Making indigenous yeast- Letto 9172 volte
How to prepare a pied-de-cuve of indigenous yeast for wine fermentation: my zero risk suggestions to get amazing aromatic results
This is a very important harvest for me: I have started to select and reproduce wild yeast from my vineyard in Tenuta Belicello. In the past years, I have experienced a yeast selection only from the Merlot grapes, which I now want to apply to all the wines at Cantine Barbera.
After a few years of experience, this decision has become a logical consequence of my commitment to quality and to a natural and sustainable grape growing and winemaking.
As a matter of fact, yeast plays a very important role in defining the aromatic profile of the wines and it is able to outline their personality and character. Different yeast has differing physiological and fermentative properties, therefore the actual strain of yeast used in the winemaking has a direct impact on the finished wine.
I expect at least two results from my choice of using wild yeast on fermentations: first of all, I am well aware that wines made with indigenous strains could be less manageable than those made with selected yeast. At the same time, I believe that what is expected to be an issue would, on the contrary, lead to a more original, probably unconventional character of the wines that I am going to make this year.
It is a difficult path, but I think it’s worth it!
How I obtained my yeast?
Yeast is micro-organisms naturally present on the grapes’ skin, which is responsible of the wine’s fermentation: the strain composition, its quality and characteristics are deeply influenced by terroir.
A clean environment and a great integrity and quality of the grapes are pre-requisites to reproduce strong yeast that should be able to bring the fermentation to its very end.
I started on July 26th to make my culture from Chardonnay grapes: 220 lbs of sound clusters, carefully selected and picked by hand in small baskets.
After picking, they were immediately brought to the winery: high acidity, amazing aromas and good sugar level were the parameters I monitored to start the culture. The grapes were crushed by hand in small stainless steel tanks. I used the whole cluster (stem, skins, seeds and juice) to obtain the maximum quantity of potential micro-organisms, and patiently waited for the yeast to develop.
Once the fermentation had started spontaneously (I waited 2 days at a fresh but not cold temperature), I separated the fermenting must from the solid parts and started to “feed” the yeast: every day, I kept on adding hand squeezed fresh juice made from selected grapes to supply sugars and acids to the culture.
After 10 days, I obtained 100 gallons of fermenting must that was used to inoculate 9 tons of pre-dawn harvested Chardonnay grapes.
A part of the grapes was crio-macerated with the skins for 12 hours and then soft-pressed before inoculation (the one in tank), the other part was inoculated before the pressing (the one in barrels).
The results are excellent so far: the yeast reproduced in both cases and developed a continuous fermentation.
In the first case the fermentation has been slower: the yeast consumed only 0.35 oz of sugars per day and has worked for over 15 days.
In the second case the must fermented only 11 days. In both situations I was surprised to have obtained a very low degree of volatile acidity, a low pH and an amazing level of total acidity. Which, translated into a spoken language, means fresh and fruity aromas, easy drinkable quality and a limited alcohol level (around 12.50).
Every aroma of banana and tropical yellow fruit, which is usually related to the use of selected yeasts, has disappeared and whatI feel right now is a citrus bouquet with a touch of herbs, and amazing flavour.
All the pictures of my experiments are available on the Flickr album.
Now I can feel the ocean!