Wine stability - troubleshooting
There are three key technical areas where problems with wines can arise:
1. Protein stability
Cloudy haze in wine can be a product of unstable wine proteins. This is usually more of a problem in white wine rather than red as tannin in red wine binds with the protein. Wines with a haze are unsaleable so it’s crucial to remove these proteins before bottling. There are various protein stability tests but no guaranteed test that will predict if protein haze will form in the bottle. However, there are methods for the removal of proteins
Copper in wines can come from grape treatment residues, fittings in tanks or pumps and the use of copper based products to help remove reductive odours. The legal maximum level for copper is 1mg/l, but the recommended maximum for wine stability is 0.3mg/l.
3. Chill stability
The result of a potentially 'chill unstable' wine is crystal formation in the bottle. Although the crystals are harmless they may render the wine unfit for sale. In UK wine the crystals are usually potassium hydrogen tartrate or calcium tartrate. Filtration is the worst offender for causing chill instability issues.