My personal opinion through experience is that the choice to add Potassium Sorbate to a wine must be made in good conscience. Potassium Sorbate is merely a yeast inhibitor and works best in a scenario where the wine has been well-clarified and so would be acting upon a minimal population of viable yeast cells.

Working in conjunction with Potassium Metabisulfite, the two are thought to work better than just meta alone. However, it is important to keep in mind that Meta is the one of the two that is an anti-bacterial and which in sufficient concentration makes the wine unsuitable for any microbial activity other than the action of desirable wine yeasts.

This is where the conundrum occurs…if Meta allows for desirable yeast, than won’t my wine with residual sugar start to ferment? The answer is quite possibly…if you don’t either a) use potassium sorbate or b) sterile filter the wine.

There are pros and cons to both. Sterile filtering can remove some of the character of the wine, but conversely is most ideal for this type of wine. The addition of Potassium Sorbate can be enough to inhibit refermentation, but needs to be added in sufficient amount to be effective and can impart a faint but noticeable and perhaps undesirable taste to the wine.

Web resources discuss the inter-relation of wine pH, concentration of free SO2, percent alcohol by volume, concentration of sorbate and viable yeast cell concentration. Assuming that pH and Free SO2 are maintained as recommended and that the wine has been clarified, the amount of Potassium Sorbate to add will decreased as the percent alcohol by volume increases. Most literature suggests that ¼ teaspoon per (~2 grams) is sufficient and you should follow the instructions provided.

One major caution, I cannot emphasize enough that Malolactic fermentation (MLF) and Potassium Sorbate do not play well. The result of introducing Potassium Sorbate into a wine that has undergone or undergoes MLF will be an irreversible geranium-like smell. It will render your wine suitable only for the drain. This is so important because it necessitates that the winemaker be conscientious in maintaining an environment in this wine that is unsuitable for MLF, which starts by maintaining an adequate level of free SO2.

An article on MLF is currently in the works…

- Nick Coppola
Juicegrape.com Support