A Craft Beer & Brewing reader recently asked us the following question:
What are the differences between the various Belgian yeast strains? How do I choose the right one?
With the vast number of yeast strains available to today’s brewer, it’s easy to get confused. “Belgian yeasts are incredibly diverse. The best place to start is to identify the technical performance characteristics you want for your homebrew: things such as optimal fermentation temperature, attentuation, and flocculation,” says Leinhart.
A yeast’s optimal fermentation temperature is actually a range of temperatures at which that yeast strain performs best. Aiming for a temperature below this range may stall the fermentation, while fermenting substantially above the temperature range can encourage the yeast to create unwanted flavors and aromas. Belgian yeast strains tend to work well at typical ale temperatures, 62–68°F (16–20°C), but some saison strains can tolerate temperatures approaching 100°F (38°C)!
Attenuation is a value that indicates the percentage of available wort sugars a yeast strain is likely to ferment. Highly attenuative strains can eat through 90 percent or more of the available sugars, while low-attenuating yeasts might barely get through 60 percent. Attenuation also depends on other factors, such as wort composition and fermentation temperature, but all other things being equal, attenuation is a good metric with which to compare two yeast strains. All yeasts are different, but as a general rule, Belgian strains tend to be big attenuators relative to other broad classes of yeast.
Flocculation refers to a yeast strain’s tendency to clump together and drop out of suspension. Highly flocculent yeast cells readily fall to the bottom of a fermentation vessel at the end of fermentation, leaving behind brilliantly clear beer. Less flocculent yeast, on the other hand, may remain in suspension even after fermentation has come to an end. While Belgian strains tend to be mildly to moderately flocculent, this certainly isn’t a rule.
“We ferment Brewery Ommegang’s Glimmerglass, a Belgian saison, with a very flocculent yeast strain,” notes Leinhart. “The cells readily clump together into a slurry on the bottom of the fermentation tanks.”
Flocculation and attenuation are loosely correlated in that yeast cells that remain suspended are more likely to fully ferment than yeast cells that drop out. The relationship isn’t absolute, but it’s a good rule of thumb.
To compare these technical specifications, Leinhart recommends contacting major yeast suppliers such as White Labs, Wyeast, and the Brewing Science Institute. These microbiology labs publish yeast performance characteristics on their websites and are always happy to answer questions about every brewer’s favorite microbe.
Yeast selection, of course, isn’t just about numbers. Stylistic considerations are also important, and the difference between a good beer and a great one can easily come down to yeast selection. While published profiles can offer some clues to the unique flavors and aromas a particular strain will lend, a yeast’s complex interaction with wort composition, hops aromatics, and even fermentor geometry means that some trial and error is often in order.
“You just have to practice and discover what works best for you,” Leinhart emphasizes.
Keep in mind that Belgian is a broad term that includes a great number of distinct styles and that some strains are best suited to certain kinds of beer. Belgian saison, for example, showcases a spicy phenolic character (think cloves and pepper) that is largely a by-product of yeast selection (some saisons are actually spiced, but this need not be the case). Fermenting a tripel with the same strain would no doubt produce an excellent ale, but it probably wouldn’t turn out a classic tripel.
Belgian pale ale is fermented with a relatively clean yeast strain that shares more similarities with Chico (American and California ale) and lager yeasts than it does with abbey-style varieties. One could ferment any ale with such a strain, but the expected esters won’t present in the desired amounts for, say, a wit.
We can divide Belgian yeasts into a few categories, according to the beer styles for which they’re best suited.
- Belgian pale ale strains are fairly neutral and can be hard to find. White Labs WLP515 Antwerp Ale and Wyeast 3655-PC Belgian Schelde Ale, available as seasonal strains, are both good choices. In the absence of these, a relatively clean American-ale strain is a good choice.
- Abbey and Trappist strains deliver the signature fruity esters and spicy phenols that characterize what most beer drinkers instantly recognize as “Belgian.” Start with WLP500 Monastery Ale (formerly Trappist Ale) and WLP530 Abbey Ale from White Labs or 1214 Belgian Abbey and 3787 Trappist High Gravity from Wyeast to get a feel for what you like and then try some of the other strains.
- Belgian Strong Ale yeasts can tolerate the high alcohol of golden and dark strong ales. White Labs WLP570 Belgian Golden Ale and Wyeast 1388 Belgian Strong Ale are classics, but Abbey and Trappist strains can turn out great examples as well.
- Saison strains include a spicy component that can come across as peppery and clove-like. They also tend to leave a distinctive dry tartness. White Labs WLP565 Belgian Saison I and Wyeast 3724 Belgian Saison are reported to have been sourced from Brasserie Dupont, but both are prone to stalling at around 1.035. Raising the fermentation temperature to as high as 95°F (35°C) can get you over the hump, or try Wyeast 3711 French Saison, which is so aggressive that you might think it will ferment through the carboy itself.
- Witbier yeast offers up a tart, fruity flavor that makes it the ideal accompaniment to the coriander and citrus typically found in Belgian whites. Classic strains for that refreshing, thirst-quenching characteristic include White Labs WLP400 Belgian Wit and Wyeast 3944 Belgian Witbier.
There are of course, plenty of other strains, including any number of lambic and sour blends, but starting out with one of these basic options will place you squarely on the path to Belgian bliss.