Wine

• Types of wine

  • Wine made from fermented fruit juice
• Requirements for fruit used in wine making

  • Must have a minimum quantity of fermentable sugars available
• Most common fruit used in wine making

  • Grapes
• Grape varieties used in wine making

  • Vitis vinifera (European grapevine)
  • Vitis abrusca (Fox grapevine)
  • Vitis Riparia (Riverbank Grapevine)
  • Vitis rotundiolia (Muscadine)
  • Vitis vulpina (Frost Grape)
  • Vitis aetsivalis (Summer Grape)
• Steps in making wines from Grapes

  1. Growing grapes (viticulture)

  2. Harvesting

  3. Preparing for fermentation

  4. Types of fermentation

  5. Sanitation

  6. Maturation

  7. Bottling
• Viticulture


  Branch of horticulture concerned with the growing of grapes used for wine making
• Factors influencing grape flavor


  • Climate of the vineyard’s region
  • Drainage around the vines
  • Humidity of the region
  • Sun exposure
  • Soil quality
• Vitis grows in most soils but requires good drainage and temperate climate. Most is grown between latitudes of 30º and 50º at average annual temperatures between 10ºC and 20ºC. It needs about 1300 to 1500 hours of sunshine p.a. and about 69 cm of rainfall (mainly during winter and spring). Sunny, dry summers are needed for harvesting; dampness when the grapes start to ripen allows microbial disease to attack and spoil/reduce yield/quality.
• White grapes do not produce anthocyanin, while red grapes do produce anthocyanin
• Harvesting grapes

  First step in wine production, can be done mechanically or manually, decision to harvest informed by the level of ripeness of the grape which determines the sugar and acid content
• Preparation for Fermentation

  Stemming/Crushing: Separation of stems and grapes, crushing to extract juice (must) from skins (marc)
• Wine production process

  Squeezing broken grapes to separate fresh juice (must) from the skins (marc), then fermentation process starts
• Preparation for Fermentation

  1. Different stages depending on the type of wine being made

  2. Red wine must consist of macerated fruit used for fermentation

  3. Carbon dioxide maceration is sometimes used to achieve macerated fruit, resulting in cell death and breakdown of cellular structure

  4. Skins and seeds are removed at the end of fermentation to allow flavors from anthocyanins to be part of the wine

  5. White wine consists of clarified grape juice that is fermented
• Fermentation

  1. Can be done by indigenous yeast or added starter yeast

  2. Starter culture is usually a preparation of dried S. cerivisiae

  3. Starter culture quantity is usually known, their fermentation characteristics are known, they are sterile

  4. Non-Saccharomycete yeasts are suppressed by the addition of sulfur dioxide and maintaining fermentation temperatures above 16 deg

  5. Starter Yeast should have high tolerance to sulfur dioxide, ethanol, sugar, high pressure, fluctuations in temperatures

  6. Starter Yeast should produce only small amounts of acetaldehyde, acetic acid, diacetyl, mercaptans
• Advantages of Using Starter Cultures

  Controlled fermentation, complete fermentation, less opportunity for off-flavour production
• Secondary Fermentation

  Encouraged activities of certain yeasts and bacteria, includes alcoholic fermentation in bottles and casks to create carbonated sparkling wines, growth of aerobic surface/film yeasts to produce fino sherry, lactic acid bacteria growth to encourage malo-lactic fermentation
• Post Fermentation Treatment/Sanitation

  Protection against Spoilage agents mainly oxidation, microbial spoilage, prevented by maintenance of anaerobic conditions, cooling, clarification
• If wine is exposed to air, it can sour from the action of aerobic bacteria
• Aerobic bacteria such as Acetobacter sp. and Gluconobacter sp. convert ethanol to acetic acid, prevented by the addition of sulfites as a preservative
• Clarification

  Stabilization of fermentation, removal of all remaining solids from the fermented liquid, done through fining, running the liquid through filters, siphoning the liquid off the top of fermenting vats after settling of solids
• Maturation/Aging


  The final stage in vinification
• Wine production

  1. Harvesting

  2. Crushing and Pressing

  3. Fermentation

  4. Clarification

  5. Maturation/Aging

  6. Bottling
• Fermentation


  Conversion of sugars into alcohol and carbon dioxide by yeast
• Clarification

  1. Causing the solids in the liquid to adhere to one another and sink to the bottom of the vat

  2. Running the liquid through coarse and fine filters

  3. Siphoning the liquid off the top of the fermenting vats after the solids have settled to the bottom
• Maturation/Aging

  1. Final stage in vinification where wine is allowed to further mature and develop flavors

  2. Transferring clarified wine into wooden barrels or metal vats for maturation

  3. Wooden casks allow wine to pick up flavors from the wood, adding greater depth to its flavors

  4. Metal vats are used for wines not suited to wood aging
• Bottling

  1. Final step of wine production

  2. Adding sulfite to preserve the wine and prevent unwanted fermentation

  3. Sealing wine bottles with corks or alternative closures like synthetic corks and screwcaps
• Production of Sparkling Wines

  1. Refers to wines that fizz due to the presence of Carbon Dioxide

  2. Four methods: Injection Method, Metodo Italiano (Charmat Process), Méthode champenoise, The transfer method
• Injection Method


  Uses a carbonator to inject carbon dioxide directly into the beverage, resulting in large bubbles that dissipate quickly
• Metodo Italiano (Charmat Process)


  1. Wine undergoes secondary fermentation in bulk tanks with yeast and sugar to produce carbon dioxide

  2. Bottled under pressure, used for Prosecco and Asti
• Méthode champenoise


  1. Effervescence produced by secondary fermentation in the bottle, used for Champagne and quality sparkling wines

  2. Yeast and sugar added to still wine for secondary fermentation in the bottle
• Transfer Method


  Secondary fermentation done in the bottle, wine transferred to tanks for filtration, then rebottled
• Most kinds of wine grapes are touchy
• If the weather is too hot

  They can produce too much sugar and not enough acid, resulting in overly alcoholic wines
• If the weather is too cool

  They won't ripen properly, and some will develop an unpleasant vegetal taste
• Rain at the wrong time of year

  Can wreak havoc on vineyards, causing grapes to rot on the vine
• The wrong type of soil

  Can leave vines with "wet feet," which can seriously hamper their growth
• Viticulture


  The science, production, and study of grapes
• Enology


  The science and study of wines and winemaking
• Commercial grapes were introduced in the 1490s and early 1500s in what is today the Dominican Republic
• Since then, grapes of Spanish origin and rudimentary wines have been produced in the country