Issue link: http://winesandvines.uberflip.com/i/766392
68 WINES&VINES January 2017 VIEWPOINT tion of RO goes up well into the NF range (500 daltons), a situation that needs reform. In my opinion, 80 daltons is ideal for wine, and anything above 150 daltons should be forbidden. The current situation only makes sense when viewed historically. The 500 MW bound- ary wasn't a scientific definition of RO. It was a demarcation of filtrate taxable as wine vs. taxable as distillate. That's fair, because per- meates in that range certainly lack vinous character. But the result now is that anybody can sell you highly porous membranes that produce great flow at the expense of the de- pletion of soluble compounds with potential wine quality impacts. Now that we know more about the applications, it's time to call upon TTB to clean up the resulting confusion. I recommend banning membranes above 150 daltons for use on wine. TTB has no jurisdiction over suppliers and does not regulate the equipment they pro- vide. It is the sole responsibility of the li- censed winery to ensure that the membranes, operating conditions, resin columns, distil- lation and other procedures employed are both legal and advisable. Try before you buy The specialized know-how and high capital cost involved have, for the past 25 years, confined RO almost entirely to a service business. We are currently experiencing an explosion of U.S. wineries producing less than 5,000 cases (there are more than 7,000 such wineries, according to Wines Vines Analytics' December 2016 numbers). These m o m - a n d - p o p s h o e s t r i n g o p e r a t i o n s throughout the United States can ill afford to lose a batch to volatile acidity, but they also have to watch their pennies. Besides the cost of a visit by a service provider, they often are equipped with low power and refrigeration capabilities that don't accom- modate large mobile systems. These challenges have been cleverly over- come by VA Filtration, whose Sweetspotter is a small VA system for rent to small wineries. They will ship it anywhere, it rents at reason- able rates, and its low-energy operation allows it to be plugged into a 20-amp 110-volt wall outlet and to operate without refrigeration. It also has a terrific instruction manual. At present, it's the only alternative for the micro-winery outside California. It's wonder- fully ingenious and a lot better than nothing. It's a shame that it is unkind to wine. VA Filtration's Sweetspotter employs NF mem- branes that can de-acidulate wine substan- TIPS FOR BUYING AND USING AN RO MACHINE 1 Buy a high-pressure machine. Despite the industry patter about "shear forces," in tens of thousands of jobs, I have not found that pressurizing wine to 70 bars does it damage. Low-pressure machines, on the other hand, employ highly porous membranes to achieve reasonable flow. That's a bad idea. 2 A 70-bar machine fitted out with Vinocon RO5 membranes can string together 12 to 16 membranes in series on the same direct-feed pump. 3 Dual-pump feed-and-bleed systems may save cost and energy but have innate disadvantages in performance. Make sure you know what you're getting. 4 Buy your machine empty and insert your own membranes based on your applications. Make sure your pump's crossflow rates conform to manufacturer's specs. 5 If you already own membranes, it's easy to tell what they are. Fill the machine with dry wine and reduce the backpressure until permeate flow drops to zero. That's your transmembrane pressure. 175 psi is ideal. Run a TA on your permeate. Even in a high-VA wine, it should be near zero. TA should not drop, and pH should not shift during a VA run. You can also recirculate 3% sodium chloride and measure your salt rejection. Anything below 99% is problematic. 6 Always store your RO membranes between uses with high SO 2 regularly refreshed or >20% ethanol in a cool environment. 7 In running a VA job, always take before-and-after samples (three each). Use potassium hydroxide rather than sodium hydrox- ide for recharge. Always return permeate through a fresh carbon cartridge, just to be safe. Don't buy anion exchange resin. It gets moldy fast. Rent it. Return after use. 8 If you want to adjust alcohol, you'll need a means to dealcohol- ize your permeate. You can distill it yourself on-site or use an osmotic transport system such as Memstar. You can ship it to an offsite distiller, but they must return the same water that was taken from the wine. Some wineries are working to change this law. 9 Hug your trained staff. Loyal, long-term employees are the key to successful high-tech ownership. TTB MEMBRANE PROCESS DEFINITIONS Processes Use Reference or limitation Reverse osmosis 1 To reduce the ethyl alcohol content of wine and to remove off flavors in wine Permeable membranes that are selective for molecules not greater than 500 molecu- lar weight with transmembrane pressures of 200 psi and greater. The addition of water other than that originally present prior to processing will render standard wine "other than standard." Use shall not alter vinous character. Ultrafiltration To remove proteinaceous material from wine; to reduce harsh tannic material from white wine produced from white-skinned grapes; to remove pink color from Blanc de Noir wine; to separate red wine into low-color and high- color wine fractions for blending purposes Permeable membranes that are selective for molecules greater than 500 and less than 25,000 molecular weight with trans- membrane pressures less than 200 psi. Use shall not alter vinous character. Electrodialysis To aid in the removal of tartrates This process must not alter the vinous char- acter of the wine. Nanofiltration To reduce the level of volatile acidity in wine (used with ion exchange) This process must use permeable mem- branes that are selective for molecules not greater than 150 molecular weight with transmembrane pressures of 250 psi or less. Osmotic transport 1 For alcohol reduction 1) Use must not alter the vinous character of the wine. 2) None of the stripping solution may migrate into the wine. 1 This process must be done on distilled spirits plant premises. However, reverse osmosis, under certain con- ditions, may be used on bonded winery premises if ethyl alcohol is only temporary created in a closed system.