A primer on yeast strains and Belgians
The story of yeast management and Belgian beers is a
fascinating one, as the practices differ significantly when compared to
more common styles. The following article provides some observations
about the Belgian phenomenon.
Much of the material comes from a talk given by White
Labs president Chris White at The Spirit of Belgium 2001, held January
13 and 14 in Arlington, Virg. The accompanying graphic gives details
about the differences between Belgian yeast strains offered by White
We’ll begin the story in 1881, when Emil Christian
Hansen developed pure culture techniques. Before this time, Belgian
style beers were, well, simply beer. But by isolating a particular
strain of yeast, Hansen’s discovery showed that one could make what
one encyclopedia calls "dependable beers."
The discovery made widespread lager brewing possible.
Ale and Belgian styles began to fade, and lagers took over the world, a
trend that was only somewhat slowed by the renaissance of craft brewing
in the past two decades. More recently, brewers are discovering that
Belgians are to craft brewing what paint is to a painter. While a few
years ago Belgians were hard to find at American microbreweries, today
about one in ten have a Belgian or two on tap. And the number is
But we get ahead of ourselves. While the world became
enchanted with clean-tasting beers, the Belgians stuck to their
traditional styles and wild yeast. (This of course changed over time.
Lagers are now the most popular beers in Belgian, too, but the
traditional styles still flourish in small and medium size breweries
around the country).
The diversity of Belgian beers almost defies
classification, but most fall into the following styles: Belgian Ale;
Belgian Strong Ale; Biere de Garde; Flanders Brown and Red Ale; Grand
Cru; Lambics — Gueze, Kriek, Saison; Trappist ales — Dubbel and
Tripel; Witbier; and Pilsner.
Belgian beers are characterized by significant yeast
character — aromatic, fruity, phenolic, strong, dry. What yeast
compounds contribute to the flavor of Belgian beers? Esters — ethyl
acetate (solvent); isoamyl acetate (banana); alcohols — isoamyl
alcohol, 2,3-butanediol; acetaldehyde (green apple); diacetyl; sulfur
compounds (H2S, DMS); and phenolics.
Characteristics of Belgian fermentation include
increased phenol production. These are hydroxylated aromatic rings,
aromatic alcohols. It is the same kind of compounds used in antiseptics
and is less volatile than aliphatic fusel alcohols.
Attenuation and flocculation is also much different
than in normal brewers yeast. Some old Saison strains only attenuate 50
percent. They have to have very low initial gravities — in the
mid-1020s. And the cells are usually smaller than other brewing yeast
and are less-clustered. What does this low attenuation mean to brewers?
Well, this is one of the main reasons that the strains are mixed, to
increase the attenuation.
Things have changed at Belgian breweries ove the past
century. Many have adopted modern brewing techniques. Father Theodore
isolated Chimay yeast in 1948, by the use of pure culture techniques.
Chimay beers have been brewed with pure strains ever since.
To Belgian brewers, yeast is everything, it is
sacred. The rest of the brewing process and ingredients are not as
heavily guarded. Indeed, some of the larger Belgian breweries and even
small ones have some of the most sophisticated lab equipment and
procedures in the industry. And their quality control is second to none.