Yeast in Wine – Port fermentation

English: Image of dry winemaking yeast and yea...

English: Image of dry winemaking yeast and yeast nutrients. (Photo credit: Wikipedia)

One of the key elements, if not the most important after the grape in the winemaking process, is the yeast. Why is yeast so important? Because despite its small size (around 0.003 mm), this microorganism has the very important task of transforming fructose into ethanol, the form of alcohol present in wine. Yeast is present in the surface of the grapes and in the vines. Once the grapes are crushed, yeast starts its mission: it immediately begins transforming the sugar of grape into alcohol. Broadly speaking, it can tolerate temperatures between 10 ºC and 35 ºC; higher the temperature, the quicker yeast works and reproduces itself.

But are all yeasts the same? No. Different vineyards within the same country or region have different yeasts. And which are the best? Probably there is no answer to that question as it depends on the kind of aroma and taste the winemaker prefers. Once grapes arrive to the winery, the winemaker has two options: rely on the native yeasts that have been adapted to the local terroir or add a selected yeast, that is very likely brought from another wine region, possibly in another country, and was developed in laboratory to drive the fermentation into a certain kind of flavours and tastes.

In the Douro we have two realities, depending if we are talking about Port or still wine. From what I see, I would say that most of the Port is made with native yeast. On the other hand, for the Douro wines, a generous number of producers use selected yeast. The fact that, within the same region, this is the Douro, for a kind of wine we usually use native yeast and for other seldom, is curious, but not difficult to explain. Port is a worldwide reference, it is copied, imitated and even faked in several and respected wine regions in the world. But looks like no other place but the Douro can make something as fantastic as Port. And besides grape quality and winemakers’ skills developed through centuries, yeast plays a very important role. Thus, Port winemakers trust that the best yeast they can use is in the Douro vineyards.

Active dried yeast, a granulated form in which...

Active dried yeast, a granulated form in which yeast is commercially sold. (Photo credit: Wikipedia)

And why using selected yeast in the still wines? It’s like buying an insurance, you know that if all goes right the insurance is not necessary, but if it goes wrong, insurance guarantees you don’t lose everything. In our case, as I guess you want to know, we use native yeast for all our Quevedo Ports except the Quevedo Rose. And for the Douro wines, we do sometimes buy an insurance!

In the future I think very commercial wines will continue to use selected yeast. But as yeast research develops, the number of selected yeast available will rise and more wine regions will use their own lab selected native yeast.

Is there any question about winemaking that you have been keeping for sometime and want to make now?

Oscar

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