Not in the yeast
Focusing on the yeast misses the point of Belgian-style beers, says Pete Brown
Ask a craft brewerin America or Britain what the defining characteristic of Belgian beer is, and they’ll likely tell you that it’s all about the yeast. When brewers tire of creating hop bombs, they invariably turn to ‘Belgian-style’ beers, and start to explore the flavour potential of yeast.
“When I think about my yeast,” says Yvan de Baets, brewer at Brasserie de la Senne and authority on the role of yeast in Belgian brewing, “I don’t regard it as an ingredient, I regard her as one of the team. She’s my best friend in the brewery.” With that kind of praise, it’s easy for those looking to mimic Belgian styles to focus on the role and character of yeast. Easy, but dangerous. We’re not exactly wrong to distinguish Belgian beers from others by focusing on the flavour characteristics of yeast. But we are in danger of missing the point.
“The reason I agreed to this interview is so I could dispel this idea that Belgian brewing is all about the yeast,” says Guido Aerts, head of the laboratory for enzyme, fermentation and brewing technology at KAHO Sint-Lievenuniversity college in Ghent. “It’s part of the story, but not the only part. If fermentation only created yeast flavours and alcohol, the beer wouldn’t be drinkable.”
Of course, that’s not what we’re saying when we talk about the yeast-driven character of Belgian beer. We understand the role of other ingredients and processes, and how it all fits together. But maybe we should try to understand them a little better.
Before Louis Pasteur published his findings on the behaviour of yeast in 1876, brewing was about knowing how to make something work rather than understanding why it did. Few brewers in the 19th century produced entirely spontaneously fermented beers. It was far more common to use a top-fermenting yeast, cropping the foam from the top of one brew and pitching it into the next.
This gave some consistency from batch to batch, but there was always a danger of infection. This danger was minimised in different ways. You could encourage yeast that created lactic acid, lowering the pH of the beer to create a less friendly environment for bacteria. You could add spices and other additives to cover off flavours (and hops became the most popular, because as well as disguising their presence, they also killed off bacteria) and you could make stronger beers, because alcohol acts as a preservative.
Each region of Belgium developed its own methods for creating beer that could be stored without spoiling: the red beers of Flanders, the lambics of Brussels and the saisons of Wallonia being three examples of solving the problem.
Pasteur’s discoveries revolutionised brewing and created modern beer. But his impact didn’t hit everywhere at the same time. He first shared his methods with British brewers, whocreated beer on an industrial scale for industrial workers in towns and cities. From here, Pasteur’steachings spread to cities – to Copenhagen, Munich and Amsterdam, where the great lager brands of the 20th century were born.
Belgium was different. Brewing was an activity for the farmhouse, the small town and the monastery. Pasteur’s influence took longer to get here. And when it did, itwasn’t adopted in quite the same way as elsewhere.
By the beginning of the 20th century, Belgian brewing was under threat from the popularity of British ales. Competitions were held to create beers that were distinctly Belgian in style. The Trappist monasteries – many of whom were only just returning to brewing after having their ancient tradition smashed by Bonaparte – built modern new breweries, embracing technology but maintaining the rural tradition. The beers got stronger, especially after a new law in 1919 prohibited the sale of spirits in bars and other public places.
The Belgian brewing tradition became defined. It stood against the belief that science was the only master. It didn’t reject Pasteur’s work, but the Trappist monks in particular believed it was being taken too far, creating beers that were purer and cleaner, but lost some desirable characteristics. For the Trappists, science was always counter-balanced by a relationship with their god and with nature.
This philosophy goes wider than the Trappists. “The Americans have isolated yeast strains from some saison bottles, cultivated them and classified them as saison yeasts,” says Yvan. “But if you were a nineteenth-century farmhouse brewer, you didn’t phone up the lab and order your saison yeast. You worked with what you had around you. I believe there’s no such thing as a saison yeast.
So Belgian yeasts set off on a different path to other cultivated strains. When we think of Belgian-style beers we often think of lambic, and Brettanomyces in particular holds a fascination for many modern craft brewers. (That we now think of ‘Brett’ as Belgian, when it was identified in 1904 in British ales by a Danish scientist who gave it a name that means ‘the British fungus’, underlines both the timing and the degree to which Belgium diverged from the global brewing norm.)
But there’s more to Belgium than Brett. Orval undergoes a mixed fermentation, first with Saccharomyces cerevisiae, then with Brettanomyces. Rodenbach is pitched with a mix of 80% standard ale yeast and 20% a house cocktail of bacteria and wild yeast.
Brewing a Belgian-style beer is not just about the yeast; it’s what you do with it – and why. In his book Brew Like A Monk, Stan Hieronymous recounts details of experiments carried out by American brewers using Trappist yeasts. They deliberately varied both the amount of yeast pitched and the temperature of the fermentation, and found the resulting beers varied widely – and none were as good as the Belgian originals. He also points out that three Trappist brewers – Achel, Westmalle and Westvleteren – all brew with Westmalle yeast, and achieve very different results with it.
Many have compared the Belgian attitude to brewing – and the characteristics of the yeast itself – to wine yeast and wine making. But you don’t often hear winemakers obsessing about their yeast; they look at the big picture, the interaction between everything they do.
Scratch the surface of Belgian brewing, and it’s going on here too. In any good Belgian beer, the balance of esters and phenols from those beloved yeasts can’t really be appreciated separately from how they interact with the rich flavours of complex malts and the impact of high alcohol.
The general belief that hops are relatively unimportant in Belgian brewing would be a surprise to Orval, where dry-hopping is a crucial part of the beer’s character. Saison Dupont was also dry-hopped until the 1960s (and was recently rereleased in a dry-hopped special edition). In 1922 Westmalle Dubbel began adding caramelised sugar syrup to raise the alcohol content without thickening the body of the beer, and it remains a key characteristic of this revered brew. Tripel Karmelliet, a relatively new addition to the ranks of famous Belgians, takes its character from an eccentric grain bill that incudes barley, wheat and oats in their raw as well as unmalted forms. And even Yvan describes his beers as hop-driven.
If you’re trying to differentiate Belgian beer from other beers, the character of the yeast is a useful signpost. But Belgian beers are not different from other beers because the yeast is different. The yeast is different because the entire approach and philosophy of brewing parted company with wider trends over a century ago, and continues to follow its own path.
“Belgian beer is for tasting, not drinking,” says Guido. “You pay attention to your beer. You take time to appreciate the glass, the beer, the foam. Smell it, taste it. Enjoy the aromas. Do that, and if all you’re getting is the character of the yeast, the brewer has failed.”