What is E571?

Complete guide to understanding E571 (Ammonium Stearate) in your food

The Quick Answer

E571 is ammonium stearate, the ammonium salt of stearic acid (a long-chain saturated fatty acid).

It’s used in food primarily as an anti-caking agent and anti-foaming agent, particularly in sugar production and powder manufacturing—preventing clumping and foam formation.

E571 is relatively uncommon in foods consumed directly by the public, appearing mainly in industrial food processing, with more common use in cosmetics and pharmaceuticals.

What Exactly Is It?

E571 is the ammonium salt of stearic acid.

Stearic acid is a long-chain saturated fatty acid (18-carbon chain) naturally found in animal and plant fats. When stearic acid reacts with ammonia (NH₃) or ammonium compounds, it creates ammonium stearate—a compound that combines the hydrophobic (water-repelling) properties of the fatty acid with the properties of ammonia.

This compound is fundamentally different from the food itself—it’s a processing aid rather than a food ingredient in its own right.

Chemical formula: (C₁₇H₃₅COO⁻)₂NH₄⁺ or C₃₆H₇₁NO₂

Molecular weight: Approximately 565 g/mol

How it’s made:

Ammonium stearate is produced by reacting stearic acid with ammonia or ammonium compounds:

• Step 1: Pure stearic acid is obtained by hydrogenation and separation of animal or plant fats
• Step 2: Stearic acid reacts with ammonia (gaseous or aqueous solution) or ammonium salts
• Step 3: The resulting ammonium stearate is crystallized and dried

Stearic acid sources:

• Animal sources: Beef tallow, lard (making E571 non-vegetarian/vegan)
• Plant sources: Palm oil, soybean oil, rapeseed oil (making E571 vegetarian/vegan)
• Hydrogenated vegetable oils: Can be used to create plant-based stearic acid

Where You’ll Find It

E571 appears in very limited food products:

• Processed and powdered sugar
• Powdered sugar products (icing sugar)
• Sugar-based powders and mixes
• Food powders where anti-caking is essential
• Powdered food ingredients and additives
• Industrial food processing (not consumer-facing)

Primary non-food uses:

E571 is much more commonly used in:

• Cosmetics (lubricant, anti-caking agent)
• Pharmaceuticals and tablet manufacturing
• Textile industry
• Rubber and plastic manufacturing
• Paint and coating production
• Metalworking fluids
• Industrial lubricants

E571 is one of the least common food additives in products consumers directly purchase. Most people are more familiar with E572 (magnesium stearate), which is more widely used in food, pharmaceuticals, and cosmetics.

Why Do Food Companies Use It?

E571’s primary function is preventing caking and foam formation in powdered products.

Food manufacturers use ammonium stearate for specific advantages:

• Anti-caking: Prevents clumping in powdered sugar, powders, and granulated foods
• Anti-foaming: Reduces foam formation during sugar processing and food manufacturing
• Moisture absorption: Absorbs moisture while remaining hydrophobic, keeping powders dry and free-flowing
• Lubrication: Provides lubrication in powder processing equipment
• Flow improvement: Improves flowability of powdered products
• Dust reduction: Reduces dust generation when handling powders
• Low addition levels: Effective at very small concentrations (typically <0.1%)
• Cost efficiency: Inexpensive additive for industrial processing
• Long shelf life: Prevents degradation and caking in stored powders

Sugar processing advantage: E571 is particularly valuable in sugar refining and processing, where anti-caking and anti-foaming properties are critical for maintaining product quality and processing efficiency during crystallization and drying.

Is It Safe?

E571 is approved by major regulatory authorities and is considered safe.

Approval status:

• FDA approved: Approved as a food additive; GRAS status (Generally Recognized As Safe)
• EFSA approved: Listed as authorized food additive in European Union
• JECFA approved: Approved by Joint FAO/WHO Expert Committee on Food Additives
• Use categories: Classified in “Group I” with “quantum satis” principle (no specific limits)

Safety profile:

• No ADI set: No specific Acceptable Daily Intake determined (indicates safety confidence)
• Toxicity: No documented toxicity at food use levels
• No carcinogenicity: No evidence of cancer-causing potential
• No reproductive effects: Safe for pregnancy and breastfeeding
• Low absorption: Poorly absorbed in the digestive tract; passes through largely unchanged
• Minimal dietary intake: Food use is minimal; most E571 exposure is from pharmaceuticals and cosmetics
• No documented adverse effects: No widespread adverse effects documented
• Insoluble in water: Does not dissolve in the gastrointestinal tract, limiting absorption
• Long history of safe use: Used safely for decades in industrial food processing

Important distinction: Because E571 is used primarily in sugar processing and industrial food manufacturing, individual consumer exposure is much lower than for more commonly used additives. Most people consume minimal amounts of E571 through food.

Natural vs Synthetic Version

E571 is derived from natural stearic acid but involves processing:

Source and production:

• Stearic acid source: From animal fats (beef tallow, lard) or plant oils (palm, soybean, rapeseed)
• Ammonia bonding: Chemical reaction between stearic acid and ammonia
• Final product: Chemically identical regardless of source

Perceived “naturalness”: E571 is derived from natural fats and oils, but it’s a processed compound created through chemical reaction—regulatory classification is “food additive” rather than “natural.”

Vegetarian/vegan status: Depends entirely on stearic acid source:
• Animal-derived stearic acid = NOT vegetarian/vegan
• Plant-derived stearic acid = Vegetarian/vegan

Natural Alternatives

Want to avoid E571 or looking for alternative anti-caking agents?

Some alternatives include:

• E572 (Magnesium stearate) – Similar function; more commonly used
• E573 (Aluminium stearate) – Similar stearate-based anti-caking agent
• E551 (Silicon dioxide) – Mineral anti-caking agent; very commonly used
• E552 (Calcium silicate) – Alternative mineral anti-caking agent
• E553a (Magnesium silicate) – Mineral alternative
• E553b (Talc) – Natural mineral anti-caking agent
• E559 (Kaolin) – Natural clay anti-caking agent
• Natural starch or cellulose – Plant-based alternatives
• Accept caking: Store powders properly in dry conditions; accept slight clumping

Comparison to Related Stearates

E571 differs from other stearate-based additives:

• E570 (Stearic acid): The parent compound; fatty acid without ammonium bonding
• E572 (Magnesium stearate): Magnesium salt of stearic acid; much more commonly used
• E573 (Aluminium stearate): Aluminum salt of stearic acid; less common than E572
• E575 (Glucono delta-lactone): Completely different compound; acidity regulator
• E576-E579: Gluconate salts; acidity regulators, not anti-caking agents

The Bottom Line

E571 (ammonium stearate) is a safe anti-caking and anti-foaming agent used primarily in industrial sugar processing and powdered food production.

It rarely appears on consumer food labels, as most of its use is in industrial food processing. It’s much more commonly encountered in pharmaceuticals, cosmetics, and other industrial applications.

E571 is approved by the FDA, EFSA, and JECFA with no specific safety concerns.

Key characteristics: E571 is water-insoluble and poorly absorbed, meaning dietary exposure is minimal. It’s effective at very low concentrations and is cost-effective for industrial processing.

Primary consideration for consumers: If you have vegetarian or vegan dietary restrictions, verify that any E571 in products comes from plant-derived stearic acid rather than animal tallow. However, E571 is so rarely used in consumer foods that this is unlikely to be a concern for most people.

E571 is significantly less common than E572 (magnesium stearate) and deserves less consumer attention for most dietary choices. Its primary role is in industrial food manufacturing rather than in consumer-facing food products.