Bubbles in a lucid nectar

At the zenith of the celebration—namely, the toast—everything must be perfect. Here, cava is the guest of honor, and as such, it must appear immaculate—dazzling, one might even say. It is absolutely not permitted, under any circumstances, to present an unseemly appearance. Since its options are limited, in the end, the most important thing is to display a crystal-clear presence, gleaming like gold and offering a beautiful show of lavish bubbles rising to the surface.

Now, let it be clear that we have nothing against cloudy wine—perhaps it’s even more beneficial, offering more nutrients—but as primates, our sense of sight plays a fundamental role in all of our experiences. The truth is that achieving such clarity is no simple task and, in fact, constitutes one of the most complex processes in the production of cava. In this article, we’ll try to explore the particularities of this stage in cava’s creation.

Clarity is a hard-earned virtue

As a result of the long resting period the bottles undergo, as well as the properties of the wines used in the second fermentation, certain residues are generated. These are mainly composed of yeast remnants, proteins, possibly some bitartrate, and the very substances used to facilitate clarification itself—which we’ll look at later. Since the entire cava production process takes place within the bottle, we must find a solution that doesn’t require opening it.

Specifically, the challenge is to ensure that all these sediments are concentrated in the neck of the bottle, so that when it is opened during the disgorging process, the residues can be easily expelled. Disgorging, in fact, is closely linked to what we’re discussing here, though we’ll delve into that in another article. For now, suffice it to say that as a result of the clarification stage, the bottles are stored in racks with the neck facing downward, and all the sediment resting against the cap.

This position is known as bottles on point. It’s important to emphasize that the lees we aim to eliminate are in no way harmful—they are perfectly safe to ingest. It is purely a matter of aesthetics.

The Hidden Allies in Cava’s Clarification

The principle that allows the sediment to move toward the neck of the bottle is none other than gravity. However, the lack of uniformity among the particles means that this process is not straightforward. What’s more, the younger the cava, the less homogeneous the sediment tends to be, making clarification all the more challenging.

One of the key strategies lies in getting the heavier particles to drag along the lighter ones, which are much harder to control. For this reason, certain substances are added during the tirage stage (the mixture of base wines and bottling prior to the second fermentation).

These substances are known as clarifiers, and among the most widely used are bentonites, thanks to their virtually inert nature. Bentonites—which come in various types—are a type of very fine-grained clay with numerous applications, including medicinal uses as a detoxifying agent.

The Art of Turning Cava

With these subtle aids, the “grace” of the process lies in performing a series of systematic movements that gradually guide the sediment toward the neck of the bottle. These movements fall into three categories: rotation, oscillation, and inclination (the bottles begin in a horizontal position and end up pointed downward). Depending on the type of cava, its age, and other conditions, the specific movements vary—this is precisely where the complexity of the process lies.

In addition, the final result depends heavily on external factors such as temperature, airflow, and others, all of which must be carefully controlled at all times. After each movement, several hours must pass for the sediment to settle again; in general, it takes several days to complete the clarification process.

The movements can be carried out manually, automatically, or semi-automatically. Traditionally, the so-called pupitres have been used—easel-shaped racks made of two surfaces joined in a triangular form, with a series of holes to hold the bottles. A single pupitre can accommodate 120 bottles, occupies about one square meter, and requires manual operation.

The semi-automatic system, on the other hand, allows for the simultaneous handling of 504 bottles arranged in a gavia—a rack that pivots on a central axis via octagonal edges. Thanks to this mechanism, it’s possible to manipulate the contents of more than four pupitres in a single operation, while occupying only slightly more space.

Finally, the automatic system holds the same number of bottles as the semi-automatic one, and the movements are performed by two motors—one for elevation and one for rotation. Once the program is set (in a manner similar to selecting a cycle on a washing machine), the process runs entirely without human intervention.

Beyond Traditional Racks

At Cavas Alsinac, this process is carried out primarily using a semi-automatic system. Beyond the romanticism embodied by the traditional pupitres—which are always charming and often still used for decorative purposes—the advantages of the other two systems are undeniable.

It’s worth noting that the clarification process often becomes a bottleneck in the cava production chain; in other words, if a sufficient number of bottles on point are not generated, there’s a risk of not having enough to meet customer demand. Since a considerable amount of space is needed to accommodate the bottles, optimizing space usage in automated systems is crucial.

Moreover, precisely because of the bottleneck potential, ongoing research efforts often focus on improving clarifying agents, with the goal of reducing the time needed to achieve fully clarified bottles ready for disgorging.

References

To prepare this article, we have used information from the following links and bibliographic sources:
– “A Review of Méthode Champenois Production”, Dr. Bruce Zoeckein, Viginia Tech
– “Remuage: come illimpidire perfettamente gli spumanti”
– “La elaboración de los vinos espumosos naturales «Cava»”, Juan José de Castro Martín, Escola Universitària Enginyeria Tècnica Agrícola de Barcelona.
– “Influencia del tipo de clarificación del vino de base y de los coadyuvantes de tiraje sobre la calidad de la espuma de los vinos efervescentes”, Guillem Vanrell et al., Facultad de Enología de Tarragona – Universidad Rovira i Virgili.
– “Bentonita”, Wikipedia.

The following posts from our blog cover topics related to this article::
– El Cava: ¿animal o vegetal?
– Fermentación: la labor invisible tras la magia de un brindis con cava.
– Taponado, controles en el tiraje y fermentación en botella.