The pressing of the grapes is a decisive phase which decides, among other things, the color of the wine being made. So, by nature, white wine can be obtained from white grapes or and red wine from red grapes. But this is not so. What actually gives wine its color are anthocyanins, tannins and generally speaking polyphenols – natural grape molecules whose presence is particularly potent within grapes. So, in order to produce a red wine, the grape must is macerated together with grape skins for either a short or long time (usually from 15 to 20 days).
White wines go through a soft pressing in order to separate the solid part and the liquid part. A more practical illustration of this is – grapes are placed in the crusher machine, inside which there is a large balloon like structure which is slowly filled with air in order to press the grapes as much as possible.
The light pressure of the balloon will crush the grapes softly, letting the must slowly pour into a basket placed at its base. The pomace will then be held behind, thanks to a net which prevents it from passing. This is why when we speak of white wine, we speak about soft pressing. The grapes are pressed slowly to avoid any contact between skins and must.
They are fermented separately and the pomace remains will almost always then end up in the production of spirits such as grappa or acquavite.