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June 2018 WINES&VINES 55 WINEMAKING This is the determining factor in measuring the tendency for cold stability and is defined as a drop-in conductivity of less than 5%. The test wines were well above the standard threshold for cold stability, which indicates that the solu- tion they were in was more conductive than those that were cold stable. Carboxymethylcellulose (CMC) is the cur- rent colloidal material used extensively to cold-stabilize wines. It does not quite lower the conductivity for all wines sufficiently below the threshold to maintain a guaranteed cold-stable wine. MTA (a commonly known polymer of tartaric acid) is a material that wineries have used to obtain cold-stability. Zenith has been shown to be better than MTA and equal to KHT. Colloidal products such as CMC have a propensity to remove color from wine, a vexing problem for winemakers. Figure 1 shows an application trial in which CMC and Zenith Color were added to samples of Shiraz and then held for six days at -4° C. Addi- tional amounts (possibly 50% or more) of CMC would be necessary to get close to cold- stabilization, and the wine still would not achieve the same color level as a wine treated with KPA. The CMC drop in color shows the degree to which color is removed from red wines when cold-stabilization procedures are introduced. When CMC is added, the material entraps the anthocyanins and might reduce or remove much of the color from red wines. In contrast, Zenith has virtually no color loss. The use of Zenith would allow wineries to lower the cost of production for sweet red wines, to market all red wines more quickly and do so without the danger of future color loss or tartrate formation. Cold-stability treatments should give winer- ies the assurance that once a wine is tested as cold-stable (Figure 2), the treatment will con- tinue to work over time. Tartrate stability is a statistical issue, defined by the chance that two ions can come together in an environment where they are locally above saturation. Crys- tallization is a lower-energy state waiting for a trigger. KHT is the enabling molecule that can trigger crystal formation and reduce the tartaric-acid molecule population to the prob- ability of crystal formation approaching zero. Stabilab is an instrument that follows the process of conductivity change. Its algorithms measure the asymptotic conductivity curve that changes with increasing amounts of time and/or KHT additions. It is a very accurate – but expensive – solution, and ultimately the winemaker chooses how far down that curve is comfortable enough for a commercial winery. The "rule of thumb" for KHT addition gen- erally has been defined as 4 g/L KHT at either 0° C or -4° C as the end point where conductiv- ity does not change by more than 5% after addition of KHT to the wine. The requirement that the wine be lowered to these temperatures while the process unfolds is time-consuming and labor-intensive. KHP addition is tested manually by mini contact test or the automated Checkstab and uses a 3% drop in µS. CMC was found to prevent crystallization with a simple liquid addition and stirring. Its mechanism of action, and that of KPA, can be likened to replacing the "empty" space be- tween the tartaric-acid molecules in traditional cold-stability action to filling the empty space with Nerf Balls. In this situation, two tartaric acid molecules can't get close enough together to crystalize because CMC and KPA molecules surrounding tartaric acid act like Nerf Balls to prevent them from getting close enough to crystalize. Whereas both molecules envelop the tartaric-acid anion, the KPA product envelops its target more tightly and thus protects it more completely from precipitation over time (Figure 3). Adding anything to a wine just before bot- tling can be a risky endeavor. Winemakers need to know that nothing will change the filterability of the wine being packaged. For- tunately, KPA does not affect the filterability of wine. There are a number of secondary benefits to using KPA. A strong trend in the wine indus- try supports the use of products that are more sustainable in terms of energy, impact on the environment and the consumption of other resources. Zenith (KPA) and CMC are shown to be close to each other as more sustainable products from a total energy-consumption standpoint. The reduction of water consumption by wineries is another critical component for sustainable product use. The industry has widely different levels of water consumption, in part depending on the cold-stabilization process used (see Figure 4). By far the worst consumer of water during cold-stabilization is electrodialysis, which has been adopted by many larger wineries because of the great energy savings over traditional cold-stabiliza- tion methods. Both CMC and KPA are among the lowest in water consumption. It should be noted that while CMC and KPA are low in energy and water consumption, only KPA is more certain to provide permanent cold-stabilization. Finally, a cost-of-use comparison shows that this product might help change how wine is produced. Only the KHT method is close to colloids when it comes to the total cost to achieve cold-stability in wine. Several wineries have tried Zenith, from very large ones such as Arterra Vins Canada in Ontario, Canada to small Eastern wineries such as Mount Felix Vineyard & Winery in Havre de Grace, Md. Others include Precept Wine Brands in Seattle and Brick & Mortar Wine Group in Healdsburg, Calif. Enartis, and the wine industry, recently learned of one regulatory step toward ap- proval. The FDA has indicated it will accept KPA as a GRAS ("Generally Recognized As Safe") product. 450 400 350 300 250 200 150 100 50 0 Wine 1 Wine 2 Wine 3 229 318 406 42 75 70 40 56 27 42 44 Control 10 g/hL CMC 15 g/hL CMC 10 g/hL KPA D Conductivity (Dµ S/cm 2 ) White Wines D µS <30 30-50 50-70 >70 Stability level very stable stable at risk unstable STABILIZATION OF 2017 WHITE WINES — CMC VS KPA Figure 2: In tests comparing CMC and KPA for stabilization in white wines, CMC did not provide as com- plete protection from bitartrate precipitation as KPA.