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WINERY & VINEYARD EQUIPMENT 46 WINES&VINES June 2017 Superior protecƟon against oxidaƟon New XtraPure® from XtraChêne is a winemaker's best ally to protect must and wine from destrucƟve oxidaƟon. Sourced from a French forest selected for its anƟ-oxidant capacity, XtraPure® is the result of extensive study, scienƟfic analysis and winemaking trials. Our unique recipe of seasoning and heat treatment maximizes the effecƟveness of XtraPure®. 707.843.4407 • sales@xtraoak.com • www.xtrachene.fr Enemy. Ally. ¨ Immediate & Guaranteed Tartrate Stability Enhanced Wine Quality Sweetspot pH/TA www.oenodia.us in the membrane system and the maximum concentration of the product until the mem- branes are fouled to the point that the process must be stopped and the equipment cleaned. Basic membrane systems Membrane systems for the wine industry break down into the following classifications: micro- filtration, ultrafiltration, nanofiltration, reverse osmosis and electrodialysis. Microfiltration is the most common produc- tion process in the wine industry, since this is the step where general clarification occurs. Particle sizes for microfiltration range from above molecular weight 100,000 to 0.45µ. The pore size most often used in the wine industry for microfiltration systems is 0.2µ, which has been identified as the sweet spot for clarity/ product flow/minimum fouling. The 0.2µ pore size is large enough to allow virtually all mol- ecules that are important for wine flavor, structure and enjoyment of wine to pass through. This type of filtration applies to the vast majority of all wines that are filtered. The only real exceptions are bigger, full-bodied reds, which have other options for preservation at bottling to provide safe packaging. Ultrafiltration comprises the next step down in molecular separation and includes the mo- lecular range from 1,000 molecular weight (mw) to 100,000 mw. Depending on the design of the system, a membrane can be supplied that accomplishes tasks including decolorization of various wines, concentration of phenolic com- pounds, astringency adjustment and oak extract concentration. However, there is not one ultra- filter membrane that will do all of these tasks. Nanofiltration filters at the molecular size range from 100 mw to 1,000 mw, which is one of the more difficult filtration ranges because of potential impact on the wine. Anyone who de- cides to use this range of tangential-flow filtra- tion should be aware of the molecular species that are moving from retentate to permeate side of the membrane and the potential impact that movement will have on the wine. Think carefully about the molecules in wine that are above 100 and below 1,000 mw. All organic acids, esters, terpenes and many small molecular weight phenolic compounds fall into this category. Nanofiltration should be used as a molecular sieve to remove flaws that small molecular weight compounds cause in wines. If further processing of the permeate stream can remove those compounds and then return the permeate back to the wine, that is a good use of nanofil- tration. Use nanofiltration cautiously, because it can irreversibly remove the heart of a wine. Reverse osmosis (RO) is a process using membranes with a molecular size range less than 100 mw to 150 mw. Within this process range there are two designations: tight and loose RO. In the wine industry, the practical use of RO is for removal of some small molecular weight spoilage compounds such as volatile acid com- pounds (acetic acid and ethyl acetate). This process focuses on tight RO (less than 100 mw). It is also used for Brett compounds such as 4-eth- ylguaiacol and 4-ethylphenol. Other smoke taint-type compounds can also be removed (loose RO less than 150 mw). The other common compound targeted for removal by RO is ethanol for alcohol adjustment. The key to these processes is closed-loop processing for TTB regulatory efficacy. To keep a wine's identity intact, RO needs to split the permeate stream and run that stream through either resins or a separate stream to a distillation column and then send that alcohol-free water back to the wine. Nanofiltration should be used as a molecular sieve to remove flaws that small molecular weight compounds cause in wines.