Copper casse preventing

The prolonged aging of wine on its yeast lees causes a significant decrease in oxidation-reduction potential, which favors the reduction of copper and, consequently, the appearance of copper casse. At the same time, the presence of yeast lees promotes the fixing of copper, which tends to prevent copper casse. For example, a copper concentration of 0.1-0.3 mg/1 in a champagne-base wine dropped to zero after second fermentation and aging in the bottle in a horizontal position, as this increased the lees/wine interface and promoted exchanges. 

Bentonite treatment (Section 10.9.3) is a simple method for protecting wines from copper casse by eliminating proteins. Gum arabic also has a protective effect, by preventing flocculation of the colloid (Section 9.4.3). This method is effective if the copper concentration is below 1 mg/1, otherwise the excess copper must be eliminated. 

The oxidation-reduction potential of white wine decreases on exposure to natural light. This property is used to reduce copper and assess the risk of copper casse (Section 4.7.3). In the past, there was even a method of preventing copper... 

Gum arable is a preventive treatment for many problems involving colloidal precipitation. It is effective in treating copper casse and was widely used when wines often contained excessive amounts of copper due to contact with bronze cellar equipment (Section 4.7.3). Doses of 10-15 g/hl were effective in preventing this problem, provided that wines did not contain more than 1.0 mg/1... 

Gnm arable is less effective in preventing ferric casse in white wines. Indeed, the nnstable colloidal ferric phosphate that is precipitated has a much greater mass than the copper snlfide involved in copper casse. A much larger quantity of gum arable would therefore be required to provide proper treatment, and this is likely to affect the wine s turbidity. Gum arable is effective to a certain extent, but the effect is variable from one wine to another and is, in any case, insnfficient to provide total protection. Recommended doses range from 20 to 25 g/hl as a supplementary treatment (Section 4.6.3). 

Bentonite 20-100 g/hl Average clarification. Treats and prevents protein and copper casse. Facilitates racking with proteins. Avoids overfining... 

Preventing Certain Types of Colloidal Precipitation Protein Casse and Copper Casse... 

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