After being harvested, the grapes are pressed for a first spill of the must so that the yeasts come into contact with the liquid which must then be transformed into wine.
In ancient times the pressing of the grapes was done with the feet in wooden vats. What was obtained was excellent because in this way a gentle pressing was carried out without stressing the grapes. Today, however, this practice is no longer considered acceptable from the hygienic-sanitary point of view, some oenological machines are used, the crushers or destemmers.
How to do the pressing
What is obtained from pressing is called must and can be subjected to special treatments to stabilize it or to help macerate the solid parts it contains. Being the first operation to which the grapes are subjected, the pressing must be done carefully if you do not want to risk compromising the quality of the wine.
Pressing and pressing
It is necessary not to confuse the pressing and pressing which are two different stages of winemaking. The pressing is the soft crushing of the grape to extract part of the liquid, while the pressing is used to extract the must present in the crushed. With the pressing, therefore, only the grapes are transformed into a liquid that contains solid parts, while pressing the first division of the solid from the liquid. The destemmed crushed grapes are made up of pulp (80%), skins (15%) and grape seeds (5%). The must is made up of water (70-80%) and sugars and other substances (10-30%).
The crushing is done with particular oenological machines: the crushers and destemmers. The destemmer-destemmers, together with the crushing, carry out the destemming, that is they remove the stalks from the crushed. The destemming takes place in a rotating perforated cage where the blades (the so-called destemming tree) rotate at low speed, pushing the grapes against the cage. The juice and the berries pass through the holes in the cage while the stalks remain inside. There are roller crushers formed by a stainless steel structure that contains various pairs of rollers in non-toxic rubber that gently press the grapes. The activity of the rollers is adjustable and depends on the characteristics of the grapes to be pressed and the type of wine to be obtained. It is important that the crushed grapes have constant qualities throughout the operation to have a uniform product and therefore a good final result.