Blending is the process of pulling samples of various, matured sour beers (and optionally clean beers), measuring out different proportions of each, mixing them together, and tasting the blended samples. The idea is that different sour beers can contribute different flavors, and balance different flavors. Since precise measurements are required, investing in cheap plastic beakers or a precise scale (0.1 g or better) is necessary. The taste tester should take thorough notes on all aspects of the beer as different proportions of blends are sampled. Note that in the USA, blending beer with wine, mead, or cider (post fermentation blends) is not legal for commercial breweries and may not be legal in other countries as well, although it is legal for homebrewers .
- Chill the samples. Taste them cold, and allow them to warm up to room temperature, tasting and smelling along the way.
- Taste each beer on it's own. Choose the best beers to begin with. Off flavors can sometimes be blended out (see Matt Miller's article below), but consider leaving beers with serious flaws out of the blend.
- Take note of everything you taste and smell, also noting the general temperature of the blend.
- Taste with friends who have good palates.
- A blend may not always taste the same once conditioned and carbonated. Predicting how a blend will taste after aging for a while is one of the most difficult aspects of blending.
- When blending a clean beer with sour beers, allow for additional fermentation to occur. Don't make any assumptions about a low final gravity of a clean beer - the Brett will probably find something to ferment.
- Make use of Michael Tonsmeire's Blending Priming Calculator if possible, or the extended version by Jeff Crane.
- To lower the acidity of a beer with a blending method, use a beer fermented with Saccharomyces and Brettanomyces (and without Lactic Acid Bacteria). You can also add water to cut down on acidity. A very small amount of non-sour beer will greatly reduce the acidity in a highly sour beer because the pH scale is logarithmic.
- Commercial brewers, especially ones who practice Spontaneous Fermentation, will often select barrels that might be bland on their own but express a desired character such as oaky, or acidic, or thick mouthfeel, or bitter, and will select other beers from individual barrels that have the other flavor components that they are looking for to complete the overall flavor profile of the blend. Using this method, individual beers are often seen as a single flavor element of a complete blend .
- A blend might taste different after it has had time to condition and carbonate. Predicting these changes takes experience.
Blending by Weight
Blending by weight allows more flexibility in trial blend volumes and with a good scale it allows finer sensitivity in the amount of each beer added to trial blends. In addition, with the appropriate scale final blending may also be carried out with good precision by weight rather than estimating volumes. Small density differences between beers included in the blend can be ignored because the density range between samples is so small (an FG difference of 1.010 from 1.000 introduces a 1% error). See Dave Janssen's blending spreadsheet for a tool that will convert blended weights into volumes if you prefer to do the final blending by volume.
On a homebrew system, using a luggage scale is useful for weighing out the final blend. Blending can be done in a vessel, preferably one that can be purged of oxygen such as a keg in case there is extra headspace. Weigh the empty keg before hand. Each gallon of beer will weigh around 8.3 pounds (3.76 kilograms). Use the luggage scale (or another type of scale) to weigh out how much beer has been added to the vessel.
Bière de Coupage
Historically the term bière de coupage (biere de coupage) referred to any blended beer, including beers containing sugar syrups, tartaric acid, or vinegar. In the best case it referred to blends of an older, perhaps sour beer, and a fresh beer to achieve a balance in flavors, or to improve head retention and aid in carbonation. The term has been applied to the various blending methods of lambic, specifically lambic and Bière de Mars (Biere de Mars, as well as to Flanders red and brown ales, and 18th/19th century porters . Recently the phrase 'bière de coupage' has been used to refer specifically to the blending of an older sour beer with a younger saison. Examples include Jester King's "Das Wunderkind!" and Salt Lick Pecan Wood Smoked Saison, Paradox Beer Company's "Shoga Kosho Biere de Coupage Farmhouse Ale".
- "Bière de Coupage: Some Background and History," by Amos Browne.
- "Bière de Coupage: Contemporary Versions," by Amos Browne.
- "Bière de Coupage: Kettle Sours", by Amos Browne.
Additional Brewing Articles
- Browne and Bitter, by Amos Browne.
- The Farmhouse Obsession, by Andrew Addkison.
- Jester King Biere de Coupage Process.
- Ale of the Riverwards article on blending a Brettanomyces saison with Wallonian saison.
Online Articles On Blending
- Practical Blending by Brian Hall.
- Blending 101 by Ed Coffey.
- Lambic Solera Update #17 Part 2 -- Three Years (Finally!) by Adam Kielich.
- Blending Out an Off Flavor by Matt Miller.
- Beer Blending Experiment by Michael Tonsmeire.
- Understanding, Brewing, and Blending a Lambic Style Kriek by Matt Miller.
- Beer Blending: Tips from the Pros by Betsy Parks for BYO Magazine, September 2011.
- Blending A Gueuze by Chris Colby.
- Sour, and Funky Mead Making Part III : Blending by David Doucette.
- Blending Red and Brown Sours by Amos Browne.
- Pale Sour Blending by Dave Janssen.
- Sour Beer Blending; Sour Beer Blog by Matt Miller.
- A Guide to Blending Sour Beer With Fruit by Matt Miller.