What Are Softgels Made Of?

How a Softgel Is Constructed

A softgel is a one-piece unit because the fill is a liquid, suspension, or paste at the moment of encapsulation. Two ribbons of softgel shell formulation meet on a rotary die; fill is injected; the piece is cut and sealed in the same motion; then it is dried. [3]

A common misconception is that a softgel is “a capsule with oil poured in.” A standard two-piece hard capsule is an open join until it is locked. A free oil or thin suspension poured into that join as the default path would leak before the bottle is labeled. Oil SKUs therefore leave two-piece shells and this dosage form is formed as a weld. Two-piece composition (dry powder) is what hard capsules are made of.

Gel mass ≠ fill. The ribbon is the container film. The fill is what is pumped. Writing “gelatin 400 mg” as the active is a composition error.

Fish-gelatin is a shell polymer source. It is not a marine-oil SKU and does not name the fill.

What Is a Softgel Shell Made Of?

Softgel shell materials are a plasticized hydrophilic film. On commercial gelatin grades the film is thermo-reversible: it flows when warm, sets on the cooling drums, then welds at the die. That gel behavior is why gelatin remains the default gelatin softgel composition for oil fills. [3]

Exact residual-moisture windows, plasticizer ratios, and additive lists sit on the grade CoA. They vary by polymer family, supplier, color, and lot — not by a generic internet percentage.

Gelatin — bovine, porcine, or fish-gelatin grade

Gelatin is collagen-derived protein. Name the source on the RFQ. Fish-gelatin is still gelatin: it is not vegan, and it does not turn the fill into a marine-oil product.

It is used because it forms a thermo-reversible gel, seals on rotary dies, and sits on the widest commercial die library. Confirm TSE/BSE and Halal/Kosher files if those claims will appear; take Bloom and viscosity from that grade’s spec; select color and TiO₂ status against the destination market.

For example, fish-gelatin grades involve different sourcing and qualification, which may raise procurement cost depending on availability. There is no universal markup on this page.

Vegetarian / plant-gel ribbons

Vegetarian softgel materials are named systems — modified starch, pectin, or carrageenan as scoped — not “vegetarian gelatin.” Pullulan, if used, is a named grade. It is not a synonym for HPMC.

Starch, pectin, and carrageenan exist because no single plant-gel matches gelatin on every axis at once. They trade off sealing, oxygen and moisture behavior, drying, and what the market file may say — not as interchangeable drop-ins for the same die and the same dry curve. Specify the system name. Verify fill compatibility and a drying curve for that ribbon.

Colorants, opacifiers, and clear shells

Color and opacity are part of softgel shell ingredients, not decoration after the fact.

Titanium dioxide (TiO₂, E171) has been used as a white opacifier in some films. The European Union no longer authorizes titanium dioxide as a food additive, so SKUs for that market often need a TiO₂-free grade. Other markets still allow it under their own rules. [4]

A clear shell is not “higher quality.” It shows the fill and often needs more light and oxidation control. Light-sensitive fills (carotenoids, some CoQ10 systems) more often need opaque or amber.

Gelatin vs Plant Gel: The Trade-off, Not a Ranking

Choosing a shell is rarely about “better.”

Gelatin remains the default commercial ribbon because most commercial rotary-die tooling, historical production experience, and validation work are built around gelatin systems. Plant-gel systems may support vegetarian positioning, but they often need dedicated drying parameters and a compatibility trial. The decision is usually commercial and technical at the same time: claim file versus die library, calendar, and leak risk.

This article explains what each family is made of. How to choose — including cost direction and a gelatin-to-vegetarian switch as a new SKU — is gelatin vs vegetarian softgels.

Why Water and Plasticizer Matter

Without plasticizer, gelatin and plant-gel films are too brittle to cast as a continuous ribbon, weld at the die, and flex in the bottle. Glycerin, sorbitol, or a mixed system on the grade you buy lowers the film’s glass-transition behavior so it stays workable during softgel shell manufacturing and through shelf life. [3]

Too little plasticizer for that gel mass and fill: the shell dries brittle — cracks, seam splits, powdering on the belt. Too much: the shell stays too soft — deformation, stickiness, and a higher leak risk because the weld and the fill can migrate.

There is no universal glycerin percentage because the ratio has to fit this polymer family, this fill viscosity, this drying curve, and this die. A gel-mass that ran on one oval will not automatically transfer to a different ribbon, a thicker oil, or a plant-gel dry cycle. The number lives on the grade specification and is confirmed on a production-relevant trial.

Residual water is a window, not a purity contest

The ribbon is cast from a wet gel mass so the polymer can hydrate and flow. After encapsulation, drying removes water until an endpoint where capsules neither stick nor shatter.

Too much residual moisture: stickiness, a soft shell that weeps, and mold risk if pack and water activity allow it. Too little: brittleness, seam failure, and leakage that gets blamed on the oil when the ribbon was over-dried.

In practice, vegetarian ribbons often need a different moisture window than gelatin. Copying a gelatin dry curve onto a plant gel is a composition-process mismatch. Drying time in days is not a public SOP.

Common Plasticizers in Softgel Shell Formulation

Softgel ribbon formulation names the plasticizer on the gel-mass spec. The three families below are directions, not a ranking.

Glycerin is the workhorse on many gelatin ribbons. It keeps the film flexible. The usual watch-out is moisture moving into or out of the fill and the pack, especially in humid lanes. Confirm identity and the ratio on the grade you will run.

Sorbitol (including sorbitol-rich blends) is used when the brief wants a different tack or moisture profile than glycerin-only. It is not “drier glycerin.” Some grades crystallize if the film and storage are wrong; supplier files distinguish crystallizing and non-crystallizing types. Select the grade against the named fill.

Mixed systems try to balance flexibility, tack, and drying for one fill. They add variables at scale-up. A bench mix that looked right is not automatically a commercial gel mass. Record the full bill — not “glycerin or equivalent.”

What Can Be Filled Into a Softgel?

Softgel fill materials are a second BOM. The shell does not become the active.

An oil solution means the named active is dissolved in a lipid. A suspension means micronized solids in a carrier because they will not fully dissolve — powder dumped into oil is not a solution. A semi-solid or paste still has to pump and seal; viscosity is part of composition. Delayed-release, dual-chamber, and nested units are specialty routes after a standard fill is feasible; advanced softgel technologies owns those files.

Whether a given active should be a solution or a suspension is oil fill vs suspension softgels. This page only names the classes.

Typical compatible classes — not a promise that every grade will run: fat-soluble vitamins (A, D3, E, K2) as oil solutions; carotenoids as oil solutions or suspensions depending on chemical form; CoQ10 and similar poorly soluble lipids, often as a suspension; botanical oils as solutions; marine or algal lipids when the brief is that oil file, not a second factory type.

For example, vitamin D3 in a lipid carrier is often an oil solution in a gelatin ribbon, with an amber or opaque pack when light is in the file — a standard commercial route when the oil and gel mass are named.

By contrast, curcumin often will not fully dissolve in the intended oil. The path is usually a suspension, then compatibility review (viscosity, particle size, seam), then a pilot batch — not “add powder to oil and quote.”

Can powder go into a softgel? Only as a designed suspension (particle size, viscosity, assay vs weight), or not at all. Dry botanical powders belong in a two-piece capsule unless an oil twin is in scope.

Can probiotics go into a softgel? Not as a default oil oval. Ribbon moisture, encapsulation heat, and gastric opening are a specialty file (often delayed-release plus a named viability spec). “Probiotic softgel” is not a synonym for gelatin plus oil.

The ribbon is a plasticized hydrophilic film around a lipid fill. High water-activity bulks, alcohol-heavy systems, strongly acidic or alkaline fills, and highly volatile essential oils fight that film. Uncontrolled oxidizers in an oil fill are a fill-and-pack problem the shell still has to survive. “Not this format” is a composition verdict, not a health claim about the ingredient.

Why HPMC Cannot Be the Softgel Ribbon

HPMC (hypromellose) is dipped into empty two-piece shells. A vegetarian softgel uses a plant-gel ribbon on a rotary die. “HPMC vegetarian softgel” on an RFQ names the wrong polymer, the wrong machine, and the wrong moisture and plasticizer file.

Dry powder plus vegetarian usually means an HPMC hard capsule. Oil plus vegetarian means a named starch, pectin, or carrageenan (or other plant-gel) softgel grade.

Before You Specify Softgel Materials

These substitutions show up on RFQs and waste the first review:

• Fish gelatin = fish oil. Fish-gelatin is a shell source. The fill is a separate oil or suspension file.
• Vegetarian = HPMC. HPMC is a two-piece capsule polymer. Vegetarian softgels are plant-gel ribbons.
• Oil fill = any oil. Viscosity, oxidation, and ribbon compatibility are named to the oil you will run.
• Powder = softgel. Unformulated powder is not a rotary-die fill. Suspension is a designed path, or the format should change.
• Clear shell = better quality. Clear shows the fill; it does not upgrade the polymer. Light-sensitive oils often need opaque or amber.

Who Reads Shell Composition

Brand owner — what the label may say (vegetarian, Halal, Kosher, “marine gelatin”) versus what the BOM can prove.
Formulator — whether the active is a solution or a suspension, and whether the ribbon chemistry will survive that fill.
Procurement — named gelatin source or plant-gel system, CoA fields, and that fish-gelatin is a qualification path, not a commodity swap.
Regulatory — destination-market additive rules (including opacifiers), certificates that match the actual shell, and that a gelatin CoA is not a finished-product CoA. [2]

Composition Problems That Show Up Later

Plasticizer imbalance, a fill the named ribbon cannot hold, an incomplete weld on an unspecified film, over-dry or under-dry endpoint, and reactive fills that can reduce gelatin solubility over time — these start as composition or process files and show up as leak, cross-linking, or migration. Diagnosis: why softgels leak.

A low-barrier bottle can look like a shell-formula failure. Pack and headspace belong in the same RFQ.

How Shell Composition Meets Rotary-Die Encapsulation

Gel mass must be castable; fill must be injectable; the die must weld the film; drying must hit an endpoint. Step order, wedge, and scale-up: how softgels are made.

Shell thickness, shell weight, and fill-to-shell ratio are die- and gel-mass-dependent. Residual moisture is the drying endpoint on the CoA / in-process file for that SKU. Do not freeze artwork on a catalog milliliter or a blog “typical 0.3 mm.”

How to Specify Softgel Materials in an OEM RFQ

Send what you have:

• Active list and chemical forms (not only consumer names)
• Target amount per softgel and per serving
• Oil solution, suspension, or “recommend”
• Shell preference: gelatin (source if known), vegetarian system, or “recommend”
• Vegetarian / vegan / Halal / Kosher claims that must be true on the BOM
• Color, clear vs opaque, TiO₂-free if the market file requires it
• Packaging intent (bottle, blister, bulk)
• Target market
• Expected MOQ or volume band
• Known stability or leak concerns; incumbent sample optional

Incomplete RFQ: “Vitamin D3 2000 IU.”
Usable RFQ: Vitamin D3 2000 IU as an oil solution; gelatin ribbon; Halal file required; amber bottle; US market.

Questions we ask before quoting

Before quotation, the formulation team normally confirms:

• Is the active oil-soluble, or is a suspension in scope?
• Is the oil (or carrier) oxygen-sensitive, and is that in the pack file?
• Is vegetarian or vegan mandatory on the BOM?
• Is there a named shelf-life target?
• What is the export destination (additive and claim rules sit here)?

During feasibility review the team evaluates shell chemistry, fill compatibility, sealing feasibility, and stability risks — including whether a pilot is required — before a commercial quotation.

If you are still unsure whether the ingredient belongs in a softgel at all, send the ingredient name, target dosage, and target market. Feasibility (standard ribbon vs format change) is decided before shell materials are recommended.

Send the shell intent, fill type, and market file. KS Nutripharma can say whether a standard ribbon path applies — then quote softgel manufacturing from that review.

Request a technical review

Related Softgel Manufacturing Guides

• Oil Fill vs Suspension Softgels
• How Softgels Are Made
• Why Softgels Leak
• Softgel vs Hard Capsule
• How to Read a COA