Handbook of Enology, Volume 2. Pascal Ribéreau-Gayon

18.2 After cold 6.97 3.04 740 0.77 7.26 9.6 9.77 −9.4 19 Activated charcoal (30 g/hl) Before cold 7.21 3.1 940 1.59 20.97 17.05 17.2 −2.7 19.75 After cold 6.89 3.1 750 1.01 10.24 9.1 10.33 −11.3 20.4 Gum arabic (3 g/hl) Before cold 7.31 3.08 940 1.45 18.07 16.8 16.98 −3.8 20.6 After cold 7.04 3.03 730 0.91 8.37 11 11.32 −10.95 21.95 Tannin (6 g/hl) and gelatin (3 g/hl) Before cold 7.25 3.08 970 1.42 18.26 18 17.97 −4.9 22.9 After cold 7.2 3.08 970 1.32 17.46 16 16.16 −5.5 21.05 Metatartaric acid (5 g/100 bottles) Before cold 7.19 3.01 975 1.23 20.35 19.25 18.91 <−3.75 >23 After cold 7.26 3.09 975 0.23 16.06 18.65 18.61 −6.09 24.7 Membrane filtered 10³ Da Before cold 6.51 3.08 955 1.25 15.83 16.9 16.54 2.85 14.05 After cold 5.67 3.01 535 0.3 2.24 1.8 0.63 −12.8 14.6 Membrane filtered 0.22 μm Before cold 7.22 3.08 970 1.54 19.8 17 17.06 −3.65 20.65 After cold 7 3.03 970 0.94 9.08 11.6 11.21 −8.5 20.1

      Wines treated with slow cold stabilization (10 days at −4°C). Assessment of protective effects (Maujean et al., 1985).

      ^a The differences, T_Sat − T_CS, were determined by dissolving 1 and 2 g/l of KHT to the wine. Conductivity was then recorded at decreasing temperatures until crystallization occurred; the T_CS values were deduced.

FIGURE 1.16 Crystallization kinetics of potassium bitartrate analyzed by measuring the drop in conductivity of a wine according to the type of treatment or fining. Samples were stored at 2°C, seeded with 5 g/l of KHT, and subjected to the static contact process for four hours (Maujean et al., 1986).

      To define a rule that would be reliable over time, i.e. independent of the colloidal reorganizations in white wine during aging, Maujean et al. (1985, 1986) proposed the following equation:

      Note that this equation totally ignores protective colloids and is valid for a wine with an alcohol content of 11% by volume. For white wines with an alcohol content of 12.5% vol., or those destined for a second fermentation that will increase alcohol content by 1.5% vol., the equation becomes

      Thus, if stability is required at −4°C, the saturation temperature should not exceed 8°C. The stability normally required in Champagne corresponds to the temperature of −4°C used in the slow artificial cold stabilization process. It is questionable whether such a low temperature is necessary