What is wine clarification?

Wine fining serves to stabilise the wine

Wine clarification is a process carried out to stabilize the wine against protein breakdown and to improve its visual appearance

Have you ever seen the grape must before the winemaking process begins? It is a liquid with a cloudy appearance because the grapes, including the skins and pips, are gently crushed to achieve this. How do wineries ensure that the must’s cloudiness gives way to the clarity and transparency of the wines? By racking, clarifying the wine and filtering methods after the wine’s alcoholic and malolactic fermentation.

Why is this done? Once fermentation is complete, most of the yeast precipitates to the bottom of the tank in which the wine is aged, giving rise, through sedimentation, to what is known as lees in the world of viticulture.

In the past, the wine was racked, that is, changed from one container to another to leave the lees behind. Nowadays, however, many wines are aged on lees that are periodically stirred, as this technique, known as batonage, brings many advantages, such as an increase in the aromatic power of the wines. In this way, racking is delayed.

In addition to the lees generated by sedimentation, which operate as a spontaneous clarification of the wine, there are other smaller particles that do not sediment but remain in suspension. Although the leaves can be separated from the wine by racking, this is not the case for these small proteins.

This is why, after racking, winemakers choose to carry out wine clarification, an oenological technique that eliminates the impurities in suspension and achieves stable, bright and clear wines.

What does wine clarification consist of, and why is it carried out?

Wine clarification is a technique that involves using substances that can agglutinate the particles in suspension and make them precipitate like the rest of the lees. These substances are known in the oenological field as fining agents.

The fining agent binds by its charge to the proteins that have remained in suspension in the wine, forming larger floccules that precipitate. As a result, the wine becomes stable against protein breakdown, a phenomenon that could cause the wine to become cloudy due to changes in temperature or storage.

Wine clarification is carried out to:

  1. Make the wine stable.
  2. Prevent protein breakdowns from clouding the wine during storage.
  3. To guarantee an excellent visual appearance of the wine when it is to be enjoyed by wine lovers.

How are fining agents used? Winemakers dilute the fining agent used in water, precisely establishing the appropriate dosage, and introduce it into the tank containing the wine to be fined. Afterward, the wine must be stirred to ensure the fining agent affects the entire production process. Subsequently, controlling how the fining agent acts is necessary to achieve flocculation.

What recommendations should be taken into account when fining wine?

  • The most important guideline to follow is that the dosage of a fining agent should be the minimum necessary to achieve the objectives, as it can affect the aromatic composition of the wine.
  • The temperature must be controlled to remain stable and neither too high nor too low.
  • Multiple laboratory tests must be conducted to select the most suitable fining agent for each wine and accurately measure the ideal dosage.
Wine clarification must be carried out with great care, choosing the most suitable fining agent

Egg whites, milk, clay… The origin of fining agents

For centuries, wine clarification was a rather rudimentary process, and winemakers relied mainly on trial and error and used too large quantities of fining agents to clean the wines in the shortest possible time to market them as quickly as possible.

However, the last half century has seen significant advances in this field. Why? The technological revolution, the increase in oenological research and the wineries’ commitment to training and innovation have provided oenologists with the resources and knowledge necessary to design and implement wine clarification precisely, adapting this process to the peculiarities of each winemaking process.

There is evidence that wine clarification was carried out in several wineries as early as the 17th century, using natural fining agents present in products that were part of people’s daily lives, such as egg whites, milk, blood, or clay.

Types of fining agents

Traditional fining agents give us clues about the two main types of substances that exist for wine clarification:

  • Organic:
    • Animal. Various fining agents of animal origin exist, such as whey, gelatine, fish glue, egg albumin, casein, bone glue, and blood albumin.
    • Vegetables. Vegetable proteins, such as peas and alginates, substances present in algae, are used as clarifiers to a lesser extent.
  • Minerals. The most commonly used mineral fining agent is bentonite, a type of clay composed of smectite, a class of minerals.
  • Some wineries choose to combine the use of organic and mineral fining agents to achieve the desired results. It should also be noted that, in recent years, several laboratories have developed synthetic fining agents.
Until they reach the market, Pazo Baión abariños undergo multiple processes to guarantee their extraordinary quality

What methods are used after wine fining and before bottling?

Although wine fining helps stabilize the wine, wineries often stabilize it by subjecting it to low temperatures for several days to avoid precipitation of natural tartaric salts.

Finally, after clarification and stabilization, the winemakers proceed to filtration in order to sterilize the wine and ensure that it is biologically stable before bottling. This is done by passing the wines through porous membranes.

Combining these oenological techniques shows that winemaking is a complex task in which enology professionals use their knowledge and experience.

The clarification of wine at Pazo Baión

Andrea Obenza, the oenologist at Pazo Baión, points out that bentonite is the only fining agent used in our winery. Why are other fining agents, such as fish glue, not used? To avoid the presence of allergens in the elaborations.

What steps are followed to clarify the wine at Pazo Baión?

  1. Tests are carried out in the laboratory to precisely calibrate the proper bentonite dosage. This is crucial because, as Obenza points out, bentonite «also carries aromas, so we must always try to use the minimum dose necessary».
  2. The clarifier is added.
  3. It is necessary to wait between 10 and 15 days for the bentonite to form larger floccules, making the wine stable against protein breakdown.
  4. The wine is analyzed again in the laboratory to check its state.
  5. The wine is filtered.

In short, thanks to wine clarification, it is possible to make the wine stable against protein breakdown that can occur if the temperature is altered or if there are changes during storage. These breaks cloud the wine and impair its visual appearance.

Pazo Baión’s oenologist emphasizes that clarifying the wine ensures that the winery’s three albariño wines, Pazo Baión, Vides de Fontán, and Gran a Gran, «reach the whole world in perfect condition». After all, every tasting begins with the visual phase.



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