The Basics of Vinification (HOW Wine is made)

So we all know that there are two very large distinctions in wine. We have the production of the red and the white. Red wines are generally made from black grapes only but winemakers can add a small portion of white grapes if the local laws permit it. White wines are made from white/light green grapes and the vinification process is very similar. However, white wines need to be treated more carefully since they are more likely to have oxidation problem than their red counterparts.

First we will look at the red wine production:

Preparation:

  • Stalks are usually removed first before the grapes are crushed. However, if the wine maker wants to increase the tannin level of the resulting wine, he will keep the stalk intact when crushing.
  • The crushing is usually not very hard so the pips will not be broken to release bitter oils which will damage the flavor of the wine to be made.
  • After crushing, must, which is the combination of juice and pulp, skins and pips are put into a vat where the alcoholic fermentation will start.
  • The vat could be a stainless steel vessel, a new oak barrel or a used oak barrel.

Fermentation:

  • For red wines, fermentation normally starts at about 20ºC and can be raised to anything between 32ºC and 35ºC if necessary.
  • Generally, the warmer the temperature, the higher levels of tannin and color can be extracted from grape skins.
  • The ideal temperature will vary from grapes to grapes and regions to regions.
  • As carbon dioxide is generated as a by-product during this process, it will carry the pulp and skins up to the top of the vat when escaping. Therefore, in order to maintain good contact between the skins and juice for optimal color extraction, the pulp and skins will be pushed down constantly by various means.
  • The length of fermentation will be up to the wine producers, being 1 to three weeks.

Maturation:

  • After fermentation, the wine can be run off from the vat naturally. This is called free-run wine. More wine can be extracted by pressing the residual (pulp and skins) left in the vat. This is known as press wine.
  • Press wine is usually darker in colour and more tannic than the free-run wine. They can be blended together before setting for maturation or they can be separated into different barrels for maturation.
  • Depending on the wine styles to be made and the grape varieties, the wines can age inside a vessel for as long as 2 years before bottling.
  • If the vessel is a new French oak barrel, the maturation process will be a spectrum of flavors and tannins to the wine which can help bottle aging. If it is a new American oak barrel, it will integrate sweet vanilla and coconut flavors to the wine.
  • If used oaks are used, it will have no or very little effects on the resulting wine dependent on the number of times used.
  • A French oak barrel is a lot more expensive than an American one.

Bottling:

  • As some consumers, particularly Americans and Japanese, expect a bottled wine to be clear and bright, therefore, the wine makers will remove any particles that may cause cloudiness. This can be completed by fining, filtration, or chemical and microbiological stabilization.

Now the production of white wine:

Preparation:

  • After the grapes arrive at the press-house, they will be de-stalked and pressed.
  • The juice may be left with skins at low temperarture for 2-3 hours for flavor extraction.
  • Afterwards, it will be drawn off from the press either into a vat or cask, where the juice will be fermented.

Fermentation:

  • Fermentation usually begins at a lower temperature, normally between 15ºC and 20ºC, sometimes as low as 9ºC.
  • The white wine fermentation process usually takes longer period then red wine. This is because more fruit flavors can be imparted to the wine and loss of freshness can be avoided.
  • As alcoholic fermentation generates heat as a by-product, so cooling is required to keep the process going under the acceptable temperature level. To date, modern wineries are all using vats with individual heating/cooling system.
  • Fermentation at higher temperature, within the acceptable level, can develop more complex aromas, but the fruit characteristics may decrease.
  • If the process is kept at a too low temperature, it creates peardrop aromas to the wine and fails to extract fruit flavor from the skins.
  • If the wine is fermented in barrel, the lees may be stirred up on a regular basis to impart additional flavor and richness.

Maturation:

  • Maturation is less common in white wines than reds. This is because the fruitiness of whites will be dissipated during the process.
  • If maturation is thought to be necessary, the aging period is normally shorter than red wines. In many cases 12 months is the upper limit.

Bottling:

  • White wines are generally bottled much earlier than reds. These wines are specially produced for early consumption.
  • Up to the time of bottling, white wines will be kept in a temperature controlled stainless-stell vat.


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