We asked Simon Hall our Winemaker at Simall Wines about yeast strains in wine making. This is what he told us as he got quite excited and animated:
“Yeasts are just so important in winemaking – without them all we’d have is grape juice!
There are an incredible number of species of yeast. They occur naturally on grapes, where the species is dependant on the terrior of the vineyard. And as a winemaker I can also select a yeast strain based on the impact I am seeking. I buy these in freeze dried packets, then rehydrate them in warm water, then add them to the grape juice where they do their thing as I make the wine.
The yeast strains I buy have been isolated from grapes occurring in specific regions around the world, mostly France. Selecting a yeast strain is a bit like reading the back of a wine label!
For example, I can buy BDX which was isolated in Bordeaux. It’s recommended for Cabernet and Merlot. The supplier says ‘Uvaferm BDXTM is a vigorous fermenter. Alcohol tolerance can be up to 16% (v/v). It optimises colour and structure with soft tannin extraction and increased mouthfeel.’Another example is RC212 which was isolated from Pinot Noir grapes in Burgundy. The supplier says‘…known for its ability to generate ripe berry, bright fruit and spicy characteristics and to consistently produce Pinot Noir with good tannin structure.’
There are hundreds of yeast strains I can choose from. I like to use some strains such as uvaferm exence in Verdelho, Chardonnay, Pinot Grigio and Viognier because it helps bring out the floral and fruity flavours that naturally exist in these wines.
Yeast strains are truly amazing. I can have exactly the same grape juice and use two different yeast strains and I will have two different results! For example, in a large winery where I use to work we used different yeast strains depending on the Semillon blend we were making:
- X5 for Semillon we were going to blend with Sauvignon Blanc because it brings out the tropical fruit and grassy flavours of Semillon; and
- Iper R which makes Semillon viscous and brings out more of Semillon’s melon flavours which suits Semillon Chardonnay blends.
Each year I experiment with different yeast strains in the same grape juice in an effort to improve my wines. Suppliers are always isolating new strains and the only way to see if they improve my wines is to try them.”