Hulls - Walnut
Hulls - Walnut
Mechotech designs and manufactures turnkey natural colour extraction plants for walnut hulls. In the Mechotech catalogue, walnut hulls are listed in both the Brown Colour group and the Grey to Black Colour group. Mechotech’s articles describe the colour as juglone, a naphthoquinone pigment, together with tannins from the green outer husk of Juglans regia and related species; the extract gives brown on its own and shifts toward grey and black with iron.
Mechotech’s walnut hulls plant is configured around the juglone and tannin pigments and the target colour extract. It is built in SS 316L with integrated solvent recovery, automation and full documentation, and is delivered as a commissioned turnkey system. Extraction is typically water-based, with mild alkali or controlled oxidation used to deepen the shade; the route and shade control are established during process development and pilot validation.
Technical Specifications
| Product | Hulls - Walnut Natural Colour Extraction Plant |
|---|---|
| Botanical Name | Juglans regia and related species, as named in Mechotech’s articles |
| Raw Material | Walnut hulls (green outer husk) |
| Plant Part / Feed Form | Hulls; green or blackened hulls give the strongest colour, and dried hulls are soaked and lightly crushed (exact feed form confirmed with the client) |
| Colour Group | Brown Colour and Grey to Black Colour |
| Pigment Class | Juglone (naphthoquinone) and tannins |
| Extract Type | Natural colour extract (liquid concentrate or dried powder, per specification) |
| Extraction Method | Closed jacketed SS 316L extraction with food-grade solvent (alcohol / aqueous), multiple cycles at controlled temperature |
| Product-contact Material | SS 316L |
| Filtration System | Plate-and-frame filter press with cartridge polish filters |
| Concentration System | Falling-film / vacuum evaporator with solvent recovery |
| Drying System | Spray or vacuum dryer |
| Automation | PLC-based |
| Plant Capacity | Configured to requirement |
| Utility Requirements | Steam, chilled/cooling water, compressed air and power (project-specific) |
| Compliance | GMP hygienic design; full documentation for qualification |
| Final Product Form | Natural colour extract (brown; grey-to-black with iron development) |
Plant Capacities
| Plant Scale | Raw Material Throughput | Typical Use |
|---|---|---|
| Pilot | Configured to your feedstock and trial plan | Product development, parameter validation |
| Semi-Commercial | Configured between pilot and commercial scale | Scale-up trials, contract manufacturing |
| Commercial | Configured to raw-material supply and confirmed buyer volume | Commercial production |
Capacity is configured to raw-material supply, confirmed buyer volume and investment timeline; a pilot plant is recommended to validate parameters before scaling.
Manufacturing Process
Raw Material Preparation
Walnut hulls are received and sorted; green or blackened hulls are preferred, and dried hulls are soaked and lightly crushed so fresh surface is exposed for oxidation and diffusion.
Extraction
The prepared hulls are extracted with water or dilute alkali, or with food-grade solvent where the route requires it, in closed jacketed SS 316L extractors over multiple cycles, encouraging the oxidation that deepens the colour.
Filtration
The extract (miscella) is clarified through a plate-and-frame filter press followed by cartridge polish filters.
Concentration & Solvent Recovery
The miscella is concentrated in a falling-film / vacuum evaporator, with solvent recovered through the condenser return system so that heat exposure of the pigment stays low.
Standardisation
The concentrate is assayed for colour strength and adjusted to the declared target specification before the final finishing step.
Drying & Quality Control
The standardised Walnut Hulls extract is spray- or vacuum-dried where a powder is required, then released after the agreed assay, residual-solvent, heavy-metal, microbial and moisture tests.
Major Plant Equipment
- Raw material cleaning and size-reduction system
- Closed jacketed SS 316L extraction vessels
- Solvent storage tanks
- Plate-and-frame filter press
- Cartridge polish filtration
- Falling-film / vacuum evaporator
- Solvent recovery unit and condensers
- Standardisation / blending vessel
- Spray or vacuum dryer
- CIP system
- Automation and instrumentation
Plant Output
Applications
- Natural colour and dye ingredient supply
- Food and beverage colour applications (subject to approval of the specific colour in each market)
- Cosmetic and personal-care colour applications
- Nutraceutical and Ayurvedic / herbal formulations
- Pharmaceutical standardised ingredient supply
Key Features
SS 316L Construction
Electropolished SS 316L product-contact surfaces with CIP operation between batches.
Closed-Loop Solvent Recovery
Integrated condenser-return recovery reuses solvent between batches and reduces solvent loss.
Shade Control by Oxidation and Iron
Oxidation, pH and optional iron development can be used to move the extract from brown toward grey and black, as described in Mechotech’s walnut hull articles.
Standardised to Specification
In-process and batch-release assay are used to check the finished extract against its declared target specification.
Gentle Concentration
Vacuum concentration keeps heat exposure low for temperature-sensitive colour compounds.
Scalable Batch Capacity
Plants are configured to requirement from pilot scale upward, with modular expansion.
Frequently Asked Questions
Does Mechotech supply the complete machinery for Hulls - Walnut?
What specification can the Hulls - Walnut plant achieve?
What production capacities are available for the Hulls - Walnut plant?
Which part of the walnut is processed in this plant?
What gives walnut hulls their colour?
Why is Hulls - Walnut listed in two colour groups?
Which related colour pages does Mechotech list with Hulls - Walnut?
Ready to discuss your project?
Get a free quote and technical consultation from our engineering team.