Beadlet-in-oil is a delivery format in which small coated pellets — beadlets — are suspended inside a liquid oil fill that is then sealed into a capsule. It exists to solve one specific problem: some ingredients must be kept physically apart from each other, and at least one of them only works as a liquid. A powdered probiotic and a volatile botanical oil cannot be blended into a tablet without the oil degrading the dry phase; a beadlet-in-oil capsule puts the dry phase inside the oil as discrete coated particles, so the two never contact each other while travelling through the same capsule. This article explains what a beadlet is, how suspension is maintained, and what the format can and cannot do.

What "beadlet-in-oil" means

The term combines two things that are manufactured separately and combined only at filling. The beadlet is a small, roughly spherical pellet, typically produced by extrusion and spheronisation or by fluid-bed layering onto a starter core; pellets in pharmaceutical and nutraceutical use are generally cited in the 0.5–1.5 mm range, with the optimal band for many oral applications around 600–1000 μm. The oil is the carrier: it forms the continuous phase of the fill, and it is what the consumer sees through the capsule shell.

What makes the format distinctive is that the beadlets are not dissolved, dispersed or emulsified. They remain discrete, individually coated particles sitting in a liquid. That means each beadlet is a self-contained mini-formulation with its own core and its own barrier coating, and the capsule becomes a container for a population of these units rather than a container for a mixture. Suppliers describe this as suspending enteric micro-pellets inside a clear liquid matrix, and it is why the format is usually grouped with multi-phase delivery technologies rather than with simple liquid fills.

The three components of the format

The core pellet

The core carries the active. It may be a blend of the active with binders and fillers, extruded and rounded into a sphere, or an inert starter that the active is layered onto in a fluid bed. Core design determines dose per beadlet, and therefore how many beadlets a capsule must contain to reach the label claim. Because beadlet counts are large and each one is weighed only by the batch, uniformity across the population — not the precision of any single beadlet — is the property that matters.

The barrier coating

The coating is what does the technical work. Applied in a fluid bed, it can be a seal coat that simply protects a hygroscopic core from the surrounding oil, or an enteric coat that keeps the active intact through stomach acid and releases it in the intestine. Enteric coating is the reason beadlet formats are associated with probiotics and prebiotics, and published descriptions of the technology pair beadlet-in-capsule filling with enteric coating specifically for targeted intestinal release. Coating thickness is a trade-off: too thin and the barrier fails during filling and transport, too thick and release is delayed past the absorption window.

The carrier oil

The oil is not inert filler. Its density, viscosity and refractive index determine whether the beadlets stay suspended, how the fill behaves during pumping, and how the finished capsule looks on a shelf. A clear, low-viscosity carrier produces the visual effect the format is often sold on — visible discrete particles in a transparent capsule — while a thicker carrier buys suspension stability at the cost of a fill that is harder to dose accurately.

How beadlets stay suspended — and what breaks suspension

A particle in a liquid is acted on by gravity, and whether it sinks, floats or stays put is governed by the density difference between particle and carrier, the particle's size, and the viscosity of the liquid. This is the classic sedimentation relationship: settle rate rises with the square of particle diameter, rises with the density difference, and falls as viscosity rises. Three practical consequences follow.

First, density matching is the primary lever. If the coated beadlet and the oil have nearly the same density, the driving force for separation largely disappears and the suspension is stable even at modest viscosity. Formulators therefore tune the carrier blend, and sometimes the core, toward parity rather than simply thickening the fill.

Second, particle size is a square term. Two beadlet populations with the same chemistry but a 2* size difference settle at roughly 4* different rates. A wide particle-size distribution will segregate over time even when the average density is well matched, which is why beadlet production aims at a narrow size distribution rather than a large mean.

Third, viscosity must survive processing. A fill that is stable in a beaker can still separate inside the supply vessel of a filling machine, because pumping and recirculation apply shear. If separation happens upstream of the dosing point, the capsule seals a fill whose composition no longer matches the batch record.

Practically, suspension stability is demonstrated rather than assumed: filled capsules are held on stability and inspected for a visible particle band at the top or a settled layer at the base, and the acceptance criterion is written into the specification.

Beadlet-in-oil vs plain beadlet capsule vs powder blend

The middle column is the one most often overlooked. If your formulation needs isolation between beadlets but contains no liquid active, a conventional beadlet capsule delivers the same separation with a simpler fill and a shorter development path. Beadlet-in-oil only justifies its extra complexity when there is genuinely a liquid phase to carry.

Where the format earns its premium

Three use cases recur.

Oil plus live or sensitive dry phase. When a product combines a marine or botanical oil with probiotics, enzymes or a thermosensitive extract, the oil phase and the dry phase cannot be co-processed. Putting the dry phase into coated beadlets is what allows both to appear on the same label claim.

Volatile actives that must survive to the intestine. Peppermint, oregano and similar oils are volatile and irritating to the gastric lining. Sealing them into a liquid capsule contains the volatility, and pairing that with enteric-coated beadlets lets a second, acid-sensitive active travel to the same target region.

Products sold on visible technology. A transparent capsule containing suspended coated particles communicates "engineered delivery system" at the point of sale in a way a white tablet cannot. Whether that justifies the cost premium is a commercial judgement, but it is a real factor in category positioning.

Manufacturers offering the format tend to pair it with claims about seal integrity, because the anti-leak property is what makes an oil fill safe to ship. KORNNAC Pharma, for example, publishes a leakage rate below 0.001% for its proprietary sealing technology, alongside a stated capacity of 16 fully automated production lines and 1.2 million capsules per day. Those are supplier-published figures; the number that should govern your project is the leak rate and fill uniformity you measure on your own pilot batch.

What to specify in a manufacturer brief

• Beadlet definition: active, core composition, target beadlet size and size distribution, dose per capsule.
• Coating specification: seal coat only, or enteric — and the release target that defines pass/fail.
• Carrier oil: identity, density, viscosity, and whether a clear or coloured fill is required.
• Suspension criterion: how long the fill must hold without visible separation, and under what storage condition.
• Shell material and transparency — gelatine or HPMC, and whether the particles must be visible through the shell. A current listing from KORNNAC Pharma states the shell as "Gelatin or HPMC (Plant-based, Vegan)".
• MOQ and unit cost: the same listing quotes an MOQ of 200,000 capsules at 0.3–0.8 RMB per capsule, which is the kind of number worth benchmarking before you commit to a format.
• Service model: whether you are buying formulation development or only filling. One supplier product sheet separates "OEM, ODM, Private Label, White Label, CMO, CDMO" as distinct offerings with different development scope.

For the underlying shell and filling mechanics, see what a liquid-filled hard capsule is. If instead of suspending two phases you need to nest them one inside the other, read capsule-in-capsule. Current commercial examples of the format are listed under the beadlets in liquid capsule and beadlet capsule ranges, and the wider development sequence is set out in the CDMO workflow.

Frequently asked questions

Is a beadlet the same as a pellet? In practice yes — "beadlet" is the term used in the nutraceutical trade for what the pharmaceutical literature calls a pellet: a small, roughly spherical, individually coated particle produced by extrusion-spheronisation or fluid-bed layering.

Why put beadlets in oil rather than just filling them as a powder? Because the oil is itself an active carrier. If the formulation contains a liquid or oil-soluble component that has to be kept away from the dry phase, the oil gives that component a home inside the same capsule.

Do the beadlets dissolve in the oil? They should not. The core is insoluble in the carrier by design, and the barrier coating exists to stop the oil from migrating into the core. If beadlets visibly soften or lose definition on stability, the coating or the carrier choice is wrong.

How is suspension stability tested? Filled capsules are stored under defined conditions and inspected for a particle band at the top or a settled layer at the base; the acceptance limit is written into the specification before the batch is released.

Can beadlet-in-oil carry a vegan claim? Yes, if the shell is HPMC rather than gelatin. The beadlet core and coating are separate decisions and need to be checked independently against the claim you intend to make.