Simple rhetoric: grapes and fermentation. This is the first step in winemaking: the process by which grape must is transformed into the alcoholic beverage that fills our glass. Chemically, what happens is that the yeast and sugars in the must react, creating ethanol—or ethyl alcohol—and carbon dioxide.
The fermentation just described is alcoholic, ethylic, or primary fermentation. It is common to all musts—red, white, or rosé—and usually takes place in stainless steel tanks (sometimes in cement, clay, or barrels), under controlled temperatures. The yeasts are responsible for converting the sugar into alcohol, contributing aroma, body, and flavor in the process, while also eliminating tartaric acid derivatives from the grapes, which helps to soften the wine.
The second fermentation—which, as we’ll see, not all wines require—is called malolactic fermentation. This involves bacteria converting the malic acid from the grapes into lactic acid (the type found in fermented dairy). Typical in red wines, this process is key because it regulates the wine’s total acidity, increases its volatile acidity, and provides stability to the final product.
While these are the basic fermentations in winemaking, it’s worth noting that in some cases, malolactic fermentation is replaced by bottle fermentation (as with sparkling wines) or barrel fermentation (also known as carbonic maceration, commonly used for very young wines with low aging potential).
No. For red wines, the first fermentation lasts between 10 and 14 days at a controlled temperature not exceeding 29°C. During this time, the so-called “pumping over” process is performed: transferring the must from the bottom of the tank to the top to stimulate yeast activity. Malolactic fermentation can take an additional 15 to 21 days.
For white wines, the first fermentation lasts around 21 days at 18-20°C. Malolactic fermentation is only carried out in aged (crianza) whites since this process diminishes their fruity aromas and freshness, affecting their characteristic acidity. Some whites, by the way, are fermented in oak barrels, which positively influences their aromas and alcohol levels.
As for rosés, the process has two parts: a rapid phase of 5 to 8 days, during which yeast activity is concentrated, and a slower phase of 5 to 10 days, during which the wine acquires the typical characteristics of its style.
As obvious as it may seem, it’s important to emphasize the role of these microorganisms—not only because they consume the fruit’s sugars to produce carbon dioxide and ethanol but also because they create other essential compounds like acetic and lactic acids and glycerol. A wide variety of yeasts are used during fermentation, starting with those naturally present on the plant and the fruit’s skin, and extending to industrially cultivated ones (At Pradorey, we don’t use the latter: we ferment our wines exclusively with native yeasts from our vineyards).
The temperature must be precise—14-18°C for whites and rosés, 22-26°C for young reds, and 26-30°C for aged reds. Otherwise, there’s a risk of killing the yeast, rendering it unable to perform its function, or destroying aromatic compounds and causing bitterness. Factors such as high or low temperatures—and others like ethanol buildup, low nitrogen nutrition, or microbial contamination—can lead to the dreaded fermentation stoppage, which occurs when the must’s sugar consumption slows significantly. Although rare, if this happens, additional yeast and nutrients can be introduced to complete the fermentation process.
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Carretera CL-619 km 66.1 Gumielde Mercado (Burgos) Espana
Carretera CL-619 km 64 Gumielde Mercado (Burgos) Espana
