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Last Updated: Mar 24, 2026Fermentation
Fermentation
Fermentation is a natural biochemichal process where yeast consumes the natural sugars (glucose and fructose) in grape juice and converts them into alcohol, carbon dioxide and heat. It can take 7 days to several weeks for complete fermentation to occur and at the end, grape juice is transformed into wine. White wines are fermented cooler (50-64°F) to retain their fruit notes, while red wines ferment warmer (68-86°F) to extract color and tannins.
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Yeast
Yeast in wine is a microscopic, single celled fungus, typically Saccharomyces cerevisiae, which triggers fermentation by transforming the sugars in must into ethanol and carbon dioxide. Yeasts are essential for converting grape juice into wine and they determine its final alcohol content, aroma and flavor profile.
Sediment
The term "sediment" signifies the natural, organic by products of the winemaking and aging process. It is made up of grape solids (skins, seeds, pulp), dead yeast cells (lees) and tartarate crystals (wine diamonds).
Lees
Lees are the dead yeast cells, grape seeds and skins left over in the fermentation tank after fermentation. There are two types of lees; gross lees and fine lees.
pH
The pH of wine is the measure of its total acidity (hydrogen ion concentration), typically ranging from 2.9 to 4.0 in most wines.
Assemblage
Assemblage is the French term for the process where winemakers combine different base wines that vary by grape variety, vintage or vineyard parcel, to create a balanced and complex final wine.
Must
Grape must is the freshly pressed, unfermented grape juice which contains the fruit's skins, seeds and sometimes stems (collectively referred to as pomace).
TCA
TCA stands for 2,4,6-trichloroanisole, a chemical compound that causes "cork taint". It forms when natural fungi in corks or wooden barrels interact with chlorine in cleaning products, resulting in musty, moldy or wet cardboard aromas in wines.
Aging
Aging is a post fermentation process where wine rests in barrels (mainly oak) or bottles to undergo chemical changes that improves stability, develops complex flavors and clarifies the liquid.
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