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g WINE g rAoKw i n g rape M ING relevant ions; this method focuses on quantifying those components. A. Concentration Product (CP) FOOD DIAGNOSTICS Ensuring quality from vine to wine • 170 Wine tests per hour • Improved efficiency • Reduced costs CP = [K+] [HTa-] = [K+] [H2Ta] x (% HTa-) • Reduced cost per test • Easy to Use • 1 Calibration per harvest Wine testing kits available Randox Food Diagnostics 515 Industrial Boulevard, Kearneysville, West Virginia, 25430 T +1 304 728 2890 F +1 304 728 1890 E enquiries@randoxfooddiagnostics.com I www.randoxfooddiagnostics.com The concentration product (CP) test measures the concentration of the tartaric acid and calculates the bitartrate concentration using the pH of the sample. The relevant cation (potassium or calcium) is also measured; alcohol is analyzed to calculate its effect on solubility and activity. These values are used to calculate the value for CP for potassium (or the equivalent for calcium): Acetic Acid Ammonia Copper Ethanol Glucose/Fructose Iron Lactic Acid Malic Acid Potassium Total Antioxidant Status Total S02 Tables were generated by determining CP values on wines treated by extended cold-hold with and without seeding. These tables are used to compare the CP values of the test wine. Variables include wine type, color, style and desired temperature of stability. This test only measures stoichiometric values, but the CP index also accounts for extended coldhold test wines, which indirectly would account for some other stability aspects. The impact of colloidal complexing molecules is the primary difference between the CP and the chemical solubility product (SP). CP methods also attempt to predict calcium tartrate stability. This test may not be appropriate for any wines treated with complexing or colloidal materials unless another set of experimentally determined CP values are generated for a wide range of wines and situations. Similarly, there is concern that the chemical composition of wines used in developing the tables in the early 1970s may not reflect the chemistry of modern wines, especially with respect to colloidal composition. However, CP values can also be used as confirmation tests for wines that have been stabilized (perhaps, for example, using a mini-contact test) to verify that cellar scale equilibrium has reached the desired concentration, rather than using the CP value tables derived from other wines. This allows for the development of "in-house" predictive indexes. Analytical method uncertainty must be considered when developing models, as any errors, particularly in potassium or tartrate concentrations, will be amplified. Summary The chemical equilibrium and kinetics of potassium bitartrate or "cold stability" in wine is not simple, and at least five issues must be considered whenever evaluating cellar or laboratory methods to understand if all known limiting factors have been addressed. Even the most coldstable wines may still throw precipitates, 62 p r acti c al w i ne ry & v i ne yard APRIL 20 13