Le cellar practices are a fundamental step in the production of wine in order to improve its stability and organoleptic qualities. As can be guessed, not all practices are positive and make for a better wine. This article explains the main cellar practices covered during the sommelier coursedecanting, racking, draining, clarification, filtration, fermentation and pasteurisation. There are also brief mentions of some common corrections (correction of acidity, colour, alcohol content...), including the 'dreaded' sulphur dioxide.

How wine is made: cellar practices


The pouring is the movement of wine from one container to another with the aim of separating the wine from the lees that settle at the bottom. In particular, this process is important for these reasons:

  1. clarity and stability: removes the sediment that can make the wine cloudy. A limpid wine is generally more attractive to consumers and considered to be of higher quality, although for sommeliers, whole wines or 'sur lie' are now clearing this thought.

  2. olfactory and taste-olfactory characteristicslees impart characteristic sensory traits and if left for too long in unsuitable wines these are not always positive.

How wine is made


During the rest period, either because of the rising temperatures (wine drops by evaporation), either because of the decreasing temperatures (wine drops due to volume contraction) and both because of theabsorption of wine by woodCOLMATION is required. Filling consists of filling the container with wine through the FILLER CAP, a small glass vessel placed in the bung (exit hole of the cask) that contains some of the same wine. When the level of wine in the cask decreases, the wine contained in the bung drops into the cask. This practice serves to prevent oxidation and the development of harmful microorganisms.


During the rest period, due to the rising temperatures (wine increases by dilatation), it is necessary to perform the DISCOVERY. The draining consists of removing excess wine from the container through the FILLER CAP, a small glass vessel placed in the bung (exit hole of the barrel) that contains some of the same wine. When the volume of wine in the cask increases, the filler cap incorporates the excess. This practice serves to prevent overflow from the container and spillage of the wine.

How to make corked wine

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Clarification is a practice carried out at low temperature that consists of adding substances that form heavy aggregates with the particles to be removed, which then settle to the bottom of the container. The added substances may be organic (animal gelatin, vegetable gelatin, albumin, isinglass) or inorganic (aluminium sulphate, bentonite, potassium caseinate...) or a combination of these.


La filtration is not a one-size-fits-all winery practice: it can have different methodologies and effects. Roughing filtration serves to remove the coarsest particles. Brightening filtration serves to eliminate all particles, even the smallest ones. Sterilising filtration not only removes all particles but also eliminates micro-organisms and makes the wine clear. Filtration, in absolute terms, neither impairs nor improves quality, it simply makes a wine with different characteristics. There are quality wines NOT FILTERED that have rested and retained their visual and organoleptic qualities intact.


Re-fermentation takes place by adding some fresh, concentrated or muted must and selected yeasts to the wine to restart fermentation. This practice serves to correct minor defects or to enrich the wine with more pronounced organoleptic characteristics. GOVERNO ALLA TOSCANA is a special form of refermentation that is made by adding a small portion of dried grapes to the new wine in December, and a second addition in spring. The resulting wine is colourful, fragrant, smooth and very balanced.


Pasteurisation is a thermal process that inactivates enzymes and destroys the microorganisms responsible for spoilage and disease. This process was invented by Pasteur in the second half of the 19th century precisely to 'sanitise' wine, which at the time was considered more hygienic than water and drunk more willingly. Today, this practice is only used for ordinary wines because, while the resulting wine is stable from an enzymatic and microbiological point of view, it loses most of its taste and smell qualities (exactly as happens in milk or in the beer).

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How wine is made: wine corrections

  • Colour correctionIf a more intense colour is desired, one can resort to cutting with wines characterised by a more vivid colour.
  • Correction of alcoholic strengthIf you want to obtain a wine with a higher alcoholic strength without resorting to the cut method, which is now in disuse, you can chill the wine to - 18°C to separate some of the water in the form of micro ice crystals.
  • Acidity correctionIf you want to obtain a wine with more acidity, you can add tartaric acid or citric acid. This practice is only recommended for young wines. If you want to obtain a wine with less acidity, you can add salts such as potassium bicarbonate, neutral potassium tartrate and calcium carbonate, which have the property of precipitating excess acids.

How wine is made: sulphur dioxide

L'sulphur dioxide (i.e. the 'dreaded' sulphites) is added to wine to reduce oxidation and make it biologically stable. Put simply, it serves to inactivate enzymes, moulds, bacteria and preserve the taste and colour of the wine. It is in fact a preservative in its own right, and can be found in food under the designation E220 (Sulphur Dioxide) and E221-E228 (Sulphites). Depending on its concentration, in combination with the alcohol contained in wine, it can have undesirable effects such as a headache, and this is also why usage limits have been established. Curiously, a number of urban legends have arisen about sulphites in wine from people who demonise them, forgetting that they are present in most food industry products such as wine vinegar, dried mushrooms, beer, fruit juices, dehydrated, glazed or candied fruit, hamburgers, seafood, shellfish, frozen vegetables, pickles and pickled oils. For further reading this article on sulphites.

Sulphur dioxide sulphites in wine enoadvance