For purchasing managers, quality assurance teams, and formulation scientists who need more than a product brochure: this guide covers the technical foundation of the Span series — from chemical synthesis and batch-level quality control to regulatory compliance and industrial safety protocols.
For help selecting the right Span for your specific application (which product for bakery, cosmetics, agrochemicals, etc.), see our Selection & Applications Guide.
1. Technical Specifications
Sorbitan Esters are non-ionic surfactants formed by the esterification of sorbitol (and its anhydrides) with fatty acids. They are lipophilic, making them excellent water-in-oil (W/O) emulsifiers. When ethoxylated, they become Polysorbates (Tweens) — the hydrophilic counterparts used in Span-Tween blends.
| Product | CAS Number | E-Number | Fatty Acid | HLB | Physical Form (25°C) | Saponification Value (mg KOH/g) | Acid Value (mg KOH/g, max) |
|---|---|---|---|---|---|---|---|
| Span 20 | 1338-39-2 | E493 | Lauric (C12) | 8.6 | Amber Oily Liquid | 155–170 | 7 |
| Span 40 | 26266-57-9 | E495 | Palmitic (C16) | 6.7 | Cream Paste | 140–155 | 7 |
| Span 60 | 1338-41-6 | E491 | Stearic (C18) | 4.7 | Tan Beads/Flakes | 147–157 | 7 |
| Span 65 | 26266-58-0 | E492 | Stearic (C18×3) | 2.1 | Tan Beads/Flakes | 176–188 | 7 |
| Span 80 | 1338-43-8 | E494 | Oleic (C18:1) | 4.3 | Amber Viscous Liquid | 145–160 | 7 |
| Span 85 | 26266-58-0 | — | Oleic (C18:1×3) | 1.8 | Amber Oily Liquid | 165–185 | 15 |
For sourcing: Sorbitan Monopalmitate (Span 40) and Sorbitan Trioleate (Span 85) extend the Span range at the higher-HLB and ultra-low-HLB extremes respectively.
2. The Manufacturing Process & Quality Control
High-purity Sorbitan Esters — required for sensitive applications like pharmaceuticals and food — depend on precise process control at every stage.
Step 1: Raw Material Selection
- Sorbitol: Derived from corn or wheat starch; pharmaceutical-grade sorbitol preferred for injectable-grade esters.
- Fatty Acids: Vegetable-sourced (coconut, palm, or olive oil fractions). Kosher and Halal certification must be verified at the raw material stage, not just on the finished product.
Step 2: Synthesis Reaction
Two mechanisms occur simultaneously:
- Dehydration: Sorbitol is dehydrated to form sorbitan (a cyclic ether). Temperature and vacuum control at this stage determine the ratio of mono-, di-, and tri-esters in the final product.
- Esterification: Sorbitan reacts with the fatty acid at 180°C – 250°C under vacuum. Catalysts accelerate the reaction; continuous removal of water by-product drives equilibrium toward ester formation.
Step 3: Refining and Purification
The crude ester exits the reactor with trace impurities. Food and cosmetic grades require:
- Decolorization: Activated carbon treatment to achieve the expected pale yellow to amber color.
- Deodorization: Steam stripping to remove volatile odor components.
- Filtration: Removal of catalyst residues to meet food-grade clarity standards.
Quality Control Parameters
Every batch at FoodEmul is tested against these three critical values:
- Acid Value (AV): Measures residual free fatty acids. Low AV = reaction went near completion. High AV indicates incomplete esterification or product degradation.
- Saponification Value (SV): Verifies average molecular weight and total ester content. A batch falling outside the SV range suggests wrong fatty acid ratio or contamination.
- Hydroxyl Value (HV): Confirms the ratio of unreacted hydroxyl groups. Critical for HLB consistency — if HV drifts, the emulsifying behavior of that batch will be different from the standard.
3. Reading a Certificate of Analysis (COA)
When you receive a batch, cross-check these values against the specification table in Section 1:
| Parameter | What It Tells You | Red Flag |
|---|---|---|
| Acid Value | Reaction completeness; product freshness | AV above spec = degraded or poorly synthesized material |
| Saponification Value | Correct fatty acid type and ratio | SV out of range = wrong fatty acid or ester distribution |
| Hydroxyl Value | HLB consistency batch-to-batch | HV drift >5% = emulsifying performance will differ from previous orders |
| Color (Gardner) | Purity; oxidation state | Darker than spec = oxidation or insufficient decolorization |
| Moisture (% Karl Fischer) | Residual water | >0.5% = risk of hydrolysis during storage |
Always request a COA with each shipment. A supplier that cannot provide batch-level COA data cannot guarantee batch-to-batch consistency.
4. Regulatory Compliance: E491–E495 Across Markets
Sorbitan Esters are approved as food additives globally, but permitted usage levels and categories vary by jurisdiction.
| Ester | EU (EC 1333/2008) | FDA (21 CFR) | GB (China GB 2760) | JECFA ADI (mg/kg bw) |
|---|---|---|---|---|
| Span 20 (E493) | 0.5–10 g/kg (varies by food category) | GRAS, 21 CFR 172.842 | Permitted, category-dependent | 0–25 |
| Span 40 (E495) | Permitted in specific categories | GRAS, 21 CFR 172.842 | Permitted, category-dependent | 0–25 |
| Span 60 (E491) | Permitted in baked goods, desserts, etc. | GRAS, 21 CFR 172.842 | Permitted in multiple categories | 0–25 |
| Span 65 (E492) | Permitted in specific categories | GRAS, 21 CFR 172.842 | Permitted, category-dependent | 0–25 |
| Span 80 (E494) | Permitted in baked goods, emulsions | GRAS, 21 CFR 172.842 | Permitted in multiple categories | 0–25 |
Always check your target market’s latest food additive regulations for category-specific maximum use levels. The values above are general ADI ranges; specific food categories have individual limits.
5. Safety Data Sheets (SDS) & Handling Protocols
While Sorbitan Esters are Generally Recognized as Safe (GRAS) and low-toxicity, industrial handling requires defined protocols.
Hazard Identification (GHS Classification)
Most Span grades are not classified as hazardous substances. However:
- Concentrated contact: May cause mild, transient eye or skin irritation upon prolonged exposure.
- Inhalation: Mists or dusts (particularly from solid beads like Span 60/65) may cause respiratory tract irritation.
- Thermal decomposition: Heating above 250°C may release irritating fumes; ensure ventilation if processing at elevated temperatures.
Personal Protective Equipment (PPE)
- Chemical-resistant gloves (nitrile or neoprene)
- Safety goggles
- For Span 60/65 bead handling: dust mask if ventilation is inadequate
Storage & Stability
- Store in a cool, dry, well-ventilated area.
- Keep containers tightly closed when not in use — moisture absorption degrades product.
- Span 80/85 (Oleates): Unsaturated fatty acid chain is susceptible to oxidation. Store under nitrogen blanket if possible; avoid exposure to air and direct light. Shelf life: 24 months from manufacture date when stored correctly.
Emergency Response (First Aid)
- Eye Contact: Flush with water for at least 15 minutes. Remove contact lenses if present.
- Skin Contact: Wash with soap and water.
- Ingestion: Rinse mouth. Do not induce vomiting unless directed by medical personnel.
Conclusion
Technical performance starts with manufacturing rigor. From raw material certification through batch-level QC testing, every step determines whether a Span 60 bead or Span 80 liquid performs identically from order to order.
At FoodEmul.com, we provide:
– Full batch-level COA with every shipment (AV, SV, HV, color, moisture)
– Kosher and Halal certification documentation
– Technical data sheets (TDS) and safety data sheets (SDS) on request
– Regulatory support for EU, FDA, and GB compliance
Contact us to request TDS, SDS, COA samples, or to discuss your specific quality requirements.
