Brewing Lambic Beer

by Mike Retzlaff

Lambic is virtually a different species when it comes to beer.  It is produced in a very specific area of Belgium and has a “Protected Designation of Origin” (PDO) – an EU “trademark” which protects the name and style.  All others not produced there are considered “Lambic Style Beers.”  The same labeling restrictions are imposed on many French and Italian wines.  Similar designations extend to Kölsch and Berliner Weisse also but I’m unsure how legally stringent these rules are. 

Lambic beers are truly a product of “The Brewer’s Art.”  Attempts to define them and how they’re made are often rather feeble.  Pajottenland is an area between the Zenne and Dender rivers.  Every brewer does things a little differently from the rest and that’s why every Lambic beer is unique. These brewers take advantage of the various wild yeasts and bacteria which come from the air, wooden kegs, and occasionally from the wooden beams on the ceiling of the brewery. This spontaneous inoculation equates to under-pitching and the reason for the “slow and steady” race to completion.

Lambics take a lot of time to produce and are not conducive to instant gratification for a home-brewer.  Fruit Lambics take even longer.  Moreover, if you want to make a Gueuze, you’re not looking at a one shot deal.  Gueuze is generally blended from one, two, and three year old Lambics.  Making Gueuze is virtually a career path.  There are many things that can make Lambic brewing time consuming and difficult but the benefits can be just as glorious. 

If I haven’t scared you off yet and you’re willing to invest a few years of your time, let’s get into the nuts and bolts of brewing a Lambic style beer.  None of this, of course, is the last word on the subject but is offered as a compilation of the highlights of the style and how to brew it.  If nothing else, brewing a Lambic is certainly easier than herding cats.

GRIST – 65% palest pilsner malt – air dried malt or “wind malt” is normal for Belgian brewers but pale Pilsner malt works fine.

35% soft white raw wheat – some brewers go as high as 40%.  Mort Subite is brewed with a blend of wheat and rye.  A bit of advice – if using raw wheat, crush it in a Corona type grain mill.  Raw wheat is not friable and when run through a roller mill will usually just deform and not break into pieces.  The alternative is to run it through a roller mill several times.

Other – It’s best to hedge your bets on the formulation by adding some dextrin malt or crystal malt in a small quantity of up to about 8% of the grain bill.  This ensures that the critters you introduce have something to eat later on in the fermentation.  Some brewers have and do use other grains such as spelt, oats, corn, and rice.  The best quality Lambic beers contain only malted barley and raw wheat.

As a start, I recommend a formulation to achieve between 1.046 and 1.053 OG with 1.050 OG being an ideal target.  Your FG should reach about 1.002 – 1.011.  For home brewing, a good recipe would contain 62% European Pils malt, 32% raw wheat, 3% CaraPils, and 3% Crystal 15 or Crystal 20.

HOPS – see AGED HOPS  – Belgian breweries often use hops grown in Kent, UK and do use Noble hops but they are always aged up to 3 years.  They’ve lost their bittering and aroma qualities but retain the preservative power; the only reason for their inclusion in this beer.  The normal dosage for aged hops is about 3½ oz. per 5 gallons added at the beginning of a 2 to 4 hour boil.  Forget about HBUs.  This convenient calculation is used only for fresh hops and deals with bitterness; it is of no value in Lambic brewing.

WATER – most breweries in the Zenne valley use well water which varies tremendously in composition.  Cantillon, in Brussels, uses ground water for brewing and city water for cleaning.  Many of these breweries use Calcium Carbonate (CaCO3) or Calcium Sulfate (CaSO4) to adjust the hardness.  Unless you have to use R/O because your source water is horrible, don’t really worry about it; just adjust for mash pH.

MASHING – Traditional Lambic brewing is done with turbid mashing.  This specialized mash procedure is rather difficult to duplicate at home.  It can be done but normal mashing methods work just fine.  Some home-brewers substitute malted or flaked wheat for the raw.  There are lots of things you can do differently but it all leads away from the real deal.  If it isn’t made in Pajottenland, it won’t be exactly the same no matter how you make it.  I am of the opinion that the more you deviate from the original plan, the more your beer will deviate also.  However, I will attempt to provide a few methods.

A traditional style mash might consist of using a step or step infusion mash.  Combine the milled raw wheat with about 10% of the barley malt with strike water to achieve 155 to 158oF.  Hold this cereal mash for 15 minutes before bringing to a boil.  Boil for 30 minutes.  While that’s happening, start the main mash by adding the remainder of the crushed grist with strike water to bring the mash to 140oF and rest for 15 minutes.  Carefully add the boiled cereal mash into the main mash to achieve a temp of 158oF.  (Don’t let the main mash exceed that 158oF temp.)  Rest for an hour before heating to 170oF by either direct heat or step infusion and rest for 10 minutes.  Start the lauter and sparge with 175oF water.  If using step infusion, you will have a rather thin mash by this time but don’t worry, that excess water will be driven off by a long boil.

In this case, there is a cereal mash to degrade the raw wheat.  The main mash starts at 140oF to hydrate the malt before the alpha and beta amylase enzymes really go to work.  With that done, the cereal mash is combined for a mash temp of 158oF which will produce dextrins in the wort which are needed later on during the extended ferment.

A modern conventional mash might consist of using flaked or malted wheat instead of raw.  Raw wheat will gelate at normal mash temps so it can still be used.  Mash in the entire grist bill at 140oF and rest for 25 minutes.  Raise the temp to 158oF by direct heat or step infusion and rest for an hour.  Raise mash temp to 170oF, rest for 10 minutes, and start lautering with 175oF sparge water.

BIAB – Yes, this works too!  With little to no variance, follow these procedures – BIAB.

EXTRACT – Yes, you can even make this beer with malt extract.  Not everyone has the facility for all-grain brewing and some A-G brewers use extract anyway.  Use 3# Bavarian Wheat DME (65% wheat), 3# Pilsen DME, and 8 oz. maltodextrin powder.  As with most any extract beer, add some yeast nutrient as insurance.

BOILING – Plan for a minimum 2 hours but this can take 5 hours or more.  Depending on the type of mash you perform, the volume of wort produced will dictate the length of the boil.  The highly sparged traditional wort can be boiled this long without caramelization.  Traditional boil times run from 3½ to 6 hours but some Belgian brewers even use wheat flour in the grist bill which requires a long boil to hydrolyze all of the starches.  Don’t use Irish Moss or other kettle finings.  The organisms you’ll be adding later will use any leftover starches, globular proteins, and free amino acids for a snack later in the fermenter.  

WORT CHILING – I doubt that anyone will build a coolship – a shallow, wide vessel (looks like a giant rimmed baking sheet) in which the wort cools.  It is open to allow the natural yeasts and bacteria to inoculate the wort.  Instead, use an IC, counter-flow, or plate chiller to bring the temp of the wort down to about 65oF.  A slower cooling will lead to excess DMS if you don’t use a much longer boil.

FERMENTING – The various cultures used to inoculate Lambic worts include:

  • Saccharomyces Cerevisiae is ale yeast with numerous strains.
  • Brettanomyces was named for the culture found in English Stock Ales and Barleywines.  There are now several isolated strains available.  It ferments much slower than its cousin Saccharomyces but produces aromas and flavors different than the former.  The main strains used are B. Bruxellensus and B. Lambicus.
  • Pediococcus Bacteria is a lactic acid producing bacteria.  The P. Damnosus strain is the dominant bacterial component in Lambic beer and works very slowly.  It directly converts glucose to lactic acid without producing CO2.
  • Enteric Bacteria includes Enterobacter cloacea, Klebsiella pneumoniae, Escherichia coli, Hafnia alvei, Enterobacter aerogenes and Citrobacter freundii.  They can lead to various flavors described as celery-like, parsnip-like, mushroom-like, smoky or moldy.  These bacteria are generally killed off as the alcohol level rises in the fermenter.  Use of such bacteria should be guarded as possibly dangerous to those with AIDS, those undergoing chemotherapy, and others with suppressed immune systems.  This class of bacteria is the cause of food poisoning and includes Salmonella.  Of course, these bacteria will die in the fermenter but the by-products may contain toxins that some people’s gastro-intestinal systems can’t handle.  As a reference, enterobacters are far more prevalent in your kitchen than in your bathroom.

If you are not relying on a spontaneous inoculation (id est – you don’t live in the Zenne valley around Brussels, aren’t ready and willing to find out if your native flora is up to the task and won’t poison you), what remains is using one of the prepared cultures from a Yeast laboratory.  Some specific strains may be purchased individually but some of these are blends of various yeasts and bacteria.  Keep in mind that most of these organisms are very slow working and may take a year or more to complete their mission.

You can either initially pitch a Lambic blend or simply use something neutral like Safale US-05.  After about a week, rack into another fermenter and add the separate Pediococcus and Brett strains.  Let the temp rise at this point to about 75oF.  You can also add some weighted oak slats (freshly boiled).  Make sure you keep the air lock topped up with cheap vodka or use a blow off tube for the duration. 

After adding the mixed cultures, the beer should be left to finish for several months to a year before bottling.  The fermenting wort may become “ropey” but don’t despair.  When the Brett cultures are fully established, the ropiness goes away.  The beer may develop a pellicle (a floating skin) but it will eventually fall back into the fermenter.  Rack into another vessel and chill in the mid 30’s F for two weeks before bottling.  Some young, unblended Lambics are served un-carbonated from the tap.  If you want some fizz in your beer, add a little fresh yeast (Safale US-05) and priming sugar to achieve 1.0 to 1.5 volumes of CO2.  Give the bottles between 2 months and 2 years to condition.  Remember, the Brett is still working and flavors continue to develop.  (I told you it was a slow process.) 

I don’t recommend the Enteric bacteria but if you carry your balls around in a wheel barrow, go for it.  They can be added by leaving your wort filled fermenter partially covered (partially open?) in your kitchen, near the sink, for a few days.  Then add the yeast which will produce ethanol to kill the enterobacters.

Some commercial strains available are Wyeast 3278 Belgian Lambic Blend  (best blend IMHO) or WLP-655 Belgian Sour Mix.  Omega also offers a blend as OYL-212 Bring On The Funk

Both Wyeast and White Labs offer several pure Pediococcus and Brettanomyces strains but buying the individual packs of organisms can get a bit expensive.

Another thing to consider before engaging in this quest is to realize that these critters, which transform sweet grain juice into a quaffable beverage, get into everything.  Most of the wild stuff we might have lurking in our brewhouse is also in the air and on virtually every surface around us.  If you get started with Lambic style beers, more intensive sanitizing routines should keep these exotic flora in check and out of your other beers. 

The same thing applies to acetobacters which are the bugs which turn alcohol into vinegar.  Being far more aggressive, don’t even consider making vinegar where you brew!

If you’ve got the time, a curious nature, and an extra ferment vessel, give it a shot and see what happens!

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