II.2.1.20 Adsorbant copolymer treatment PVI/PVP

Classification:

• PVI/PVP copolymer: processing aid

Definition:

The addition of polyvinylimidazole – polyvinylpyrrolidone copolymers (PVI/PVP) in order to reduce copper, iron and heavy metal contents.

Objectives:

a)        To prevent defects caused by too high metal contents (for example ferric casse).

b)       To reduce undesirable high concentration of metals due to:

• Must contaminated by metal cations (for example by residues from phytosanitary products containing copper),
• Metal cation contamination during must treatment from winemaking equipment.

 

Prescriptions:

a)        The amount used should be less than 500 mg/l.

b)       When musts and wine are treated with PVI/PVP copolymers, the accumulated dosage should be less than 500 mg/l.

c)        The copolymers should be eliminated by filtration no later than two days after the addition taking into account the precautionary principle. In the case of cloudy musts, the copolymer must be added no earlier than a maximum of two days before filtration.

d)       The adsorbant copolymers used should comply with the prescriptions of the International Oenological Codex and in particular monomers limits.

e)       The implementation of the procedure shall be placed under the responsibility of an oenologist or a specialised technician.

Recommendation of the OIV:

Admitted