6.1.1.c Adapting different clarification methods to the wine's requirements

Basic factors to control turbidity

It is not always easy to understand a wine's "behaviour" throughout the vinification and ageing process, and elevated turbidity can have many explanations. Before opting for a separating technique, it is best to take into account certain parameters that favour a natural sedimentation process as well as each stage of vinification and ageing.

Environment

When turbidity remains elevated and does not decrease, it is possible that the environment in the winery is a contributing factor. Temperature variations can hinder natural sedimentation, as well as ground vibrations that can be caused by the use of pumps and hoses (even the presence of a lift, closing/opening doors, air-conditioning systems, proximity to a road, etc.).

The amount of dissolved CO2

A high CO2 level keeps the particles in suspension and prevents or reduces the wine's natural sedimentation. Sometimes, a simple racking of a tank or a batch of barrels can help to slightly lower the amount of CO2 in the wine and reduce turbidity.

Natural sedimentation during racking

During the ageing process, a sedimentation phenomenon is observed, which allows a natural clarification of the wine. Turbidity decreases more quickly if the fluid is immobile, as the particles are not put back in suspension.
This phenomenon is more pronounced when the wine is aged in barrels, as the volume is smaller. Racking involves removing the deposits (the lees) that have settled. Moreover, racking also helps to degas the wine by removing CO2.

Separating practices and operations

When the winery's environment is not an issue, various techniques can be implemented to reduce suspended particles and therefore turbidity; the objective being to obtain a sufficiently reduced turbidity where the wine's filterability is improved and it becomes more stable (less risk of tartar precipitation, breakdown, microbiological deviations, etc.).

Holding at low temperature: Although it is mainly a wine treatment, particularly for tartaric stabilization, holding at a temperature lower than or equal to 5°C can also be used to clarify a wine.

Fining: this subject has already been discussed in the section on wine operations during ageing.

Enzyme enrichment: Enzyme enrichment is the practice of adding enzymes to the must or wine. Enzymes have a catalytic power that allows them to accelerate and improve naturally occurring phenomena during the winemaking process (enzymes are not always present in sufficient quantities). Depending on their nature, they can be used for settling, phenolic extraction or clarification. This method is particularly useful for pressed wines, which are often richer in pectins.

Pre-filtration: It is possible to pre-filter a cloudy wine in preparation for fining or final filtration at a later date before bottling. Pre-filtration reduces the risk of clogging during the final filtration.