Fermentation
Fermentation in winemaking is the biochemical process by which sugars present in grape must are converted into ethanol and carbon dioxide by the action of yeast[1]. This transformation, central to wine production for millennia, not only produces alcohol but also generates a wide range of secondary metabolites that contribute to the aroma, flavour, and texture of the finished wine[2]. While the fundamental reactions have remained constant, contemporary winemaking applies refined control over fermentation variables to influence wine style and quality[3].
Historical context
The use of fermentation in winemaking dates back to the earliest known viticultural civilisations of the Caucasus and Mesopotamia, where wild yeasts present on grape skins initiated spontaneous fermentations[4]. Ancient Egyptians, Greeks, and Romans documented methods to encourage or control the process, often by managing vessel design, temperature, and exposure to air[5]. Although the microbial nature of fermentation was not fully understood until the 19th century, practical techniques for ensuring consistent wine production were developed over centuries through empirical observation.
Process and characteristics
In winemaking, fermentation is the metabolic conversion of grape sugars, primarily glucose and fructose, into ethanol, carbon dioxide, and heat by yeasts, most commonly strains of Saccharomyces cerevisiae[6]. The process may occur spontaneously through indigenous yeasts present in the vineyard and winery, or it can be initiated with cultured yeast inoculation to provide greater control over flavour and fermentation kinetics[7].
Fermentation is influenced by factors such as temperature, oxygen availability, nutrient levels, and the initial sugar concentration of the must. Cool fermentations tend to preserve volatile aroma compounds, while warmer conditions can enhance extraction of colour and tannin, particularly in red wine production[8].
Role in winemaking
Fermentation is the central biochemical transformation in winemaking, determining the wine’s alcohol level, flavour profile, and overall stability[9]. Beyond alcohol production, yeast metabolism generates secondary compounds such as esters, higher alcohols, and volatile acids, which contribute to aromatic complexity[10].
In red wine production, fermentation often coincides with maceration, allowing extraction of phenolic compounds from skins and seeds. For white wines, fermentation typically occurs after pressing, with minimal skin contact to preserve freshness and varietal character. Fermentation can also be arrested or conducted at reduced temperatures to retain residual sugar, producing off-dry or sweet styles.
See also
References
- ↑ Robinson (ed.), The Oxford Companion to Wine, Oxford University Press, 2015, ISBN 978-0198705383.
- ↑ Peynaud, Enology, Wiley, 1984, ISBN 978-0471881491.
- ↑ Jackson, Wine Science: Principles and Applications, 5th ed., Academic Press, 2020, ISBN 978-0128161180.
- ↑ Boulton, Singleton, Bisson & Kunkee, Principles and Practices of Winemaking, Springer, 1999, ISBN 978-0834217011.
- ↑ Rankine, Making Good Wine, Macmillan, 1996, ISBN 978-1864482694.
- ↑ Jackson, Wine Science: Principles and Applications, 5th ed., Academic Press, 2020, ISBN 978-0128161180.
- ↑ Peynaud, Enology, Wiley, 1984, ISBN 978-0471881491.
- ↑ Robinson (ed.), The Oxford Companion to Wine, Oxford University Press, 2015, ISBN 978-0198705383.
- ↑ Rankine, Making Good Wine, Macmillan, 1996, ISBN 978-1864482694.
- ↑ Boulton, Singleton, Bisson & Kunkee, Principles and Practices of Winemaking, Springer, 1999, ISBN 978-0834217011.