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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 5 in both wines, sensory analysis couldn't detect any changes. The take away: When filtered and unfiltered red wines were compared after two months in bottle, filtered wines were high- er in mixed berry and stone fruit aromas, while unfiltered wines had more earthy, grassy, oak and smoke aromas. If style preferenc- es favor the rapid development of secondary aromas, the results of this study could point winemakers away from using hollow fiber cross flow membranes. These results mirror those of a 2004 study by Rektor et al, con- ducted on sensory analysis of musts of Hungarian varieties that had undergone malolactic fermen- tation and filtration with hollow fiber cross flow, in which tasters preferred filtered samples with fruit-forward flavors (where the off- flavors were less intense). At ATP Group, Garbo points to oxygen pick-up and pressure as factors that have the most signifi- cant impact on quality. "Cross flow exerts up to one and a half bars, while DE filters can exert four to five bars of pressure during filtra- tion," he says. When comparing the sensory qualities of filtered wines that have been subjected to lower pressure and temperatures, anecdotal evi- dence aligns winemakers' percep- tions with what's being recorded in the lab. When he was working with Peterson at Ravenswood in the late 1990s, Sitton ran a num- ber of trials with standard DE and a .65 micron yeast-sterile ceramic weight carbohydrates and protein colloids. As such, the long-term impact of different types of cross flow filtration on a healthy wine's longevity is still unclear. ROI METRICS In addition to quality, flow rates and recovery are key metrics for determining the size of the equip- ment and the return on investment in a cross flow filter. "ROI is tied to throughput and recovery," says Garbo. "Your ROI can be different for units from different manufac- turers. Size, throughput, recovery and filtrate quality are all important factors to consider. We've been in the U.S. market for more than five years and, within that time, 95% of our customers for the Dynamos [which ranges in price and configuration from $35,000 to $1 million] have achieved a return on their investment within one to two years." G i v e n t h e o p t i o n s c u r r e n t l y available from cross flow filtra- tion vendors and the increasing performance and decreasing cost of membranes, from this vantage point, state-of-the-art filtration tech- nology has cleaned up its act. Deborah Parker Wong is the Northern California editor for The Tasting Panel magazine, and a long- time contributor to Vineyard & Win- ery Management. She earned her WSET Diploma in 2009. Comments? Please e-mail us at feedback@vwmmedia.com membrane. The pair conducted what Sitton described as "a lot of sensory work" and determined they couldn't detect the difference between the two wines immedi- ately after filtration — but, when tasting at six months and one year after bottling, they preferred the membrane-filtered wines. While studies comparing filtra- tion characteristics between organ- ic and inorganic membranes have thus far been confined primarily to flux decline and the amount of housekeeping related to optimal performance, both membranes r e m o v e s o m e h i g h m o l e c u l a r Gary Sitton of Ravenswood Winery in Sonoma, Calif., uses cross flow for some of the winery's products. S U B S C R I B E T O D AY ! Available in print and digital www.vwmmedia.com/magazine/subscribe.asp NORTH AMERICA'S LEADING INDEPENDENT WINE TRADE PUBLICATION WWW.VWMMEDIA.COM MARCH - APRIL 2016 WWW.VWMMEDIA.COM SEPTEMBER - OCTOBER 2016 NORTH AMERICA'S LEADING INDEPENDENT WINE TRADE PUBLICATION + Water-Saving Technologies + Financing + Craft Beverages Report NEW WWW.VWMMEDIA.COM JULY - AUGUST 2016 NORTH AMERICA'S LEADING INDEPENDENT WINE TRADE PUBLICATION The Dawn of Agtech Winemaking Nutrients Annual Suppliers Guide Here Come the Italians! NORTH AMERICA'S LEADING INDEPENDENT WINE TRADE PUBLICATION WWW.VWMMEDIA.COM Eco-Packaging Evolves B o t t l i n g L i n e s * H a z a r d o u s W a s t e * M a k i n g M e a d MAY - JUNE 2016