What does EDTA do in mayo? The science of shelf-stable mayonnaise

November 14, 2025 •

3 min read

While home-made mayonnaise lasts only a few weeks, commercially produced mayonnaise can last for months or even a year thanks to ingredients like calcium disodium EDTA. Understanding what does EDTA do in mayo is key to appreciating the science behind modern food preservation and why this additive is considered safe for consumption.

Quick Summary

EDTA, a chelating agent, binds to trace metal ions in mayonnaise, preventing them from catalyzing oxidation that leads to rancidity and discoloration. This action preserves the product's flavor, color, and stability, significantly extending its shelf life.

Key Points

Chelating Agent: EDTA in mayonnaise functions as a chelating agent, binding to and trapping trace metal ions like iron and copper.
Prevents Rancidity: By neutralizing metal catalysts, EDTA prevents the oxidation of oils and fats, which is the primary cause of rancidity in mayonnaise.
Extends Shelf Life: This stabilizing effect protects the product's flavor, color, and texture, allowing it to remain fresh and safe for a much longer period.
FDA Approved: The Food and Drug Administration (FDA) considers calcium disodium EDTA to be 'Generally Recognized as Safe' (GRAS) for use in food within regulated limits.
Poorly Absorbed: The human body absorbs very little of the EDTA in food, and what is absorbed is quickly eliminated via the kidneys, posing no significant health risk at typical consumption levels.
Maintains Emulsion: It helps preserve the emulsion's stability, ensuring that the oil and water-based components in the mayonnaise do not separate over time.

The Science of Mayonnaise: More Than Just Oil and Eggs

Mayonnaise is an oil-in-water emulsion made from ingredients like egg yolks, vegetable oil, vinegar, and seasonings. The unsaturated fats in the oil are particularly vulnerable to oxidation, a process that results in rancidity (off-flavors and off-odors). To give commercial mayonnaise a longer shelf life and maintain its quality, additives like calcium disodium EDTA are used.

The Role of EDTA as a Chelating Agent

EDTA, or ethylenediaminetetraacetic acid, is a synthetic compound that acts as a chelating agent. Chelators form strong bonds with metal ions, like iron and copper, which can enter food during processing. These metal ions can act as catalysts, speeding up oxidation and causing degradation. By binding to these metal ions, EDTA neutralizes them and prevents them from causing spoilage.

Why is EDTA Necessary in Mayonnaise?

Preventing oxidation is vital for mayonnaise, a product high in oil. Trace metals can accelerate oil breakdown, leading to issues such as:

Rancidity: Development of unpleasant tastes and smells.
Discoloration: Changes in the mayonnaise's appearance over time.
Emulsion Breakdown: Separation of oil and water components.

EDTA safeguards the mayonnaise's quality, ensuring it remains good to eat throughout its shelf life.

The Safety and Regulation of EDTA in Food

Calcium disodium EDTA's use in food is regulated by agencies like the U.S. Food and Drug Administration (FDA). The FDA has determined it is 'Generally Recognized as Safe' (GRAS) when used within set limits.

Its safety is supported by:

Limited Absorption: Less than 5% of ingested calcium disodium EDTA is absorbed by the body.
Quick Elimination: The majority is rapidly removed from the body by the kidneys.
Strict Usage Limits: The amount of EDTA in food is well below levels that have shown negative effects in studies.

It's important to distinguish the small amounts of food-grade EDTA from the high doses used in medical chelation therapy.

Comparison: Homemade vs. Commercial Mayonnaise


Feature	Commercial Mayonnaise (with EDTA)	Homemade Mayonnaise (no EDTA)
Ingredients	Typically pasteurized egg yolks, vegetable oil, vinegar, salt, sugar, spices, and a chelating agent like calcium disodium EDTA.	Fresh egg yolks, vegetable oil, vinegar, salt, and spices.
Shelf Life	Months to a year or more when unopened, due to pasteurization and additives like EDTA.	A few weeks at most, and must be refrigerated, as it lacks chelators and pasteurization.
Risk of Spoilage	Very low risk of oxidation and rancidity, with consistent flavor and color over time.	Higher risk of fats oxidizing and becoming rancid, especially if not stored properly.
Flavor Consistency	Highly consistent, uniform flavor and texture over time and across batches.	Flavor and texture can vary and may degrade noticeably over time.
Processing	Uses modern food manufacturing processes that can introduce trace metals, making EDTA a necessary safeguard.	No industrial processing, but still susceptible to trace metals from ingredients or kitchen utensils.

The Function of EDTA in Food Processing: Beyond Mayonnaise

Chelating agents like EDTA are used in various food products to control reactions catalyzed by trace metal ions.

Canned Foods: Prevents discoloration in canned produce.
Beverages: Inhibits benzene formation in some drinks containing ascorbic acid and sodium benzoate.
Seafood: Helps prevent struvite crystal formation in canned seafood.
Fortified Foods: Stabilizes vitamins and improves mineral absorption in fortified grains.

The goal in these applications is to improve the product's safety, stability, and sensory quality by neutralizing trace metal ions. For information on food additive regulations, consult the U.S. FDA website.

Conclusion

EDTA is a crucial chelating agent in commercial mayonnaise. It binds to trace metal ions, preventing oil oxidation, preserving color and flavor, and maintaining the emulsion's stability. This additive is a key factor in the long shelf life and consistent quality of store-bought mayonnaise. Considered safe by regulatory bodies, its use in small, controlled amounts ensures food safety and quality for consumers. While not needed in fresh homemade versions, it is essential for mass-produced condiments.

Frequently Asked Questions

No, calcium disodium EDTA is considered safe for consumption by the FDA within regulated limits. The amount used in food is very small and is poorly absorbed by the body, with most of it being rapidly excreted.

Food-grade EDTA (calcium disodium EDTA) is used in very small amounts to preserve food. Medical-grade EDTA is used in much higher doses for chelation therapy to treat heavy metal poisoning and is administered intravenously under strict medical supervision.

EDTA does not add any flavor. Instead, it prevents the development of off-flavors caused by rancidity, thus preserving the intended taste of the mayonnaise over its shelf life.

Yes, homemade mayonnaise is made without EDTA. However, it has a much shorter shelf life and must be refrigerated, as it lacks the preserving and stabilizing effects of the chelating agent.

While vinegar provides some antimicrobial benefits due to its acidity, it does not stop the chemical process of metal-catalyzed oxidation that causes rancidity. EDTA specifically addresses this issue by chelating the metal ions.

Food companies may use other methods, such as natural antioxidants like ascorbic acid (vitamin C) or rosemary extract, or different processing techniques, to prevent spoilage. However, EDTA is highly effective for its specific role in chelating metals.

The amount of EDTA in a serving of mayonnaise is extremely small and well below the Acceptable Daily Intake (ADI) set by health authorities. The FDA limits its concentration to a maximum of 165 parts per million.

Some environmental concerns exist regarding EDTA's poor biodegradability and its potential to mobilize heavy metals in aquatic ecosystems once it enters the wastewater system. This has led to research into more biodegradable alternatives in some industries.