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Colloids & emulsions Published physics Educational models Planned capability

An emulsion lasts only while its droplets do not rise, cluster, merge or ripen; small droplets alone prevent none of these

How nanoemulsions differ from microemulsions, the five ways an emulsion changes on the shelf, and the physics that sets each rate.

Status. EUTECNIQ has no laboratory, homogenizer, formulation or stability data; formulation work is planned for the Phase I laboratory (facility plan, October 2026). Every curve is an educational model or a published value.

3.5–7.3×slower Ostwald ripening when 40% of the Tween 20 was replaced (curcumin–MCT nanoemulsions)
≈66%β-carotene bioaccessibility in vitro with long-chain oil, against ≈2% with medium-chain oil
100×slower creaming for a droplet ten times smaller (Stokes' law)
2–2.5 °Ctemperature rise per 10 MPa in each homogenizer pass

Kim et al., Prev Nutr Food Sci 2016, Table 2; Qian et al., Food Chem 2012; Stokes' law (McClements, Food Emulsions, 2015); Patrignani et al. 2019; Romano et al. 2021.

Ostwald ripening, simulated

Left alone, an emulsion coarsens as small droplets dissolve into larger ones and the mean radius cubed climbs

Lifshitz–Slyozov–Wagner ripening of 130 droplets, simulated: shrinking droplets in rose, growing ones in steelSimulation, model output

Droplets left 130 of 130Mean radius 1 × startTime τ 0.0Oil volume kept 100.0%

Growth law dr/dτ = k(1/r)(1/r̄ − 1/r), the mean-field form of Lifshitz–Slyozov–Wagner (LSW) theory (Lifshitz & Slyozov 1961; Wagner 1961; Taylor 1998), with r in units of the starting mean radius and k = 1 or 0.01 for the two oils. LSW theory predicts that r̄³ eventually rises linearly at 4k/9; over the time shown this small population has not reached that regime, so its trace is steeper, and each step marks a droplet disappearing. 130 droplets, log-normal start (σ = 0.22), fixed positions, total oil volume held constant. A teaching simulation, not a prediction for any product.

Ripening speed scales with the oil's solubility in water: with a 100-fold less soluble oil, the same droplets barely change over the same time.

Explanation, details and sources

Oil dissolves slightly into the water around each droplet, more so around small, strongly curved ones (Laplace pressure). Oil therefore diffuses from droplets smaller than the mean to larger ones; the small ones vanish and the number of droplets falls while the total oil volume stays the same. In the mean-field theory the critical radius equals the number-mean radius, which conserves volume exactly. The rate constant k stands for c(∞)γVmD/(ρRT); its physical value for a chosen oil is computed in the calculator further down this page, and measured ripening rates for a published nanoemulsion are charted beside it.

Limits: dilute emulsion, no coalescence, creaming or flocculation, no micelle-assisted transport. Real emulsions are measured (see the measurement section).

What this page answers

Delivery claims for oil-soluble botanicals rest on emulsion physics that can be measured long before any human study

Four rungs of a delivery claim can be measured in a laboratory; only the top one needs peopleEvidence hierarchy
Evidence ladder for a delivery claim: physical stability, chemical stability, dispersibility and bioaccessibility can be measured in the laboratory; only human pharmacokinetic data show systemic bioavailabilityClaimWhat establishes itWhat it does not establishSystemic bioavailabilityHuman pharmacokinetic data: exposure in theblood≠ Clinical efficacyBioaccessibilityRelease into a digestion model; ranks formulations≠ Systemic bioavailabilityDispersibility in waterA fine, stable dispersion of an oil-soluble active≠ Solubility in water, or absorptionChemical stability of the activeA validated assay of the active over the samestorage≠ A validated commercial shelf lifePhysical stability of the dropletsSize, charge, cream layer and free oil tracked overtime and under stress≠ That the active itself survivesmeasurable in the laboratory, before any human studyneeds a human studyEvidence ladder for a delivery claim, from physical stability up to systemic bioavailability in peopleSystemic bioavailabilityHuman pharmacokinetic data: exposure in theblood≠ Clinical efficacyBioaccessibilityRelease into a digestion model; ranks formulations≠ Systemic bioavailabilityDispersibility in waterA fine, stable dispersion of an oil-soluble active≠ Solubility in water, or absorptionChemical stability of the activeA validated assay of the active over the samestorage≠ A validated commercial shelf lifePhysical stability of the dropletsSize, charge, cream layer and free oil tracked overtime and under stress≠ That the active itself survives
After McClements DJ. Soft Matter. 2011;7(6):2297–2316 (nanoemulsions can increase bioavailability and may change the biological fate of components) and McClements 2007 (several complementary stability methods). Digestion models rank formulations; human pharmacokinetic studies establish systemic exposure (see evidence and pharmacokinetics).
Text version of the evidence ladder
  1. Physical stability of the droplets: size, charge, cream layer and free oil tracked over time and under stress. It does not show that the active itself survives.
  2. Chemical stability of the active: a validated assay of the active over the same storage. A stable laboratory batch is not a validated commercial shelf life.
  3. Dispersibility in water: a fine, stable dispersion of an oil-soluble active. It is not solubility in water, and not absorption.
  4. Bioaccessibility: release into a digestion model, which ranks formulations. It is not systemic bioavailability.
  5. Systemic bioavailability: exposure in the blood, shown only by human pharmacokinetic data. It is not clinical efficacy.
  • Nanoemulsion stability≠demonstrated bioavailability
  • Dispersibility in water≠solubility in water
  • Droplet radius below 100 nm≠a microemulsion
  • Bioaccessibility in a digestion model≠systemic bioavailability
  • Physical stability≠chemical stability of the active
  • A stable laboratory batch≠a validated commercial shelf life
Explanation, details and sources

A lipophilic active, one that dissolves in oil rather than water, can be carried in oil droplets dispersed in water. Each rung of evidence below needs its own measurement.

EUTECNIQ would
  • Choose oil, emulsifier and process for an active
  • Measure size, charge and change over time
  • Stress-test dilution, pH, temperature, freeze–thaw
  • Transfer a working process to pilot scale
Proposed
Qualified partners would
  • Measure before EUTECNIQ's laboratory exists
  • Provide imaging such as cryo-electron microscopy
  • Run digestion models or human studies
External partner
EUTECNIQ does not claim
  • Formulation, droplet-size or stability data
  • That small droplets raise absorption in people
  • A proprietary delivery technology
Limits
Nano versus micro

Nanoemulsions and microemulsions can share a droplet size; thermodynamics is what separates them

Free energy of the dispersed state compared with separated oil and waterSchematic, not to scale

State 1: separated oil and water. State 2: dispersed droplets. In a nanoemulsion state 1 has the lower free energy, so state 2 survives only because the barrier slows breakdown; in a microemulsion state 2 is the minimum at its composition and temperature.

After McClements DJ. Soft Matter. 2012;8(6):1719–1729. The formation free energy is ΔGformation = γΔA − TΔSconfig: the interfacial tension γ times the new interface ΔA, minus the configurational entropy gained by dispersing the droplets. Curve shapes are drawn for explanation only.

McClements DJ. Nanoemulsions versus microemulsions: terminology, differences, and similarities. Soft Matter. 2012;8(6):1719–1729. The response row is an inference from the stability definitions, not a quoted result.

Explanation, details and sources

A microemulsion is thermodynamically stable and forms on its own at the right composition and temperature. A nanoemulsion is unstable and lasts only because breakdown is slow, called kinetic stability (McClements 2012). Both can have droplet radii below about 100 nm.

PropertyNanoemulsionMicroemulsion
Thermodynamic statusUnstable; persists because breakdown is slow (kinetic stability)Stable at its composition and temperature
How it formsNeeds energy input, such as a high-pressure homogenizer or ultrasound, or a low-energy route that traps fine dropletsForms spontaneously once the right components are combined
Droplet radiusCan be below about 100 nmBelow about 100 nm
Response to dilution or heatingDroplets persist for a time, then break down by the mechanisms belowCan change structure or break down once dilution or temperature moves it outside its stability region
How to tell them apartBehavior over time and after perturbation, not droplet size
Instability mechanisms

Creaming can be undone by mixing; coalescence, ripening and phase separation cannot

Five ways an oil-in-water emulsion changes, starting from the same fresh emulsionSchematic
Mechanism classes after McClements DJ. Crit Rev Food Sci Nutr. 2007;47(7):611–649, and McClements DJ. Food Emulsions. 3rd ed. CRC Press; 2015. Ostwald ripening: Taylor P. Adv Colloid Interface Sci. 1998;75(2):107–163. Droplet positions are drawn for explanation.
At droplet scale, four mechanisms have four different driving forces, and only two can be undonePublished mechanisms
Four instability mechanisms at droplet scale: creaming, flocculation, coalescence and Ostwald ripening, each with its driving force, reversibility, remedy and measurement1Creamingcreamv = 2r2​Δρg / 9ηDriving forceGravity acting on the densitydifferenceReversible?Reversible by gentle mixing, if nodroplets have mergedWhat slows itSmaller droplets, a smallerdensity difference, a moreviscous water phaseHow it would be measuredCream-layer height orbackscatter along the containerover time2Flocculationeach droplet keeps its own filmattraction > repulsionDriving forceAttraction between dropletsexceeds electrostatic or stericrepulsionReversible?Often reversible, for weak flocsWhat slows itSurface charge or a thickadsorbed layer; control of pHand saltHow it would be measuredMicroscopy; apparent sizegrowth; zeta potential as a guide3Coalescencefilm ruptureslarger dropletΔG = γ ΔA < 0Driving forceLower total interfacial energy:the film between two dropletsrupturesReversible?IrreversibleWhat slows itA dense, well-anchoredemulsifier layer; small dropletsHow it would be measuredGrowth of the droplet-sizedistribution; free oil4Ostwald ripeningsmall: high 2γ/rlarge growsdissolved oil diffusesΔp = 2γ / rDriving forceHigher oil solubility next to small,curved droplets: oil diffuses fromsmall to largeReversible?IrreversibleWhat slows itOils with very low watersolubility, or an added insolubleoilHow it would be measuredMean radius cubed rising linearlyin time (LSW theory)End point of coalescence: phase separation, a continuous oil layer or an inverted emulsion. Creaming and flocculation can be undone; coalescence, ripening and phaseseparation cannot.Four instability mechanisms at droplet scale: creaming, flocculation, coalescence and Ostwald ripening, each with its driving force, reversibility, remedy and measurement1Creamingcreamv = 2r2​Δρg / 9ηDriving forceGravity acting on the density differenceReversible?Reversible by gentle mixing, if no droplets havemergedWhat slows itSmaller droplets, a smaller density difference, amore viscous water phaseHow it would be measuredCream-layer height or backscatter along thecontainer over time2Flocculationeach droplet keeps its own filmattraction > repulsionDriving forceAttraction between droplets exceeds electrostatic orsteric repulsionReversible?Often reversible, for weak flocsWhat slows itSurface charge or a thick adsorbed layer; control ofpH and saltHow it would be measuredMicroscopy; apparent size growth; zeta potential asa guide3Coalescencefilm ruptureslarger dropletΔG = γ ΔA < 0Driving forceLower total interfacial energy: the film between twodroplets rupturesReversible?IrreversibleWhat slows itA dense, well-anchored emulsifier layer; smalldropletsHow it would be measuredGrowth of the droplet-size distribution; free oil4Ostwald ripeningsmall: high 2γ/rlarge growsdissolved oil diffusesΔp = 2γ / rDriving forceHigher oil solubility next to small, curved droplets:oil diffuses from small to largeReversible?IrreversibleWhat slows itOils with very low water solubility, or an addedinsoluble oilHow it would be measuredMean radius cubed rising linearly in time (LSWtheory)End point of coalescence: phase separation, a continuous oillayer or an inverted emulsion. Creaming and flocculation canbe undone; coalescence, ripening and phase separationcannot.
McClements 2007; McClements 2015 (Stokes' law); Taylor 1998 (Ostwald ripening, LSW theory); ripening inhibitors: Pavoni L, et al. Nanomaterials. 2020;10(1):135. Laplace pressure Δp = 2γ/r. Droplets are drawn for explanation, not to scale.
Text version: the five mechanisms

Each mechanism has its own driving force and remedy. Kinetic stability is a rate, so it is measured at the conditions of use and over time.

MechanismWhat happensDriving forceReversible?What slows itHow it would be measured
Creaming or sedimentationDroplets move up (oil lighter than water) or down, but stay intactGravity acting on the density differenceYes, by gentle mixing, if no droplets have mergedSmaller droplets, a smaller density difference, a more viscous water phaseCream-layer height or backscatter along the container over time
FlocculationDroplets cluster but keep their own interfacial filmsAttraction between droplets exceeds electrostatic or steric repulsionOften, for weak flocsSurface charge or a thick adsorbed layer; control of pH and saltMicroscopy; apparent size growth; zeta potential as a guide
CoalescenceThe film between two droplets ruptures and they mergeLower total interfacial energyNoA dense, well-anchored emulsifier layer; small dropletsGrowth of the droplet-size distribution; free oil
Ostwald ripeningOil dissolves from small droplets, diffuses through water and deposits on large onesHigher solubility next to small, curved droplets (Laplace pressure)NoOils with very low water solubility, or an added insoluble oilMean radius cubed rising linearly in time (LSW theory)
Phase separationA continuous oil layer forms, or the emulsion invertsEnd point of coalescenceNoPreventing the mechanisms aboveVisible oil layer; oil quantified after storage
Gravity

Creaming speed rises with the square of droplet size, so a tenfold smaller droplet creams a hundred times more slowly

Stokes velocity · gravitational lengthv = 2 r2 Δρ g9 η lg = kBT(4/3)πr3 Δρ g
Stokes velocity
Time for a cream layer across the height
Gravitational length lg
lg ÷ liquid height
Time to form a cream layer versus droplet diameterModel output

Stokes' law and sedimentation–diffusion equilibrium as presented in McClements DJ. Food Emulsions. 3rd ed. CRC Press; 2015. Water viscosity 0.890 mPa·s at 25 °C: Pátek J, et al. J Phys Chem Ref Data. 2009;38(1):21–29. Shaded: droplet sizes whose gravitational length exceeds the liquid height.
A nanoemulsion droplet creams slowly because velocity scales with r², but its small radius raises the Laplace pressure that drives Ostwald ripeningSchematic; worked arithmetic
Schematic cross-section of one oil droplet in water, coated by a single layer of surfactant molecules whose water-loving heads face outward and oil-loving tails point into the oil core. Beside it, the Laplace pressure equation and Stokes' law for creaming, with worked examples showing why small droplets cream slowly but are prone to Ostwald ripening.
Schematic, not to scale. Nanoemulsion definition: McClements DJ. Soft Matter 2012;8:1719–1729. Laplace pressure and Stokes’ law with the inputs shown on the figure. Generated illustration, EUTECNIQ. Full-size SVG
Method, assumptions and limits
What it calculates
The rise (or settling) speed of one droplet, the time to cross the liquid height at that speed, and the gravitational length at 25 °C.
Equations
v = 2r²Δρg/(9η); t = H/v; lg = kBT/((4/3)πr³Δρg). The concentration of droplets at equilibrium falls with height as exp(−z/lg).
Variables and units
r droplet radius (m); Δρ density difference (kg/m³); g = 9.80665 m/s²; η viscosity (Pa·s); H liquid height (m); kB = 1.380649 × 10⁻²³ J/K; T = 298.15 K. Dimensions: (m²·kg/m³·m/s²)/(Pa·s) = m/s.
Assumptions
Dilute emulsion; rigid, non-interacting spheres; Newtonian water phase; no convection. A denser oil sediments at the same speed.
Valid range
Particle Reynolds number far below 1, true for every setting here. Droplet diameters 20 nm to 20 µm; viscosity 0.89 to 1,000 mPa·s.
What it does not establish
Concentrated emulsions cream more slowly than Stokes predicts; flocculated droplets cream faster as clusters; thickened or gelled water phases need measured rheology. It says nothing about coalescence, ripening or chemical stability.
Verification
Independent Python reference cases in tests/numerics/ref/technologies-emulsions-colloids.py, checked against the page by tests/e2e/numerics.js.
Explanation, details and sources

Stokes' law gives the speed of an isolated droplet in a still liquid. Below a certain size, Brownian motion spreads droplets faster than gravity collects them; the gravitational length marks that crossover.

Making small droplets

Three devices tear droplets apart with force; low-energy methods let chemistry do the work

How each method breaks oil into fine dropletsIllustrative schematics
Pressures of 50–200 MPa; size falls with pressure and passes; sonication can damage components, for example by lipid oxidation: Pavoni L, et al. Nanomaterials. 2020;10(1):135. Temperature rise of about 2–2.5 °C per 10 MPa downstream of the valve, with exposure under 1 s: Patrignani F, et al. Front Microbiol. 2019;10:246; Romano E, et al. Int J Mol Sci. 2021;22(18):9896. Low-energy methods need a high surfactant-to-oil ratio and usually synthetic surfactants: Choi SJ, McClements DJ. Food Sci Biotechnol. 2020;29:149–168.
Droplet size versus number of passes, at three pressuresIllustrative trend
Shape follows the trend reported for clove-oil nanoemulsions at 50, 100 and 150 MPa over 1–20 passes: size fell from pass 1 to 5, further reduction was negligible after 10 passes, and the smallest droplets (about 150 nm) came at the highest pressure (Majeed H, et al. Food Chem. 2016;197:75–83, as summarized by Pavoni et al. 2020). Curves are illustrative, not the measured data.
Laplace pressure: the smaller the droplet, the harder it is to breakYoung–Laplace equation
Δp = 2γ/r. Interfacial tensions of 5 and 20 mN/m are examples. In turbulent breakup the largest stable droplet shrinks with the energy dissipation rate to the −2/5 power (Hinze JO. AIChE J. 1955;1(3):289–295); scale-up of that rule is on the process engineering page, and power-per-volume and tip-speed rules for homogenizers and mixers are on scale-up and technology transfer.
Each pass through a valve homogenizer heats the product by about 2 to 2.5 °C per 10 MPa: 30 to 37.5 °C at 150 MPaPublished rates, computed per pass
Temperature rise per pass after a homogenizing valve: about 2 to 2.5 °C per 10 MPa, so 10 to 50 °C per pass across the 50 to 200 MPa range0102030405060Temperature rise per pass, °C050100150200Homogenizing pressure, MPa50–200 MPa: the range reported for valve homogenizers (Pavoni et al. 2020)50–200 MPa in use2–2.5 °C per 10 MPa (Patrignani et al. 2019; Romano et al. 2021)2.5 °C per 10 MPa2.0 °C per 10 MPapublished range50 MPa: 10–12.5 °C per pass10–12.5 °C100 MPa: 20–25 °C per pass20–25 °C150 MPa: 30–37.5 °C per pass30–37.5 °C200 MPa: 40–50 °C per pass40–50 °CPer pass, and it adds upThe product passes the valve inunder 1 s, but each pass adds therise again, so cooling is needed athigh pressure.Adiabatic checkAll pressure energy ends as heat: ΔT= Δp / (ρ cp​) = 2.4 K per 10 MPa forwater (cp​ 4.18 kJ/(kg·K)), 2.5 K for cp​4.0; dashed line.Temperature rise per pass after a homogenizing valve: about 2 to 2.5 °C per 10 MPa, so 10 to 50 °C per pass across the 50 to 200 MPa range0102030405060Temperature rise per pass, °C050100150200Homogenizing pressure, MPa50–200 MPa: the range reported for valve homogenizers (Pavoni et al. 2020)50–200 MPa in use2–2.5 °C per 10 MPa (Patrignani et al. 2019; Romano et al. 2021)50 MPa: 10–12.5 °C per pass100 MPa: 20–25 °C per pass150 MPa: 30–37.5 °C per pass200 MPa: 40–50 °C per pass2.0 to 2.5 °C per 10 MPa per pass: 10–12.5 °C at 50 MPa,20–25 at 100, 30–37.5 at 150, 40–50 at 200Per pass, and it adds upThe product passes the valve in under 1 s, but each passadds the rise again, so cooling is needed at high pressure.Adiabatic checkAll pressure energy ends as heat: ΔT = Δp / (ρ cp​) = 2.4 Kper 10 MPa for water (cp​ 4.18 kJ/(kg·K)), 2.5 K for cp​ 4.0;dashed line.
Temperature rise of about 2–2.5 °C per 10 MPa downstream of the valve, with exposure under 1 s: Patrignani F, et al. Front Microbiol. 2019;10:246; Romano E, et al. Int J Mol Sci. 2021;22(18):9896. Operating range 50–200 MPa: Pavoni et al. 2020. Adiabatic line: ΔT = Δp/(ρcp) with ρ = 1,000 kg/m³ and cp = 4.18 kJ/(kg·K). Per pass, without cooling between passes.
Text version of the temperature rise

At 2–2.5 °C per 10 MPa, one pass raises the temperature by 10–12.5 °C at 50 MPa, 20–25 °C at 100 MPa, 30–37.5 °C at 150 MPa and 40–50 °C at 200 MPa. An adiabatic energy balance gives 2.4 K per 10 MPa for a water-like product (2.5 K with cp 4.0 kJ/(kg·K)). Each pass and each step up in pressure buys a smaller droplet, with fast diminishing returns.

Explanation, details and sources

High-energy devices break droplets apart, and the emulsifier must cover the new interface before fragments merge. Low-energy methods form fine droplets when the right oil–surfactant mixture meets water.

High-pressure valve homogenizer

A sub-second burst of pressure and shear

  • Pressure: 50–200 MPa; size falls with pressure and passes
  • Heat: 2–2.5 °C per 10 MPa per pass (chart above)
  • Time: under 1 s in the valve
Pavoni et al. 2020; Patrignani et al. 2019; Romano et al. 2021
Microfluidizer

Two jets collide in an interaction chamber

  • Size: falls with passes and pressure
  • Chambers: Y- and Z-type designs are common
Choi & McClements 2020
Ultrasonication

Collapsing cavitation bubbles tear droplets

  • Size: set by time, intensity, emulsifier and viscosity
  • Risk: can denature proteins, depolymerize polysaccharides or oxidize lipids
  • Use: refines an emulsion or emulsifies in one step
Pavoni et al. 2020; Choi & McClements 2020
Low-energy emulsification

Chemistry instead of force

  • Heat: none for spontaneous emulsification; the phase-inversion temperature method warms, then cools
  • Cost: a high surfactant-to-oil ratio, usually synthetic
  • Watch: stability on dilution or changed conditions
Choi & McClements 2020; Pavoni et al. 2020
Ostwald ripening

Small droplets feed large ones, and the oil's water solubility sets the pace

LSW ripening rateω = dr³dt = 89·c(∞) γ Vm Dρ R T
Ripening rate ω
Time to double the mean diameter
Mean droplet diameter over timeModel output

Lifshitz IM, Slyozov VV. J Phys Chem Solids. 1961;19:35–50. Wagner C. Z Elektrochem. 1961;65:581–591. Taylor P. Adv Colloid Interface Sci. 1998;75:107–163. Equation form and remedies (oils of very low water solubility, or a second, insoluble oil): Pavoni et al. 2020. Limonene: PubChem CID 22311.
Method, assumptions and limits
What it calculates
The LSW ripening rate for a limonene-like oil of chosen water solubility, the mean diameter over time and the time for the mean diameter to double.
Equations
ω = (8/9)(c(∞)/ρ)(γVm/RT)D; r³(t) = r0³ + ωt; doubling the diameter needs t = 7r0³/ω.
Variables and units
c(∞) oil solubility (kg/m³); ρ = 840.2 kg/m³ and M = 0.13623 kg/mol for limonene, so Vm = M/ρ (m³/mol); γ = 5 mN/m and D = 7 × 10⁻¹⁰ m²/s (examples); R = 8.314 J/(mol·K); T = 298.15 K. ω comes out in m³/s.
Assumptions
Steady-state ripening of a dilute emulsion; no coalescence, creaming or flocculation; interfacial tension and diffusivity fixed.
Valid range
Solubility 10⁻⁴ to 100 mg/L; starting diameter 60–300 nm. The curve is clipped at 1 µm.
What it does not establish
Absolute times depend on the example γ and D; real emulsions are measured. Mixtures of oils, surfactant micelles and polydisperse droplets can ripen faster or slower than LSW predicts.
Verification
Independent Python reference cases in tests/numerics/ref/technologies-emulsions-colloids.py.
Measured: replacing 40% of the Tween 20 with a second emulsifier cut the ripening rate of curcumin–MCT nanoemulsions 3.5- to 7.3-fold at every pressurePublished data
Data table (Kim et al. 2016, Tables 1 and 2)
Droplet size, polydispersity and Ostwald ripening rate of curcumin-loaded MCT nanoemulsions
PressureEmulsifier (wt%)Day 1, nm (PdI)Day 28, nm (PdI)ω, × 10⁴ nm³/h (R²)
5,000 psiTween 20 (10)106.97 (0.139)121.80 (0.096)9.07 (0.9808)
5,000 psiTween 20 : sorbitan monooleate (6:4)89.13 (0.097)94.71 (0.110)2.54 (0.8446)
5,000 psiTween 20 : soy lecithin (6:4)105.50 (0.135)109.30 (0.124)1.91 (0.8292)
10,000 psiTween 20 (10)85.85 (0.160)111.37 (0.104)11.65 (0.9953)
10,000 psiTween 20 : sorbitan monooleate (6:4)77.44 (0.098)82.24 (0.106)1.72 (0.8457)
10,000 psiTween 20 : soy lecithin (6:4)77.21 (0.146)86.33 (0.131)3.16 (0.8972)
15,000 psiTween 20 (10)89.08 (0.137)109.23 (0.114)9.68 (0.9876)
15,000 psiTween 20 : sorbitan monooleate (6:4)73.43 (0.081)77.38 (0.084)1.32 (0.7879)
15,000 psiTween 20 : soy lecithin (6:4)67.68 (0.143)77.88 (0.141)2.76 (0.9022)

Rate ratios (Tween 20 alone ÷ mixed system) are computed here: 3.6 and 4.7 at 5,000 psi, 6.8 and 3.7 at 10,000 psi, 7.3 and 3.5 at 15,000 psi. The linear fits for the mixed systems are weaker (R² 0.79–0.90). 5,000, 10,000 and 15,000 psi are 34.5, 68.9 and 103.4 MPa.

Kim SH, Ji YS, Lee ES, Hong ST. Prev Nutr Food Sci. 2016;21(3):289–295, Tables 1–2 (open access): 0.15% curcumin, 10% MCT oil, 10% emulsifier; microfluidizer, 4 cycles; dynamic light scattering after 1,000-fold dilution; stored 28 days at room temperature; mean of n = 3. A 28-day storage test ranks formulations; it is not a validated shelf life.
Explanation, details and sources

Oil dissolves slightly into the water around each droplet, more so around small ones. Oil therefore migrates from small droplets to large ones, and the cube of the mean radius grows linearly in time (Lifshitz–Slyozov–Wagner, or LSW, theory).

Self-emulsifying systems

A self-emulsifying mix must stay finely dispersed along its whole dilution path, and only a measured phase diagram shows it

Where a mix disperses into fine dropletsSchematic, not data
Mix A stays a fine dispersion along its whole dilution line; mix B, with less surfactant, crosses into the coarse region. Region shapes are schematic; real boundaries are measured. Lipid formulation types: Pouton CW. Eur J Pharm Sci. 2006;29:278–287 (see delivery systems).

Mix A stays fine all along its dilution line; mix B, with less surfactant, does not. Only a measured diagram shows which a real blend does.

Explanation, details and sources

Oil, surfactant and cosurfactant blends disperse into fine droplets when diluted, as in the gut. The region where they do so is mapped by titration for each pair.

  1. Pick the oilLow water solubility resists ripening; the oil also has to dissolve the active.
  2. Map the diagramTitrate oil–surfactant mixes with water and record where they stay clear.
  3. Make and measureSize by light scattering, then track it over time and through dilution.
  4. Test the claim separatelySmall droplets disperse an active; only human data show better absorption.
Measurement

No single measurement shows that an emulsion is stable, so size, charge, appearance and the active are tracked together

Six measurements, six different properties: a stability study needs several of them at every time pointQualitative summary of the table
Matrix: each of six measurements reports one property of an emulsion; none covers droplet size, the micrometer tail, charge, images, change on storage and loss of the active at onceSize below 1 µmMicrometer tail(coalescence)Surface chargeDirect imagesChange afterstorage or stressLoss of the activeDynamic light scatteringDynamic light scattering · Size below 1 µm: highDynamic light scattering · Micrometer tail (coalescence): lowLaser diffractionLaser diffraction · Size below 1 µm: lowLaser diffraction · Micrometer tail (coalescence): highElectrophoretic light scatteringElectrophoretic light scattering · Surface charge: highOptical and electron microscopyOptical and electron microscopy · Size below 1 µm: lowOptical and electron microscopy · Micrometer tail (coalescence): lowOptical and electron microscopy · Direct images: highStorage and stress testsStorage and stress tests · Change after storage or stress: highAssay of the activeAssay of the active · Loss of the active: highreports this directlypartly or indirectlydoes not report it
Rows and limits as in the table below: USP ⟨429⟩, ⟨430⟩, ⟨776⟩; ISO 22412:2025; ISO 13320:2020; McClements 2007.
Zeta potential and particle size are calculated from mobility and diffusion, and salt thins the charge layer that zeta describesSchematic; computed profiles
Schematic of the ions next to a negatively charged oil droplet surface in water: a compact Stern layer of adsorbed counter-ions, the slipping plane where zeta potential is defined, and a diffuse layer in which counter-ions thin out with distance. Below, computed potential profiles show the layer shrinking as salt rises. Beside it, the Debye length, Smoluchowski and Stokes-Einstein equations with worked values.
Debye–Hückel screening, Smoluchowski equation and Stokes–Einstein relation as in standard colloid texts (e.g., Israelachvili JN. Intermolecular and Surface Forces. 3rd ed. 2011); CODATA constants; water at 25 °C. Potential profiles computed from an assumed zeta potential. Generated illustration, EUTECNIQ. Full-size SVG
Show the table (6 rows)
MethodWhat it reportsMain limitStandard
Dynamic light scatteringHydrodynamic diameter (z-average) and polydispersity of droplets below about a micrometerIntensity-weighted: a few large droplets or dust dominateUSP ⟨430⟩; ISO 22412:2025
Laser diffractionVolume-weighted size distribution; catches the micrometer tail that signals coalescenceModel-based inversion needs refractive indicesUSP ⟨429⟩; ISO 13320:2020
Electrophoretic light scatteringZeta potential, a guide to electrostatic repulsion between dropletsDepends on pH and salt; it predicts, it does not measure, stabilityMethod-specific
Optical and electron microscopyDirect images of droplets, flocs and crystalsSmall fields of view; preparation can create artifactsUSP ⟨776⟩ for optical microscopy
Storage and stress testsCream layer, free oil and size change after storage, dilution, pH change, centrifugation or temperature cyclingStress results rank formulations; they do not set a shelf lifeProtocol-specific
Assay of the activeChemical stability: whether the active itself degradesA physically stable emulsion can still lose its active to oxidationValidated chromatographic method

USP general chapters ⟨429⟩, ⟨430⟩ and ⟨776⟩ (USP–NF); ISO 22412:2025, Particle size analysis — Dynamic light scattering (edition 3, September 2025; replaced the withdrawn 2017 edition); ISO 13320:2020 (laser diffraction, about 0.1 µm to 3 mm); McClements 2007 for the use of several complementary stability methods.

Explanation, details and sources

Each method sees part of the picture. A sound stability study measures several of them at the same time points, under storage and stress conditions. Instrument principles are on the analytical page.

From droplets to a claim

A stable nanoemulsion improves how an oil-soluble active disperses; whether it improves absorption in people is a separate question

Same nanoemulsion size class, three carrier oils: β-carotene bioaccessibility ranged from about 66% to about 0%Published data
Data table
β-carotene bioaccessibility by carrier oil, Qian et al. 2012
Carrier oilBioaccessibilityReason given by the authors
Long-chain triglyceride≈66%Mixed micelles formed that could solubilize β-carotene
Medium-chain triglyceride≈2%Mixed micelles too small to solubilize β-carotene
Orange oil≈0%No mixed micelles formed
Qian C, Decker EA, Xiao H, McClements DJ. Nanoemulsion delivery systems: influence of carrier oil on β-carotene bioaccessibility. Food Chem. 2012;135:1440–1447 (abstract values). Tween 20 nanoemulsions, d < 200 nm; in vitro mouth, stomach and small-intestine model. Bioaccessibility in a digestion model is not systemic bioavailability.

Droplet size did not decide the result; the oil's digestion products did. Bioaccessibility in a model is still not absorption in people.

Explanation, details and sources

McClements (2011) describes nanoemulsions as able to increase bioavailability and also notes possible risks from changing the biological fate of components. EUTECNIQ would therefore treat a delivery benefit as a hypothesis: digestion models can rank formulations, and only human pharmacokinetic data establish systemic exposure.

Where the evidence goes next. Pharmacokinetic study design and how exposure is measured are covered on evidence and pharmacokinetics; carrier choice for a given molecule is on delivery systems. Source: McClements DJ. Edible nanoemulsions: fabrication, properties, and functional performance. Soft Matter. 2011;7(6):2297–2316.

Discuss a delivery-system question

Partners with an oil-soluble botanical active can describe the problem; EUTECNIQ would respond with a proposed study plan and its limits.