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Wine 101... and then some!
 What is wine? Wine is the alcoholic beverage obtained from the juice of freshly gathered grapes, the fermentation which is carried out in the district of origin according to local tradition and practice.
• Viticulture is the growing of the grapes, which are used for wine production.
• Vinification is the process of making wines from the grapes.
• What is Fermentation?
– The process by which grape juice turns to wine.
– SUGAR + YEAST = ALCOHOL + CO2
• When does fermentation begin? Fermentation begins when grapes are crushed and ends when all sugar converted to alcohol, or when the alcohol level has reached levels high enough to kill off the yeast.
• Sugar is naturally present in the ripe grape.
• Yeast also occurs naturally, on the grape skin, however, natural yeast is not always used in today’s winemaking. Instead, laboratory strains of pure yeast have been isolated and are typically used in the Vinification process. Each strain contributes something unique to style of wine
– Carbon Dioxide (CO²) dissipates into air
• EXCEPT in Champagne and sparkling wines
• Gas retained through special process
Types of Wine
– Still wine: produced from black (red) and white grapes in a fermentation, which is allowed to complete naturally.
– Light wine: official name of unfortified wine.
– Heavy wine: official name for fortified wine. Wines that are made by adding grape spirit (or brandy) during or after the fermentation process.
– Sparkling Wine: are produced be allowing the natural carbon dioxide produced during fermentation to be retained in the bottle, or by the addition of carbon dioxide at a later stage.
The production of wine
There are many factors that may contribute to the quality of wine:
• The grape
• The soil
• Climatic conditions, location
• Viticulture
• Vinification
• Luck of the year
• Storage
The Grape
There are many species of grapes worldwide, but the majority of wine produced is from the species Vitis vinifera
• The vinifera grape is very versatile, however, it is not well suited to cold or humid climates.
• In the Eastern United States, native grape varieties such as Concord and Scuppernong are grown for winemaking.
– These grapes are typically found on the East Coast of North America, and are naturally resistant to pests of the region.
• To combine the hardiness of American varieties with the flavors of European (vinifera) varieties, the two were crossbred to produce hybrids.
• Grafting takes a cutting, from a vinifera variety and affixing it to a rootstock from American grapes that are phylloxera resistant.
• The result is a vine that has roots that are resistant to phylloxera and produces vinifera fruit for winemaking.
– There are many different rootstocks that are adapted to a variety of growing conditions
There are two colors of grapes which are Black Grapes commonly known to us as “red” and White Grapes.
The pulp in the wine is colorless and produces the grape juice (known in wine terminology as the must).
Can white wine be produced from “black” grapes?
The color of wine comes entirely from the grape skins. If the skins are removed immediately after pressing, no color is imparted to wine, and wine will be white.
– Most famous is Champagne! In the Champagne region of France a large percentage of the grapes are Pinot Noir, however, most of the resulting wine is white. In California, some sparkling wine is made from the Pinot Noir grape and White Zinfandel is made from the Red Zinfandel grape!
• What is a Tannin? Natural substance from skins, stems, pips and the wooden barrels used for aging. Tannins act as a preservative, without it, certain wines wouldn’t improve in bottle. Generally, red wines have a higher level of tannin than whites.
What is meant by Acidity? All wines have a certain amount of acidity. Typically, white wines have more acidity than reds. The winemaker’s task is to balance the fruit and acid. Acidity in wine is needed to give wine a lasting finish. If a wine is too low in acid, it tastes flat and dull. If a wine is too high in acid, it tastes too tart and sour. Usually, the winemaker can easily manipulate the acidity.
The acids in wine are tartaric acid (cream of tartar) and malic acid. The amount of tartaric and malic acids vary depending on the grape variety and on where the grapes are grown. Tartaric and malic acids are produced by the grape as it develops. In warm climates, these acids are lost through a biochemical process. Therefore, grapes grown in warmer climates have lower acidity than grapes grown in cooler climates. For example, Napa Valley produces grapes with lower acidity because the climate is warmer.
Sugar production is the complete opposite of acid production. The warmer the climate the higher the sugar content of the grapes. Sugar content of grape juice is expressed in ° Brix. In summary, warmer climates result in high sugar and low acid whereas cooler climates result in low sugar and high acid
• The malolactic fermentation (MLF) is an important natural process for adjusting the acidity in wine. The MLF lowers the acidity by converting malic acid to lactic acid and carbon dioxide. Many white wines undergo MLF, while most all red wines "automatically" undergo MLF. There are some wines that have less malic acid in them than others, and the MLF does not play a significant role in shaping the wines as in those with a higher malic acid content. The conversion of malic acid to lactic acid produces a buttery texture.
• What is “vintage”? A vintage indicates the year the grapes were harvested, so every year is a vintage year.
The Soil
• Poorer soil traditionally produces better grapes, because the roots push downward to find water, picking up minerals and trace elements.
• Deep roots are less affected by weather conditions, such as the cold nights or drought.
• Soils that are shallow or low in nutrients may produce a lower cropload with less vegetative growth.
• Less vegetative growth, will not provide shade for the grape clusters allowing increased sun exposure.
• A soil’s makeup is contingent upon:
• The material or rock of which it is comprised (clay, silt, sand)
• The size of the material or rock the soil is made of: (For example clay is made of very fine particles, silt has larger particles and sand is even larger.)
• The chemical composition of the soil
• The organic matter and nutrients in the soil
• The depth of the soil
• Soils are characterized by the ratio of sand, silt, and clay that are present in them.
• Soils that have a high ratio of clay are said to be heavy.
• Sandy soils are called light.
• Loam is a mixture of clay, silt, sand, and organic matter that is fertile and drains well.
• Alluvial soils lie in the floodplains that flank rivers and streams; they are usually a mix of silt, sand, gravel, and loam.
• Grapevines need adequate, but not excessive, nutrients from their soil for healthy growth.
• A vineyard’s topography is as important as its soil. Within a vineyard, there may be several different typographies.
• A vineyard on a south-facing hillside will absorb more sunlight and be warmer than the north side of the hill.
• Hillside vineyards have better drainage but will be more susceptible to erosion and wind damage.
• Cold air will settle into valleys and low-lying areas on still mornings without wind making these locations more susceptible to spring frost and winterkill.
Climate and location
• Vines grow best in 30-50 latitude north and south.
• Frost is the most dangerous climactic condition.
• Cold or wet weather at flowering may cause coulure, which is the non-pollination of blossoms, causing the grapes to fall off or never develop.
• The ripening period in Sonoma and Napa is from June to September. 85 to 100 days of sunshine are needed to ripen the grapes for harvesting.
A lack of sunshine during these months produce grapes with a lack of sugar.
Too much sunshine produces grapes high in sugar, low in acid (maybe producing “flabby wines”).
Too much rain during this time will cause the grapes to swell weakening the resulting juice. Hail may damage the grapes, causing mold to form and spoil. Heavy mist or rain at harvest may prevent the crop from being picked at the correct time, ruining an entire year’s work
• These broad weather conditions of a particular wine-growing region are defined as the macroclimate.
• The weather in a particular vineyard or portion of a vineyard is referred to as the mesoclimate or microclimate.
– Terroir is the French term to describe all the environmental factors that are found in a given vineyard, such as soil, topography, and all the climatic conditions.
• Grapevines are grown on an artificial support called a trellis.
• There are several different types of trellis systems from simple to complex.
Growing cycle
Beginning of the growing cycle
• The growing season begins in the early spring usually between February and April in Sonoma and Napa.
• When the average temperature reaches 50°F (10°C), the vines end their winter dormancy.
• Shoots, or canes, sprout from the buds and begin to grow quickly. At this point, the shoots are sensitive to below freezing temperatures.
– Spring frosts are common in low-lying vineyards where the cold air can settle in the early morning hours.
– Vines are protected from frost by wind machines or sprinklers.
Bloom
• Flower clusters at the base of the young shoots look like miniature clusters of grapes.
– About eight weeks after budbreak, they begin to bloom.
– Once fertilized, a grape flower will begin to develop into a berry.
– If a flower is not fertilized, it will drop off the cluster in a process called shatter.
– For optimum pollination, warm, even temperatures are desired, without too much wind or wet weather
• Véraison is the beginning of ripeness and starts in mid to late summer about eight to ten weeks after bloom.
• At véraison:
– The hard and green berries begin to swell and change color.
– The sugar from photosynthesis is now going into fruit development instead of vegetative growth.
– Irrigation is diminished to help the fruit ripen by slowing vine growth.
Harvest known in the wine community as “The Crush”
• Six to ten weeks after véraison the grapes will be ready for harvest.
– The time of harvest depends on the variety, the weather conditions, and the degree of ripeness desired.
– The decision to harvest is based on the maturity of the fruit as well as operational concerns.
– Grapes can be picked either by hand or by machine.
– Hand picking is gentle to both the fruit and the vines is selective: only the healthy ripe fruit is picked and requires more labor
– Mechanical harvesters are not as gentle or selective as hand picking. However, they have the advantage of also being operated at night so that they will bring in cooler fruit. Mechanical harvesting requires less labor (more cost-effective). With the technical advancements, each method, if done properly, can provide the winery with high-quality fruit.
Dormancy
• At the first frost after the harvest, the leaves will fall off marking the beginning of the winter dormancy period. While the vine is dormant, little growth occurs, making the vine less sensitive to climatic conditions.
• Vineyard operations during dormancy include
– adding fertilizers and soil adjustments.
– a cover crop that may be planted to control erosion.
– pruning the vines.
Malolactic fermentation
Takes place after the alcoholic fermentation. It is the conversion of malic acid into lactic acid and a some carbon dioxide.
Malic acid is harsh, this causes the wine to soften.
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