An old professor began his course by saying, “Wine is a product of the generosity of the land, the complicity of the climate and the enthusiastic work of man.” It is a phrase that perfectly sums up the complexity involved in making a good wine, but it doesn’t touch upon the enjoyment of wine. That is what we will try to reflect in this manual.
The grapevine is a plant that is capable of putting down very deep roots if the soil permits. Once there, the roots will seek out certain nutrients and a stable source of water that will allow the vine to withstand the rigors of summer. The orientation of the vineyard and its slope affect the sunshine that the grapes receive, and therefore the growth and maturation of the grapes.
The weather also decisively influences the grapes; all winegrowers fear a spring frost, an extreme drought, and late rains before harvest that slow the maturation of the grapes and encourage disease…these factors give rise to the concept of a vintage.
Finally, man is an integral part of both cultivating the plant (pruning, treatments, tillage, weeding, etc.) and creating the wine. Human intervention is essential because even the best grapes can become the worst vinegar if one does not orient, direct and control the transformations taking place during the fermentation and aging of a wine. However, 90% of a wine is based on the grape from which it comes. That is, a good winemaker can create an exceptional wine using exceptional grapes, but can never create a remarkable or notable wine with merely mediocre grapes. As for the composition of the cluster: it is composed of the stems (small woody stems that are attached to grapes) and the grapes themselves, also called berries. The stems taste sour, bitter and astringent (the Latin term for these stems, rachis, means “to scratch”), so they are usually removed as soon as the grapes are brought to the winery with a machine called a de-stemmer, or thresher. The only time when they are not removed is when we want to make wine using the system of carbonic maceration, or whole cluster pressing. The parts of the grape are the skin or peel, the pips (seeds) and the flesh.
The skins: Depending on the variety, the skins account for between 8% and 20% of the total weight of the berry. The skin is where we find the pigments, tannins and aromatic substances which accumulate as the grapes reach maturity. The skin is covered with a kind of wax, which is why when you rub a grape, the skin becomes shiny and looks polished. It is in this wax that the natural yeasts from the environment accumulate.
Pips: Grape seeds, called pips, represent between 0% and 6% of the weight of a grape. Inside the seeds, in addition to oils, one finds the extremely bitter substances that give a “green” character to a wine. Because of the bitter substances found within them, it is important that the grapes be ripe when pressed, so that the pips are hard, crunchy, and have strong woody walls that enclose these substances and do not allow them to be released in large amounts during fermentation. For the same reason, the grapes must be handled gently in order not to break them.
Flesh: The flesh of the grape is, by weight, the most important part of the berry (between 75% and 85%). The flesh is what actually results in the wine that we drink, being composed primarily of water, sugars, acids, minerals and nitrogen.