It is not always easy to understand some terms related to the winemaking process. We often hear about yeasts, which are nothing but a microscopic fungus, and are in charge of the alcoholic fermentation when they enter in contact with the must. This is a key process in winemaking. However, not all the yeasts are the same: there are many kinds and species. This time, we will focus on the indigenous yeasts, namely, those that can be found naturally in the grape, without human intervention.
But let’s go one step at a time. Laboratories select commercial yeasts that come from different parts of the world; they are dehydrated products that we add to the must. But indigenous yeasts are a completely different thing; you can imagine how we obtain them with this example: if we go to the vineyard, and we crush a bunch of grapes to obtain the must –and we leave it in a container– after a few days, must fermentation will take place spontaneously through the action of lots of yeasts attached to the skin of the grape. Those are the indigenous yeasts.
Each region, even each vineyard, has its own indigenous yeasts. They are essential because, when performing the alcoholic fermentation, they pass on their distinct character to the wine. This is a part of what we call ‘terroir’, making that wine different to other produced wines, even with the same variety. However, a wine produced like this doesn’t behave in the same way every year, since it won’t develop the same yeasts because the development of the so-called ‘microbial flora’ depends on the weather and environmental conditions and the usage of phytosanitary products. Furthermore, some of these yeasts won’t be able to carry out the alcoholic fermentation completely, or even they could transmit bad aromas and undesired flavours to the wine. For this reason, the vast majority of the wineries use commercial yeasts to carry out a controlled alcoholic fermentation.
In Bodega Cuatro Rayas, we have been performing a selection process of our indigenous yeasts since 2012 vintage, in a project developed with the support of LEW 2050, a company related to the Universidad of Navarra. The Department of Oenology at Bodega Cuatro Rayas is the responsible for this, selecting the most suitable yeasts, among all spontaneous fermentation yeasts, to transmit our wines the character of the vineyards of our region. In this way, using our yeasts, we make wines with character and a particular authenticity.