Encapsulation & Solid Dose

Softgel Encapsulation

Forming, filling, and sealing a one-piece soft capsule in a single motion — purpose-built for oils and liquids, where the hermetic seal and the shell aren’t packaging, they’re the product.

Where softgel encapsulation sits in the line — the family of encapsulation and solid-dose forms.See the other solid-dose technologies A one-piece capsule formed, filled, and sealed in a single motion — the softgel route to a swallowable dose.Browse capsule technologies Built for oils and liquids a powder capsule or tablet can’t carry — dosed accurately and sealed from air.Browse liquid-handling technologies
What it is

Shell, fill, and seal — made at once, around a liquid.

Softgel encapsulation is a form-fill-seal operation that builds a one-piece sealed soft capsule in a single step. Two ribbons of gel — gelatin or a plant-based polymer — run over rotating dies that simultaneously shape the shell, inject a metered liquid or semisolid fill, and heat-seal the two halves together. There’s no separate fill-then-close: the capsule is made and filled in one motion.

It exists for what a powder capsule or tablet can’t carry well: oils, solutions, and suspensions, dosed accurately and sealed away from air and light.

The levers are the gel-mass formulation, ribbon thickness, fill metering, seal integrity, and the drying curve. The wet softgel that comes off the die still has to lose moisture to a target — tumble-dried, then tray-dried — and where that drying ends decides whether the shell is supple or brittle.

Gel-mass quality, set by its formulation and bloom strength, governs how cleanly the shell forms and seals. Drift there and shell quality drifts with it, batch to batch.

Process flow
1

Gel mass prepared (gelatin/plasticizer or plant polymer) and cast into two ribbons

2

Fill material prepared and metered

3

Ribbons meet at rotating dies; the die forms the shell, injects fill, and seals in one motion

4

Wet softgels tumble-dried, then tray-dried to target shell moisture

5

Inspected, sized, and polished

Sealed softgels at a controlled fill weight and shell moisture

The leversGel-mass formulation, ribbon thickness, fill metering, seal integrity, and the drying curve.
Why it matters

The seal and the shell are the product — not the wrapper.

A softgel’s stability lives in its seal and shell. A weak seal leaks, or lets air in to oxidize the fill. Shell moisture out of range makes softgels brittle or tacky and shifts how they dissolve. For an oxygen- or light-sensitive oil, the hermetic shell is the stability strategy — so its integrity isn’t cosmetic, it’s the whole defense.

That reframes what counts as control. Seal testing has to find leakers, not just pass a visual; the drying end-point has to land shell moisture in spec; and for sensitive oils, oxidation has to be tracked over shelf life, not assumed away by the shell. Get those right and the softgel protects its fill to expiry; get them wrong and the product degrades inside an intact-looking capsule.

21 CFR 211 · drugFor a drug softgel, form-fill-seal is a validated process under cGMP — in-process fill-weight and content-uniformity checks, finished-capsule testing against release specs, and stability data proving the sealed shell holds the fill to expiry.
21 CFR 111 · supplementFor a supplement, the fill-weight, seal-integrity, and shell-moisture specs live in the master manufacturing record, and each batch record verifies the finished softgels met them before release.
USP <905> · uniformityUSP <905> sets the uniformity-of-dosage-units acceptance — the test filled softgels must pass, and what the fill-metering loop has to hold to satisfy it.
USP <701> / <2040> · disintegrationUSP <701> (drug) and <2040> (supplement) set disintegration and dissolution — proof the shell opens and releases on time, with the enzyme allowance for gelatin shells that cross-link and slow release as they age.

The governing rule follows the product class; uniformity of dosage units and disintegration/dissolution acceptance criteria anchor the rest.

How it compares

Why a maker reaches for a softgel — and what they trade.

The softgel wins on liquids and protection. Knowing what it was chosen over tells you what the fill needed.

vs.

Two-piece capsules

Two-piece capsules suit powders, pellets, and dual-release combinations.

The tradeSoftgels suit liquids and oils and give a hermetic single-piece seal with better oxygen and UV protection.
vs.

Tablets

Tablets are durable and cheap at volume — but they can’t deliver a liquid fill.

The tradeSoftgels carry oils and dissolved actives at an accurate dose a tablet simply can’t hold.
vs.

Liquid in a dropper bottle

A multi-dose liquid is simple but leaves dosing and stability to the user and the bottle.

The tradeSoftgels give a precise single dose and better stability than an opened multi-dose liquid.
Where it tends to go wrong

The gaps a reviewer looks for on a softgel.

None of these are exotic. They’re the quiet places a softgel operation drifts out of control — recognizable the moment you’ve run one.

Seal integrity isn’t tested for leakers beyond a visual check — so a slow leaker reaches the bottle.

Shell moisture and the drying end-point run uncontrolled, giving brittle or tacky softgels.

Fill-weight — and therefore dose — variation isn’t monitored across the run.

Oxidation of sensitive oil fills isn’t tracked — peroxide value left unmonitored over shelf life.

Gel-mass and bloom strength aren’t specified, so shell quality drifts from batch to batch.

Microbial growth risk in the wet stage and drying area goes unaddressed.

If this is your operation

Six things to check against your own records.

Not an audit — a read you can run yourself before anyone else does. Pull one recent batch and walk it.

01

Ask how seal integrity and leakers are tested — not just inspected.

02

Check the shell-moisture spec and how the drying end-point is set.

03

Look at fill-weight monitoring across the batch.

04

For oils, review oxidation indicators (peroxide value) over shelf life.

05

Confirm gel-mass and bloom-strength specs.

06

Review microbial control in the wet and drying stages.

Applications

The same operation, across very different fills.

The die doesn’t change — the fill does. What stays constant is the control problem: seal it tight, dry it right, protect the oil.

Supplement

Fish oil, vitamins & oil-based actives

The signature softgel category — omega-3s, fat-soluble vitamins, and oil-dissolved botanicals, where the hermetic shell guards a readily oxidized fill.

Pharma

Liquid-fill & lipid formulations

Dosing dissolved or lipid-based actives — including poorly soluble drugs delivered in a solubilizing vehicle — at an accuracy a powder can’t match.

Cosmetic / specialty

Single-use beauty & topical doses

Twist-off and burstable softgels delivering a precise single dose of serum or oil, sealed against air until the moment of use.

Food & specialty

Functional oils & flavor systems

Encapsulating functional oils and concentrated flavor or aroma systems where a sealed single dose beats an open, oxidizing bottle.