🍷 Mutage

Mutage is the addition of spirit of wine origin to grape must that is still fermenting. The spirit stops fermentation, so part of the grape sugar never turns into alcohol, and the wine stays both sweet and strong. The earlier the spirit is added, the more sugar remains.

For Port, the technical file of the protected designation of origin requires wine spirit approved by the IVDP with a strength of 77.0 ± 0.5% vol.; the amount is set each year in the harvest notice, and after fermentation is stopped the wine must keep more than 17.5 g/l of sugars from the grapes. For French vins doux naturels such as Banyuls and Rivesaltes, the specifications require neutral spirit of wine origin of at least 96% vol., amounting in pure alcohol to 5 to 10% of the volume of must, added before 31 December of the harvest year. In Banyuls mutage may also be done on the crushed grapes, «mutage sur grains», so that the wine keeps macerating on the skins.

If spirit is added to grape juice that has not fermented at all, the result is not a wine made by mutage but a mistelle. WHO notes that no level of alcohol consumption is safe for health.