What Foods Contain Propionic Acid? Understanding Natural and Added Sources

December 5, 2025 •

2 min read

Propionic acid is a naturally occurring short-chain fatty acid (SCFA) that plays a dual role in our food system: as a naturally occurring byproduct of fermentation and as a widely used food additive. This means that when asking, "what foods contain propionic acid?", the answer covers a wide spectrum from traditional artisanal cheeses to commercially produced baked goods.

Quick Summary

Propionic acid is found in Swiss-type cheeses and other fermented dairy due to bacterial action, and as a common preservative in packaged bread, cakes, and other processed foods. It is also a natural metabolite in shellfish and some fermented soy products.

Key Points

Natural Fermentation: Swiss-type cheeses like Emmental are a primary natural source of propionic acid, produced by Propionibacterium bacteria during fermentation.
Food Additive: Propionic acid salts, such as calcium propionate and sodium propionate, are widely used as preservatives to inhibit mold growth in commercial baked goods and processed foods.
Flavor and Preservation: In cheese, propionic acid contributes a characteristic nutty, sweet flavor, while its preservative form functions to extend shelf life in packaged products.
Gut Microbiome Production: The human gut microbiota naturally produces propionic acid as a short-chain fatty acid when fermenting dietary fiber from sources like whole grains and legumes.
Widespread Presence: Beyond cheese and baked goods, propionic acid can be found naturally in some fermented soy products and shellfish, and as an additive in various items like processed meats and certain beverages.

Naturally Occurring Propionic Acid in Foods

Propionic acid is produced naturally by certain bacteria, notably Propionibacterium, through the fermentation of sugars and lactates. This process contributes to the unique flavor and preservation of certain foods.

Dairy Products: Swiss Cheese and Fermented Milks

Swiss cheeses like Emmental, Gruyère, and Jarlsberg are well-known natural sources of propionic acid. The bacteria Propionibacterium freudenreichii ferment lactic acid, producing propionic acid and carbon dioxide. Propionic acid gives these cheeses their characteristic flavor, while CO2 creates the "eyes". Fermented milk products may also contain small amounts.

Other Natural Sources

Traditional Asian fermented soybean products, including Korean Chunggukjang, have been found to contain naturally occurring propionic acid from microbial fermentation. Additionally, some types of shellfish, particularly certain clams and scallops, and trace amounts in certain medicinal herbs can also be sources.

Propionic Acid as a Food Additive

Propionic acid and its salts (propionates) are frequently added to foods to prevent mold and bacterial growth, extending shelf life. They are commonly used in the bakery industry to inhibit mold and "rope" spoilage, found in products like commercial bread, cakes, pastries, tortillas, and pizza crusts. Propionates also act as preservatives in other processed items such as deli meats, some yogurts, grated cheeses, jams, and packaged snacks.

Comparing Natural vs. Additive Propionic Acid

While the compound is chemically the same, the source and function differ.


Feature	Naturally Occurring	Food Additive (Propionates)
Source	Bacterial fermentation in foods like Swiss cheese.	Synthetic salts added for preservation.
Function	Contributes flavor/texture in fermented foods.	Inhibits mold/bacteria to extend shelf life.
Examples	Swiss cheese, fermented soy, some shellfish.	Bread, cakes, processed meats, snacks.
Concentration	Varies; can be higher in some natural sources.	Regulated levels, typically low (e.g., 0.1–0.4%).

Propionic Acid in Gut Health

Propionic acid is also a key short-chain fatty acid (SCFA) produced by beneficial gut bacteria when they ferment indigestible carbohydrates like dietary fiber. A high-fiber diet increases SCFA production, including propionate, which is thought to support metabolic and immune functions. While food intake contributes, internal production from fiber is a significant source.

The Importance of Fiber

Increasing dietary fiber supports your gut bacteria's natural propionate production. High-fiber foods include:

Legumes: Beans, lentils
Whole Grains: Oats, barley
Vegetables: Garlic, onions, asparagus
Fruits: Apples, bananas

Conclusion

Propionic acid is found in various foods, both naturally through fermentation in items like Swiss cheese and fermented soy products, and as an additive (propionates) in many baked goods and processed items to prevent spoilage. Furthermore, our own gut microbiomes produce this SCFA from dietary fiber. Understanding these diverse sources clarifies its presence in the modern diet. For more detailed information, consult resources like {Link: foodadditives.net https://foodadditives.net/preservatives/propionic-acid/}.

Frequently Asked Questions

Swiss-type cheeses, including Emmental, Gruyère, and Jarlsberg, naturally contain significant amounts of propionic acid, which is responsible for their characteristic nutty flavor and large holes.

Propionic acid can be both naturally occurring and synthetically produced as an additive. While it is naturally present in fermented foods, its salts (propionates) are widely added to commercial products as a preservative.

Propionic acid, typically as calcium propionate, is added to bread and other baked goods to inhibit the growth of mold and the bacteria that cause spoilage, thereby extending the product's shelf life.

The chemical compound is the same, but the source differs. Naturally occurring propionic acid is a byproduct of bacterial fermentation, while additive propionic acid is synthetically produced and added to foods for preservation.

Yes, propionic acid is one of the short-chain fatty acids (SCFAs) produced by your own gut bacteria when they ferment dietary fiber. This internal production is considered beneficial for gut health.

Beyond baked goods like bread and cakes, propionates are used in processed meats, certain dairy products like yogurt and grated cheese, some fruit juices, and packaged cereals.

While Swiss cheese contains propionic acid, a beneficial short-chain fatty acid, the amount from cheese is generally small. The most significant source of propionic acid for gut health comes from the fermentation of dietary fiber by your gut microbiome.