Definition - What does Filtration mean?

Filtration is a winemaking process that occurs during clarification (right before bottling). It involves passing the wine through a filtration medium to separate any particles from the liquid in order to remove the opaqueness of the wine and create a clear final product. While there are many ways to filter a wine, the desired result is the same – to produce a stable, clear wine that will arrive to the consumer perfect. Nearly all whites and most reds have been filtered at least once.

WineFrog explains Filtration

Wine contains suspended materials created by chemical reactions during the winemaking process. These insoluble particles float in the wine, making it cloudy and dull; they can also change the wine’s characteristics or cause further unintended chemical reactions in wine after bottling.

Winemakers will use one of several filtration methods to ensure that the wine bottled is as close to perfect as possible. Which process they use is determined by the winemaker’s desired style, the size of the particles in the wine and the type of wine being made (whites, for example, require additional filtration to preserve color and stability).

Depth Filtration

Depth filtration is done immediately after fermentation. It involves using a thick filter that traps the particles within it (hence the name “depth” filtration). The wine is pushed through a thick layer of pads made from cellulose fibers, diatomaceous earth or perlite. Depth Filtration includes the following methods:

  • Earth filtration
  • Pad filtration
  • Membrane filtration

Surface Filtration

This method, also known as “Cross-flow filtration”, is used right before the wine is bottled. The wine is run over a thin membrane; the liquid parts of the wine pass through the membrane, while the undesired particles and solids are pushed across the membrane. The wine that has passed through the membrane is the product that is bottled. Surface filtration includes the following methods:

  • Ultrafiltration
  • Reverse Osmosis
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