4 factors that determine wine quality

1.        The plant’s environment


Factors like climate, weather and soil affect the quantity and quality of the fruit. Heat is essential: the plant uses sunlight and chlorophyll to produce the glucose it needs for growth and vigor by combining CO2 and water.


In simple terms, the goal of viticultural practices is to concentrate the glucose in the fruit, not just in the vine. Left to its own devices, the plant will use all available resources to grow stronger and bigger.



1.1      Climate and weather


It is important to differentiate climate and weather: Climate refers to the average weather characteristics over a period of several years. The changes produced in these characteristics constitute the weather.



1.1.1 Types of climate:


Continental: Areas located away from large bodies of water. Significant difference in temperature between the hottest and coldest months of the year. Short, warm and dry summers. Cold, severe winters.

Maritime: Very little difference in temperature between the warmer and colder months of the year. Rainfall is distributed throughout the year, which has a moderating effect on temperature.

Mediterranean: the characteristics of the Mediterranean climate are very similar to those of maritime climates, except that summers are hotter and drier.



1.2    Temperature


During its growth cycle, the vine needs an average temperature of 16 to 22ºC to undergo photosynthesis.  In addition, different varieties need different amounts of heat to reach optimal ripeness. 


In the wine world, the temperature scale is categorized as follows:


·         Cool: Regions with an average temperature equal to or below 17ºC during the plant's growth cycle.  Ideal for short-cycle varieties.


·         Mild: Regions with an average temperature of 17 to 18.5ºC.


·         Warm: Average temperature of 18.5 to 21ºC. Ideal for long-cycle varieties.


·         Hot: Temperatures above 21ºC. These regions are not the most suitable for winegrowing. 




1.3    Sunlight 


As previously mentioned, light is essential to the vine's development: without light there is no photosynthesis, and the plant dies.

The amount of light absorbed by the plant determines the rate of photosynthesis. In other words, the more light there is, the more glucose the plant produces.

Excessive sunlight exposure, however, can also be harmful: the skin of the grapes can burn, resulting in a bitter flavor that affects the quality of the wine.




1.4   Soil 


The vine grows in soil that consists of differently sized rock particles, humus (decomposing organic matter) and nutrients.

The ideal winegrowing soil is nutrient poor, well drained and capable of storing the amount of water the plant needs to grow.




1.4.1  Soil and water


Good soil should have the capacity to store sufficient amounts of water at the beginning of the plant's growth cycle to make sure it gets a strong start. In the summer, the plants are subjected to slight levels of water stress after veraison to encourage ripening.



1.4.2  Soil and nutrients


The soil should contain small quantities of certain basic nutrients: nitrogen, phosphorus and potassium. If the nutrient levels are very high, the plant grows too vigorously, resulting in an excessively dense canopy. This would prevent sunlight from reaching the grapes and impede their ripening. 



2.      Species and varieties



Did you know that there are more than sixty different species of grapevine? Vitis Vinifera, however, is the only one used for winemaking. 


·         Other species (Vitis Riparia, V. Rupestris, V. Berlandieri) originating from North America are used as rootstocks, because they are immune to phylloxera.  Although now under control, the pest is still a concern to this day.


·         From a layperson's point of view, the way grapevines are grown and reproduce is quite odd. For example, if we planted a seed—a Cabernet Sauvignon pip—the resulting plant would NOT be Cabernet.


·         In order to propagate a variety, we have to take cuttings from an existing plant which, in turn, derives from a single “mother” plant.  


·         The varieties that have managed to thrive in different parts of the world are known as international varieties:Cabernet, Merlot, Syrah, Pinot Noir, Chardonnay, Sauvignon Blanc.





3.      Viticultural practices



As previously mentioned, if the winegrower did not intervene, the plant would direct all of its resources to growing freely. The resulting fruit would be sufficiently ripe to attract birds, but not to make wine.



In order to control the plant, a few musts should be kept in mind:



3.1 Training and trellising


These systems determine the direction in which the shoots will grow. The positioning of the vines follows the selected trellising system. This refers to the system of posts and wires that we see in vineyards, which support the vine shoots.



3.2 Pruning


Pruning is designed to limit the size of the vine and control yields by eliminating canes and leaves.  The goal is to set the number of buds that will subsequently grow out and produce fruit. 



3.3 Canopy management


This involves limiting canopy growth by removing leaves and vine shoots to direct glucose production toward the fruit. It also allows us to increase and improve the fruit's sunlight exposure.


3.4 The harvest


The harvest begins when the winegrower and the enologist decide that the grapes have reached the perfect balance between sugar levels and physiological maturity.

Sometimes the harvest has to be brought forward to avoid threatening weather conditions. Hail can damage the grapes whereas excessive rainfall fills the berries with water, thus diluting the sugar and affecting the quality of the subsequent wine.



3.4.1 Mechanical harvest


·         Speed is the main advantage of mechanical harvesting. This is particularly advantageous under bad weather conditions in order to avoid oxidation and premature fermentation.


·         In addition, it allows for nighttime harvesting, which delivers the grapes to the winery at a lower temperature. This means wineries save energy, because the grapes don't have to be chilled prior to fermentation.


·         Mechanical harvesting, however, does not allow for selective grape-picking and collects undesirable grapes, insects, leaves and more along the way.




3.4.2 Manual harvest


·         Manual harvesting is slower and demands a bigger workforce, but allows pickers to select the grapes.


·         In addition, whole-cluster harvesting reduces the risk of damage to the fruit.


·         Manual harvests can be performed in all kinds of terrain. In fact, in vineyards located on steep hillsides, manual harvesting is the only option (Mosel, Douro, Northern Rhône.)





4.     Enological practices


Oxygen management, sulfur dioxide use and oak influence are common elements in the processes of vinification and aging. 




4.1    Oxygen, sulfur dioxide and oak



·         Oxygen is a highly reactive gas, which means that when it combines with other molecules, it alters their properties.


·         Keeping in mind that oxygen oxidizes wine, its proper management is crucial during vinification and aging in order to obtain the desired result.


·         If we're looking to preserve varietal aromas then oxygen should be avoided at all cost. Remember: as wine oxidizes, it loses its fruit aromas.


·         In order to avoid this, the grapes are kept cool until reaching the winery, because low temperatures slow down the chemical reactions; in addition, winemakers use antioxidants like sulfur dioxide, which also acts as an antiseptic. An absolute must in a winery.


·         During aging, it is important to control the amount of oxygen that enters through the oak, which is permeable. The level of oxidation depends on the size of the barrel, the length of time the wine remains in the barrel and whether it is full or not.


·         In these types of wine, oxidation develops and adds aromatic complexity. As a result, the wines become more flavorful and earthy. In red wines, it softens the tannins and stabilizes color.

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