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The natural occurrence of fermentation means it was probably first observed long ago by humans. [3] The earliest uses of the word "fermentation" in relation to winemaking was in reference to the apparent "boiling" within the must that came from the anaerobic reaction of the yeast to the sugars in the grape juice and the release of carbon dioxide.
Yeast need a reliable source of nitrogen in forms that they can assimilate in order to successfully complete fermentation. Yeast assimilable nitrogen or YAN is the combination of free amino nitrogen (FAN), ammonia (NH 3) and ammonium (NH 4 +) that is available for a yeast, e.g. the wine yeast Saccharomyces cerevisiae, to use during fermentation.
Wine is usually made from one or more varieties of the European species Vitis vinifera, [65] such as Pinot noir, Chardonnay, Cabernet Sauvignon, Gamay and Merlot. When one of these varieties is used as the predominant grape (usually defined by law as a minimum of 75% to 85%), the result is a " varietal " as opposed to a "blended" wine.
This liquid is often brought to temperature of 40 °C (104 °F) prior to the introduction of the yeast (though some yeast strains may need temperatures below 38 °C (100 °F) [1]) to allow the cells to disperse easily rather than clump and sink to the bottom of the container.
When the base wine (or cuvee) has been produced from single grape varietals or a blend, the wine is bottled with a mixture of yeast and fresh sugar known as the "liqueur de tirage". This secondary fermentation, also known as bottle fermentation, is the process that makes the wine "bubbly" due to the containment of carbon dioxide which is ...
Recently, several vintners have utilized native yeast fermentations. Skin-fermented orange wines and effervescent pétillant naturel wines (i.e., pét-nats) have popped up from producers across ...
Lager yeast normally ferments at a temperature of approximately 5 °C (41 °F) or 278 k, where Saccharomyces cerevisiae becomes dormant. A variant yeast known as Saccharomyces cerevisiae var. diastaticus is a beer spoiler which can cause secondary fermentations in packaged products. [68]
A winemaking process where wine is chilled to near freezing temperatures for several weeks to encourage the precipitation of tartrate crystals. Compte Classification system used in the Armagnac and Cognac region based on the age of the spirit ranging from 00 for a newly distilled spirit to 2 for a VS ("Very Special"), 4 for a VSOP Reserve, 6 ...