Facts about pinking
- The exact mechanism of pinking is still unknown. It involves the oxidation of one or more phenolic compounds in the presence of metals such as iron and copper.
- Pinking affects various white cultivars, especially Sauvignon blanc.
- Wines differ in their susceptibility for pinking.
- Pinking can sometimes alter the taste of a wine (new research results).
- Pinking can be prevented.
Harvest winemaking practices that increase a wine’s susceptibility for pinking:
- Increasing grape ripeness
- Cold processing (more dissolved oxygen)
- Whole bunch pressing (stems contain high concentrations of phenolic compounds)
- Reductive winemaking
- High pH (less molecular SO2)
Practical advice on how to prevent pinking in susceptible musts and wines:
- Consider using products that contain PVPP (lowers phenolic content) or PVI/PVP (lowers heavy metals) as a preventative measure before or during fermentation. Suppliers can advise.
- Maintain a high (45 mg/l) free SO2 environment before and after fermentation when the wine is off the yeast lees, and during all movements of the wine until it is in the bottle.
- Maintain a low dissolved oxygen environment in the wine after it is off the yeast lees, especially after a movement where oxygen pick up can take place.
- Sparge the wine before bottling to remove oxygen.
- Consider adding ascorbic acid before bottling. Great care must be taken with the use of ascorbic acid as it can also promote oxidation under certain conditions. Suppliers can advise.
References