Pressing the Must

How long after fermentation you wait before pressing the must is up to the winemaker, but I generally press about 3 weeks after crush. Fermentation is complete at this point, and the natural coolness of the garage 'refrigerates' the must while various compounds continue to be extracted from the skins. After pressing, the skins, seeds, and pulp are thrown out, and the resulting wine is stored in barrels or tanks to begin the aging process.

Once the free run juice (the juice that can be separated from the wine without any mechanical squeezing of the skins) is pumped out of the fermentation vessel the skins, seeds and pulp are left over. This is then manually loaded into the press to extract the wine that is left within these elements.

Free Run vs. Press Wine

About 10% of the total volume of the wine is gained during pressing, but the quality of the wine extracted this way is much less. For this reason, many wineries keep their free run wine separate from their press wine. The press wine is then sold off or used in the winery's lesser blends. Starting with the 2001 vintage I am keeping the press wine and free run wine separate to improve the quality of my best wine.

The Science of Pressure

There are many different types of presses on the market, and which one is used will have an effect on the quality of the wine it produces. I have been renting a press from a local winemaking shop that uses a screw to apply pressure to grapes in a basket. Some of the fancier tools are now using compressed air or compressed water to inflate bladders which exert a more even pressure on the skins so as to extract more wine, but do so gently. The gentleness is important, since rough pressing will release harsh tannins into the wine.