Homemade Wine: Fermentation

In my previous post about making wine we finished with the harvest, crushed the grapes and put everything in barrels.

I’ll write about two methods of fermentation: classic and cold fermentation.

Classic fermentation

On the day after the harvest my Dad adds yeasts to the barrels to help fermentation, and also food for the yeast. You can buy that in any agriculture shop.

Then the fermentation starts. My father leaves the juice, and berries and rachises in the same barrel during the whole period of fermentation which lasts around two weeks.

Sugar can be added at any time during the fermentation if the sugar level is too low.

You need to blend all together two to three times every day until the fermentation stops, because the top layer always has some contact with oxygen and if you don’t blend it the result will be harshly unpleasant drink.

It is interesting that red and white grapes are not blended in the same way. Red grapes are blended hard with strong moves because you want the wine to have strong color. On the other hand, when blending white grapes you don’t really blend it…you just slowly press it down to mix the grapes but to have the clear color in the end. You don’t want to have yellow white wine.

After two weeks (or sooner, depending on the sugar level) wine juice is decanted, put in clean barrels and covered with plastic foil. At the top of the barrel a little pipe is put with one end below the foil and the other end dunked in water.

You can also decide to decant the juice out at some point (maybe after 3 to 5 days) and let the fermentation continue only with the juice. Then, the process will be a little bit slower. The decision is up to every winemaker and it’s not that one way is correct and the other is not. If you notice that the berries and rashies are getting spoiled maybe you can decide to take the juice out sooner.

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Decanting wine throiugh a colander
Decanting wine through a colander

Cold fermentation

If you have the needed equipment, cold fermentation is definitely a better and more controlled way to make wine. When I say equipment, I mean a way to control the temperature of grape juice in a barrel. You can buy it or do it by yourself at home if you’re handy with this stuff.

You need to do all the same on Day 1 – harvesting, crushing and adding potassium metabisulfite. On the second day grape juice is taken out of the barrel (leaving the berries and rachises in the first barrel) and put it in a barrel where the temperature can be controlled. The juice is kept below 10 °C in order to avoid the fermentation from starting.

What is left in the first barrel (the berries, rachises and the rest of the juice can continue the fermentation in the classic way.

With cold fermentation after 4 days the grape juice is decanted, the sediment is removed from the bottom of the barrel. And the grape juice is returned back to the cleaned barrel.

The yeasts are then added to the juice together with yeast’s food so the fermentation can start. The juice is then kept at 15-16 °C for the next approximately 30 days (depending on the sugar level). Another dose of yeasts food is added a week after the fermentation has started.

The actual temperature depends on the speed of sugar transforming to alcohol. If it’s too fast, the temperature is set to 1-2 °C lower. Sugar ratio should decrease every day for around 0.5 °C.

When the sugar ratio drops below 10 %, refractometer can not be used for measuring anymore because at that point it is not precise anymore and then my Dad starts using the classical meter.

Refractometer - Measuring sugar level
Measuring sugar level. Refractometer shows around 10.5% of sugar.

Stopping the cold fermentation – the ‘silent’ fermentation starts

When the sugar drops below 4%, my Dad stops the cold fermentation. This gives the wine the frizzante effect and dryness. The wine is then transferred in a new barrel (you can also use the same barrel after cleaning it), covered with a floating oil lid. The lid floats on the wine, and the oil is put all around on the rim to prevent contact with oxygen.

If you leave the cold fermentation going until the sugar drops to zero, then the wine can get hard and very soon develop the ‘old wine’ taste.

At 4 % the fermentation is still not completely over, and the process from now on is called ‘silent’ fermentation because it is not so noisy and active as the first one. This goes on for another month or two, and then the wine is then decanted and put into a clean barrel and the process of winemaking is over. This is usually done on Saint Martin’s Day which is celebrated on November 11. The holiday celebrates the end of agrarian year and the end of harvest, the end of winter preparation and that the newly produced wine is ready for drinking.

The wine is then put again barrels covered with oil floating lid.

There are many articles and books written about winemaking but actually every winemaker makes his own decisions and with time gets to know his grapes.

Making wine isn’t an easy job, even an experience winemaker can easily make mistake if it’s not careful. It takes time and commitment to make a good wine everyone wants to enjoy.

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