II.3.4.19 Treatment of wines using inactivated yeasts with guaranteed glutathione levels

Classification

• Inactivated yeasts with guaranteed glutathione levels: Processing aid

Definition:

Addition of inactivated yeasts whose cells have guaranteed reduced-glutathione levels.

Objectives:

a)        To limit the oxidation in wines of certain varietal aromatic compounds revealed by the metabolism of yeasts (particularly thiols).

 

Prescriptions:

a)        The addition of inactivated yeasts with guaranteed glutathione levels at the start of maturing or during storage of wines is recommended;

b)       the dose used of glutathione, supplied directly or via yeasts with guaranteed glutathione levels, should not exceed 20 mg/L, in order to avoid any risk of reduction and the emergence of a yeast taste;

c)        the inactivated yeasts with guaranteed glutathione levels should contain a reduced form of glutathione; this may be accompanied by the presence of its precursors (cysteine and particularly gamma-glutamylcysteine);

d)       the inactivated yeasts with guaranteed glutathione levels should comply with the prescriptions of the International Oenological Codex.

Recommendation of the OIV:

Admitted