Originally Published by Jim Liddil and Martin Lodahl in Brewing Techniques (Volume 5, Number 3)
Part I —Wort Preparation
Lambic represents an irresistible challenge to many beer aficionados’ most deeply ingrained beliefs about brewing. With the advent of commercially available wild yeast and bacteria cultures, home and professional brewers can now emulate the style away from its Belgian home.
In recent years, interest in Belgian lambic has grown to an extent few predicted. Even such relatively mainstream publications as Scientific American have carried articles on lambic, and a 1995 BrewingTechniques article on the style won a gold medal for beer journalism. The fact that true lambic can be made in only one area of the world gives it an air of mystery, but this limitation has unfortunately also contributed to the style’s near-extinction. Not only is its production area limited, but changing economic markets and shifting consumer preferences in its home region are bringing changes to the techniques and markets of some of Belgium’s traditional breweries.
With the commercial availability of “wild” yeast and selected bacteria cultures, however, it is now possible to brew lambic-style* beers anywhere in the world. This article is the first of three installments on brewing “authentic” lambic-style beers at home. This first part provides an overview of the beer and traditional lambic brewing methods and outlines various methods for preparing lambic-style wort for fermentation. Part II will focus on the mysteries of lambic-style fermentation, and Part III will cover conditioning, blending, packaging, and other miscellany.
*I refrain from using the word “lambic” to describe any beer made outside Belgium. True lambic is only made in a small area outside Brussels (though one American commercial brewer might have you thinking otherwise). I prefer to use the term “lambic-style” to describe similar beers made by home brewers. On the internet discussion group Lambic Digest, you can see the term “plambic” used, in reference to pseudo-lambics. The point is that real, true lambic can be made only in Belgium, the only place in which the unique wild yeasts that ferment lambic wort can be found in just the right balance.
The Anachronisms of Traditional Lambic
Lambic is defined by Belgian law and further protected by a European Union ordinance established in 1992 and by an appellation contrôlée from the European Beer Consumers Union (5). Belgian law defines lambic as spontaneously fermented ales made up of a grist of at least 30% unmalted wheat. Many additional idiosyncrasies combine to the make the style what it is.
Incompletely converted mash: Turbid mashing is the most traditional of lambic brewing techniques. It is similar to decoction, except that it involves removing and boiling liquid (rather than grain) portions of the mash. Unlike more mainstream mash methods, turbid mashing results in large amounts of unconverted starch in the finished wort.
Oxidized hops: Whereas most brewers want only the freshest of hops, lambic brewers rely instead on hops that have been stored in the open for 2–3 years until thoroughly oxidized and leached of their bittering properties. Old hops retain properties that allow lambic brewers to tame some of the beer’s “wildness” by controlling certain bacteria.
Intentionally “infected”: Lambic worts are not pitched with a pure strain of yeast, but are instead allowed to cool overnight in open cool-ships — large, shallow basins that maximize surface area for heat transfer and exposure to the air. During the night the wort is inoculated with wild yeasts and bacteria that waft in through open windows. Lambic breweries typically only operate from about October to May due to lambic’s dependence on naturally occurring microbes, which can get out of hand during the summer months.
No stainless steel: The inoculated wort is fermented not in stainless steel vessels, but in old, unsanitized oak casks (pictured below). Some American home brewers intentionally infect their own casks to help authenticate their lambic-style ales.
Generously aged: Freshness dating will never be an issue in lambic circles. Lambic production is slow; it involves a period of fermentation and aging as lengthy as that of wine (one of the reasons lambic is considered a footbridge between the worlds of wine and beer).
Blended to taste: Lambic brewers manage the ever-changing flavors of aging lambic by blending old and young batches. Often sweeteners or fruit are added to subdue some of the lambic tang; sweetened or blended variants are regarded as styles in their own right:
Faro. A sweet, light table beer made by sweetening blended lambic with dark candy sugar and caramel.
Gueuze. A sparkling, fruity beer made by blending young and old lambic and then filtering and bottle-conditioning the mixture to achieve a naturally carbonated effervescence similar to that of champagne.
Fruit lambic. Made by re-fermenting young lambic with whole fruit (cherries, strawberries, peaches, grapes, etc). The fruit/lambic blend is generally matured for several months and then bottle-conditioned with another addition of young lambic.
The fascinating history of lambic has been covered in depth elsewhere by authors such as Martin Lodahl, Michael Jackson, and Jean-Xavier Guinard, and I will not revisit it here. Instead, I will attempt to decipher the lambic brewing process from a scientist’s perspective and translate it to a home brewing scale. This article represents a condensation of material gleaned from research papers and dissertations from Belgium, books and articles written by various other authors, personal accounts from people who have been to lambic breweries, postings from the internet’s Lambic Digest, and my own personal experiences. All aspects of the process of lambic production — from wort production to fermentation to blending and bottling — are included in the hope that this article may help other brewers in their attempts to understand and make authentic-quality lambic-style beer.
A Style from Another Era
Some might say I live for lambics. As one of my favorite quotes from Michael Jackson says, “The lambic family are not everybody’s glass of beer, but no one with a keen interest in alcoholic drink would find them anything less than fascinating. In their ‘wildness’ and unpredictability, these are exciting brews. At their best, they are the meeting point between beer and wine. At their worst, they offer a taste of history”.
Lambic is the product of some of the most idiosyncratic brewing methods in the world. Its production calls for unmalted wheat, old hops, and years of fermentation with wild yeasts and bacteria conducted in unsterile oak casks. Lambic stands out among today’s brewing standards more than ever as beverages of utterly unconventional, antiquated, and pretechnological charm.
Unfortunately, the beer’s artisanal appeal has not been fully embraced outside of connoisseur ranks. People are often shocked by the extreme flavor profile of real lambic or by the lengths required to recreate the style. Too often people immediately dismiss the beer as undrinkable and infected without really “tasting” it — not unlike the reaction of a hard-core Budweiser drinker tasting a Chimay for the first time. Even in the style’s backyard, shifts in locals’ tastes threaten the very existence of such treats as Cantillon Rose de Gambrinus or a Boon vintage-dated Mariage Parfait. With care and patience, however, the style may extend its native boundaries and thrive, in an adapted form, in the kitchens of dedicated home brewers.
Psychic Preparation for Lambic Brewing
Making a lambic-style beer at home can be as simple as boiling up some extract and hops and adding a few yeast and bacteria cultures. Or you can go to the extreme and use traditional turbid mashing schedules, spontaneous fermentation, and oak casks. As home brewers we have many choices; we do not have to follow tradition to the letter. Most of us do not live in Belgium, nor have we been making beer by this method for hundreds of years. Besides, innovation and creativity are the hallmarks of home brewing.
Based on my experience, however, the one key ingredient is time. No matter what recipe you follow, you can’t expect to have a product of character similar to any of the real lambic beers within a few weeks or even months. To do it right, you really need to wait at least a year before even bottling your beer or adding fruit to it, then another year or more while it further conditions in the bottle. (My Wild Pseudo-Lambic ale, which won the gold in the AHA’s national homebrew competition in 1994, was a year old when it was judged.)
Many brewers expect that they will have a product that is ready to bottle within a few months, and ready to drink within another few weeks. I have seen internet discourses, recipes from the AHA National Homebrew Competition, and even Jean-Xavier Guinard’s book perpetuating the belief in unnaturally short fermentation schedules.* Having spoken with Dr. Guinard, I realize that he and his publishers knew that few home brewers would even think about buying a book that had recipes suggesting the beer be allowed to ferment for a year or two and then undergo bottle conditioning for another year or more. Most brewers who have tried to make pure-culture lambic-style beer will agree that these published fermentation schedules are far too short to achieve a product with a character truly similar to the real thing.
Jean-Xavier Guinard’s Lambic describes all aspects of lambic beer and brewing, including its history, its traditional production processes, and the breweries that still produce the style. It also goes into a fair amount of detail in outlining the microbiology of spontaneous fermentation and describes methods for making a pure-culture lambic-style ale at home. The information in the book is accurate and concise, with the exception of a few minor details (for example, I have yet to find a reference that indicates that Kloeckera apiculata have any proteolytic activity as described in the book). Those of us who have pursued this type of brewing have found the book to be an invaluable resource and an excellent stepping stone. I highly recommend Lambic to anyone considering making pure-culture lambic-style beer.
Just keep in mind that there is no such thing as “instant” lambic-style ale. The microorganisms used to ferment lambic grow very slowly and are equally slow at producing the flavor profile that gives the style its true depth of character. You cannot buy a kit or follow some recipe in a homebrew shop catalog and end up with a well-balanced, complex product of true Belgian character. Your beer is not going to develop Brettanomyces character or the proper acidity in a few weeks. It will not become a melange of flavor after two weeks in the bottle. The path to the Holy Grail may well take a lifetime.
Most important, understand that success is to a large degree a matter of chance and that you may fail, even after investing a great deal of time and effort into your beer and after following all the procedures meticulously. You can use traditional mashing techniques, use all the right ingredients, and add all kinds of wild yeast and bacteria, ferment in a cask for years, and still end up with an utterly disappointing product.
There is little you can really do to change what ultimately happens in the fermentation vessel. Either the beer will develop the classic Brettanomyces pellicle (film), ropy mouthfeel, and character — or it will not. Your beer may end up so acidic you will want to use it for cleaning calcium deposits off of your brew kettle, or it may be so mild that it barely passes as infected beer. Even after bottling, lambic-style beers can undergo large changes in flavor.
These precautions should not be taken as discouragement from brewing this most challenging beer style. These are merely the facts of lambic life. Belgian brewers manage this level of variability and uncertainty by strict adherence to traditional methods and by what may seem like a bit of a cheat — blending. All lambics are variable, and the art of successful commercial lambic brewing is in blending various batches to create a balanced, complex, and pleasing flavor profile.
My warnings are done. With a bit of effort and patience, anyone can produce a reasonable lambic-style ale in the home setting. What follows is a studied and emphatically positive account of lambic-style home brewing.
The grist: A lambic grist is usually composed of Pils-type barley malt mixed with 30–40% raw wheat. The most traditional method of working with the grain in lambic brewing is called turbid mashing. Turbid mashing is a time-consuming and labor-intensive process that was devised to effectively break down the proteins in ungelatinized raw wheat while leaving a good supply of starches and free amino nitrogen for the yeast and bacteria to feed on during the long fermentation. Home brewers, however, have various forms of wheat available to them, many of which can simplify the procedure greatly. The box, “Types of Wheat Available to Home Brewers,” describes the options. You can decide for yourself what works best in your brewery.
Types of Wheat Available to Home Brewers
Lambic-style recipes call for wheat as 30–40% of the grist. Traditional lambic brewers used raw wheat, which requires a complex mashing method to break down its proteins while leaving a good supply of starches and free amino nitrogen for the yeast and bacteria to feed on during the long fermentation.
Wheat is available to home brewers in various forms, including whole wheat berries (hard red or soft white varieties), flaked or rolled wheat, and malted wheat. The form you choose will likely be based on the equipment you have and how traditional you want to be in your recipe formulation.
Like any adjunct, wheat must be precooked somehow before mashing to gelatinize, or disperse, its tough starches so that the enzymes can work on them. Turbid mashing is one means of accomplishing this goal. You could, of course, pregelatinize your own raw wheat (see the “traditional turbid mash” and “shortcut mash” discussions in the Wort Preparation section of the main text).
Crushing raw wheat: If you work with raw wheat, you will have to deal with crushing it. Raw wheat is not friable because it has not yet been malted or kilned; it therefore has a tendency to squish rather than crush, making it difficult to mill, even with a roller mill. Running the wheat through a roller mill several times will help reduce it to fairly small particles. This is one instance in which a Corona-type mill (designed for grinding rather than crushing) may have an advantage over any of the various roller-type mills available. Because wheat has no husk, grinding it into a fine powder is not a problem.
Wheat flour: A few individuals have replaced the wheat fraction of the grist with whole wheat flour without encountering any problems with stuck mashes or slow runoffs. Of course, as they say, your mileage may vary. Whether or not this will work for you will depend on your mashing and lautering setup and your level of experience. If you feel adventurous, give it a try.
Rolled, Flaked, or Malted Wheat
Guinard suggests flaked or rolled wheat or malted wheat as alternatives to raw wheat (4). Wheat flakes and rolled wheat are pregelatinized, which makes for a less time-consuming mashing procedure. These forms of wheat can be found at most homebrew supply stores and often at natural food stores or cooperative markets, along with raw wheat of either the hard or soft varieties. Malted wheat also simplifies the mashing step and is usually readily available through most homebrew stores.
The mash: Whatever you choose for the grist, the goal is to produce a wort that is high in amino acids and dextrins and light in color. You can achieve this composition in a few different ways, from simple extract brewing to the complex traditional turbid mash method. Whether or not a turbid mash is required to achieve optimal flavor is a matter of debate, and not all lambic brewers use this method. However, two of the most traditional breweries, Boon and Cantillon, do.
The extract option. Tradition is nice, but you can make lambic-style beers even if you are not an all-grain brewer. The simplest approach to making lambic-style ale is to use dry or liquid malt extract. Since you need extra amino acids and dextrins in the wort to support the long fermentation, you may consider using an extract meant for making wheat beer. These are typically made from 60–70% malted wheat and are readily available. My prize-winning 1994 lambic-style beer was made using a wheat-based extract produced by Briess Malting Company called CBW Bavarian Weizen. If you wish, you can also blend 100% wheat extract with malted barley extract to achieve the traditional 30–40% wheat content.
If you use extracts, get the freshest extract possible and boil for a full hour to maximize the extraction of the hop antiseptic compounds and to precipitate the excess proteins in the extract. The main problems with extracts as a whole are that they generally produce beers darker than equivalent all-grain beers, and the extracts themselves may be somewhat nutrient deficient.
The all-grain option. If you are an all-grain brewer, you can use malted, flaked, or raw wheat in your mash and choose from a variety of mash routines. Probably the simplest grist comprises 30–40% malted wheat — which is easier to mill than raw wheat — with the remainder being two-row Pils or lager malt.
The grain can then be mashed using a single-step infusion in the 150–155 °F (65–68 °C) range to produce a reasonably dextrinous wort that is also very light in color. Or you could modify the mash schedule by using a step mash or decoction mash of the type outlined by Eric Warner. Warner’s technique helps break down the excess wheat proteins and provides the extra amino acids needed by the various yeast and bacteria. One problem, though, with such an intensive mash schedule is that it can lead to too much breakdown of the dextrins in the grist and thus too little carryover into the wort.
If you choose to use raw wheat, you have several options that traditional brewers didn’t have. Using pregelatinized flakes, or pregelatinizing the wheat yourself before the mash (see the “shortcut” mash method, below), can allow you to stick to simpler mashing techniques.
The traditional turbid mash. The goal of the turbid mashing procedure is to break down the larger proteins of the raw wheat and malt into free amino acids and to produce a wort high in dextrins and starches. The process of turbid mashing is somewhat like inverse decoction mashing; it involves removing the liquid portion of the mash, boiling it, and then reintroducing it to the whole mash (in decoction, the grain is included in the removed portion). This process of removing, boiling, and returning is repeated a number of times until the mash reaches saccharification temperature. After a two-hour saccharification rest, the wort is run off and the grains sparged with near-boiling water. The whole process is followed by a 4- to 5-hour boil that reduces the large volume of liquid, precipitates the excess proteins, and bursts any suspended starch granules.
A Scaled-Down Mash Schedule from Cantillon Brewery
The following is a homebrew-scale version of the Cantillon Brewery’s (Brussels, Belgium) turbid mash schedule. Based on the information presented in Martin Lodahl’s article (2), the Cantillon Brewery gets about 33–34 points/lb/gallon. The Cantillon grist is composed of 34% raw wheat and 66% malted barley. The recipe is scaled down here to yield 5 gallons of wort with an original gravity of 1.048 (11.86 °P), or 5 x 48 = 240 points. If we assume we will get 30 points/lb/gallon, then 240 ÷ 30 = 8 lb of grain. The barley malt fraction is 66% of 8 lb, or 5.3 lb of malt, leaving the remaining fraction of raw wheat at 2.7 lb.
The Cantillon schedule calls for mashing 1,300 kg of grain into 850 L of water (2,860 lb grain into 900 quarts water), or 3.2 lb grain/qt water, or 0.3 qt water/lb grain. Our 8 lb of grain therefore requires 8 x 0.3 quarts, or 2.4 quarts of water.
In all of the following steps, the temperature and water additions were taken directly from the Cantillon schedule as published and scaled accordingly.
A test batch using this method yielded a wort with an original gravity of 1.040 (9.97 °P). At about 25 points/lb/gal, the mash efficiency was not as high as that obtained at Cantillon, but the yield could probably be improved by extending the times for the various rest steps. It may also be a good idea to heat the liquid withdrawn from kettle #1 each time at a very slow rate. To play it safe, you may want to start out with a larger grain bill based on the more conservative yield of 25 points/lb of grain. Clearly, your own results will vary with your methods and equipment.
The Boon turbid method. A simplified turbid mashing method was proposed by Frank Boon of Brouwerij Frank Boon (a lambic brewer and gueuze blender based in Lembeek, the town south of Brussels that is considered the Tigris-Euphrates of lambic). Boon suggested mashing in at around 86 °F (30 °C) using as little as 0.5 quarts water/lb of grist. The mash can then be stirred and the milky wort run off and boiled for a few minutes. In the meantime, Boon recommends adding fresh water to the grist and performing a step mash of the brewer’s choosing. After the stepped mash reaches the 140 °F (60 °C) range, the boiled, milky wort is added back to the mash to raise the temperature to the saccharification range. Once this rest is completed, the wort can be run off and the grain sparged. This method also produces a large volume of liquid, again requiring the suggested 5-hour boil.
The “shortcut” mash. An even easier route would be to grind the raw wheat and then gelatinize it before adding it to the mash.
First, add water to the wheat at the rate of 1.5–2 qt/lb, then add 10% of the malted barley and heat the mixture to the 150 °F (65 °C) range, letting it stand for 15–30 minutes to allow the enzymes in the malt to act on the wheat starch and to aid in their hydration.
After the temperature rest, heat the whole mixture to boiling with constant stirring. Feel free to add more boiling water as the mixture begins to thicken. Be sure not to heat it too fast or stop stirring, or you will have a big, gummy, burnt mess.
After it has boiled for 15 minutes, add it slowly to the main mash (I prefer to have the main mash at 100 °F [37 °C]), stirring so as not to raise the temperature of the mash too quickly or unevenly. The temperature will settle in the 120–130 °F (49–54 °C) range, depending on the volume.
Then begin gradually to heat the entire mash to the various step temperatures.
A faster step schedule would be to rest at 130 °F (54 °C) or so for 15 minutes, raise the temperature to 145 °F (63 °C), hold it there for 15 minutes, and then raise it again to 152 °F (67 °C) and hold it for another 30 minutes, followed by mash-out and sparging.
The sparge: The sparging of a lambic mash is typically carried out with water that is hotter than customary sparge temperatures, usually close to 190 °F (88 °C). This temperature helps to extract dextrins and unconverted starches from the mash. The process extracts tannins from the malt as well, but these are precipitated out or broken down over the long fermentation cycle and do not contribute any significant astringency to the finished beer.
The use of hotter-than-normal sparge water is particularly important if you follow a true turbid mash–type schedule because of its poor conversion. Bear in mind that in conventional beer production, you do not want starches and tannins extracted into the wort, but in lambic brewing they are needed to support the long fermentation process and will ultimately be used by the yeast and bacteria. Without these usually undesirable products, the lambic organisms may not thrive, and the finished beer may not have the right flavor characteristics.
The boil: The boil should be vigorous and last 1.5–2 hours or longer, depending on the initial volume of the wort. The boil serves a number of functions, including the precipitation of excess proteins from the wheat and the reduction of the volume of liquid collected. The long boil in lambic brewing makes Irish moss or other clarifying agents unnecessary; any excess proteins that may remain in solution will either be used or precipitated during the lengthy fermentation process.
Hops: The hops used in lambic production should be aged for one to three years, to the point at which they have lost all of their bittering power and so do not detract from the acidic, pungent character of the beer. According to Dr. Roger Mussche of Destelbergen-Heusden, Belgium, aged hops also contain tannins that give lambic its dry, astringent taste, and antioxidants from hop resins allow the lambic a longer shelf life and help control levels of undesirable Gram-positive bacteria such as Bacillus, Sarcina, Streptococcus, and others.
The varieties typically used are of the low to medium alpha-acid range, such as Hallertauer, Tettnanger, or Brewers Gold. Almost any hop variety will do, though, with the exception of high alpha-acid varieties such as Chinook, which tend to retain bittering power and intense flavor even after long aging.
The aging process. Home brewers have a couple of options for achieving the effect of aged hops. Once again, you’ll have to reverse everything you’ve learned about hops and the importance of keeping them fresh.
One strategy is to buy fresh hops and leave them out at room temperature for a year or two, but this requires planning and is not convenient for the beginning lambic-style ale brewer. You or a friend may have some old hops that you just could not part with but that have never been used, and if these are old enough they may serve the purpose. Newer hops can be heated at low temperatures (<200 °F [<93 °C]) on a cookie sheet for 4–5 hours. The idea is to heat the hops until all of their aroma has been driven off. Be aware that the smell may not be one that others find pleasant.
As hops age they take on a very pale green to yellow color and lose all aroma; the lupulin in whole hops turns from yellow to orange-brown. They also go through a stage of smelling rancid and cheesy. This smell is unpleasant, so it is best to leave them in a well-ventilated area.
I have found that leaving hops outside in the Arizona summer sun for a week or two seems to do a very good job of aging them. And if you have a total aversion to “ruining” perfectly good hops you may be able to purchase end-of-the-year hops at a reduced price from your local homebrew shop or from one of the many homebrew mail order supply companies. Alternatively, the herb departments of many natural food or cooperative stores stock hops that are usually well-aged and devoid of aroma with well-oxidized lupulin glands.
Whether you choose to use whole or pellet hops does not seem to matter as long as the hops are well-aged. Both forms can be used alone and together, depending on what’s on hand. Crushing the pellets into powder will help to enhance the oxidation process. You may want to put the hops into a container with a fine mesh cover of some sort and shake the container every once in a while to enhance oxidation.
Next Step: Fermentation
The selection of hops is the last stage of the lambic brewing process over which you have a reasonable degree of control. Once your lambic-style beer begins the fermentation process, you have no option but to dig in and let the microorganisms do their work. Part II of this article will enter the world of lambic fermentation, starting with the principles of wort cooling and continuing with a map of the microbiological terrain of the lambic fermentor.
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