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Brewing Belgian styles, part 4: yeast and fermentation

In this series we have examined Belgian beers, the various styles and their ingredients. And an interesting picture emerges: while these wonderful ales are like nothing else and form a class of their own, their ingredients are nothing special. Granted, the brewing grains should be of the highest quality, but they're nothing special. And while the use of dark sugars in some Belgian styles to add complexity is not all that common elsewhere, it's not unique either, especially not in some traditional English ales. The use of European noble hops is also not exactly restricted to Belgium alone.

So what makes these glorious beers stand out so much? The answer is simple: it's the yeast.

If you were to brew a Belgian ale with, say, an American ale yeast, the resulting beer would probably be a good beer, provided its gravity would be on par with what the yeast can handle and alcohol balance would be a sensible one for such a beer. But it would not be a Belgian ale by any stretch of the imagination. For that you need a proper Belgian yeast.

It should be noted that all yeasts produce a wide range of fermentation products. The most well known of these are, of course, alcohol and carbon dioxide gas. But if these were the only fermentation products, all we would taste in a beer would be malt and hop notes, and most beers would be rather uninteresting. Fortunately, all yeasts produce a certain amount of other compounds as well: diacetyl (which has a buttery or honey-like flavour), dimethyl sulphide (reminiscent of cooked vegetables), acetaldehyde (cidery, like green apple) and what not. In some beers these are undesirable flavour components, in other styles they are essential, but by and large these all play a minor role in the beer. Far more important groups of chemicals are the esters that produce a variety of fruity flavours and sometimes for bubblegum or other candy aromas, and the volatile phenols which create a wide range of spicy notes ranging from pepper to cloves. It is here where Belgian yeasts stand out.

Unique traits

A closer look at classic Belgian ale yeasts reveals a few characteristics that few other yeasts have. To the microbiologist their unique character immediately becomes clear under a microscope: the cells have a different cell wall and a smaller surface area than other beer yeasts, and taxonomic studies have revealed that Belgian yeasts have a lot in common with wine yeasts and almost certainly have some wine yeast in their ancestry. (While asexual reproduction by means of budding is beer yeast's preferred mode of propagation, yeast is capable of exchanging genetic material under certain conditions.) This may be of passing interest to the brewer, but the question of how the yeast behaves during fermentation is of course much more important. So let's look at how these unique traits translate into brewing.

Firstly, Belgian strains are very robust yeasts with a remarkably high alcohol tolerance. Alcohol is essentially toxic to yeast. If the alcohol levels in a beer rise to more what the yeast can handle, the alcohol will inhibit further fermentation. But while a typical regular ale yeast throws in the towel at eight or nine percent of alcohol by volume, a Belgian ale yeast merely laughs at such a piddly brew and happily ferments a beer up to 15% or even considerably more.

Belgian yeasts also exhibit a more than common degree of yeast growth. Per amount of wort fermented, Belgian yeast strains tend to produce more new yeast cells than any other yeast. In fact, many traditional Belgian brewers routinely remove a portion of the yeast during the fermentation to prevent it from getting out of hand, and in a home brewing situation it is not uncommon to have a layer of Krausen (which is mostly yeast) floating on top of the beer that is so thick and solid that it could be used to pave your driveway with. Incidentally, this thick paving tile of yeast, which is sometimes so dense it has the consistency of putty, protects the beer from oxidation and infection, which makes it particularly suited for use in traditional open fermenters. Because an open square fermenter allows the yeast to get rid of its carbon dioxide gas more than any other fermenter configuration and because carbon dioxide inhibits the formation of fruity flavours to some extent, this allows for the production of beers that are particularly fruity. While most commercial breweries have replaced their old open fermenters with modern stainless steel conical tanks in order to obtain better microbial control, this does reduce the amount of fruity flavours in the beer, which is why some traditional brewers still prefer the medieval open fermentation style.

Another particular property of Belgian yeasts is that they don't seem to be afraid of sucrose. Many brewers prefer not to use too much (or any) sucrose (i.e. table sugar) in their worts, because this can easily lead to "cidery" flavours in the beer. However, Belgian yeasts seem far less prone to creating such off-flavours even when the wort contains 20% or so of sucrose.

Belgian yeasts also have a tendency to produce higher alcohols in significant quantities. While ethanol (generally known as consumption alcohol) is the type of alcohol that brewers aim for, higher alcohols may also be produced in the course of the fermentation. In fact they usually are, because all yeasts do produce a certain amount of higher alcohols as a matter of course, but Belgian yeast strains are particularly good at it. Compounds like n-propanol, amyl and isoamyl alcohol, phenyehtyl alcohol and even propyl alcohol (i.e. cleaning alcohol) are regular fermentation products when a Belgian yeast is at work. The amount of these higher alcohols is dependent on fermentation temperature. Too many higher alcohols in the beer are a problem, because they give the beer a "hot" alcohol aroma and a solvent-like character that is more appropriate for nail polish remover than for a beer. Higher alcohols are also a prime ingredient of hangovers. Unwanted higher alcohols are generally known as fusels but in Belgian ales a small amount of these alcohols is essential because they are an important part of the complex flavour of the beer. Therefore in Belgian ales these higher alcohols are generally not referred to as fusel alcohol but simply as higher alcohols. That said, while a certain level of higher alcohols in these beers is a good thing, too much higher alcohol (even by a little bit) is not.

Fortunately Belgian yeasts are also particularly good at converting these higher alcohols, along with some other compounds, into the esters that give these ales their characteristic fruity flavours. A good Belgian fermentation, therefore, converts almost as much higher alcohol into fruity esters as it produces. These esters are an essential part of the characteristic flavours and complexity that make Belgian ales so special. Apple, pear, tangerine, plum, fig, raisin, strawberry, pineapple and perfumy rose are all aromas and flavours that play a role in the character of a Belgian ale. And the list doesn't stop there: literally hundreds of these esters have been identified so far.

Phenols and the POF gene

While fruity flavours are one thing that Belgian ales are known for, the other is the characteristic presence of spicy notes. While some Belgian ales are aromatized with small amounts of spices, this is less common than many people think. Instead the spicy character of these beers mainly comes from the yeast, which produces them in the form of volatile phenols. Phenols are a group of chemicals known for their aromatic quality, and in fact many of these occur naturally in spices and other aromatic foods.

Phenols are aromatic organic compounds. They occur in a wide variety, from disinfectants to plastics to natural flavour compounds in food. In most beer styles the formation of phenols during fermentation is considered a bad thing to be avoided at any cost. Phenols, especially polyphenols, are usually formed from substances occurring naturally in malts and hops, but other factors may play a role as well. The most well-known undesirable polyphenol is known as trichlorophenol (or TCP for short) which is formed if traces of chlorine compounds (from chlorinated tap water or from cleaning and sterilizing of brewing equipment) end up in the beer. Tannins extracted from the husks of over-sparged grain or finely ground grain husks (both of which are incorrect brewing practices) are also notorious for ruining a beer, and tannins belong to the group of phenols as well.

These phenols tend to create off-flavours and aromas reminiscent of hospital bandages, improperly pickled olives and disinfectant, and produce an astringent, puckering mouthfeel. They can completely ruin a brewer's day.

But not all phenols are bad. Capsaicin in chili peppers, methyl salicylate in wintergreen and thymol in thyme are all examples of beneficial phenols that give these foods their desirable flavours. So it is not surprising that in some beers phenols are absolutely essential. The most well known example is the spicy clove-like flavours that German Weizen is known for (along with banana which is a fruity ester) but Belgian ales would not be what they are without the presences of certain volatile phenols.

Where phenols are concerned, yeasts essentially come in two categories. One type of yeast has a gene that enables it to produce phenols, the other doesn't. The gene responsible for the yeast's capability to produce phenols is known as the POF gene. POF stands for Phenolic Off Flavours" which is essentially a misnomer, based on the fact that most research on phenol formation was initially focused on lager brewing and completely ignored the fact that phenols are not off-flavours in styles where they are desirable.

Yeasts that are genetically incapable of producing phenols, such as English and American ale yeasts or lager yeasts, are known as "POF negative" strains (often written as POF-) while those that do produce phenols, e.g. German Weizen and Belgian ale yeasts, are known as "POF positive" (POF+) strains.

Traditional Belgian ale yeasts are, by and large, all POF+ strains. This genetic trait probably comes from the wine yeast that is part of the Belgian yeasts' ancestry, although it may also have been "imported" from one of the wild yeast strains that are still being used in the brewing of certain traditional Belgian ales. (Most wild yeasts are also POF+.) The domestication of yeast strains over the centuries have almost certainly promoted the more desirable phenols over the less flavourful ones (by selecting those yeast varieties that produce a good flavour and discarding the ones that don't) and these days Belgian ale yeast strains are known for their spicy character.

While German Weizen yeast strains are known for creating a volatile phenol that gives the beer a clove-like spiciness, Belgian yeasts don't stop there. Next to cloves they produce a wide range of spicy flavours including but not limited to pepper, cinnamon and smoky accents. And that is not all: spicy phenols may interact chemically with a variety of fruity esters to produce a variety of new flavours that would not be possible with either fruity esters or phenols alone, and thereby create a flavour more complex than what is found in any other beer.

Spicy phenols are formed from compounds present in the grain and hops, and are not a factor of fermentation temperature, oxygenation or other fermentation factors. However, these fermentation factors do have an effect on the formation of fruity esters, which help to balance out and/or mask the spicy phenols. So while the amount of spicy phenols is more or less constant (being mostly a factor of yeast genetics) the fermentation will affect how they come through on the palate.

Brewing a Weizen usually involves an additional mashing rest to promote the formation of ferrulic acid, which is a compound derived from the grains (mainly the wheat) that is essential to the formation of the clove-like flavours in Weizen. In the brewing of Belgian ales such a rest isn't common. Most traditional Belgian brewers use a simple, single-infusion mash (usually fairly cool in order to promote wort fermentability) and then leave the production of phenols to the yeast. Only Belgian beers brewed with significant amounts of wheat sometimes undergo a special rest during the mash which promotes the formation of clove-like flavours.

The secrets of Belgian fermentations

Unsurprisingly, yeasts with such a special character do call for a bit of proper care in order to do their best work. There is nothing complicated about fermenting Belgian beers, but since we're not dealing with your average lager or American ale here and given the fact that Belgian beers are essentially created in the fermentation, a few basics should always be observed.

  1. Always start the fermentation cool. The formation of higher alcohols is a product of fermentation temperature. If the fermentation starts too warm, even at the low end of the yeast's recommended temperature range, too many higher alcohols will be formed early in the fermentation, and not all of these will disappear later in the fermentation during the formation of fruity esters. This results in a beer with a "hot" and solvent-like alcohol character. Starting the fermentation cool helps to prevent this. Many brewers actually pitch Belgian yeasts well below the minimum fermentation temperature and let wort slowly come up to the low end of the fermentation temperature range.
  2. Keep the temperature in check. When yeast ferments sugar into alcohol, it essentially digests the sugar. This produces heat, just like the digestion of food keeps the human body warm. Since a Belgian wort can have a very high starting gravity, the fermentation temperature can easily spike as a result of the massive amount of fermentation taking place. This in turn makes the yeast even more active so the fermentation accelerates even further, producing even more heat. This chain reaction continues until the temperature spirals out of control. Keeping the temperature down through cooling and thereby limit the speed of fermentation prevents this. (That said, some Belgian yeasts in some types of wort don't even blink when the temperature exceeds ridiculous levels and still produce a fine beer. However, prevention being worth a pound of cure, most brewers don't want this to happen, in the interest of product consistency if nothing else.)
  3. Raise the fermentation temperature gradually. Ramp up the fermentation temperature in a slow and controlled manner (e.g. half to one degree per day) until the high end of the yeast's temperature range has been reached, and keep it there. Too low a fermentation temperature may lead to an incompletely fermented beer. However, don't raise the temperature too quickly, because this will create too many higher alcohols and fruity esters.
  4. Do not lower the temperature during fermentation. If the temperature exceeds what is desirable, the logical thing to do is to crank up the cooling until the temperature drops. The problem with Belgian yeasts is that they hate this and tend to "crash". They stop fermenting, drop out of suspension and can't be roused again. The only solution at that point is to pitch new yeast. So if the temperature rises too far try to keep it from rising further but don't lower it. Just letting the yeast go is the lesser evil at this point. However, when a yeast "goes over the top" there is often little one can do to save it, and pitching fresh yeast is the only option to continue the fermentation.
  5. Give it time. While the initial fermentation will usually proceed at a fairly normal pace, Belgian yeasts often take a lot of time to complete the fermentation and can have a tendency to slow down as the fermentation progresses. It is not unusual for a Belgian yeast to take 80% of the time to perform the final 20% of attenuation. In a Belgian fermentation is it also not uncommon for the conditioning phase to take twice as long as the primary fermentation. Many commercially brewed Belgian beers spend a week in primary fermentation followed by two weeks or even more of conditioning before being transferred to the next stage of the process (which is usually bottling or tank maturation).
  6. Pitch yeast generously. While pitching enough yeast is always a prerequisite for a good fermentation and the amount of yeast pitched per volume of wort should always be a factor of wort gravity, Belgian fermentations can benefit from even higher pitching rates. While normal pitching rates can work, there is a risk that the yeast won't complete the fermentation (Belgian yeasts do tend to slow down as the fermentation progresses, see above) and having lots of yeast cells on the job helps to ensure a complete fermentation. Belgian yeasts are also prone to creating high levels of esters, and high gravity worts also promote the formation of esters. A generous pitching rate helps to keep the esters in check. Higher alcohols are also created in larger quantities at lower pitching rates, and more higher alcohols increase the perception of esters, especially banana flavours, so in order to prevent a "hot" alcohol character make sure to pitch enough yeast.
  7. Provide enough oxygen. Belgian yeasts can benefit from extra oxygenation and/or aeration. They exhibit a huge yeast growth factor for which oxygen is a requirement. More oxygen also limits ester production, so under-aerating or under-oxygenating may lead to an overly estery beer.

Note that some of these factors work against each other. For example, too low a fermentation temperature may cause the fermentation not to complete, but at the same time a higher fermentation temperature may promote the formation of too great a quantity of esters and higher alcohols. While too much higher alcohol in the beer is undesirable, a certain amount of it is a prerequisite for the formation of fruity esters and some specific higher alcohols are part of the characteristic flavour of Belgian beers.

Nevertheless, with a little care and caution all these factors can be balanced against each other. Pitching enough yeast and providing enough oxygen helps keep the formation of fruity esters in check. Raising the temperature from a cool "fail-safe" point at the correct pace and at the right times during the fermentation (sometimes using different temperature "steps") will produce just the right amount of higher alcohols at the right time, and convert enough of them into fruity esters but not too much. This allows the spicy phenols to come through on the palate in a balanced complement to the fruity esters.

Some brewers leave out the sugars that are of ten used in high gravity worts and pitch a "partial" wort with a lower gravity. Once the attenuation is underway and the gravity has begun to drop, they add the sugars gradually. When they do this depends on the brewer and the beer; some begin to add sugar 20% into the attenuation, others wait until the gravity has dropped to 50%, or anything between or outside these points. The gradual addition of sugars helps to keep the speed of fermentation and the formation of fruity esters in check.

Bottle conditioning and maturation

By the time a Belgian beer is ready to be packaged it has spent considerable time in fermentation, conditioning and optionally lagering (to which Belgian brewers usually refer as cool or cold conditioning). It is not uncommon for the beer to be five or six weeks old already by the time it reaches the bottle.

While some of the more modern and more widely marketed Belgian beers are force-carbonated, kegged and served on tap (Grimbergen is a good example) the vast majority of Belgian ales is still bottle conditioned. And for good reason: bottle conditioning is what makes these beers shine. Bottle conditioning is actually a mini-fermentation that takes place in the bottle. Belgian brewers often refer to this as re-fermentation ("hergisting" in Flemish) or double fermentation.

However, the method used by the various breweries differs. The more traditional ones simply bottle the beer (along with priming sugar, of course) with whatever of the original yeast used in the brew still floats around in it. Other breweries centrifuge or filter the beer to remove the old yeast (which has been through a major battle during the fermentation) and pitch fresh yeast. In some cases this fresh yeast is the same yeast that was used to brew the beer, others prefer to use a special bottling yeast. The latter is usually a yeast strain that only ferments mono- and disaccharides and leaves the maltotriose in the beer untouched, which means the body and residual sweetness of the beer will remain largely unchanged during bottle conditioning.

Once bottled along with a measured amount of priming sugar and either the original yeast or fresh yeast, the beer is left to mature. This usually takes place in a warm room initially (around 25°C or so) in order to start the carbonation process quickly. The yeast ferments the added sugar, producing a little more alcohol (usually on the order of 0.3 to 0.5% by volume) and carbon dioxide gas. Because this fermentation takes place within the hermetically sealed bottle, the carbon dioxide gas can't escape, so it stays in solution and makes the beer fizzy. The yeast also consumes much of the oxygen in the bottle (some of which has been dissolved into the beer during bottling or transferring, the rest from the head space under the bottle cap) which gives bottle conditioned beer its very long shelf life.

After two weeks or so the beer is usually well carbonated. What happens then depends on the brewery and the type of beer we're dealing with. Sometimes the beer is sold immediately, but more often it is transferred to a cellar where it matures for several months. Duvel is a good example: the Moortgat brewery produces tens of millions of litres of Duvel each year, but not a single drop is allowed to leave the brewery until it has spent three months in quiet maturation. Some beers mature at room temperature, other at cellar temperature (around 6-8°C).

What happens during this maturation period is what Belgian brewers refer to as "flavour evolution". The bottle fermentation includes a conditioning stage during which the yeast continues to improve the flavour of the beer by processing the compounds produced during the initial fermentation. Typically the yeast survives in the bottle for up to six months or so until it dies of old age. However, this is not the end of the beer's maturation. Complex biochemical reactions continue to take place at a very slow pace and, just like wine, some of these beers continue to improve for several years. Because the yeast has removed a significant portion of the oxygen from the bottle during carbonation and other oxidative reactions that are part of the flavour evolution process remove even more of it, many Belgian ales can easily be cellared for three years or more.

Note that some brewers take the opportunity to radically change the character of their beer during maturation! Orval is perhaps the best example. It is brewed with a "regular" beer yeast, but bottled with a wild yeast culture that occurs naturally in the region. This culture contains a variety of yeasts that consume malt sugars left by the original brewing yeast (maltotriose) and attenuates the beer much further. This makes the beer dryer and the body lighter which allows the hops to come through on the palate, and creates the leathery flavours and aromas that the beer is so well known for.

Meet the yeast...

Many traditional Belgian breweries use yeast strains that have evolved over the course of decades and even centuries. Some Trappist breweries use each other's yeast, others have a "house yeast" that has been in use for many years. However, it is important to realize that yeast changes over time as it mutates in response to variations in its environment. In other words, a brewery may have been using the same yeast for half a century or more, but today that yeast is not precisely the same yeast as it was all those years ago. While modern industrial megabreweries usually go to great lengths to ensure their yeast remains constant (often growing batches from a single cell in their own microbiology labs) the more traditional Belgian approach is to accept the fact that yeast adapts to its environment and in order to keep it happy the best thing is to let it do what it wants. Yeast adaptation is usually a good way to ensure that the yeast is best equipped to function under the conditions it finds itself in.

With that in mind let's look at some of the most well-known Belgian yeast strains that are commercially available at the moment. Many of the commercially available Belgian strains have actually been taken from the house yeasts that have been used decades or more by Belgian brewers, both monastic and commercial. However, as mentioned above, it is important to realize that yeasts do change over time, and a strain originally taken from, say, the Rochefort or Westmalle Trappist breweries twenty or thirty years ago will no longer be quite identical to what the breweries use today.

Sadly, the best Belgian yeasts are only available in liquid form. While all yeast strains can be dried, only a few perform well immediately after rehydration. While there are a few Belgian dry yeasts available (which we will discuss below) one really needs to look at liquid yeasts in order to get the best results in Belgian brewing. Unfortunately liquid yeasts are difficult to find in South Africa and are expensive when found. Quality and consistency is also an issue; because liquid yeasts have to be handled through a proper cold chain and can suffer severely from spending even 24 hours at room temperature, liquid yeasts in South Africa can be quite unreliable.

The main suppliers of liquid Belgian strains are White Labs and Wyeast, both American. A good supplier might be able to obtain these yeast for you. The list below outlines White Labs strains only, however Wyeast equivalents exist for all of these.


Code   Name   Originating brewery
WLP400   Belgian Wit   Hoegaarden
WLP410   Belgian Wit II   Duvel / Moortgat
WLP500   Monastery   Chimay
WLP510   Bastogne   Orval *)
WLP515   Antwerp Ale   De Koninck
WLP530   Abbey   Westmalle
WLP540   Abbey IV   Rochefort
WLP545   Belgian Strong Ale   Val-Dieu
WLP550   Belgian Ale   Achouffe
WLP564   Leeuwenhoek Saison Blend   Blend of multiple strains
WLP565   Belgian Saison 1   Brasserie Dupont
WLP566   Belgian Saison 2   Brasserie Dupont
WLP568   Saison / Belgian Ale Blend   Blend of multiple strains
WLP570   Belgian Golden Ale   Duvel / Moortgat
WLP575   Abbey Blend   Blend of multiple strains
WLP590   French Saison   Brasserie Thiriez?

*) As stated previously, Orval derives much of its unique character from having been bottled with a wild yeast culture. The yeast listed in this table is the one used during fermentation. In order to achieve an Orval-like character the correct bottling yeast culture must be used as well.

While a yeast's origins are important, keep in mind that the yeasts listed here have had decades to adapt to new conditions since they were cultured from the original house yeasts used by the breweries listed. WLP410 is a particularly good example: this yeast strain is being popular with several major American microbreweries and has originally been cultured from yeast used at the Duvel Moortgat brewery, but has since diverged quite a bit from the original strain. At this point it exhibits peppery rather than clove-like phenols and has a much higher flocculation than the original Witbier yeast and it could be argued that this yeast is now closer to what Trappist brewers originally used to brew their own table beers. It is possible that this yeast has acquired some genetic properties from other Belgian strains in the process of migrating to the US, but no hard taxonomic data seems to be available at this time, so this remains a matter of speculation. Still it illustrates how these yeasts will change and diversify after being moved from one brewery (or country) to another.

Note that several of the yeasts listed above are blends. While there are drawbacks to blending yeast, especially when it comes to brewing reproducibly, there are cases in which yeasts do play nicely together. It is not uncommon for traditional English breweries to have a house yeast culture that incorporates three or four different strains, which have adapted to each other and combined to a harmonious culture that propagates without undergoing much change and allows to brew beers in a consistent and reproducible manner. Belgian ale yeast also seem particularly well suited for blending, and brewing with multiple yeasts can add subtle levels of complexity and refinement to the beer.

While the best Belgian yeasts are sold as liquid yeasts (i.e. vials of sludge or sachets of cells in a nutrient solution) a few strains are available in dried form from Fermentis (France) and Lallemand (Canada). Both brands of yeast have their good and bad points.

Fermentis' oldest Belgian yeast strain on the market is T-58. For many years Fermentis have tried to market S-33 as a Belgian yeast, but it simply isn't . (S-33 is actually a classic Edme strain originating from the UK.) While T-58 will work in some Belgian ales, it is not the most "Belgian" type of yeast around. According to Fermentis product data is is one of the most fruity yeasts of their range but in practice it produces only moderate levels of fruitiness, and the spicy character is dominated by peppery notes. T-58 is also known for imparting a certain amount of sour notes to the beer. It does not form a proper yeast sediment after fermentation but a powdery layer of flakes that are difficult to keep out of the beer.

Fermentis BE-256 (Abbaye) is a bit of a strange beast. It is a POF negative yeast which means it has literally none of the spicy flavours that are so characteristic for the abbey beers that Fermentis recommends this yeast for. It is, on the other hand, incredibly high in banana esters which dominate the flavour to the point of obliterating just about everything else, and its nickname "The Banana Bomb" is well deserved.

The only other Belgian dried yeast option from Fermentis is BE-134, which his is one of their most recently introduced products. Fermentis positions this as a Saison yeast, which is not bad seeing as this yeast does produce the right type of spicy phenols and a well balanced fruitiness to go with it. However, a Saison is more than just that, and BE-134 has an unusually low alcohol tolerance for a Belgian yeast (Fermentis positions it at 9% maximum). It also does not form a sediment but, like T-58, it settles down to a powdery and flaky layer that is not conducive to a clear beer. But most notably is BE-134s tendency to produce lots of "hot" higher alcohols unless all fermentation factors are tightly controlled.

Lallemand's Abbaye yeast performs a little better. Its fruity esters are fairly well balanced but not over the top, and its spicy notes are more proper to a Belgian ale than what Fermentis T-58 or BE-256 produces. It has a decent Belgian alcohol tolerance of 14% and a moderate but still decent amount of higher alcohols that lack the overly "hot" character of BE-134.

Lallemand's only other Belgian yeast is Belle Saison. This is also a bit of an oddball yeast. It produces fairly high levels of peppery notes and acidity and is in that respect much like Fermentis T-58, although it is better balanced. However, while this yeast is specified to produce low to very low levels of fruity esters, it seems to be more prone to creating unwanted bubblegum flavours than the other dried yeasts.

All in all, none of these dried yeasts are even close to ideal for brewing a "proper" Belgian. But that doesn't mean we should write them off. When used properly, i.e. at the right temperatures, pitching rates and levels of oxygenation and with the right wort composition they can produce excellent beers. They are just a little unwieldy and temperamental compared to mainstream liquid Belgian yeast strains.

...and send in the clowns

Any discussion on Belgian yeasts and fermentation is not complete without mentioning a completely different yeast: Brettanomyces. This yeast is considered a wild yeast, although it has been harnessed and cultivated and is used under as much control as is the case with Saccharomyces (which is the "standard" family of baking, brewing, wine and distilling yeasts).

Brettanomyces is a yeast strain known for its "funky" flavours. Like practically all wild yeasts it is POF+ and produces numerous phenols with a range of aromas that at first glance appear dubious at best: sweaty horse blanket, barnyard, or Band-Aid aromas, foot odours and even putrefied cheese! None of these aroma's should work in any beer, or even near it. But in some beers, somehow, they do. Brett is also capable of producing pleasant smoky and spicy notes when no-one is looking.

Like most other yeasts Brettanomyces (or Brett, as it is colloquially known) was being used long before anyone realized it was actually there. It is the main part of the seasonal wild yeast cultures that occur naturally throughout the Zenne valley near Brussels. Beers brewed in that region were naturally inoculated with these wind-borne yeast cultures as the yeast naturally permeated the air in and around the breweries and, along with the inevitable lactic acid bacteria that accompanied the wind-borne yeasts, produced the traditional Lambic and Geuze styles that the region is known for.

While the Brettanomyces family includes at least five main strains, two have been cultivated for brewing: B. Bruxellensis and B. Lambicus. B. Bruxellensis is a main ingredient of the yeast culture used to bottle condition Orval and is known for its sweaty, horsey Brett character and is available to home brewers as White Labs WLP650 and Wyeast 5112. B. Lambicus is a bit softer and adds some sour cherry and other fruit aromas as well as lots of typical flavours that can only be described as "Brett flavours". It is used in Lambic and Geuze as well as Red Flanders Ale, Oud Bruin (Flemish for Old Brown) and some other niche styles. This strain is available to home brewers as White Labs WLP653 and Wyeast 5526.

Brettanomyces is not available in dried form.

Belgian are easy!

Or so Randy Mosher states in his book "Radical Brewing". And you know what? He's right. Keep your temperature in check, have a sensible wort composition, give your yeast plenty of air, plenty of time and plenty of hands-on-the-job in the form of a generous pitching rate and start the fermentation cool. Be conservative when it comes to using spices, don't be afraid of significant amounts of sugar (even up to 20% of sucrose) to keep very high gravity worts fermentable, and brew for drinkability which means not to go overboard in any single direction. Strive for a balance between fruity esters, spicy phenols and a malty backbone. Stick to European hops, preferably noble strains or cultivars like it, sparge slowly to ensure you won't undershoot your original gravity, and boil for 60 minutes. That's essentially it.

Also keep in mind that these beers are individualistic, creative and unique. There's nothing wrong with entering them into a brewing contest, but keep in mind that beer judges will likely be relatively unfamiliar with the style and judge beers by fitting them into categories, something that Belgian beers simply will not sit still for! So brew to enjoy, not to win prizes. Enjoyment is what Belgian brewing is all about, anyway.


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