The role of stirring has:

Benefit 1: Cooling

After the grape pomace floats up to form the skin cap, it is tightly covered on the top of the grape fermentation liquid, and the fermentation process will be exothermic, and the temperature inside can't be dispersed in a timely manner. The optimal temperature for wine fermentation cannot exceed 30 degrees, so by stirring, it can play a role in cooling down the heat.

Benefit 2: maceration.

The uplifted grape skin residue is necessarily dry and not showered with wine liquid. And the process of producing wine requires the color of the skins, the tannins of the seeds, and the natural yeasts present on the skins. So by stirring, you are able to allow the grape skin pomace to be impregnated and produce a more beautiful, flavorful wine.

Benefit #3: Degassing.

Many winemakers are sealing or basically sealing when they do one-fermentation. And the fermentation process will produce a lot of carbon dioxide gas, so by stirring regularly, you can let the carbon dioxide produced get discharged in time, to avoid the risk of bursting the bottle,

Bleeding at the same time, there is fresh air into the yeast reproduction can provide oxygen.

Benefit 4: anti-variation.

The skin of the grapes that is exposed at the very top is the same as the grapes that are left outside waiting to rot, because it is not drenched with alcohol and carbon dioxide, it increases the possibility of bacterial reproduction, and eventually makes the wine bad, sour and of insufficient quality. At the same time it allows the newly added sugars to fully contact the wine liquid, allowing for a more even fermentation.