The other day reading an article about fermentations and yeasts, I read a sentence that said that you had to act quickly by adding commercial yeasts, so that the native yeasts could not act.
Native yeasts and commercial yeasts.
To put ourselves in the situation a bit, when we talk about native yeasts we refer to those that are found in the grape naturally , without human action. While we call commercial yeasts those yeasts developed by laboratories, in the form of a dehydrated product, which we can add to fermentations.
Why do we use commercial yeasts if our grapes already have their own yeast?
For a long time the commercial houses of oenological products have been strongly positioned in the market, with a large portfolio of oenological products, including yeasts, yeast activators, etc.
With the use of commercial yeasts, what is done is to establish a population of the genus Saccharomyces cerevisiae, which overcomes the native yeasts, accelerating fermentation and ensuring their work . In this way, by controlling the fermentation a little with temperatures around 24ºC, the fermentation will end correctly and at a much higher speed than with spontaneous fermentation.
It should be noted that using this type of yeast we destroy the autochthonous yeasts from the vineyard , which have been achieved after a year of work in the field and those that will give us that characteristic of our plot with its microclimate and soil in special.
It is important to keep the native yeasts because they give the autochthonous character to the wine , as well as the essence of winemaking. But in order to carry out this type of fermentation, it is necessary to keep a good control of the temperature and the density to determine if they are working on the decomposition of sugars. As well as knowing the vineyards and the grapes with which they are working very well.
It may be the case that in some fermentations the yeasts do not reproduce or have a very slow reproduction, even the smell of glue appears due to the appearance of the acetic bacteria. At that time, it is interesting to colonize with a population of commercial yeasts to try to correct the problem and for the fermentation to come to an end.
Is it necessary to use commercial yeasts?
It will depend on how the fermentation process unfolds.
Although we can conclude that commercial yeasts are not always necessary, they should be used for emergencies: in case of fermentation stops to reactivate them, or of some microbiological problem; as well as they can also be useful to accelerate vinification processes and thus be able to shorten the terms of winemaking.