International Code of Oenological Practices

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Partial dehydratation of musts

II.2.1.12 Partial dehydratation of musts


Process consisting in the elimination of a certain quantity of water in grape must.


a)        To increase the sugar level of a must intended to be fermented;

b)       To produce caramelized musts;

c)        To produce concentrated musts;

d)       To prepare grape sugar.


a)        The objectives can be reached by various techniques called subtractive richness techniques:

  • cold concentration;
  • Inverse osmosis
  • Partial evaporation by vacuum;
  • Partial evaporation by atmospheric pressure;

b)       For objective under a), concentration cannot lead to a reduction of more than 20% of initial volume nor increase more than 2% of the initial, potential alcoholic strength of the must.

c)        The elimination of water in the must cannot be cumulated with the elimination of water in the corresponding wine (only for objective a).

Recommendations of the OIV:

To refer to the sheets concerning the above-mentioned practices and treatments.