Wino Word of the Day - Fermentation

Fermentation: Grape juice is joined by other ingredients resulting in a chemical reaction that produces wine.

Yeast is added to the juice, which converts sugars (fructose and glucose) contained in the grapes into ethanol and carbon dioxide. Eventually, the carbon dioxide releases into the air and the alcohol remains. Once all of the sugar turns into alcohol (meaning it is at 15%) and the yeast is completely destroyed, the wine is now ready for the next stage.

Usually red wine is fermented in oak barrels and white is stored in stainless steel vats at much colder temperatures. Nitrogen is added to prevent hydrogen sulfide gas from invading the wine. If the gas does attack the grapes, a rotten egg smell will stink up the mixture. Now this liquid is called the "must" and has to be stirred in order to avoid harmful bacteria from invading. Bubbling will occur anywhere from 8 to 20 hours. First stage of fermentation process for red wine is 5-10 days, while white sits for 10-15 days.

The second phase of fermentation occurs when the wine is siphoned into an airtight container-- no additional oxygen is allowed! This phase creates a higher alcohol content. Now, it is up to the winemaker to decide on what extra ingredient(s) to add. It can be anything, such as more yeast or blended finished wine.