Filtration

Filtration involves passing the wine through a filter to physically remove suspended solids and microbes, including yeast and bacteria, which may cause haze or instability.

Filtration provides a high level of clarity and microbial stability, ensuring that the wine is visually appealing and less likely to spoil after bottling. It is a more controlled and predictable process compared to sedimentation or fining.

Some winemakers argue that filtration can strip the wine of subtle flavors and aromas, leading to a less complex final product. Over-filtration, in particular, may lead to a loss of texture and mouthfeel.

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Depth Filtration

Depth filtration uses a filter to trap particles inside the filter while wine passes through.

Filters are rated by microns (coarse, medium, fine):

• Coarse filters can polish a wine without losing its color or body.

• Medium filters will only take a limited amount of body and color out of a wine.

• Fine filters remove 80% or more of yeast and sediment and are best used after medium pads.

In the filters, particles build-up, causing pressure to increase and flow rate to decrease. When this reaches a point, the winemaker must clean the system before continuing.

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Surface Filtration

Surface filtration uses a filter that block particles on the surface of the filter.

It blocks particles larger than the filter pores, like a fine sieve or a coffee filter.

In a first filtration, a coarse filter can remove yeast particles that give the wine a cloudy appearancene.

In a second filtration, a finer filter remove can bacteria before the wine is bottled.

Rotary Vacuum Drum

The rotary vacuum drum (1872) is one of the oldest filter methods used in wine production.

• A large rotating drum is submerged in a slurry with a mixture of wine and solids.

• The drum is covered by a cloth that acts as a filtration medium.

• As the drum rotates in the wine, particles are stucked on the surface of the cloth.

• A cake of solids builds up on the cloth, which is then removed by scraping or washing.

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Cross-Flow Filters

Cross-flow filtration is widely regarded as a modern, eco-friendly, and effective method in winemaking, ensuring high-quality wines with reduced manual intervention.

Cross-flow filters are handy because they self-cleans as it is filtering the wine. Unlike deep filters, cross-flow filters can filter wine with a high load of particles quite quickly without the need for pre-depth-filtering.

Cross-flow filters are expensive. But, it may be worth to invest in a machine that does the whole job.

How it Works

• Tangential Flow:
  Wine flows tangential (parallel) to a membrane surface instead of through it. This reduces clogging and improves efficiency.

• Selective Permeation:
  The membrane allows smaller molecules (water and alcohol) to pass through, while retaining larger particles (yeast, bacteria, microbes).

• Continuous Process:
  The wine circulates. Only clean wine passes through the membrane, leaving behind impurities in a concentrated form for disposal.

Advantages

• Higher Efficiency:
  Removes particles down to microscopic levels (0.2 microns or smaller).

• No Pre-filtration Needed:
  Handles high haziness (cloudiness) without clogging as quickly as traditional filters.

• Improves Stability:
  Eliminates spoilage organisms, reducing the need for preservatives like sulfur dioxide.

• Minimizes Waste:
  Unlike deep filters, it does not leave large quantities of disposable filter media.

• Preserves Wine Quality:
  Operates at low pressures, maintaining wine aroma and flavors.