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68 practical winery & vineyard February 2015 w i n e m a k i n g bilizing methods, another subtractive technique has been introduced to the winemaking industry: electrodialysis. In electrodialysis, ion-selective membranes are utilized to lower the potassium, cal- cium and tartaric acid concentrations to levels determined by pretreatment test- ing that should result in stabilization of the wine against KHT and CaHT precipi- tation events. The replacement of temperature re- duction of the target wine allows for a significant reduction in energy input to the stabilization process. Electrodialysis, however, can require a sizable capital investment, exhibit limited throughput and have significant water-use require- ments. The benefits and obstacles of elec- trodialysis have been discussed in many prior publications. 10 (Practical Winery & Vineyard, Sept./Oct. 2008, Jan./Feb. 2004.) Innovative non-subtractive technologies for tartrate stabilization Since their discovery and introduction into the EU market, carbohydrate poly- mers with tartrate crystal inhibitory properties have shown great utility and benefit. With the 2006 EU introduction of a specific mannoprotein MP40, 5 which inhibits bitartrate nucleation in a non- subtractive manner, a new paradigm was established for KHT stabilization. Following the specific mannoprotein MP40, another polymer, carboxymethyl cellulose (CMC), was introduced in the EU in 2008. CMC provides protection from KHT precipitation by inhibiting the growth of KHT crystals. Since their initial discovery, these innovative tech- nologies have been introduced, accepted and approved around the world in every major winegrowing region, and follow- ing the 2012 U.S. introduction they are now entering the final stage of TTB regu- latory approval. 4 Application of the mannoprotein and CMC differ with mannoprotein being appropriate for use in all wines — red, white and rosé — within instructional guidelines and use criteria, while CMC is recommended for all white wines and most rosé wines depending upon any interactions with color material in the wine. In white wine applications, CMC has been shown to be effective 100% of the time when pretreatment criteria and application guidelines are followed. Rosé wines can be slightly more chal- lenging with the complication being in- teraction with unstable color compounds; around 80% – 85% of rosé wines are suit- able for CMC application, so trials at the bench-scale should be done before full treatment. Investigation of the use of two different CMCs for KHT stabiliza- tion in comparison to metatartaric acid and gum arabic in both Chardonnay and Pinot Blanc illustrated the utility of spe- cific CMC in achieving KHT stability. 3 Lab validation of tartrate stabilization Initial determination of the tartrate sta- bility status of a wine can be estimated through current test methods such as standard University of California, Davis (UC Davis), conductivity testing, concen- tration product testing or Stabilab DIT analysis, although the percent instability values given by UC Davis conductivity and DIT are preferred for interpretation of the applicability and dosage of non-sub- tractive methods for tartrate stabilization. Since non-subtractive tartrate stabiliza- tion methods do not physically remove potassium ions or tartrate molecules from the wine as a result of treatment, the use of traditional test methods for tartrate stability after treatment tend to give false negative results. A specific method, the ISTC50 that as- says the effectiveness of non-subtractive stabilization treatments, was developed by Eurodia for the Stabilab instrument that is based upon conductivity change