Every single wine kit that I’ve ever purchased comes with a package of potassium sorbate. The instructions that come with the wine kits tell us to add sorbate at the same time that we are to add potassium metabisulfite. However, many winemakers balk at adding sorbate to their wine and don’t always follow instructions.

Why the balking? Many believe that potassium sorbate adds a bubblegum flavor to wine, or as some call it, “kit wine taste.” So why do so many advise to add this stuff to our wines after the fermentation has been completed?

Well, let’s bust one common myth right at the outset. Potassium sorbate does not kill yeast. Many believe that the purpose of this additive is to kill yeast. What sorbate does, at the correct quantity, is slow down and stop the reproduction of yeast. It will not stop yeast from continuing to ferment a wine, nor will it prevent a fermentation when it’s added to juice before the juice has been inoculated with yeast.

Primarily, it is used to prevent a re-fermentation of the wine if there is enough residual sugar left in the wine after it has been bottled or if a wine has been sweetened after it has fermented. You may have heard stories – or perhaps it’s happened to you, where a home winemaker has bottled their wine, only to start hearing corks popping out of the bottles six months later. This is because there was enough sugar in the wine for some yeast cells to feed on and begin reproducing. As they feed on the remaining sugar, the produce more alcohol and carbon dioxide. The carbon dioxide build up in the bottles creates enough pressure that the corks are forced out of the bottles and the wine inside blasts out.

Dry wines that have fermented to very little or zero residual sugar and that will be bottled without a sugar based sweetener added do not need any additions of potassium sorbate. If there is no sugar for any remaining yeast cells, there will be no re-fermentation by yeast.

If the winemaker is making an off-dry or sweet wine, potassium sorbate should be added to the wine to stabilize it. Generally, the rate of 1/2 teaspoon per gallon is the rule of thumb.

If you’re new to winemaking, I’d recommend that you use the potassium sorbate additive in your wine until you are very comfortable using a hydrometer to measure the specific gravity and understand the relationship of sugar and yeast. Wine kit makers don’t want to take any chances that you may not have fermented your dry wine completely, and therefore instruct that you add sorbate at the same time as sulfite. Potassium sorbate is more effective when used in conjunction with potassium sorbate.