Grape is the most raw material of wine. “Wine grapes grow almost exclusively between thirty and fifty degrees north or south of the equator. As a rule, grape vines prefer a relatively long growing season of 100 days or more with warm daytime temperatures (not above 95°F/35 °C) and cool nights (a difference of 40°F/23 °C or more).”
The grape berry in its early weeks after flowering is a tiny, green-colored, very acidic pellet. During ripening the berry increases in volume so that after a few weeks the tiny berry becomes a plump, sweet, colored fruit. When the berry changes its color the veraison phase is reached. From an oenological perspective, veraison can be divided into different sub-stages based upon berry metabolism and the continued transport of substances to the vine. During veraison, water, sugars, and nitrogen compounds are transported to the berry via the phloem. Sucrose is hydrolyzed to glucose and fructose and flavour and aroma compounds are synthesized within the berry. The fruit does not increase in volume indefinitely. When the fruit has reached normal maturity there is a cessation of cell enlargement and a decrease in volume can occur under warm conditions. During these physical changes other chemical changes also occur.
It is the grape quality rather than any other factors that determines the quality of the wine. The quality is defined by different parameters: 1. permanent (variety, soil, climate, exposure), 2. variable (the weather during the growing season), modifiable (the time of harvest, pruning), 3. accidental (hail storm, diseases).
Reference “Grape as a Raw Material for Wine Making – Page 2.” Grape as a Raw Material for Wine Making – Page 2. N.p., n.d. Web. 28 Apr. 2015.