What is E502?
Complete guide to understanding ammonium carbonates in your food
The Quick Answer
E502 is ammonium carbonates—a mixture of ammonium carbonate and ammonium bicarbonate—used primarily as a leavening agent (raising agent) and acidity regulator in baked goods.
When heated or exposed to moisture, it rapidly decomposes into ammonia, carbon dioxide, and water, which creates the bubbles that make cookies, crackers, and flat breads light and fluffy.
It’s one of the oldest leavening agents, traditionally called “salt of hartshorn,” and was used for centuries before modern baking powder was invented.
📌 Quick Facts
- Category: Leavening Agent & Acidity Regulator
- Found in: Cookies, crackers, biscuits, flat breads, pastries
- Safety: FDA-approved, EFSA-approved at food use levels
- Approved by: FDA, EFSA, JECFA
- Key Fact: Thermally unstable; decomposes when heated to produce leavening gas
What Exactly Is E502?
E502 is ammonium carbonates, which includes two related compounds: ammonium carbonate (i) and ammonium bicarbonate (ii).
Ammonium carbonate (i) is technically a mixture of ammonium carbamate, ammonium bicarbonate, and ammonium carbonate. Ammonium bicarbonate (ii) is the pure chemical form NH₄HCO₃. Both are white crystalline powders with a slight ammoniacal odor.
The defining characteristic of ammonium carbonates is their thermal instability. When heated or exposed to moisture, they rapidly decompose into three gases: ammonia (NH₃), carbon dioxide (CO₂), and water (H₂O). This decomposition is the key to their function as leavening agents.
In technical terms, E502 functions as both an acidity regulator and a raising agent. It’s part of a broader family of carbonate additives that includes E500 (sodium carbonates), E501 (potassium carbonates), and E504 (magnesium carbonates), all serving similar functions.
Where You’ll Find E502
E502 appears primarily in flat baked goods requiring leavening:
– Cookies and biscuits
– Crackers
– Flat breads
– Pastries and cakes
– Confectionery products
– Powdered drink mixes
– Cough syrups (pharmaceutical use)
– Cacao and chocolate products (as acidity regulator)
If you eat cookies, crackers, or biscuits, you’ve likely consumed E502. It’s particularly common in European and Scandinavian baking traditions.
💡 Pro Tip: Look for “Ammonium carbonate,” “Ammonium bicarbonate,” “Ammonium carbonates,” “Salt of hartshorn,” or “E502” on ingredient lists. It’s especially common in cookies and crackers where its leavening properties are essential.
How E502 Works in Food
E502’s function as a leavening agent depends entirely on its thermal instability.
As a leavening agent: When E502 is added to cookie or cracker dough and exposed to heat in the oven, the compound rapidly decomposes. This decomposition produces carbon dioxide gas, which creates thousands of tiny bubbles throughout the dough. These bubbles expand with heat, causing the product to rise and become light and fluffy instead of dense and compact.
Decomposition reaction: NH₄HCO₃ → NH₃ + CO₂ + H₂O. The carbon dioxide is the key—it’s the gas that leavens the product.
As an acidity regulator: E502 is alkaline, so it neutralizes acids in food systems and helps regulate pH. In some applications like cacao products, this pH regulation is the primary function.
Key advantage: Unlike modern baking powder (which requires an acidic component to react), E502 works solely through thermal decomposition. A single compound produces all the leavening needed.
Why Do Food Companies Use E502?
E502 is an effective, economical, and time-tested leavening agent.
For flat baked goods like cookies and crackers, E502 has been the preferred choice for centuries. It requires no acidic component to activate (unlike baking powder), making formulation simpler. It’s inexpensive and produces consistent results. Most importantly, it’s been proven safe through more than 200 years of use.
Many traditional European and Scandinavian baking recipes specifically call for ammonium carbonate because bakers understand its properties and the results it produces.
Is It Safe?
Regulatory authorities approve E502 as safe for food use at approved levels.
The FDA approved ammonium carbonates as food additives, specifically noting: “The substance is approved as a food additive by the Food and Drug Administration (FDA) and as an inert pesticide ingredient by EPA, no toxic endpoints have been identified.”
The EFSA has authorized E502 as a food additive under Regulation (EC) No 1333/2008. Food-grade ammonium carbonates are safe at approved use levels in food.
✓ Safety Confirmed: FDA and EFSA both approve E502 as safe for food use. No toxic endpoints have been identified at approved food-use levels. The compound has been used safely in food for over 200 years.
Safety Profile and Hazard Classification
While E502 is safe at food-use levels, the pure chemical has hazard classifications for industrial/handling purposes.
For industrial handling and storage, ammonium carbonates are classified as:
– Acute Toxicity (oral), Category 4 – Harmful if swallowed in large amounts
– Eye Irritation – Can cause eye irritation if direct contact occurs
– Aquatic Hazard – Harmful to aquatic life at high concentrations
Important context: These classifications apply to handling the pure chemical in industrial settings, not to the trace amounts used in food products. At food-use levels, no adverse health effects have been documented.
Toxicity Data
Animal toxicity studies show low acute toxicity for ammonium carbonates:
– Oral LD50 in rats: >1,800 – <2,150 mg/kg (ammonium carbonate)
– Dermal LD50 in rats: >2,000 mg/kg
– Inhalation LC50 in rats: 6.6-4.74 mg/l
– Assessment: Moderate toxicity only after single ingestion of large quantities; low acute toxicity overall
At food-use levels (trace amounts in baked goods), exposure is far below these levels of concern.
Thermal Decomposition and Ammonia Release
When E502 is used as intended in baking, decomposition is complete, and ammonia is substantially eliminated.
E502 decomposes at temperatures starting around 60°C. Since baking typically occurs at 160-220°C, complete decomposition happens during the baking process. Most ammonia gas is released into the oven environment or escapes during the normal baking process.
Finished baked goods contain only trace residual ammonia, not meaningful amounts. This is why freshly baked goods made with E502 may have a slight ammoniacal aroma that dissipates as the product cools.
Potential Side Effects
At approved food use levels, no adverse health effects are documented.
Consuming finished baked goods made with E502 poses no health risk. The compound has been used safely in food for over 200 years, and no toxic endpoints have been identified by regulatory agencies.
At excessive ingestion of the pure chemical (not typical in food), E502 might cause gastrointestinal irritation due to its alkaline nature. Inhalation of dust might cause respiratory irritation.
Historical Background and Traditional Use
E502 (ammonium carbonates) has an exceptionally long history of safe use in food.
Historical name: “Salt of hartshorn” (sal volatile) was produced commercially beginning in the 1700s and 1800s. It was obtained by the dry distillation of nitrogenous organic matter such as hair, horn, and leather.
Traditional use: Before modern baking powder was invented, ammonium carbonates were the primary leavening agent in home and commercial baking. Many Scandinavian and Northern European baking cookbooks still refer to it as “hartshorn” or “hornsalt.”
Widespread historical use: Centuries of use across multiple cultures and populations provide extensive real-world safety evidence.
Manufacturing Process
E502 is manufactured through a simple, well-established chemical process.
Production method: Carbon dioxide gas is passed into aqueous (water-based) ammonia. The chemical reaction CO₂ + NH₃ + H₂O → (NH₄)HCO₃ produces ammonium bicarbonate.
Key conditions: The reaction solution must be kept cool (around 30°C or below) to promote crystallization of the solid product.
Separation and drying: The white crystalline solid is filtered, washed, and dried to produce the final food-grade product.
Global production: Approximately 100,000 tons of ammonium bicarbonate are produced annually worldwide through this process.
Storage and Handling
E502 is thermally and moisture-unstable, requiring specific storage conditions:
– Temperature: Store in cool locations; decomposition accelerates if heated
– Pressure hazard: If heated in sealed drums, internal pressure can build and cause rupture
– Moisture protection: Must be kept away from moisture; compound decomposes readily with water exposure
– Packaging: Appropriate multi-layer kraft paper or plastic film packaging required to maintain integrity
– Segregation: Store away from nitrites and alkaline substances
Vegan and Dietary Status
E502 is suitable for all dietary preferences:
– Vegan ✓ (fully synthetic chemical, no animal products)
– Vegetarian ✓
– Gluten-free ✓
– Kosher ✓
– Halal ✓
E502 is a fully synthetic chemical compound produced from ammonia and carbon dioxide, with no animal-derived components.
Comparison with Related Additives
E502 is part of a broader family of carbonate leavening and acidity-regulating agents:
– E500: Sodium carbonates (sodium carbonate, sodium bicarbonate)
– E501: Potassium carbonates (potassium carbonate, potassium bicarbonate)
– E502: Ammonium carbonates (ammonium carbonate, ammonium bicarbonate) ← This product
– E504: Magnesium carbonates
All function similarly as acidity regulators and leavening agents, but E502’s ammonia-releasing property makes it particularly effective for flat baked goods.
Regulatory Approval Across Regions
E502 approval is nearly universal:
– United States (FDA): Approved as food additive
– European Union (EFSA): Authorized per Regulation (EC) No 1333/2008
– International (JECFA): FAO/WHO approved
– Australia/New Zealand: Approved
This universal approval reflects confidence in its safety across different regulatory systems.
Environmental Considerations
E502 is environmentally benign at typical use concentrations:
– Biodegradability: Compound decomposes readily into ammonia and carbon dioxide, both naturally occurring substances
– Aquatic hazard: Only harmful to aquatic life at much higher concentrations than food-use levels
– Soil mobility: Does not adsorb to soil; unlikely to persist in environment
– Bioaccumulation: No bioaccumulation expected
The Bottom Line
E502 (ammonium carbonates) is a traditional, effective, and safe leavening agent used primarily in cookies, crackers, and flat breads.
It works through thermal decomposition, releasing carbon dioxide gas that creates the light, fluffy texture characteristic of these products.
Regulatory authorities (FDA, EFSA, JECFA) approve E502 as safe for food use. No toxic endpoints have been identified at food-use levels.
E502 has been used safely in food for over 200 years—longer than almost any other modern food additive—providing extensive real-world safety evidence.
At approved food-use levels, no adverse health effects are documented.
E502 is fully synthetic but derived from abundant, naturally occurring substances (ammonia and carbon dioxide), making it economical and environmentally benign.
It’s suitable for all dietary preferences (vegan, vegetarian, gluten-free, kosher, halal) as it’s purely chemical with no animal-derived components.
Most people eating cookies, crackers, or flat breads consume E502 regularly without any documented health concerns.
As always, food labels must declare E502 when used, enabling informed consumer choice.