The process of fermentation converts grape juice into an alcoholic medium called “must”, while at the same time extracting colour pigments and tannins from the skins. Once the wine has completed fermentation, the winemaker will separate the free run juice from the skins.
Just as a saturated sponge will retain water until lightly squeezed, the remaining skins will retain wine rich in colour and structure. To release this quality press wine, we use a traditional basket press at De Toren to apply light pressure to the skins in order to to release the wine.
Interestingly enough, 2007 saw the discovery of the world’s oldest complete winery in a cave just outside a small Armenian village. This cave winery held reminiscences of clay fermentation vats, a rudimentary predecessor of a basket style press, pressed grape skins and seeds, as well as a drinking cup. All these artefacts have been dated to the late Chalcolithic Period, also known as the Copper Age, some 6000 years ago. In later years, the Romans and Greeks improved these crude presses by evolving them into the basket press we know today. This begs the question, how could equipment and technology some 6000 years old still be relevant today, let alone be the preferred way that De Toren presses its grapes?
At De Toren the drained skins are loaded into a basket made of high density polyethylene staves by hand. We replaced our wooden staves for greater sanitary precision). A platform that perfectly fits into the basket is then carefully and slowly pushed down by a hydraulic piston. As the platform starts compressing the skins, wine starts flowing from the skins, through the staves and into a basin. At this point the pressing process becomes a very important and intimate winemaking technique.
- As the pressure increases the pressed wine will start evolving in character: The first fraction will deliver wine similar in quality to the free run juice. Most of the wine extracted during pressing will be from this fraction and the pressure necessary to release this wine will be as little as 0.1 – 0.2 Bar.
- The next fraction contains wine that is more neutral in character. This fraction does not last long.
- The third, and probably most important fraction, is when the skins start to release wine rich in phenolic compounds. This wine is typically very structured, very flavoursome, inky dark in appearance and concentrated. It is this fraction that can propel a good wine into a great wine. Normally it require as little as 0.6 Bars of pressure to achieve the extraction of this great fraction from the skins.
- The fourth fraction does not contribute towards wine quality. It is hard, dry and overtly tannic and the tannins tend to have a sharp, green, bitter edge to them. This fraction, even in small quantities, can ruin a great wine.
The key is thus to stop the whole action, as press fraction three reaches its pinnacle and this is where our small, hands on basket press is such a vital part in our production. During the pressing process, wines are tasted at least every minute in the beginning, allowing us to form a relationship with each press load, and get to know the wine as it evolves. As we reach press fraction 3, wines are tasted at even shorter intervals and as the pinnacle of this fraction approaches, wines will be tasted continuously to stop the process from proceeding into fraction 4.