II.2.2.9 Treatment using inactivated yeasts with guaranteed glutathione levels

Classification:

inactivated yeasts with guaranteed glutathione levels: processing aids

Definition:

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

Objectives:

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

b)       to promote yeast metabolism through the provision of naturally-occurring nutritional compounds.

Prescriptions:

a)        The addition of inactivated yeasts with guaranteed glutathione levels at the start or during the alcoholic fermentation is recommended, ensuring that the assimilable nitrogen level is sufficient to avoid the use of glutathione by the fermentative yeasts;

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