Manufacturing — Core format
Liquid-filled capsules and dual caps for demanding formulas.
Liquid-filled hard capsules hold oils and liquid actives; dual caps combine two phases in one dose. Both need specialist equipment and experience. We identify the partner suited to your formula and coordinate development, production and release.
The format
Liquid in a hard capsule — and two phases in one.
A liquid-filled hard capsule is a two-piece capsule — HPMC or gelatine — filled with an oil or liquid formulation and sealed so it cannot leak. It is an alternative to a softgel when the brand wants a plant-based shell, a visible fill or a different product presentation.
Dual caps go one step further: a smaller capsule placed inside a larger one, so two formulation phases — for example an oil and a powder — sit in a single dose without mixing. Both are specialist formats offered by a limited number of manufacturers, which makes partner selection central.
- Fills
- Oils and liquid formulations; powder + liquid in dual caps
- Shell
- Two-piece hard capsule, HPMC or gelatine
- Partner selection
- Specialist equipment; capability confirmed per formula
When it fits
Liquid-filled hard capsules vs softgels.
Both hold liquids. The choice depends on shell, fill and positioning.
- Plant-based shell
- HPMC hard capsules give a vegetarian option for liquid fills, where many softgels use gelatine.
- Distinctive presentation
- A visible liquid or two-phase capsule can set a product apart on shelf and online.
- Smaller or specialised runs
- Depending on the partner, hard-capsule liquid filling can suit volumes or formulas a softgel line does not.
- When a softgel is better
- For some oils and high volumes, a softgel remains the more established route — we say so when it is.
Product examples
Formulas suited to liquid fill.
Examples are indicative. Compatibility of the fill with the shell is tested per formula with the selected partner.
- 01
Oil-based supplements
Plant and marine oils delivered without the need to convert them into a powder.
- 02
Lipid-soluble actives
Fat-soluble vitamins and other actives dissolved or suspended in an oil carrier.
- 03
Botanical oils
Seed and botanical oils and oil-based extracts.
- 04
Specialty liquid formulations
Combinations of oils and actives designed for a specific product concept.
Format comparison
Three ways to deliver a liquid.
A simplified comparison. The final choice depends on the formula, positioning and the partner's capabilities.
Liquid-filled hard capsule
- Two-piece HPMC or gelatine shell
- Sealed or banded to prevent leakage
- Visible or opaque liquid fill
Softgel
- One-piece soft shell, often gelatine
- Established route for many oils
- Typically dedicated softgel lines
Dual cap
- Inner capsule within an outer capsule
- Two separate formulation phases
- Specialist equipment and experience
Dual caps
Dual caps: two phases in one capsule.
In a capsule-in-capsule product, a smaller inner capsule is filled and placed inside a larger outer capsule, with the remaining space filled with a second phase. The result is one dose that carries two separate formulations.
Dual caps are a specialist format. Equipment and process experience vary between manufacturers, so feasibility, configuration and documentation are confirmed with the partner early in the project.
Why brands separate two phases.
- Separate incompatible actives
- Keep ingredients that should not be in direct contact in different phases.
- Combine an oil and a powder
- Deliver a liquid and a dry ingredient in a single dose instead of two products.
- Differentiate the product
- A visible capsule-in-capsule presentation communicates a premium, considered formula.
- Simplify the routine
- One capsule instead of two for the consumer, where the doses allow.
Technical considerations
Technical questions to resolve early.
Liquid fills involve more variables than powders. We work through them with the partner before committing to a route.
Fill and shell compatibility
Some liquids interact with the shell. Compatibility is tested with the chosen shell type before scale-up.
Oxidation and stability
Oils can oxidise. Antioxidants, processing conditions and packaging are considered together to protect the product.
Viscosity and fill volume
The fill must be pumpable and sit within the capsule's volume. Viscosity and dose determine capsule size and count.
Sealing and banding
Liquid-filled hard capsules are sealed to prevent leakage. The sealing method depends on the selected partner's equipment.
Dual-cap configuration
Inner and outer capsule sizes, phase volumes and order of filling are defined with the partner.
Partner-dependent variables
MOQ, batch size and lead time.
Specialist formats depend even more on the partner. We explain the drivers and compare real quotes rather than quoting generic numbers.
- 01
Minimum order quantity
Set by the partner's equipment and setup effort, which is higher for liquid and dual-cap filling.
- 02
Batch size
Matched to the fill preparation and the filling line, balanced against forecast and shelf-life.
- 03
Lead time
Includes compatibility and stability work for new formulas, plus raw materials and slots.
- 04
Unit cost
Shaped by fill cost, capsule configuration, sealing and packaging.
Packaging
Packaging and protection.
Oil-based capsules often benefit from packaging that limits light and oxygen exposure. Bottles, jars and blisters are all possible depending on the product and market.
The pack is specified together with the formula and stability considerations, then coordinated with the filling partner.
Quality & documentation
Specification, documentation and release.
Each product is made against a written specification covering the fill, the capsule configuration and finished-product limits. Raw-material documentation and certificates of analysis are reviewed before production, and batches are released against the agreed specification.
Quality systems and certifications are held by the relevant manufacturing partner and checked against the product and market before selection.
Quality framework
Standards represented across our manufacturing partners.
We work with certified specialist manufacturing partners and prioritise partners operating under relevant quality and food-safety standards. Certifications are held by the respective partners; applicability is confirmed for each product and manufacturing route.
Partner standards · where applicable
GMP
Good Manufacturing Practice
ISO 22000
Food safety management
FSSC 22000
Food safety system certification
HACCP
Hazard analysis & critical control points
EKO
Organic certification
Origin signal
Made in EU
Production within our European partner network. A positioning signal — not a certification.
Certifications are held by individual manufacturing partners where applicable. AVENTRO does not itself issue or hold these certifications.
Manufacturer selection
Choosing a specialist partner.
Few manufacturers run liquid-filled hard capsules and fewer run dual caps. We compare on:
- 01
Liquid-fill capability
Equipment and sealing method suited to the fill and the shell.
- 02
Dual-cap experience
Proven capsule-in-capsule production where the concept requires it.
- 03
Formulation support
Ability to test fill compatibility and stability with you.
- 04
Documentation
Quality system and certifications appropriate for the product and market.
- 05
Commercial terms
MOQ, unit cost and lead time compared on one specification.
- 06
Continuity
Capacity for repeat orders in a format with fewer alternative suppliers.
Product route
Custom formulation or an existing formula.
Custom formulation
Your own liquid or dual-phase formula, developed with compatibility and stability in mind before production is placed.
Existing or partner formula
Some partners may offer established liquid-fill formulas. Availability is limited and confirmed per project.
Manufacturing route
From brief to released batch.
- Step 01
Concept
Actives, phases, dose, positioning and volumes.
- Step 02
Feasibility
Format choice and fill/shell compatibility assessed with partners.
- Step 03
Partner comparison
Specialist partners shortlisted and quoted on one specification.
- Step 04
Production
Fill preparation, encapsulation and sealing scheduled with packaging.
- Step 05
Release
Batch released against specification, packed and dispatched.
The AVENTRO role
How we place your liquid-fill product.
AVENTRO is not tied to a single production facility. We define the specification with you, shortlist specialist partners from our European network, compare them on technical and commercial fit, and remain your point of contact from technical transfer to released batch.
Related formats
Other core formats.
Services often combined with it.
Start a project
Have an oil-based or two-phase concept to develop?
RFQs and project briefs: inquiry@aventro.eu