Filtering is employed to remove solid particles and improve the clarity of a wine. Filtration occurs when wine is pumped through a membrane where particles are trapped on the filter’s surface.
Vigilant winemakers choose the size and style of the filter carefully so the complexity and character of the wine isn’t compromised during the process. If excessive filtration is used, loss of tannic structure, flavors and color may occur.
Filtration occurs in graded stages. Initially, a coarse filter (called a “bug catcher”) is used to remove larger particles before moving onto a finer graded filter that improves clarity to the desired state. Prior to bottling, white wines that have not undergone malolactic fermentation, are usually sterile filtered. Sterile filtration uses a very tight membrane to remove all yeast and bacteria from a wine to prevent a second fermentation from occurring in the bottle.
Many producers choose to have their wines produced without any filtration as they feel it strips the wine of flavors and a rich mouthfeel. Unfiltered wines tend to have more sediment and stand a slightly greater chance of being affected by harmful bacterial.
