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February 2015 practical winery & vineyard 69 w i n e m a k i n g under the conditions of the modified test. Both the DIT and ISTC-50 are rapid tests with results usually available on a next- day basis. An alternative test is the OIV-certified cold test that consists of freezing a sam- ple at a consistent temperature of -4º C for six days and assaying the KHT crys- tal status of the sample. This test relies upon a dedicated -4º C freezer that is constant temperature (not frost-free) and a lengthy waiting period, both of which bring a level of inconvenience to the test- ing process. What is CMC and what properties are important for proper performance? CMC has been used for many years in a multitude of everyday food products where it serves as a stabilizer, emulsifier and thickening agent in diverse products such as ice cream, cake and batter mixes, frostings, pie fillings and toothpaste to name a few. CMC is produced under controlled chemical conditions to yield a specific de- gree of polymerization (DP) and degree of substitution (DS) characteristics. These physical measures, DP and DS, deter- mine many of the properties of CMC that make it so useful in KHT stabilization. The degree of polymerization of CMC influences the physical characteristics of the molecule in solution such as viscos- ity and fluidity. In terms of mixing, we recommend to dilute the liquid CMC in twice its volume of wine. (This can vary from one supplier to another as CMC concentration does vary greatly from one product to another.) Mixing of the tank through a pump over of 1.5 to two times the tank volume is recommended. The degree of substitution along the cellulose polymer of CMC influences many of the functional properties includ- ing: solubility of the CMC in water and wine, efficiency of the CMC in inhibiting KHT crystal growth as explained below and determination of the extent of in- teractions with other wine matrix com- ponents that may be detrimental to the proper functioning of CMC in wine. The negatively charged CMC polymer interacts with the nascent crystal surface and prevents further growth (Figure 5). No potassium or tartaric acid is removed, thus preserving the wine's natural bal- ance, but crystallization is inhibited so no precipitates form in the treated wine. How does CMC actually work to inhibit Figure 3. the chemical reaction process for sodium carboxymethyl cellulose (Na-CmC) production by treating the glucose polymer cellulose with chloroacetic acid under basic conditions. 4 Excess proteins in unstable wine can interact with the negatively charged CMC and may result in a haze formation in the treated wine. Providing leading wine makers with stainless steel barrels of high quality, durability, and design. phone: 773.735.0700 • toll free: 800.441.8780 www.skolnikwine.com • email: sales@skolnik.com