I was becoming convinced that all the experimental wines we made tasted the same because of the bought-in commercial yeasts we used. Now it was time to prove this. So in we went to Bordeaux and bought Agar petri dishes, Pasteur loups and so on – the essential kit for a small wine laboratory. My old brass microscope was taken out of its wooden box ready for use. We were now ready to isolate the different natural yeasts from a ferment of Rahoul’s white wine.
We were in luck. We found three volatile and two ‘first class’ yeasts which dominated the fermentation. Between the two good ones we now had to choose. We fermented some of each in tiny five millilitre glass jars, and after a week we put them to the sniffing test. As we stood in the kitchen, our noses in those tiny ferments, Susie pointed to ‘R2’. We all agreed.
From that point on, it became my absolute conviction that wherever I was, the local yeast, for better or worse, would be the one I used. Generations of winemakers at Bordeaux University’s faculty of oenology have been filled with nonsense about the ‘dangers’ of using wild yeasts as they would not see a ferment through to its completion and the wine would be spoiled. Professor Ribereau Gayon did not believe in my theories, but I was going to prove him wrong. Luckily, not everyone at that establishment was as conservative as him.
In 1985, I finally managed to broaden the experiment by fermenting three different yeasts in batches of the same must from a parcel of white Sémillon vines behind the main house at Rahoul. To one, I had added the yeast of Château Lynch-Bages (my friend Jean-Michel Cazes had given me his natural yeast), to another I added yeast from Château Angludet (where Peter Sichel had done the same), and in the third, I used our own strain from Rahoul. The must was then chilled and settled.
We made two barrels of each batch, which after fermentation and racking became one barrel, so 300 bottles were made from each of these wines. And each batch turned out not only to be totally different, but true to the taste of its own château. Finally I had cracked the mystery. My theories confirmed. The natural yeasts gave a fingerprint to the wine.
I began to feel bold. My next step was to invite the members of the Académie du Vin de Bordeaux and the Union des Grands Crus2, plus Professor Ribereau Gayon from the University of Bordeaux to a tasting held at Rahoul in the spring of 1986 after the wines had settled down and were bottled. Needless to say, it caused quite a stir. A few days later, I got a letter from the Académie congratulating me on my work and informing me that they had elected me a corresponding member. A great honour indeed.
Denis Dubourdieu (another leading professor) came to dinner at Rahoul one evening with Bruno Borie from Château Ducru-Beaucaillou. They tasted the three wines and Denis was so impressed he said: ‘You’d have to be an idiot not to believe in this!’ and went on to create a dedicated yeast laboratory at the University of Bordeaux. There, he proved scientifically what I had discovered simply by tasting.
It may be immodest to say so, but this was actually the start of what would develop into one of the world’s most significant yeast discoveries. I had given some of the R2 to Brian when he left to go back home and he in turn lent it out to his friends at the Australian Wine Research Institute. So in the end, the big industries got hold of it, made it famous, and no doubt earned untold millions from it, but sadly neither Brian nor I ever saw a penny.
Some years ago I had a message from my nephew Peter ‘Ping’ Sisseck, who told me that he had recently dined with Denis, who told him: ‘Peter intuitively saw and understood what had taken me 20 years to prove scientifically.’ I was very proud to hear this and thought back to those evenings at home during my childhood when I was allowed to taste different wines from different, but not geographically distant, vineyards. We learned to recognize the differences in the wines by colour, by taste and by their vintage, but the differences we perceived must also have resulted from the natural yeast strains that created them. The discovery I made perhaps had less to do with science and more to do with culture and common sense.
These days, microbiological biogeography is ‘in’ and some very interesting findings are emerging from the labs. It has now been established that ‘wild’ yeasts do not just originate from the winery environment but from the vineyard itself, which we believe is responsible for much more than the 10% of active yeast in the ferment we thought accurate back in my Stellenbosch days. Now we understand that the percentage of vineyard yeasts is naturally much higher. There is also a theory that fermentation temperature plays a much greater role in the activation of specific yeasts than we had originally thought.
Let me just add that when we left Rahoul a few years later, I also left the R2 yeast there. At Château de Landiras (which I’ll come to later) we again isolated the local yeast. And now at Montecarrubo in Sicily, with less than 100 metres between our two vineyards, Vigna Grande and Vignolo, we use the indigenous yeasts from each and produce two totally different and easily recognizable wines, just proving how important it is to adopt the local yeast population wherever you are. We think the difference can mostly be accounted for by the fact that Vigna Grande was at one time a coral reef – it’s a fact that surely must have some influence.
All the way through there have been many who refused to believe my theory. I remember giving a tasting for a class of MW students in London where I talked about the findings that yeasts were far more important than had been previously acknowledged. The idea was met with some reserve. Jasper Morris, who was one of the students, asked the teacher if they would fail the exam if they wrote what I had just told them. I can’t remember the answer – maybe because there was none – but Jasper passed his MW, so perhaps the realization had begun to dawn…
Perhaps more interesting was the discovery by the American Nobel Prize winner George Wald – honoured in 1967 for his studies of pigments in the retina – who explained how we can see everything in colour. He also told us: ‘Humans are more like yeast than unlike it, because yeast and man have a common ancestor. Some of the ancestor’s progeny became yeasts and some became men, and those two journeys resulted in a change of only 43 nucleotides out of 312.’ That is a moving truth – that as living creatures we are more like yeast than unlike it.
Denis Dubourdieu died far too young in 2016, and we lost a great friend.
This is an excerpt from the chapter from the book Viking in the Vineyard: Stories from a revolutionary winemaker, by Peter Vinding-Diers. To order the book with a £5 discount, visit academieduvinlibrary.com and quote the code CLUB21 on checkout