II.3.1.1.3 Treatment with ion exchangers

Definition:

Operation consisting of passing the wine through a column of polymerised resin that acts as an insoluble polyelectrolyte whose ions are able to be exchanged with ions of the wine. According to their polar groupings, ion exchange resins are categorised as cation exchangers and anion exchangers.

Objectives :

a)        Treatment with cation exchangers:

1. To stabilise the wine with regard to tartrate precipitation (see II.3.3.3 ‘Tartrate stabilisation by treatment with cation exchangers’),
2. To lower the pH of wines of low fixed acidity and high in  cations,
3. To avoid metallic hazes.

b)       Treatment with anion exchangers:

1. To reduce the titratable acidity,
2. To de-sulphite wines,
3. To reduce the sulphate content.

Recommendation of OIV :

• For objective a)1 and a)2 : Admitted
• For the other objectives: Not admitted