II.3.4.11 Treatment of wines with urease

Classification:

• Urease: processing aid

Definition:

Addition to wine of an active acid urease, produced from Lactobacillus fermentum.

Objective :

To reduce the level of urea in wines, when this is excessive, in order to avoid the formation of ethyl carbamate during ageing.  The enzyme transforms urea into ammonia and carbon dioxide.

Prescriptions :

a)        It is preferable to add the urease to wine already clarified by spontaneous sedimentation of the lees.

b)       A knowledge of the level of urea in the wine will allow assessment of the dose of urease to be added.

c)        The urease will be eliminated during the filtration of the wine.

d)       The urease shall comply with the prescriptions of the International Oenological Codex.

Recommendation of OIV:

Admitted