The magic of yeast!
This is one of the singlehandedly most important steps in a wines life. It's basically what's makes it a "wine"!
The process is initially a bit different from whites and rosés to reds:
White/Rosé:
After being pressed and pumped into the stainless steel vats the juice is initially cooled down to 12 degrees to help the must settle and do a cold precipitation. After a few days we rack the wines to a new clean tank separate them from the dirt now safely resting at the bottom of the tanks (this is called "Racking"). This is done in order to prevent potential off-flavours to form during fermetation.
Pic: dirt in the bottom of the tank is separated from the wine
Reds:
The grapes for the red wines are pumped directly into the vats after destemming and crushing and slowly allowed to start fermenting on the skins by raising the temperature. During the fermentation of the reds we work with both pump-overs and punch downs (this is also called "pigeage") to extract the perfect amount of color, tannin and aroma compounds from the skins. This is done on an individual basis for each tank, depending on grape variety, plot, vintage and what wine we envision to make from it. There is no recipe that suits all.
Pic: Manuel pump-over and punch down (we have machines to do this automatic.
When we feel that the given wine has done enough extraction we press the skins off the reds and return the now clear red wine to the tanks. Sometimes, and especially for our Pinot Noir, we first let all the juice that runs off the tank by itself do so without pressing. This is the so-called "free flowing juice". Only after that we press the remaining skins etc.
Mother Nature decides
(Whites, rosés and reds)
As we’re dealing with Mother Nature here, each fermentation runs a bit different. Sometimes faster and sometimes slower, and a few times it even stops! This resulted in our very first sweet wine being made in 2022. As we prefer working with nature instead of against, it we usually let the wine do what it wants! So if a given wine in a given year decides to go a bit slower or faster, we trust that it knows best itself and don’t try to oppose too much.
Note that we use cultured yeast (saccharomyces cerevisiae) in order to ensure a picture-perfect fermentation. Natural yeast is present in our vineyards, but we are still not familiar with which strains, so we use some very specific cultured yeasts in order to be able to control the fermentation process 100% and ensure that we end up with exactly the wines we want. We use several different types of yeast from different manufactures, as each different yeast brings out different things from the wine. Some bring out more tropical fruit notes, some grapefruit notes and some helps create a more red fruit character etc. When we speak of "cultured" yeasts they are of course non-GMO and "natural", but very simply grown in a lab to ensure a healthy culture and only one yeast strain versus the many mixed ones you'd find outside in our vineyards.
We use a different yeast for each tank/fermentation, even for different tanks of the same grape variety, in order to create even further complexity in our wines. It's quite remarkable how different the initially same must can smell and taste when being fermented with different yeasts!
We add the yeast to the wine just after it's been racked into a fresh clean tank on day 1-2 after pressing for the whites/rosés and almost immediately for the reds, but we don't just add the yeast directly. It first needs to be rehydrated and "activated", just like when you bake bread! (The yeast comes packed under vacuum and dehydrated and has to be stored in the fridge)
First we measure the right amount of yeast for the given tank, then we dissolve it in water at 35-38C. Then we slowly and step by step cool down the mixture by adding must from the tank it will later be added to. The yeast wake up because of the water, temperature and sugar in the must. We need to slowly bring the temperature of the yeast mixture within a 10C range of the temperature of the tank in order to not give it a temperature chock when added. It also needs to start "eating" sugar slowly in order to not be overwhelmed when added to the tank.
Finally the yeast mixture is added and magic starts happening! The must will bubble and even create foam on the top. A fermenting wine neither smells nor looks very tasty! But once the yeast has eaten all the sugar, dies and sink to the bottom of the tank we have a beautiful, and now dry, wine! We leave the dead yeast cells on the bottom of the tanks for a while as they impart further complexity. Some producers even stir them up and mixes them into the wine at a regular basis. This is called "battonage" (especially when done within a barrel! ) But that is a whole other story and not something we do at Binivista, at least not yet!
Our whites and rosé wines ferment at around 16-19 degrees and the reds at 24-27 degrees for about 15 days. During this period we monitor the vats on a daily basis and check how the fermentation is coming along.
