When you say saison yeast is a “myth,” what do you mean?
I mean that for many people, a saison can be made only with “saison yeast.” But what is it? A “saison yeast” seems, for some, to be a yeast named “Saison Something” or “Something Saison,” sold by a commercial yeast company. It’s a sort of magic powder: You add it to a wort, and you get a genuine saison.
There are different things to say about that.
First, there are, to my knowledge, currently three main strains on the market, adopted by the yeast companies from bottles of Dupont, Blaugies, and Thiriez. The Blaugies yeast is actually an offshoot of Dupont’s—Pierre-Alex Carlier and Marie-Noelle Pourtois selected it at one moment of its development in a wort, isolated it, and cultivated it. Even if the two strains give slightly different results, we can say they’re the same yeast. The Thiriez one is different. It’s funny that it’s now called “French Saison” because it is used by Thiriez, but its origin is Belgian: It comes from the yeast bank of the brewing school where I studied in Brussels.