What is E1517?

Complete guide to understanding E1517 (Glycerol Diacetate/Diacetin) in your food

The Quick Answer

E1517 is glycerol diacetate (also called diacetin or 1,2-glyceryl diacetate)—a synthetic ester created by partial acetylation of glycerol (two hydroxyl groups acetylated instead of three). It’s a colorless, oily liquid used in food as a plasticizer, humectant, flavor carrier/solvent, and stabilizer.

It’s used in food primarily to soften and stabilize products, retain moisture, carry and distribute flavorings, and improve texture—found in chewing gum, baked goods, candies, flavorings, and other processed foods requiring texture enhancement and moisture retention.

E1517 is FDA recognized as safe and approved in the EU for specific applications as a solvent/carrier for flavorings. It’s closely related to E1518 (triacetin—with three acetate groups), but E1517 has only two acetate groups, making it slightly less hydrophobic but more hygroscopic.

What Exactly Is It?

E1517 is glycerol diacetate (C₇H₁₂O₅), a synthetic ester created by partial acetylation of glycerol—attaching two acetate groups to glycerol’s three hydroxyl groups (leaving one hydroxyl intact). It’s a colorless, oily, viscous liquid with a faint odor.

Think of it as glycerol with two of its three “arms” wrapped in acetate coats. This partial modification creates a compound that’s less hydrophobic than triacetin (E1518—with three acetate groups) but more hydrophobic than pure glycerol, giving it a balanced solvent profile.

Key characteristic: The partial acetylation creates a compound with mixed properties: hygroscopic (water-absorbing) from the unacetylated hydroxyl group, while the acetate groups provide solvent properties for lipophilic compounds—making it useful for both moisture retention and flavor carrying.

Chemical composition:

• Molecular formula: C₇H₁₂O₅
• IUPAC name: 1,2,3-Propanetriol diacetate (exists as isomeric mixture)
• CAS Number: 25395-31-7
• Molecular weight: 176.17 g/mol
• Density: 1.17 g/cm³
• Melting point: −30°C (remains liquid at cold temperatures)
• Boiling point: 280°C (very high—useful for solvent applications)
• EC Number: 246-941-2

How it’s made:

E1517 is produced by partially acetylating glycerol with acetic acid or acetic anhydride:

• Basic process: Glycerol (C₃H₈O₃) + 2 Acetic acid (CH₃COOH) → Glycerol diacetate (C₇H₁₂O₅) + 2 Water (H₂O)
• Isomeric mixture: The reaction produces primarily 1,2-glyceryl diacetate and 1,3-glyceryl diacetate (regioisomers)
• Alternative method: Glycerol reacted with acetic anhydride (more efficient, commonly used)
• Glycerol source: Can be petroleum-derived or vegetable-derived (from biodiesel production or food processing)
• Control: Reaction carefully controlled to produce diacetate (not monoacetin or triacetin)

Natural components: Both building blocks (glycerol and acetic acid) occur naturally. However, the final diacetin is synthetically manufactured.

Where You’ll Find It

E1517 appears in a specialized range of food products:

• Chewing gum – plasticizer for softness and texture
• Baked goods and pastries – humectant, moisture retention, prevents staling
• Candy and confectionery – texture improvement, moisture retention, softening
• Chocolate products – texture softening, flavor carrier
• Flavorings and flavor compounds (as solvent/carrier)
• Beverages and soft drinks – flavor carrier
• Liqueurs and alcoholic beverages – flavor carrier and enhancer
• Cosmetics – humectant, solvent, plasticizer (widespread use)
• Pharmaceuticals – excipient in preparations
• Food packaging and contact materials
• Tobacco products – humectant for moisture retention

Regulatory use scope: EU Authorization—E1517 authorized as a solvent/carrier for other food additives (particularly flavorings). FDA—recognized as safe for food use (GRAS status for similar glycerol esters).

Primary food application: E1517 is most common in chewing gum and baked goods where it functions as plasticizer/humectant for texture softening and moisture retention.

Why Do Food Companies Use It?

E1517’s primary function is serving as a plasticizer and humectant with good solvent properties for flavorings.

Food manufacturers use diacetin for multiple strategic advantages:

• Plasticizer: Softens products; improves flexibility and texture
• Humectant: Absorbs and retains moisture; prevents drying out
• Flavor carrier/solvent: Dissolves and carries flavorings and fragrances; enables even distribution
• Shelf life extension: Moisture retention slows staling and degradation
• Texture improvement: Softens products; improves palatability
• Stabilizer: Maintains product consistency during storage
• Emulsifier: Improves mixing of incompatible ingredients
• Antifungal preservation: Fungistatic properties through release of acetic acid
• Processing aid: Enables incorporation of difficult-to-dissolve ingredients
• Cost efficiency: Effective at low concentrations
• Regulatory universality: Approved worldwide
• High boiling point: Remains stable during processing; doesn’t volatilize

Unique advantage: E1517 provides a balance between E1518 (triacetin—more plastic-like) and pure glycerin—offering moderate solvent properties with good humidity-retention, making it suitable for products requiring balanced properties.

Is It Safe?

E1517 is safe at approved food use levels and has been approved by regulatory authorities.

Regulatory approval:

• FDA status: Recognized as safe (similar glycerol esters have GRAS status)
• EU authorized: Approved as food additive E1517 for use as solvent/carrier
• JECFA recognized: Recognized as safe food additive
• International approval: Approved by regulatory bodies worldwide

Safety profile:

• No acute toxicity: No documented toxicity at food use levels
• No chronic toxicity: Long-term exposure at approved levels shows no harm
• No adverse effects: No documented adverse health effects in any population
• No carcinogenicity: No evidence of cancer-causing potential
• No reproductive/developmental effects: Safe for pregnancy and breastfeeding
• No genotoxicity: No evidence of genetic damage
• Metabolism: Metabolized to glycerol and acetic acid (both normal dietary components)
• No bioaccumulation: Does not accumulate in tissues
• Long history of safe use: Decades of food, cosmetic, and pharmaceutical use
• Pharmaceutical use: Approved as pharmaceutical excipient
• Cosmetic use: Decades of established use in cosmetics
• Similar to E1518: Similar safety profile to triacetin (E1518) but with slightly different properties

Acceptable Daily Intake: Some sources reference ADI of up to 20 mg/kg body weight (similar to related compounds), though specific modern ADI assessments may vary.

E1517 vs E1518: Key Differences

Selection criteria: E1517 chosen when balanced solvent/humectant properties needed. E1518 chosen when stronger plasticizing effect required (particularly chewing gum). E1517 potentially preferred for baked goods (more moisture-retention). E1518 iconic in chewing gum.

Natural vs Synthetic Version

E1517 is synthetically produced but derived from natural-origin components:

Source and production:

• Glycerol source: Petroleum-derived or vegetable-derived (biodiesel byproduct, food processing)
• Acetic acid source: Petroleum-derived or fermentation-derived (vinegar fermentation)
• Synthesis: Chemical acetylation of glycerol
• Final product: Chemically identical regardless of source

Vegetarian/vegan/dietary status:

• Vegan: Yes—no animal products in chemical synthesis
• Vegetarian: Yes
• Kosher: Yes
• Halal: Yes
• Gluten-free: Yes
• Dairy-free: Yes

Natural Alternatives

Want to avoid E1517 or looking for alternative humectants and plasticizers?

Some alternatives include:

• Glycerin (E422) – Natural humectant; less effective as plasticizer
• E1518 (Glycerol Triacetate) – Stronger plasticizer; more hydrophobic
• Propylene glycol (E1520) – Synthetic humectant and solvent
• Sorbitol (E420) – Sugar alcohol; humectant; sweetener
• Honey – Natural humectant
• Vegetable oils – For flavor carriers
• Simply accept texture changes – Products will dry out or harden faster

The Bottom Line

E1517 (glycerol diacetate/diacetin) is a synthetic ester with two acetate groups used primarily as a plasticizer and humectant with solvent properties for flavorings—found in chewing gum, baked goods, candies, and other processed foods.

It’s approved by regulatory bodies worldwide as a safe food additive.

Key advantages: E1517 is safe at food use levels. EU authorization indicates regulatory confidence. No documented adverse effects. Metabolized to glycerol and acetic acid (normal diet components). Decades of use in cosmetics and pharmaceuticals confirm safety. Provides balanced solvent/humectant properties.

For consumers: E1517 is safe when encountered in food products. While synthetic, it’s approved by major regulatory authorities. If preferring natural alternatives, glycerin (E422) offers humectant properties, though with less plasticizing effect.

Comparison to E1518: E1517 (two acetate groups) provides more moisture-retention than E1518 (three acetate groups), but E1518 provides stronger plasticizing effect. E1517 better for products requiring balanced properties; E1518 iconic in chewing gum.

Historical perspective: E1517 has decades of established use in cosmetics and food applications without safety concerns, demonstrating reliable safety profile.