Labo VinCuvage or maceration
Macerating (cuvage) the crushed fruits allows the liquefaction and, foremost, the extraction of flavours, tannins and dyes from the skins. A temperature of about 20-30 °C is ideal. Use a container of white food plastic, glass, wood or stainless steel, never another metal (iron, copper, zinc...). Ideally, the container will be higher than wide, preferably covered.
The cuvage consists in letting the crushed fruits incubate for a while that can vary from few hours to several days (6 days maximum recommended). When the cuvage lasts several days, the fermentation is activated by seeding the must with yeasts (levurage).
The cuvage is short for white and rosé wines, and is not used for white wines coming from fruits with colourless juice and coloured skin.
Pectinase [ The pectinase is an enzyme (protein, biological catalyst) that destroys the pectin. It follows a better flavours extraction, a better sap yield, along with a good ulterior clarification. The pectinase is sold as a liquid or a powder. Conform to the manufacturers instructions. Too much pectinase is not damaging, but it is wasting. ] has to be added to liquefy the viscous ground material by hydrolyzing the pectin [ Mixture of methylated polygalacturonic acids. By enzymatic hydrolysis, the pectin releases toxic methanol. It forms a net that traps the juice, rendering it viscous, so decreasing the yield at the pressing stage. ] . That makes extraction and pressing easier. The pectinase is dissolved in a little juice then mixed with the whole. The amount to use varies according to the brand; see the instructions of use.
For red wines, add 40-50 mL metaK [ Solution 0.25 M of potassium metabisulfite (K2S2O5, Mr=222), prepared by dissolving in water 55.5 g potassium metabisulfite (failing which, 47.5 g sodium metabisulfite - Na2S2O5, Mr=190) for 1 L solution.
10 mL of this solution equals 320 mg SO2 (5 millimoles).
This solution can be kept for a long time in a tightly sealed bottle. ] (128 to 160 mg SO2) for 10 litres; cuve between 24 and 48 hours.
For other wines, add 30 mL metaK (96 mg SO2) in 10 litres. Press as soon as the liquefaction is fine (maximum one night).