Potassium Sorbate: The Mold Inhibitor in Your Cheese and Salad Dressing

Mold doesn’t need much to set up shop. A little moisture, some organic material, the right temperature, and it’s growing. That’s the problem food manufacturers face with products like shredded cheese, salad dressing, and wine. Refrigeration helps, but it’s not enough on its own. That’s where potassium sorbate comes in.

What Potassium Sorbate Actually Does

Potassium sorbate is the potassium salt of sorbic acid. When it dissolves in food, it releases sorbate ions that, under acidic conditions, convert to sorbic acid. Sorbic acid is the molecule that actually does the work.

Think of sorbic acid like a key that fits into the cellular machinery of fungi and some bacteria. It disrupts the proton gradient across the cell membrane and interferes with enzymes involved in energy metabolism. Without functioning energy production, the cell can’t grow or reproduce. The organism doesn’t die outright but it can’t multiply, which is exactly what food manufacturers need.

The compound is what chemists call fungistatic. Not fungicidal.

This distinction matters in practice. Potassium sorbate won’t rescue food that already has visible mold. It prevents new growth from starting. That’s why manufacturers combine it with proper processing, pH control, and good packaging.

Where It Works Best

Potassium sorbate has a pH dependency that’s worth understanding. The active form is sorbic acid, which exists at low pH. In high-acid foods (vinegar-based dressings, wine, yogurt, most cheeses), more of the compound exists in its active acid form. As pH rises toward neutral, efficacy drops.

This makes it a good fit for:

• Salad dressings (typically pH 3.5-4.5)
• Wine (pH 3.0-4.0)
• Dairy products like sour cream, shredded cheese, and cottage cheese
• Fruit juices and beverages
• Baked goods (combined with other preservation methods)
• Dried fruits and fruit preserves

You’ll sometimes see it combined with sodium benzoate, another preservative that also works best at acidic pH. The two have different (though overlapping) spectra of activity, and together they provide more complete protection than either alone.

Regulatory Status

The FDA classifies potassium sorbate as GRAS (Generally Recognized as Safe) under 21 CFR 182.3640. JECFA, the joint expert committee that sets international food additive standards, has established an acceptable daily intake (ADI) of 25 mg per kilogram of body weight per day. For a 70 kg adult, that’s 1,750 mg daily.

Actual exposure from food is far below that threshold. EFSA’s 2015 re-evaluation of sorbic acid and its salts, covering European dietary habits, found that even high-end consumers (the 95th percentile) stay well within the ADI.

EFSA concluded there were no safety concerns at current use levels.

What Happens to It in Your Body

Potassium sorbate follows the same metabolic path as other short-chain fatty acids. The body oxidizes it through normal fatty acid metabolism, ultimately converting it to carbon dioxide and water. It doesn’t accumulate. It doesn’t behave unusually. Your body processes it the same way it processes the butyric acid produced when gut bacteria ferment dietary fiber.

There are no credible studies linking normal dietary exposure to potassium sorbate with cancer, reproductive harm, or chronic disease. The compound has been used in food since the 1950s with an extensive safety record at commercial use concentrations.

The “It’s a Chemical” Concern

Some food labeling advocates list potassium sorbate alongside more controversial additives as a reason to choose “clean label” products. That framing doesn’t hold up.

Sorbic acid is a naturally occurring compound. It was first isolated from mountain ash berries in the 1850s. The commercial version is synthesized, but it’s chemically identical to the natural form. And more to the point, the safety profile of the molecule itself is what matters, not whether it came from a berry or a production vessel.

The molecule is used at concentrations typically between 0.025% and 0.1% of the final product. At that level, it’s one of the better-studied and better-characterized preservatives in the food supply.

If you’re comparing it to other preservatives, it stacks up well. It’s not sodium nitrite (which can form nitrosamines under certain conditions). It’s not the subject of any ongoing regulatory concern. It’s a well-understood organic acid that’s been doing the same job for 70 years.

A Note on Wine

Wine producers use potassium sorbate to prevent refermentation after a wine has been sweetened or bottled. It stops any residual yeast from consuming the added sugar and producing unwanted carbonation or off-flavors.

It’s not universally used. Many wines don’t need it, particularly dry wines fermented to completion. But in sweet wines, in-bottle stability requires either sterile filtration or a preservative. Potassium sorbate is one common choice.

Some wine drinkers report a faint “geranium” off-note they attribute to potassium sorbate. This is technically accurate but incomplete. The geranium smell comes from a compound called 2-ethoxyhexa-3,5-diene, which forms when sorbate reacts with lactic acid bacteria. Proper winemaking practice avoids the conditions that allow this reaction. When wine smells like geranium leaves, it’s a sign of a winemaking error, not of the additive itself.