Fermentation
/ˌfɜːr.mɛnˈteɪ.ʃən/
winemaking, microbiology, yeast, alcoholic-fermentation, malolactic, sparkling-wine, cellar-practice, wine-chemistry•Last updated December 27, 2025
In wine, fermentation is the biochemical process in which yeasts (and sometimes bacteria) convert grape sugars into alcohol, carbon dioxide, and a range of aroma- and flavor-forming compounds, transforming grape juice (must) into wine. In practice, the term covers both primary alcoholic fermentation and, when applicable, secondary fermentations such as malolactic fermentation or the second alcoholic fermentation for sparkling wines.
Examples
- A winemaker cools freshly pressed Sauvignon Blanc juice and inoculates it with a selected yeast strain to carry out a slow, temperature-controlled fermentation in stainless steel, preserving bright, fruity aromas.
- In traditional-method Champagne, a base wine is bottled with added sugar and yeast so that a secondary fermentation occurs in the bottle, producing the dissolved carbon dioxide that creates the wine’s fine bubbles.
- After alcoholic fermentation of Chardonnay in oak barrels, the cellar team encourages malolactic fermentation to soften acidity and add creamy, buttery notes to the finished wine.