Sorbic acid is normally used as its salt, potassium sorbate, because the acid is difficult to dissolve in wines. This additive is a fluffy, crystalline material commonly added to homemade wines to inhibit the reproduction of yeasts, and so avoid re-fermentation following sugar additions when preparing the wine for bottling. It is important that the wine first have its yeast count reduced to a low level by fining and filtration.
Sorbate is effective in inhibiting yeast reproduction, but will only act efficiently if used together with SO2. It does not kill yeasts at the dosages shown below.
Potassium sorbate easily dissolves in cold water, but not in alcohol solutions or in warm water.
A convenient solution can be made by dissolving 30 grams in 1 litre cold water. The following table lists recommended dosages of the solution. The effectiveness of potassium sorbate increases markedly with higher alcohol levels and with lower values of pH.
Potassium sorbate, used in the dosages below, cannot be used to arrest the activity of an active colony of yeast. To accomplish that purpose would require addition of a dose that would spoil the flavour of the wine.
| Alcohol | pH 3.1 | pH 3.2 | pH 3.3 | pH 3.4 | pH 3.5 |
|---|---|---|---|---|---|
| 10% | 5.5 ml/l | 6.0 ml/l | 7.0 ml/l | 8.0 ml/l | 9.0 ml/l |
| 11% | 4.5 ml/l | 5.0 ml/l | 6.0 ml/l | 7.0 ml/l | 7.5 ml/l |
| 12% | 3.2 ml/l | 3.5 ml/l | 4.0 ml/l | 4.5 ml/l | 5.0 ml/l | 13% | 2.6 ml/l | 3.0 ml/l | 3.2 ml/l | 3.5 ml/l | 4.0 ml/l | 14% | 2.0 ml/l | 2.2 ml/l | 2.4 ml/l | 2.7 ml/l | 3.0 ml/l |
Sorbate does not kill or inhibit reproduction of bacteria. Be aware that sorbate in wine is subject to attack by malolactic bacteria, if present. Their breakdown of the sorbate will produce a substance that has the pronounced odour of crushed Geranium leaves, and renders the wine unfit.
See Potassium Sorbate for further info.