History of Wine - Cultivation
The vine contributes to the carbon cycle through its foliage and the photosynthesis of its fruits (grapes), which produces the sugars needed for storage. Grapes are essentially “storehouses” of sugars that are then used in the fermentation of wine. Growing vines requires constant monitoring of the gradual “storage” of sugars in the fruit. Any issue that alters or breaks this balance, such as pruning, can cause the accumulation of sugars in a limited number of fruits. When soil is moderately wet, roots penetrate deeper to extract vital minerals (mainly potassium). The harmony between the content of sugars and acids is essential for the final quality of the wine.
Generally, the longer the vine receives sunlight, the more sugar is found in the grapes; on the other hand, limited exposure to the sun leads to a minimum amount of sugar (and, therefore, to a lower amount of alcohol). This proportion of sugar in grapes is usually controlled in different countries and is usually determined with a portable refractometer (only a small amount of must is needed to detect the concentration of sugar in Brix degrees). Therefore, to maximize the amount of light obtained, the vines are designed in the shape of a pergola to capture as much sunlight as they can.
As the grape ripens on the vine, there is an alteration of the fruit that in Spanish is known as envero, and in French as “véraison”. This is a new expression that has just been incorporated into French dictionaries. At that time, grapes alter their metabolism and begin to accumulate more sugar while their acidity decreases. Normally, this phenomenon occurs in July, in the Northern Hemisphere, when the grapes on a vine go from green to yellow, if it is a white grape variety, or to red, if it is a red grape variety.
Not all vines in the vineyard experience the same phenomenon at the same time. The winter marks the beginning of the countdown to the harvest. Other factors, such as the change in color of grape seeds, which tend to change from green to brown, or the maturation of polyphenols, also determine the time of harvest. In the past, experienced winegrowers would pick a grape every day from the vineyard to know when the harvest should begin, based on the different flavors and aromas they detected. Nowadays, this is done through the use of instruments such as refractometers, etc.
have obtained positive results, although potentially too practical. At the University of Davis, in California, by focusing simply on viticulture and not on ampelography, ampelology or ampelometry, they have achieved much-praised achievements in the academic field. Even with their lower yield, older vines have many supporters; however, it has been discovered that this highly desirable result is not due to the age of the vines, but rather because, as they are old, the few grapes they produce are exposed to more sunlight. The same result can be achieved with new vines, ensuring that they are exposed to more sunlight and that the grapes are not restricted to each other from light.