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Wine Production. Enology and Viticulture. Viticulture is the Science of Grape-Growing Enology is the science of wine (making ). Wine. Wine is fermented fruit juice. The most important fruit is Vitis vinifera ( Vitaceae ), but any fruit can be used.
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Enology and Viticulture • Viticulture is the Science of Grape-Growing • Enology is the science of wine (making)
Wine • Wine is fermented fruit juice. The most important fruit is Vitisvinifera (Vitaceae), but any fruit can be used. • Yeasts occur on the skins of most fruits and if the fruits are mashed, the sugar-containing juices begin to ferment.
History and Origin • Winemaking probably began as one of the earliest of human enterprises (8000-3000 B.C.). • The wine grape was domesticated by at least 4000 B.C. Wine was used for Egyptian worship ceremonies. • Wine only became a popular beverage about 2000-1000 B.C. in Greece.
About 600 B.C., wine growing reached France. • Wine grapes were introduced early into the United States. • The Spanish introduced grapes into California in the 1700's.
Stages (Harvest & Selection) • Harvest • There are over 4000 varieties of grapes used in the production of wine. • Grapes are usually harvested from early September to the beginning of November.
It starts in the vineyard at harvest: • It is important to wait until the grapes reach the proper maturity for the variety of grape & style of wine being made. • As the grapes ripen, the sugar level increases and the acidity decreases. • The sugar level is measured in units of “Brix”; wine grapes are usually harvested at a Brix of 22 to 28. • Ripening will depend on many factors, such as the temperature, amount of sun and rainfall, availability of nutrients. • The grapes can be harvested manually or by mechanical pickers. Manually picked grapes are typically higher quality.
Grape Selection/Processing • Grapes must be treated with 50-75 ppm of free sulfur dioxide. Sulfating is done to remove unwanted bacteria before the next step of the process. • Equipment must also be sanitized. This is usually done with an O2 based caustic solution, water, and then a anti-bacterial sulfite solution. Finally another water rinse.
After harvesting: • The grapes are transported to the winery where they undergo de stemming and crushing. • There are a variety of presses that are used to produce the juice, which is called “must”. • The sugar in the wine is used by the yeast to produce ethyl alcohol and carbon dioxide gas, thus making wine. • The type of yeast can affect the qualities of the wine as will the other compounds in the wine - some naturally occurring and some that are byproducts of the winemaking process.
Fermentation and Aging: • After crushing and pressing the must is transferred to large, refrigerated stainless steel tanks where it is fermented to produce wine. • Once fermentation is complete, the wine can be transferred to oak barrels for aging for 6 to 24 months. But, not all wine is oak aged. • The barrels are usually made from either French or American Oak, which give differing qualities to the wine. • Some wine is aged in old barrels and some in new to produce different characteristics, as well. • The wine maker will then blend the various lots of wine to produce a finished wine ready for bottling.
Bottling and Cellaring: • After the wine is complete it is transferred to bottles. • Most wine is consumed within three years of bottling. • But some fine wines gain added flavor and bouquet with time in the bottle if it is stored at 50 to 60 F. But, humidity is also important so that the corks do not dry out, which spoils the wine.
Principle • Fermentation Process: • C6H12O6 + yeast 2C2H4OH + 2CO2 • The alcohol solution that results from fermentation contains about 12%-15% ethanol. • This correlates to the conditions that yeast cells can survive in, higher concentrations of ethanol will kill the yeast. • For every gram of sugar that is converted about a half gram of alcohol is produced. • To achieve 12% alcohol concentration, starting material must contain about 24% sugars.
Malo-lactic fermentation (secondary fermentation) • Malic acid is converted into lactic acid and carbon dioxide • Changes the flavor of the wine from crisp to creamy buttery as well as reducing the amount of acidity (increases pH from .3-.5 units) • This can be introduced or happen naturally – and monitored by testing with paper chromatography. • Controlling the pH (best around 3.0-3.5) • High pH results in less flavor production in the wine • To lower pH, tartaric acid is added at the beginning of the fermentation process. • Oxidation Reactions • Acetobactorbacteria will react with the oxygen to convert the wine into vinegar.
During fermentation the most harmful bacteria that can grow is of the genus Acetobacter. • However, this bacteria is sensitive to the free sulfur dioxide, which is why the cleaning process is important. • Burnt match smell • SO2 levels are greater than 40 ppm • Overly sweet wine • Fermentation can be restarted to convert the residual sugar into alcohol
White wine • When processing grapes for White wine, after the cleaning process they are immediately pressed and the juice is sent to the tanks .
Fermentation temperature is usually about 15-18°C • Sweet wine are made by leaving some residual sugar after fermentation • This is done by: • Harvesting later • Freezing the grapes to increase the sugar concentration • Killing the yeast before fermentation is complete
Red wine • Grapes are usually crushed with all parts together and they then go straight to fermentation • The skin and seeds are important to pass on tannins and the bitter taste unique to red wine – this mixture is called “must” • Fermentation process is usually quicker for red wines • This is because red wines can be fermented at a higher temperature due to the nutrients it contains. • Fermentation temperature is usually 22-25°C
After the must is transferred to the fermentation tanks a “cap” is formed which prevents air from reaching the juice • The cap is created by the solids that are pushed to the top due to the carbon dioxide production • This cap is kept in contact with the juice as much as possible in an effort to retain the color and tannins • This is done by punching the cap down manually or by pumping the cap over mechanically • This process is done approximately twice a day
Once the juice has been transferred to the fermentation tanks, the yeast is added and the oxygen is removed. • By removing the oxygen from the tanks, the oxidation process is halted, which helps prevent any bacteria growth. • Yeast • Saccharomyces cerevisiae is the species of yeast used in the fermentation process. • This yeast species has been acclimated to the effects of the free sulfur dioxide. • Other species of yeast are intially present on the grapes, however are killed in the cleaning process
Different types of wine • White Wine • Red Wine • Blush Wine • Champagne (Sparking) Wine • Fortified Wine
White Wine • Grapes for white wine are harvested and pressed. • The must is fermented in stainless steel tanks. • Some white wines, such as Chardonnay, is aged in oak barrels. • The wine is bottled • Most white wines are not bottle aged but consumed with in 3 years of bottling. • However, an exception is particularly fine wines made from Chardonnay and Champagne
Red Wine • Grapes for red wine are harvested, crushed. • The must is left with the skins during fermentation to produce the red color. • Red wine is commonly aged in oak barrels for 6 to 24 months. • The wine is bottled. • Many red wines are ready to drink after bottling. • However, some red wines, such as Cabernet Sauvignon, will benefit with some bottle age.
Blush Wine: • Red grapes are harvested for Rose or Blush wine. • Before fermentation the must is left with the skin for a short time. • The must is fermented in stainless steel tanks. • If a sweet wine is desired then the fermentation is stopped before all of the sugar is consumed. • Blush wines are not commonly bottle aged but consumed within 3 years of bottling.
Champagne (Sparking) Wine • Grapes for sparking wine are harvested and pressed. • It is fermented like a white wine. • More sugar and yeast is added to the wine. • The wine is bottled. • The additional sugar and yeast produce carbon dioxide, which carbonates the wine. • The second fermentation is stopped. • Most sparkling wines are made to drink young. But, fine Champagne will benefit with additional bottle age.
Fortified Wine • Grapes for fortified wines are harvested like for other wines. • Depending on the type of wine, the must may be handled in different ways to intensify the flavor before and during fermentation. • Most fortified wines have an addition of alcohol (brandy) to stop fermentation and increase the alcohol content. • Fortified wine maybe aged in oak barrels before bottling. • Many fortified wines will benefit with bottle age.
Famous red wine types:Shiraz • If this varietal is South African or Australian, it's generally called Shiraz. Anywhere else, it's referred to as Syrah. • Shiraz displays strong blackberry and peppery flavor characteristics and are generally very earthy.
Pinot Noir • One of the most difficult grapes to grow, but one of the easiest and most food friendly wines out there is Pinot Noir. • This wine is full bodied, but not to a point of sensory overload. Its flavor characteristics are that of dark, ripe cherries with herbaceous hints of rosemary.
Tempranillo • For Spanish and Portuguese wines, the Tempranillo grape is king. • The Tempranillo grape is what the majority of wines labeled Rioja are made from. • Wines made from this grape have leather and tobacco flavor characteristics with hints of plum and cassis.
Bordeaux • Probably one of the most famous wines to ever come out of France, you will rarely, if ever, go wrong with a good bottle of Bordeaux. • Wine from one of the 57 appellations in this region are big, full bodied, tannic wines
Cabernet • Though this grape varietal is used mainly for blending with other grapes, it is sold as a stand alone varietal. • If people are looking for something in between the big, bold flavors of a Cabernet Sauvignon and the sometimes thin body of a Merlot, Cabernet Franc is the perfect choice.
White wine types :Pinot Grigio • Pinot Grigio is the most popular white wine in Italy. • All those Italians simply cannot be wrong. This wine is light, fruity and friendly with citrusy overtones. • A glass of Pinot Grigio lends itself well to seafood and many white pasta sauces
Bordeaux • Bordeaux isn't just for the reds. • White Bordeaux is equally as coveted and most of the time, equally as expensive. • These wines are lush, refined and full of soft fruit flavors.
Is wine good for you? • Studies have been done to show that wine drinkers are less prone to heart disease, cancer and other diseases • This could be a result of the antioxidant resveratrol which may reduce cholesterol and the risk of Alzheimer’s disease. • However this antioxidant can also be found in other foods, avoiding the harmful effects of alcohol. • The study of wine is becoming so popular that now a Bachelor of Science degree in oenology is available .
