What is Natamycin (E235)?
Natamycin, also known as pimaricin, is a polyene macrolide antimicrobial agent derived from the fermentation of the bacterium Streptomyces natalensis. As a biopreservative, its primary function is to prevent the growth of yeasts and molds, extending the shelf life of food products. It is effective at very low concentrations and operates across a wide pH range, from 3 to 9, making it suitable for many different types of food. A key characteristic that sets natamycin apart from many chemical preservatives is its poor solubility in water, which means it tends to remain on the surface of food products where most fungal contamination occurs.
How Natamycin Works to Inhibit Fungi
Unlike chemical preservatives that may have broad antimicrobial effects, natamycin's action is specific to fungi. It binds irreversibly to ergosterol, a vital component of fungal cell membranes, but does not affect bacterial cell membranes which lack this compound. This binding process disrupts the cell's integrity, leading to the leakage of essential cellular components and ultimately inhibiting the growth of yeast and mold. This selective mechanism is particularly beneficial for products that rely on bacterial fermentation, such as cheese and dried sausages, as it prevents fungal spoilage without disrupting the bacterial cultures crucial for the aging and flavor development process.
Global Regulatory Status and Safety Assessments
Globally, numerous regulatory bodies have approved natamycin for use as a food additive under specific conditions, leading to the general conclusion that it is safe for consumption when used within specified limits.
- Food and Drug Administration (FDA): In the United States, the FDA permits the use of natamycin on the surface of cuts and slices of cheese. It is also considered Generally Recognized As Safe (GRAS) for use in certain beverages and yogurt at very low levels.
- European Food Safety Authority (EFSA): The EFSA has reviewed natamycin and permits its use as a surface preservative on certain cheeses and dried sausages, with strict limits on its penetration depth. A 2009 assessment concluded there were no safety concerns for its approved uses.
- World Health Organization (WHO): The Joint FAO/WHO Expert Committee on Food Additives (JECFA) has established an Acceptable Daily Intake (ADI) of 0.3 mg per kg of body weight per day.
Addressing Concerns About Resistance and High Dosage
While generally considered safe, some studies have raised concerns about the potential for natamycin to exert a selective pressure on the intestinal fungal flora at higher exposure levels, hypothetically jeopardizing the efficacy of polyene antifungals used in human medicine. These potential risks are primarily associated with the homogeneous addition of high concentrations of highly soluble natamycin to products like yogurts or beverages, which are not representative of standard surface-treatment applications. For example, a 2015 review highlighted that surface treatment of solid food is considered safe, but mixing highly soluble formulations into beverages could lead to high faecal natamycin concentrations. The poor absorption of natamycin from the gastrointestinal tract, however, minimizes systemic exposure, and studies have shown minimal toxicity at low, food-grade doses.
Comparison of Natamycin and Other Preservatives
To better understand the benefits of natamycin, it is helpful to compare it with other common food preservatives, both natural and synthetic.
| Feature | Natamycin (E235) | Potassium Sorbate (E202) | Sodium Benzoate (E211) |
|---|---|---|---|
| Origin | Natural (bacterial fermentation) | Synthetic (potassium salt of sorbic acid) | Synthetic (sodium salt of benzoic acid) |
| Target Microbes | Yeasts and molds only | Molds, yeasts, and some bacteria | Yeasts, molds, and some bacteria (pH dependent) |
| Specificity | High specificity against fungi, leaving bacteria unaffected. | Broader spectrum, can interfere with desired bacterial cultures. | Broader spectrum, can interfere with fermentation processes. |
| Effect on Taste | Odorless and tasteless; does not alter food flavor. | Can impart a bitter or pungent aftertaste at higher concentrations. | Can affect the taste profile, especially in acidic products. |
| Solubility | Poorly soluble in water, staying on the surface. | Highly soluble in water, can penetrate deeper into food. | Highly soluble in water, distributes throughout the food matrix. |
| Best Application | Surface treatment of cheese, sausages. | Widely used in beverages, baked goods, cheese. | Used in carbonated drinks, jams, and pickles. |
| Consumer Preference | Favored as a "natural" alternative. | Viewed as a synthetic chemical preservative. | Viewed as a synthetic chemical preservative. |
Practical Applications of Natamycin in the Food Industry
Natamycin's unique properties make it ideal for several specific food preservation applications, particularly where bacterial cultures are beneficial, and surface mold growth is the primary concern.
- Cheese: Applied as a spray or dip on the surface of cheeses like Swiss and aged cheddars, natamycin prevents mold growth and extends shelf life. Since it does not penetrate deep into the cheese, it does not interfere with the bacterial ripening process that gives cheese its characteristic flavor.
- Sausages: Similarly, for fermented and dried sausages, natamycin is applied to the casing to inhibit mold growth. It is more effective and durable than alternatives like potassium sorbate for this purpose.
- Yogurt and Beverages: In these products, natamycin is added at low concentrations to inhibit yeasts and molds, extending shelf life. Recent studies have investigated more soluble forms for better integration in liquid products.
- Baked Goods: Natamycin is increasingly used in baked goods with a short shelf life to control surface mold.
Conclusion
For consumers asking, "is natamycin okay?", the answer is generally yes, especially when used within established regulatory guidelines. As a natural, fermentation-derived preservative, natamycin offers an effective way to control fungal spoilage in food without affecting desirable bacterial cultures or altering the product's taste and appearance. Its safety has been reviewed and approved by major food safety authorities like the FDA, EFSA, and WHO. While a minimal risk regarding polyene resistance has been theorized in the context of high, homogeneous oral intake, this is not a concern for its approved uses in surface-treated foods. Compared to many chemical preservatives, natamycin provides a cleaner, more targeted approach to food preservation, aligning with consumer demand for more naturally preserved products.
To learn more about food additives and their regulations, consult the U.S. Food and Drug Administration's website for detailed information.
Key Takeaways
- Natural Origin: Natamycin is a natural antifungal preservative produced by the bacterium Streptomyces natalensis.
- Antifungal Specificity: It specifically targets yeasts and molds by disrupting their cell membranes but does not harm beneficial bacteria.
- Regulatory Approval: Major food safety authorities worldwide, including the FDA, EFSA, and WHO, have approved its use within safe limits.
- Primary Uses: Its poor water solubility makes it ideal for surface treatment on products like cheese and dried sausages to prevent mold growth.
- Low Toxicity: At approved food additive levels, natamycin has very low toxicity and is poorly absorbed by the human body.
- Minimal Impact: It does not impact the taste, color, or aroma of the foods it protects.
FAQs
Question: Is natamycin an antibiotic, and is it safe to eat? Answer: Yes, natamycin is classified as a polyene macrolide antibiotic, but it's important to distinguish between medical and food-grade applications. When used as a food preservative, it is considered safe by regulatory bodies because it is applied at very low levels and is poorly absorbed by the gastrointestinal tract.
Question: Why is natamycin used in cheese if it's an antibiotic? Answer: Natamycin is used in cheese specifically because its antifungal properties target mold and yeast on the surface without harming the bacteria cultures essential for the cheese's fermentation and aging process.
Question: Does natamycin affect beneficial gut bacteria? Answer: No, natamycin does not harm beneficial gut bacteria because its mechanism of action is specific to fungi, which have different cell membrane structures. Bacteria are unaffected.
Question: Are there any side effects of consuming natamycin? Answer: For most people, consuming natamycin at approved food levels causes no side effects due to poor intestinal absorption. Some individuals with specific mold allergies may experience a reaction, but allergic incidents are rare.
Question: Is natamycin a natural or chemical preservative? Answer: Natamycin is considered a natural preservative because it is produced via the fermentation of the naturally occurring bacterium Streptomyces natalensis. This is a key reason for its growing use as a more consumer-friendly alternative to synthetic chemicals.
Question: Can natamycin be found in organic products? Answer: The use of natamycin is generally restricted in products labeled as 'organic' due to strict regulations regarding additives. However, this varies by country and specific certifying body, so it's best to check individual product labels or certifications.
Question: How does natamycin prevent spoilage compared to other preservatives? Answer: Natamycin is particularly effective because of its surface-specific, antifungal action and high potency at low concentrations, which is superior for preventing external mold growth compared to water-soluble alternatives like sorbates, which can penetrate and alter the food product.
