasting blackberry Year Two
Update 17 part 1 - 3 years; brewing Year Four
Update 17 part 2 - Bottling Year Three and blending gueuze 1
Update 18 - 38 months
Update 19 - 44 months and tasting notes on gueuze 1 and Year Three
Update 20 part 1 - 4 years; brewing Year Five
Update 20 part 2 - bottling Year Four
Update 21 - 5 years; bottling Year Five and brewing Year Six
Update 22 - Tasting Year Four and Year Five
Update 23 - Bottling Year Six and Gueuze 2



Spontaneous Fermentation Project 2

(For an intro to spontaneous fermentation, see the notes to Spontaneous Fermentation Project 1.)

In an effort to persist in my desire to successfully brew spontaneous beer and learn from the disaster of project 1, I decided to make another go at spontaneous fermentation and coolship playtime. This project began as an effort to try to iron out my process and, if possible, develop a consistent process to brew spontaneous beer on a small, one gallon scale. It presents challenges, especially with coolshipped wort cooling too fast, but will also me to brew more lambic-esque spontaneous beer and blend without having to work with large volumes to produce quality blends. 

An ancillary goal is to experiment with ingredients slightly different from the traditional Belgian lambic ingredients. Specifically, whether pale malt produces a good beer in this manner and how American aged hops might affect fermentation and the final product. So you'll see these beers have slightly different grain bills and unusual hops. 

Batch 1: Brewed November 2016 - First batch using pale malt, American aged hops and first attempt coolshipping a single gallon of beer
Batch 2: Brewed January 2017 - Same recipe, slightly different hopping due to available inventory of aged hops
Update on Batches 1 and 2 and Blending - April 2018 blended batches 1 and 2 together with tasting notes on each surprisingly not-sour-at-all batches

Spontaneous Fermentation Project 1


The term "spontaneous fermentation" relates to the use of wild microbes lured into wort by cooling it by exposure to the ambient environment by way of a coolship. A coolship is nothing more than an open vessel that spreads out the wort and allows the wort to cool by contact with the air. While the wort is cooling the air currents allow yeast and bacteria to descend into the wort. The cooled wort is then transferred into fermentation vessels where the air-provided microbes plus anything already in the fermentation vessels will ferment the beer. No yeast or bacteria is added from lab-produced pitches or carrying over slurry from a prior batch. This method of natural cooling and spontaneous fermentation was the method of cooling and fermenting beer in the days of yore.

Cooling beer in coolships continued as the normal practice until mechanical cooling was developed in the nineteenth century. That does not mean all beer was spontaneously fermented before that time. As far back as the middle ages brewers carried slurry from batch to batch to start fermentation in subsequent brews. These beers were cooled in coolships, which means all beers underwent some form of mixed fermentation between the microbes carried over from the prior batch and whatever drifted into the cooling wort. Some beers were brewed exclusively by spontaneous fermentation from coolshipping beer whether by choice or because they lacked a healthy slurry from a prior beer.

Lambic brewing has carried forward this trend of relying on spontaneous fermentation (in addition to the microbes hiding in barrels and resting tanks), eschewing mechanical cooling and controlled fermentation. It is the most emulated style of brewing spontaneously fermented beer. It is also the style emulated in my own attempt at a spontaneously fermented beer. The posts below document this project.

Part 1 - Introductory thoughts on the spontaneous beer
Part 2 - Explanation of the processes and equipment used
Part 3 - The recipe and brewday
Part 4 - A pictorial review of the first week of fermentation
Part 5 - Week 2 of fermentation
Part 6 - Week 3 of fermentation
Part 7 - Week 4 of fermentation
Part 8 - Week 11 of fermentation
Part 9 - Week 21 of fermentation
Part 10 - Week 23 of fermentation
Part 11 - Week 30 of fermentation
Part 12 - Week 34 of fermentation
Part 13 - Week 38 of fermentation
Part 14 - One year of fermetnation
Part 15 - 13 months into fermentation
Part 16 - 18 months into fermentation; cultured a second round of microorganisms and sent them into the beer to try to do what the original spontaneous culture failed to produce.

End result: Total failure. Dumped.


Sour Mash/Sour Wort


Sour mashing or sour worting is a process of souring wort through the use of the microbes naturally present on grain prior to the boil which will kill off those microbes once the desired level of sourness has been achieved. This creates a bacteria-free but sour wort that can be fermented in equipment without fear of infection from the souring bacteria. There are a number of processes available in the sour mash or sour wort category, each with their own benefits and drawbacks. Like spontaneous fermentation, it is an imperfect process due to the reliance on the unknown assortment of microbes. Rather than controlling the assortment of microbes, these processes control the conditions of the wort to encourage the right assortment to sour the wort with as little off flavor as possible.

With the growing availability of lactobacillus strains for brewing and through probiotic supplements, reliance on grain-based microbes has declined in favor of a more controlled approach. This kettle souring technique has become a popular method of brewing sour beer both at home and commercially. It offers the benefits of sour mashing or sour worting without any of the drawbacks. I continue to use sour worting myself but some of these resources may be useful even for those kettle souring with lab-provided bacteria.

A primer on sour mashing and sour worting - An old but popular post about different techniques to sour mash/sour wort your beer.

Style guidelines for using sour mashing/sour worting - A companion piece discussing some ideas to use sour mashing/worting in different beer styles.

Sour Blending Project


I am a big fan of blending beers and one of my homebrewing goals has been to experiment more with blending sour beer and brett beer. I devised this project using four base sour beers to blend by sharing the sour beers across different oaking regimes using wine and spirits to emulate barrel aging.

Introductory post - Discussing the styles selected for the project and how I selected those beers.
Proletariat - Sour rye pale ale based on Firestone Walker Agrestic.
Belgian Brown - Just like the name says; a middling strength Belgian brown ale soured.
First Year Blending - Blending out two blends from the two base beers and some other notes
Test Pale Ale 1 - Tested out changing the sour rye pale ale recipe with positive results


All Other Mixed Fermentation Recipes


In addition to the lambic solera and spontaneous beer described above, I have brewed a number of other sour beers. These recipes range from classic sour styles to unusual experiments (not all turned out well). They are duplicated on the Recipes page as well. There are also several mixed fermentation/brett saisons on the recipe page.

Brett/Wild Non-Sour Beers

Lucky Pierre - A brett beer primary fermented with brett custersianus and secondaried with brett anomalous
Petrus Aged Pale Clone - Just what the name says


Blended Brett Brown - Initially described incorrectly as an oud bruin this wonderful brown ale is a blend of an actual oud bruin recipe fermented with a Belgian sacc strain and an all brett brewed pale ale. The series of posts include recipes, evolution and blending

Hot Carl 1 - An early attempt at culturing wild yeast
Hot Carl 2 - Attempt #2 culturing wild yeast

Mixed Fermentation Sour Beers

Barrel Aged Americanized Oud Bruin - Small wheat whiskey barrel oud bruin recipe similar to the Rare Barrel oud bruin recipe


Lincoln Logs - A Belgian sour brown ale
Deflated Balls - A sour brown ale made out of leftover grains from other batches
Battery Acid - Sour black ale later blended with a Belgian stout
Ground Cherry Pale Sour - Pale sour beer with ground cherries added in secondary

Sour Mash/Kettle Sour

Yellow Umbrella - Sour mashed blonde ale with apricots
Sour Mashed Kriek - A sour cherry ale soured with a sour mash rather than post-fermentation souring
Midnight Train Going Anywhere - A kettle soured rye Belgian stout

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