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w w w. v w m m e d i a . c o m N o v - D e c 2 016 | V I N E YA R D & W I N E RY M A N A G E M E N T 4 1 Cross flow filtration — a syn- onym for cross flow clarification also known as tangential flow fil- tration — includes three families of tighter filtrations: ultrafiltration, nanofiltration and reverse osmo- sis; it had its beginnings in France about 20 years ago, then migrated to the Veneto region of Italy, where the latest advances in ceramic membranes have been realized. It's now being used by the largest win- eries in the United States, including Gallo and Constellation. After an initial period of trial and error span- ning eight to 10 years, the price of membranes has dropped, and cross flow has evolved as the gentlest and most sustainable method of fil- tering wine. "There've been considerable advances over the last 10 years, particularly in the polymers used for hollow fiber cross flow mem- branes," says Stefano Mignotti of WineTech, a filtration service pro- vider that designs proprietary cross flow equipment and is based in American Canyon, Calif. "Using as little intervention as possible, con- cerns about scalping, stripping and heat transfer are generally a thing of the past." ORGANIC OR INORGANIC MEMBRANES The cross flow process is named for the principle action of the wine during clarification — wine flows wine quality as its ultimate benefit over dead-end filtration techniques that push wine through a filtering medium like DE or a cellulose pad where it picks up oxygen and off flavors along the way. According to Mignotti, who pre- fers to use polymer membrane fil- ters (bundles of hollow polymer through or "across" a hollow mem- brane that can be made of either an organic polymer or an inorganic ceramic, typically with 0.2 microns (or finer) porosity. Smaller mole- cules pass through the membranes as permeate, while larger mole- cules are filtered out as lees. Pro- ponents of cross flow filtration cite + Cross flow filtration has minimal risks and consider- able rewards. + The technology can be largely automated, but requires a skilled operator. + The filters are easy to clean and maintain. + The long-term effects of filtration are unknown at this time. AT A GLANCE StaVın Inc, P.O.Box 1693, Sausalito,CA 94966 (415) 331-7849 f (415) 331-0516 stavin.com © 2016 StaVin Inc. ® Twenty four years ago, we opened our doors for business. And while some years have been better than others, we can't complain. Our innovations have far exceeded our original hopes and changed for good the way winemakers approach their craft. But that's not what we're most proud of. It's the people who work with us. They've bought their own homes, sent their kids to college and genuinely love coming to work. Which, in our book is what you'd call a dream come true.