Agricultural Studies Wine Production Grade 11 Mosweu A.M.
13 May 2009
Contents
Fruit of Vine
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Grapes for wine making are grown in many areas in U.S. including France, Chile , Australia and South Africa Many categories of winemaking grapes are cultivated throughout the world Vitis Vinifera- European type: Chardonnay, Cabeernet Sauvignon, Merlot, Reiesling There are some hybrids also namely: Baco Noir, Chambourcin etc.
How to Plough Wine trees Chemicals in the Soil
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While the role of chemicals in the soil is not clearly understood, we do know that: – Too much nitrogen yields heavy leaf growth and shade, while too little produces hydrogen sulfide. – Too little potassium makes plants vulnerable to drought and disease and yields grapes that are low in sugar. – pH is not critical, because grapes grow in a variety of soil pH levels.
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Too much organic material yields too much nitrogen and water, but too little will not support many soil organisms (earthworms).
Harvesing • When grapes start falling is indication of readiness for harvesting • Some vineyards use mechanical harvesting techniques • Most hire workers to pick the grapes by hand • The grapes then taken to winery • For far wineries grapes shipped by refrigerated trucks where they crushed to form must
Wine Production • •
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Red-grape must is sent directly to ferment tanks White-grape must is sent first to a wine press to separate juice from skins White wines are fermented from skinless grapes Wine press consists of a stainless steel cylinder with inflatable bladder inside which is inflated with air The skins are recycled to local nurseries for fertilizer. The juices are collected and sent to the fermentation tanks
Fermentation Process • • •
The fermentation tanks are airtight, made of stainless steel with capacity 11 356 litres The tanks are cooled with glycol to maintain a temperature Sugar and yeast are added to kick start the process of fermentation
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How Yeast Makes Alcohol and Carbon Dioxide When the yeast first hits the wort, concentrations of glucose (C6H12 O6) are very high, so through diffusion, glucose enters the yeast (in fact, it keeps entering the yeast as long as there is glucose in the solution). As each glucose molecule enters the yeast, it is broken down in a 10-step process called glycolysis. The product of glycolysis is two threecarbon sugars, called pyruvates, and some ATP (adenosine triphosphate), which supplies energy to the yeast and allows it to multiply. The two pyruvates are then converted by the yeast into carbon dioxide (CO ) and
Bottling • Cork in the bottle after the wine has aged are bottled for sale • The operators pump the wine from the storage tank to the bottling machine and fill bottles • The operators load the bottles into a case for shipping and distribution • They may also have a tasting rooms where one can sample and purchase their products
Types of wine Products • The grapes are grown and fermented the same as with any other wine. • After fermentation, the wines are aged for about five months. • The wine is bottled with extra yeast and sugar. The bottles are capped to allow for a second round of fermentation, which lasts for about a year. • The wine is aged for one or more years after the second fermentation. • The yeast is removed through riddling, whereby the bottle is placed upside-down and rotated one-eighth of a turn every day. The dead yeast cells settle into the neck of the bottle. • The neck of the bottle is frozen in an ice/salt water bath and the cork is removed. The pressure forces the frozen plug of dead yeast cells out of the bottle. This process is called disgorging. • A mixture of white-wine brandy and sugar (dosage) is added to top off the bottle.