Reverse Osmosis (RO) is a special type of filtration which has many applications in the production of quality wines. Unlike traditional wine filtration, the filtrate which passes through the filter membrane does not contain the flavor and color components of the wine. It contains virtually no anthocyanins, phenolics, tartaric, malic, or citric acids. Thus the characteristics that make up a fine wine, never actually go through the filter.
With an RO filtration plant, unlike a traditional filter, you generally keep what does not go through the filter. Depending on what the winemaker is trying to accomplish, the filtered material is either discarded, or may be further treated and blended back into the wine.
Because the filter membrane is so tight (10,000 times tighter than a sterile filter), large flows of wine are recirculated across the filter surface (Cross Flow) to scrub the membrane and keep it from fouling. Only the smallest molecules present in wine can pass through the filter membrane. Manly water and ethanol which make up 75%, acetic acid 60%, ethyl acetate 40%, and lactic acid 15%.
The most common uses for a RO Filtration Plant include:
•Volatile Acidity Reduction
•Juice Concentration (Water Removal)
•Restarting Stuck Fermentations
•Cold Stability without Refrigeration