Potassium Sorbate And Malolactic Fermentation
I’ve never concerned myself with Malolactic Fermentation (MLF) because all the red wines I’ve made are from kits. I did try a red wine once – where I picked up the must from a vineyard – however, they had neglected to call me ahead of time to let me know when it would be ready. By the time I had picked it up which was about four days after the grapes were harvested and crushed, a wild yeast had already fermented it. And it did not turn out well.
So I’m no expert on MLF. This evening, I was browsing the site of a self proclaimed “winemaking expert” and came across a post about adding potassium sorbate (K sorbate) to wine after it has completed fermentation. Someone commented on the post to the effect that when making dry wines, he never added potassium sorbate. The wine expert then replied that the winemaker should still be adding potassium sorbate to the wine to prevent malolactic fermentation occurring in the bottle.
Well, this is simply not true. Malolactic fermentation can most certainly occur in the presence of potassium sorbate! In fact, according to what I’ve read, not only can MLF occur after potassium sorbate has been added, when it does occur at such times, it could cause a dreadful smell in the wine.
I never add potassium sorbate to wines that I have fermented to dryness. Some suggest that sorbate can cause a “kit taste” to such wines, especially those that I am bulk aging.
On the other hand, the presence of sulfite will inhibit malolactic fermentation. All potassium sorbate does is inhibit mold and prevent yeast from renewing a fermentation.