Once fermentation is complete the wine is pressed. Well for reds at least; white wines remember are fermented without their skins and are therefore pressed before fermentation. Pressing is the process for separating the juice that will eventually become the wine from the skins, and sometimes stems. There are two different types of presses that can accommodate this. One is called a bladder press and is the most common in today’s commercial wineries. A baldder press is in effect an inflatable balloon, or bladder, that is slowly expanded, filling the space and squeezing the juice away from the grape solids. A bladder press is a very gentle way to extract the juice from the grape solids, which is the reason it is now the preferred method today. A gentler extraction means leaching less bitterness and tannins into the juice from the grape solids.
But before the bladder press there was the simple basket press. A basket press is a vessel into which the must is placed, the must being the mixture of both juice and grape solids, and on which a wooden or metal plate is lowered through a screw drive. This will eventually squeeze the juice through a grate at the bottom of the press, which allows the juice to flow out, leaving behind the grape solids. While the bladder press may be much more popular in commercial wineries, us home winemakers still mostly rely on the traditional basket press to make our wines, usually taking care to not try and wretch the last bitter drop of juice out of the skins.
Aside from all this pressing it should be noted that a good portion of “premium” wines are made solely from free run juice. Free run juice is the juice that runs from the press without any added pressure being applied. However, it should also be noted that this juice, while certainly delicious and free from any excess bitterness or tannins from the skins or stems of the wine, accounts for a very small percentage of the juice that can be produced from grapes. Which means that while super premium wines may be made according to this practice, most wines that you drink will not be.
Regardless of your method, once you have your juice you essentially have wine; except at this point it will taste a lot more like Welch’s grape juice than any wine; to change that it needs to age, most typically in an oak barrel. But more on that next time.