Before fermentation can begin, the grapes need to be picked and crushed.
Choosing the right moment to harvest the grapes is essential to wine quality. A great wine can only be made from ripe grapes.
But the longer it is left on the vine, the greater the chance that the crop will be damaged, either by cold or disease.
Conventional winemakers get round this by picking early, before the grapes are ripe, and attempting to correct for it in the winery.
For natural winemakers it's a question of instinct and nerve.
To make a good natural wine, grapes must be hand-picked.
There are several reasons for this :
- Hand-picking is selective. Unripe or damaged grapes can be rejected.
- Harvesting machines damage grapes. They work by slapping the vine foliage with fibreglass rods and catching the grapes as they fall.
- Harvesting machines are large. In order to accommodate them, vines have to be widely spaced and trellised in a certain way. These are both compromises which damage wine quality.
As it is picked, the fruit must be collected into small containers, to avoid being crushed under its own weight, and taken to the winery as quickly as possible.
Crushing and pressing
These are not the same thing, but are often confused.
Crushing grapes means breaking their skins and releasing the juices so that fermentation can begin. Crushed grapes are a sugary pulp of juice and skins called the must.
Pressing is the removal of the skins and any other solid matter from the must. The juice is pressed out, rather as you might squeeze an orange, and the skins thrown away. It is not necessary to press the must for fermentation to begin.
The period between crushing and pressing, when the juice is still in contact with the skins, is called maceration.
The skins may be removed before, during, or after fermentation.
For dark red wines maceration is longer than for lighter reds. White wines will be pressed and crushed simultaneously.
The winemaker must also choose when to destem the fruit. Leaving the stems in during maceration gives a more tannic, astringent wine.
Carbonic maceration takes place when whole bunches of grape are held in carbon dioxide.
Within the grapes, small amounts of sugar are converted into alcohol without the need for yeasts. Eventually this causes the grapes to burst so that normal fermentation can begin.
It produces light, fruity red wines and is most famously used in Beaujolais and the Loire.