# Sodium Potassium Tartrate (E337)

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**Safety rating:** SAFE
**E-number:** E337
**CAS number:** 304-59-6
**Category:** emulsifier
**FDA GRAS:** yes
**Adverse events (FDA AERS):** 0
**FDA recalls:** 0
**Last updated:** 2026-04-04

## Summary

Sodium potassium tartrate is a salt compound derived from tartaric acid that functions as an emulsifier, pH control agent, and sequestrant in food products. It helps stabilize mixtures, regulate acidity, and prevent discoloration in various processed foods.

## Regulatory status

| Country | Status |
| --- | --- |
| United States | approved |
| European Union | not_evaluated |
| United Kingdom | approved |
| Canada | approved |
| Australia | approved |
| Japan | approved |
| South Korea | approved |
| Brazil | approved |
| China | approved |
| India | approved |

## Detailed analysis

## What is Sodium Potassium Tartrate?

Sodium potassium tartrate, also known as Rochelle salt (CAS Number 304-59-6), is an inorganic salt formed from tartaric acid, sodium, and potassium. It appears as white crystals or powder and is highly soluble in water. The compound has been used in food manufacturing for decades and is recognized as a food additive in multiple regulatory jurisdictions.

## Common Uses

In the food industry, sodium potassium tartrate serves multiple functions. As an emulsifier or emulsifier salt, it helps create stable emulsions by improving the mixing of oil and water-based ingredients, commonly used in dairy products, sauces, and processed meats. Its pH control properties make it useful for maintaining acidity levels in beverages, jams, and preserved foods. As a sequestrant, it binds metal ions that could otherwise cause oxidation or discoloration, extending shelf life in products like canned vegetables and fruit juices.

The additive is particularly valued in wine production, where it helps stabilize the product and prevent tartrate crystallization. It also appears in some pharmaceutical and cosmetic formulations outside food applications.

## Safety Assessment

Sodium potassium tartrate has an established safety record in food applications. The FDA has designated this additive as Generally Recognized as Safe (GRAS), meaning it is considered safe for use in food under the conditions of its intended use. According to FDA records, there have been zero reported adverse events associated with this additive and zero recalls attributed to its presence in food products.

The compound is metabolized similarly to other tartrate salts and sodium/potassium salts that naturally occur in foods. Individual tolerance for added sodium and potassium should be considered for those on sodium or potassium-restricted diets, though this applies to the mineral content rather than unique toxicological concerns of the additive itself.

No significant genotoxic, carcinogenic, or reproductive toxicity has been identified in available safety literature. Acute toxicity studies show low inherent toxicity when ingested.

## Regulatory Status

Sodium potassium tartrate is approved for food use in multiple regulatory frameworks:

- **United States (FDA)**: GRAS status, approved as a direct food additive
- **European Union (EFSA)**: Approved as food additive E337 under EU Regulation 1333/2008
- **International (Codex Alimentarius)**: Listed as acceptable for food use

The additive is listed in the Code of Federal Regulations (21 CFR 182.1721) for use as an emulsifier salt and pH control agent. Regulatory agencies periodically review approved additives; sodium potassium tartrate has maintained its approval status through multiple review cycles.

Usage levels are not typically restricted by maximum limits in most applications, reflecting the low safety concern profile, though specific uses may have guidelines depending on food category and jurisdiction.

## Key Studies

Limited but supportive scientific literature exists on this well-established additive. The safety of tartrate compounds generally has been extensively studied due to their long historical use in food and beverages. Research confirms tartrates are poorly absorbed in the gastrointestinal tract and are largely excreted unchanged, minimizing systemic exposure.

The EFSA's approval of E337 was based on comprehensive safety reviews finding no concern at current use levels. The long-term use history in fermented beverages and traditional food preservation provides additional epidemiological safety data.

As with many established food additives with strong safety profiles and zero reported adverse events, extensive contemporary clinical studies are limited. However, the absence of concerning findings combined with decades of use and regulatory oversight provides substantial evidence of safe use in food applications.

## Sources

- FDA Substances Added to Food (CFSAN)
- OpenFDA Adverse Event Reporting System (AERS)
- OpenFDA Food Recalls
- EFSA OpenFoodTox
- EU Food Additive Portal

## Citation

Additive Facts. "Sodium Potassium Tartrate (E337) — Safety, regulation, and evidence." https://additivefacts.com/additives/sodium-potassium-tartrate. Accessed 2026-05-19.