Every formulator has sat in front of a bench-top emulsion that looked perfect yesterday — and separated overnight. The fix, more often than not, comes down to the Span-polysorbate ratio. These two surfactant families are two halves of one system: Span grabs the oil, polysorbate grabs the water. Blend them right and your emulsion survives heat cycling, freeze-thaw, and months of shelf life. At FoodEmul, we work with these pairings every day — and the system is simpler than the HLB tables suggest.
Below is the chemistry that connects Span and polysorbate, the math for picking ratios, and the pairings that ship in real formulations. For individual product specs, jump to the linked guides on Span 60, PS80, and their application limits.
At a Glance: Span vs. polysorbate
Span and Polysorbate surfactants belong to the non-ionic class. Our introduction to non-ionic surfactants explains the charge chemistry, HLB system, and why non-ionics dominate food and cosmetic formulations.
| Span Series | polysorbate Series | |
|---|---|---|
| Chemical Class | Sorbitan esters | Polyoxyethylene sorbitan esters (ethoxylated Spans) |
| HLB Range | 1.8–8.6 (lipophilic) | 10.0–16.7 (hydrophilic) |
| Water Solubility | Insoluble to dispersible | Soluble to highly soluble |
| Physical Form | Solid flakes, beads, or waxy paste | Viscous liquids or soft paste |
| Primary Use | W/O emulsions, co-emulsifiers, crystal modifiers | O/W emulsions, solubilizers, wetting agents |
| Paired Together | Span + polysorbate blends produce more stable emulsions than either alone | |
Fundamental Chemistry: From Sorbitol to Surfactant
Both Span and polysorbate start from the same molecule: sorbitol, a sugar alcohol. The synthesis pathway is where they split — and that split is what gives you the full range from oil-loving to water-loving surfactants.
Sorbitan Esters (Span Series)
Sorbitol is dehydrated into sorbitan (a cyclic ether), then esterified with a fatty acid — lauric, palmitic, stearic, or oleic. The fatty acid chain dominates the molecule’s polarity, which is why Spans are lipophilic: they dissolve in oil, not water. The sorbitan core acts as a small polar head that anchors at the oil-water interface, while the fatty acid tail extends deep into the oil phase.
Key Span products: Span 20 (C12 lauric), Span 40 (C16 palmitic), Span 60 (C18 stearic), Span 65 — Sorbitan Tristearate (Span 65/E492) product details and pricing (C18 tri-stearic), Span 80 (C18:1 oleic), Span 85 (C18:1 tri-oleic). For specifications, see our Span 60 product page.
Polysorbates (polysorbate Series)
Take a Span molecule, treat it with ethylene oxide, and long polyoxyethylene chains (~20 EO units each) attach to the free hydroxyl groups on the sorbitan ring. These chains shift the balance dramatically toward water — the polyoxyethylene portion stretches into the water phase while the original fatty acid tail stays in the oil. The result is a surfactant that’s mostly water-soluble but still has enough lipophilic character to hold the interface.
Key polysorbate products: polysorbate 20 (C12 lauric), polysorbate 40 (C16 palmitic), polysorbate 60 (C18 stearic), PS65 (C18 tri-stearic), PS80 (C18:1 oleic). For specifications, see our PS80 product page.
The HLB System: How to Pick the Right Emulsifier
HLB (Hydrophilic-Lipophilic Balance) runs from 0 to 20. Zero means completely oil-soluble. Twenty means completely water-soluble. The number does two things: it tells you which phase the emulsifier prefers, and it predicts what kind of emulsion you’ll get.
| HLB Range | Emulsifier Behavior | Application |
|---|---|---|
| 1–3 | Anti-foaming | Defoamers in processing |
| 3–6 | W/O emulsifier | Margarine, butter, fat-based fillings |
| 7–9 | Wetting agent | Wetting powders, dispersing in water |
| 8–13 | O/W emulsifier | Most food emulsions — beverages, creams, sauces |
| 13–15 | Detergent / solubilizer | Flavor emulsions, clear beverages |
| 15–18 | Solubilizer | Highly water-soluble; microemulsions |
HLB Blending: The Math
You almost never use a single emulsifier. Blends are more stable. The blended HLB is a weighted average:
HLB(blend) = (HLB₁ × weight₁ + HLB₂ × weight₂) / (weight₁ + weight₂)
Example: 3 parts Span 60 (HLB 4.7) + 2 parts polysorbate 60 (HLB 14.9) = (4.7×3 + 14.9×2) / 5 = HLB 8.8 — ideal for an O/W cream or cake batter.
Complete Span and polysorbate Product Reference
| Product | E-Number | Fatty Acid | HLB | Form at 25°C | Best Application |
|---|---|---|---|---|---|
| Span 20 | E493 | Lauric (C12:0) | 8.6 | Liquid | Flavor emulsions, solubilization |
| Span 40 | E495 | Palmitic (C16:0) | 6.7 | Waxy solid | Cake emulsifiers, creams |
| Span 60 | E491 | Stearic (C18:0) | 4.7 | Powder/wax | Margarine, chocolate, fillings |
| Span 65 | E492 | Stearic ×3 | 2.1 | Waxy solid | W/O systems, crystal control |
| Span 80 | E494 | Oleic (C18:1) | 4.3 | Liquid | Soft margarine, fluid emulsions |
| Span 85 | — | Oleic ×3 | 1.8 | Liquid | W/O emulsions, industrial |
| polysorbate 20 | E432 | Lauric (C12:0) | 16.7 | Liquid | Solubilization, beverages |
| polysorbate 40 | E434 | Palmitic (C16:0) | 15.6 | Liquid | O/W emulsions |
| polysorbate 60 | E435 | Stearic (C18:0) | 14.9 | Paste | Dairy, bakery, whipped toppings |
| PS65 | E436 | Stearic ×3 | 10.5 | Waxy solid | Frozen desserts |
| PS80 | E433 | Oleic (C18:1) | 15.0 | Liquid | Beverages, flavor emulsions |
Practical Blending Strategy
- Determine your target HLB. What type of emulsion? W/O (HLB 3–6) or O/W (HLB 8–16)? Match the target to your oil phase.
- Pick your Span. Match the fatty acid chain to your fat system. Stearic (C18:0) for palm/dairy. Oleic (C18:1) for liquid oils.
- Pick your polysorbate with the same fatty acid. Span 60 + polysorbate 60 (both C18:0 stearic). Span 80 + PS80 (both C18:1 oleic). Matching chains = tighter interfacial packing = better stability.
- Calculate the blend ratio. Use the weighted average formula. Start at the calculated ratio, then adjust ±10% based on actual emulsion stability testing.
- Total dosage: 0.1–0.5% for most food emulsions. Higher fat = higher emulsifier. Higher water = higher emulsifier in W/O systems.
Common Span/polysorbate Pairings by Application
| Application | Span | polysorbate | Ratio | Combined HLB | Purpose |
|---|---|---|---|---|---|
| Margarine (block) | Span 60 | polysorbate 60 | 3:1 to Span alone | 4.7–7.3 | W/O stability, firmness |
| Ice cream | Span 60 | PS80 | 1:2 to 1:3 | 11–12 | Fat destabilization, melt resistance |
| Cake gel | Span 60 | polysorbate 60 | 1:2 to 1:3 | 11–12 | Foam generation + stability |
| Coffee creamer | Span 60 | polysorbate 60 | 1:1 (in GMS blend) | ~10 | Thermal shock resistance |
| Beverage cloud | Span 60 | polysorbate 60 | 1:3 to 1:4 | 12–13 | Sub-micron emulsion, opacity |
| Flavor emulsion | Span 80 | PS80 | 1:4 | ~13 | Cold-process, flavor oil dispersion |
Key Takeaways
- Span = oil side. polysorbate = water side. Blend them together for emulsions more stable than either alone.
- Match fatty acid chains: Span 60 + polysorbate 60 (both stearic C18:0). Span 80 + PS80 (both oleic C18:1). Matched chains = tighter interfacial packing.
- Calculate blended HLB: HLB(blend) = weighted average of components. Target HLB 3–6 for W/O, HLB 8–16 for O/W.
- Start at 0.1–0.5% total emulsifier. Adjust ratio ±10% based on stability testing, not the calculator.
- For product-specific application guides: Span 60 Limits, polysorbate 60 Limits, PS80 Specs.
Need help with your Span-polysorbate ratio? We ship Span 60, PS80, and the full range worldwide. Contact us for technical support or to request a sample.
