Are Fermented Foods Pasteurized? What You Need to Know

While many people consume fermented foods for their probiotic benefits, it's a common misconception that all of them contain live cultures. In reality, a significant portion of commercial fermented foods may be pasteurized, a heat treatment that eliminates beneficial microbes. The answer to 'Are fermented foods pasteurized?' is not a simple yes or no, but depends entirely on the product and its processing.

Quick Summary

Many fermented foods are pasteurized for extended shelf life, a process that kills the live probiotic cultures, but others are intentionally kept raw. This article explains how to distinguish unpasteurized, live-culture products from their heat-treated counterparts by checking storage, ingredients, and labels.

Key Points

• Not all fermented foods are pasteurized: The heat treatment depends on the product and producer, with many commercial brands opting for pasteurization for shelf stability.

• Pasteurization kills live cultures: The heat process eliminates the beneficial probiotic bacteria, removing a key health benefit of raw fermented foods.

• Check labels and refrigeration: To find unpasteurized products, look for terms like "raw," "unpasteurized," or "live cultures," and ensure the food is sold from a refrigerated case.

• Yogurt is a special case: The milk is pasteurized before fermentation, but live cultures are added back in, so it still contains probiotics.

• Benefits remain in postbiotics: Even if pasteurized, fermented foods retain certain nutrients and metabolic byproducts, called postbiotics, though the live cultures are gone.

• Flavor profile is affected: Pasteurization halts the fermentation process, resulting in a consistent flavor, whereas raw ferments have a more complex and evolving taste.

• Raw ferments require proper storage: Unpasteurized products must be kept cold to control microbial activity and maintain their probiotic content.

The Purpose of Pasteurization in Fermented Foods

Pasteurization is a heat treatment that kills microorganisms, both harmful and beneficial, to increase a product's shelf stability and reduce the risk of foodborne illnesses. For commercial fermented products, this process prevents further fermentation, ensuring a consistent flavor and texture that won't continue to evolve on the shelf. However, this stability comes at a cost, as the high temperatures are indiscriminate and destroy the live probiotic cultures that are a primary reason many people seek out fermented foods.

Unpasteurized Fermented Foods (Contain Live Cultures)

These products are typically raw and have not undergone heat treatment, preserving their living microbial content. They must be kept refrigerated to slow down the fermentation process and maintain their quality. To identify them, look for labels stating "unpasteurized," "raw," or "live and active cultures," and always find them in the refrigerated section of the store. The flavor of these products can also continue to develop over time as the bacteria remain active.

Examples of Live, Unpasteurized Ferments:

• Kimchi: Traditionally made kimchi is unpasteurized and continues to ferment in the fridge.
• Sauerkraut: Raw, refrigerated sauerkraut is teeming with probiotics, unlike its shelf-stable, pasteurized counterpart.
• Kombucha: Many high-quality brands are raw and unpasteurized to maintain the live bacteria and yeast from the SCOBY (Symbiotic Culture of Bacteria and Yeast).
• Fermented Pickles: Lacto-fermented pickles, which use salt and water instead of vinegar, are unpasteurized and found in the refrigerated aisle.
• Water or Milk Kefir: These cultured drinks contain a rich diversity of live microbes and require refrigeration.

Pasteurized or Heat-Treated Fermented Foods

These products are heated to kill microbes, ensuring a long, shelf-stable life. While they retain the flavor and some nutrients from the fermentation process, they do not contain live probiotic organisms unless a specific strain is added back after pasteurization.

The Yogurt Exception

Commercial yogurt follows a specific process that ensures both safety and the presence of live cultures. The milk is pasteurized first to kill any harmful bacteria, then cooled before specific bacterial starter cultures are added for fermentation. The final yogurt product is typically not re-pasteurized, which allows it to contain live cultures and carry the "live and active cultures" label.

Examples of Fermented but Not Live Foods:

• Shelf-Stable Sauerkraut: Found on non-refrigerated shelves, these products are pasteurized for longevity and often use vinegar to replicate the sour taste.
• Some Vinegars: While fermented, many commercial varieties are pasteurized, which removes the probiotic 'mother' culture. Raw, unfiltered options contain live microbes.
• Most Breads: Sourdough bread is made with a fermented starter, but the baking process kills all the active microbes.
• Beer and Wine: The fermentation is critical to their production, but processes like filtration and pasteurization kill the yeast before bottling.

How to Identify Live, Unpasteurized Ferments

Determining if a fermented food contains live cultures requires careful attention to product details. The primary indicators are storage location and labeling. Always look for products in the refrigerated section, as live cultures require cold temperatures to slow fermentation and prevent spoilage. A product's label is the most important clue; search for specific terms that confirm the presence of live microbes.

Label Clues for Unpasteurized Foods

• "Raw" or "Unpasteurized": A direct indication that the food has not been heat-treated.
• "Live and Active Cultures": Commonly found on yogurts and kefirs, this confirms the presence of beneficial bacteria.
• Ingredient List: In fermented vegetables, look for simple ingredients like vegetables, salt, and spices, with no added vinegar.

Comparison: Unpasteurized vs. Pasteurized Fermented Foods

Feature	Unpasteurized (Raw)	Pasteurized (Heat-Treated)
Live Cultures	Yes, teeming with probiotics and beneficial microbes.	No, heat treatment kills all microbes.
Health Benefits	Probiotic benefits for gut health, immunity, etc..	Primarily nutritional and flavor-related; lacks live cultures.
Storage	Requires refrigeration to control fermentation.	Shelf-stable and can be stored at room temperature.
Shelf Life	Shorter due to ongoing microbial activity.	Extended, stable shelf life.
Flavor Profile	Complex and evolving with time.	Consistent, stable flavor profile.
Cost	Often more expensive due to smaller-scale production and refrigeration needs.	Generally less expensive for large-scale producers.

Conclusion

In short, whether or not fermented foods are pasteurized is entirely dependent on the specific product and its processing. For consumers seeking the live probiotic benefits, it is crucial to understand these differences. Many store-bought fermented vegetables like sauerkraut and kimchi, as well as beverages like kefir and kombucha, come in both pasteurized and unpasteurized versions. The key to making an informed choice is to check the product's storage location and scrutinize the label for indicators of live cultures, such as "raw" or "unpasteurized." While pasteurization enhances shelf life, it ultimately removes the very microbes that make many fermented foods so valuable for gut health. For the full spectrum of probiotic benefits, opting for the refrigerated, unpasteurized option is the best choice.

Learn more about the science behind fermented foods by exploring the resources at Stanford Medicine's Nutrition education pages.(https://med.stanford.edu/nutrition/education/Resources/Fermenting-the-Facts/How-to-Recognize-Fermented-Foods.html)

Frequently Asked Questions

Is kimchi pasteurized?

Authentic, traditional kimchi is typically not pasteurized and remains a live, fermented food. It is found in the refrigerated section of stores. The live cultures continue to work, which is why the flavor can change over time.

Is store-bought sauerkraut pasteurized?

It depends on where you find it. Shelf-stable sauerkraut, found on unrefrigerated aisles, is pasteurized. Raw, unpasteurized sauerkraut, which contains live probiotics, is always stored and sold in the refrigerated section.

Are pickles fermented and pasteurized?

Not all pickles are fermented. Traditional lacto-fermented pickles are unpasteurized and contain probiotics, while many store-bought pickles are simply acidified with vinegar and pasteurized, so they do not contain live cultures.

What happens when you pasteurize a fermented food?

When you pasteurize a fermented food, you apply heat to kill all microorganisms, including both harmful and beneficial bacteria. This extends the product's shelf life but eliminates the live probiotic cultures.

Do all fermented foods contain probiotics?

No. While all fermented foods undergo fermentation, only those that are unpasteurized (or have live cultures added back, like yogurt) will contain probiotics. Examples like bread, wine, and shelf-stable versions of other ferments do not have live cultures.

How can I tell if a fermented food is unpasteurized?

Check the label for keywords such as "raw," "unpasteurized," or "live cultures." Unpasteurized foods are also always stored in the refrigerated section to prevent spoilage and control fermentation.

Why do some companies pasteurize fermented foods?

Companies pasteurize fermented foods primarily to extend their shelf life and maintain product consistency. It prevents the ongoing fermentation that can alter flavor and texture, which is advantageous for mass production and distribution.