Everything You Know About Saison is Wrong

Yvan De Baets is a brewers’ brewer. When De Baets talks, brewers listen. And when De Baets gave a presentation on saison at the 2026 Craft Brewers Conference, it was standing room only. Attendees walked away with minds blown.

Historical Research Into A Historical Beer Style

With a short stature and small, round glasses, De Baets looks like an academic. True, he is head brewer, co-owner and co-founder of Brasserie de la Senne in Brussels, but he is also a beer scholar. With formal brewing education from the Maurice Institute for Brewing and Malting Science in Brussels and now a guest speaker there, the student has become the master. De Baets also teaches at the postgraduate program of Malting and Brewing Sciences at KU Leuven University, and in the International Brewing Methods course at Weihenstephan Brewing School in Freising, near Munich.

After writing the chapter on the history of saison in Phil Markowski’s book Farmhouse Ales, De Baets discovered a passion for one of his country’s most famous beer styles. “As many Belgians, I thought that just because I’m Belgium, I knew everything about saisons,” said De Baets. “And then by starting the research, I realized that basically I knew almost nothing about it. And I realized that the subject is extremely complex, and I really fell in love with that complexity and I really wanted to know everything.”

The first thing De Baets discovered is that saison is just one style of a family of beers that were meant to be kept for a very long time. “Now, when you say to something tastes of an old beer, it doesn’t seem very sexy,” says De Baets, “But at the time, ‘old’ was a very positive word. It was super, super positive to talk about an old sour beer–a well kept, well-aged sour beer.”

So, historically saison had a sourness akin to lambic and Flemish oude bruins, both of which have retained that sharp bite. “Clean” saisons today are not representative of historic saison.

This includes the modern-day archetype of saison, Saison Dupont. “Saison Dupont is a wonderful beer. It’s absolutely great,” says De Baets. “But you have to think about the context of that very brewery. And the context of Dupont is that … it was run by a guy … his name was Silva Rozier, and he was obsessed by technology and by innovation in a small brewery in the middle of nowhere.… So he modernized his small brewery very, very early. And one thing he did about his process for saison is that already in the 1930s, instead of aging them in wooden barrels like everybody would do, he decided to go in metal tanks instead of wooden barrels. And of course, when you do that, it has a huge influence on the kind of microorganisms that are involved in your fermentation.”

“And for the Brettanomyces, it’s not a great thing to go from wood to metal,” says De Baets. “It doesn’t mean that the Bretts totally disappeared from the brewery. But it lowered their presence dramatically for sure. And then after the war … it’s really the years where a lot of breweries started to select some strains of yeast that they considered were the major yeasts involved in their fermentation.”

For whatever reason, Brettanomyces was not included in that selection and Dupont began being fermented by just one main yeast strain and perhaps one or two other ones, “But they are a little bit secretive about that,” says De Baets. “But they selected one for sure that became the famous Dupont yeast, and it’s a yeast that that is extremely typical because it’s a phenolic bump when you open a bottle of any beer from Dupont in a room, your nose will detect it even if you are far from the bottle because it’s so typical…. But this beer, Saison Dupont, it’s just the way that a specific brewery, only one brewery, decided to evolve in its own history. So it’s totally a valid beer for the Dupont brewery, but it doesn’t represent the way that all the other saisons were made at the time.”

There Is No Such Thing As Saison Yeast

De Baets points the finger at yeast companies for taking that Dupont yeast strain and marketing it as “saison yeast.” In fact, De Baets thinks the very concept of a saison-specific strain of yeast is “pure bullshit.” So too is the belief that saison must be fermented with a POF+ yeast or a diastatic yeast.

“What’s very important to understand in the ancient way of making saisons is that there were two fermentations…: the primary and the secondary fermentation. And actually, the secondary fermentation was even more important than the primary,” says De Baets. “And to start the primary fermentation of your saison, you could use basically any kind of yeast…. I have traced in all the brewing records of breweries using many, many different kinds of yeast for making the first fermentation.”

“Those brewers, like their customers, they wanted to have a constant taste in their in their season,” says De Baets. “But they knew they would get it. Why? Because after the main fermentation, the saisons would age in wooden barrels, and what lives in a wooden barrel in a small brewery in Belgium at the time? It’s of course Brettanomyces.”

“And so the main thing to remember, that if there exists one saison yeast,” says De Baets, “It is the Brettanomyces.” As part of a research project with the brewing school in Weihenstephan, De Baets both tasted and had scientifically analyzed beers from defunct saison breweries. “The bottles are dating from the 1970s, 60s, 50s. Even one bottle is from 1939,” says De Baets. “And in all of the bottles but one, we found Brettanomyces, and so this really proves that the typical yeasts for saisons were Brett.” As for that characteristic phenolic note? “We had phenols from Brettanomyces—tons of them—not the phenols like the ones we have in Saison Dupont…. And the attenuation of saison has to be high, but we are not aiming for a total super attenuated beer. It can happen, and when it happens, it’s most of the time because of the Brettanomyces.”

Saisons should be sour and saisons should have Brettanomyces. Historically, those were their unifying characteristics.

Grains Are Fun

At is/was brewing, in the Ravenswood neighborhood in Chicago, saison reigns supreme. Of 14 is/was beers available in their taproom, 12 are saisons, ranging from 3.2% ABV to 7.1% ABV, though most fall between 5% ABV and 6% ABV.

“The philosophy is to be respectful of the history, tradition, and techniques of brewing saison, while also being aware of and responsive to advances in brewing technology, or flavor technology, or just the modern American palate, to make things that are simultaneously traditional and forward thinking,” says Mike Schallau, co-founder and brewer.

In his modern interpretations of saison, Schallau uses a commercially-available yeast branded as a saison strain. “And then most of the beers, towards the tail end of fermentation, have a blend of Brettanomyces added to them,” says Schallau. “And that’s just added from previous batches of beer that have had Brettanomyces in them.” De Baets would approve.

“We also tend to use a lot—20 plus percent—of adjunct grains in the mash often, to add body and character,” says Schallau. “Our flagship beer is a combination of spelt and triticale. We use a lot of spelt. We use wheat. We use rye. We use oats…. That allows us to kind of push and pull on the different things the yeast wants to do. The yeast will become more phenolic if we feed it more ferulic acid from the wheat, and less phenolic if we use spelt, which is why we choose spelt more often.”

“We’re trying to make a more ester-driven saison as opposed to a more phenolic-driven saison,” says Schallau.

Use Hops and Water … For Body???

“One of the other touchstones is that most of the beers … use a very high amount of very low alpha acid hops– things that are like 3% alpha acid or lower tends to be the wheelhouse for us,” says Schallau. “That helps us have a lot of polyphenol in there, which, along with a lot of those high protein malts and the yeast selection, creates much more body than you would have otherwise because these beers are finishing very, very, very dry.” Schallau credits De Baets for the idea to use large amounts of low-alpha hops. “[It’s] something I got out of Yvan’s section of the saison and farmhouse ales book.”

“One other thing we think we do that’s a little bit different … is a very chloride heavy water profile,” says Schallau. “If we’re going to offer [people] this very, very dry thing, it might be helpful to have this chloride…. It helps build the body out again. Body helps replace the sugar that gets taken away when these beers get very dry.”

In the modern beer-drinkers’ consciousness, saison come to be defined by a single Belgian brewery. And while that brewery may make great beer, research of historical records shows that much of what modern brewers and beer lovers believe about saison is not true. Inspired by that research, breweries today, including De Baets’s Brasserie de la Senne and Schallau is/was, are now rediscovering variety that was once offered by this beer style.

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