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Dried Herbs Processing PLANT

Dried herbs process differently from seed spices in one fundamental way — their fibrous, leafy cell structure resists impact milling and requires clean cutting action instead. Attempting to impact-grind kasuri methi or curry leaves in a standard hammer mill produces a mix of fine dust, partially ground fibres and intact cell debris that does not sift to a uniform particle size and loses most of its colour and aroma in the process. The cutter mill — not the hammer mill — is the correct primary size reduction tool for dried leaf herbs, and the distinction matters significantly for both product quality and equipment life.

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All Process Solutions

Cut — not impact — milling for leaves

Green colour retention priority

Low-heat aroma-protective processing

The various colorful spices at the spice bazaar
CHILLI VARIETIES WE can help you PROCESS
Eight herb categories, distinct processing requirements each
Dried herbs vary in leaf structure, moisture sensitivity, stalk-to-leaf ratio, volatile oil content and how easily the cell wall fractures. These differences determine whether a cutter mill, hammer mill or a combination approach is used — and at what moisture level the herb should enter the line.

Kasuri Methi (Fenugreek Leaf)

India's highest-volume dried herb. Small, brittle leaf with strong fenugreek aroma. Stalk-to-leaf separation critical for premium grades. Fibrous stalk requires different cut configuration from soft leaf.

Mint (Pudina)

High volatile oil content — menthol and menthone are extremely heat-sensitive. Deep green colour is a primary quality indicator. Requires the lowest processing temperature of all common dried herbs.

Curry Leaves (Kadi Patta)

Waxy leaf surface resists grinding. Characteristic citrus-curry aroma from carbazole alkaloids and terpene compounds. Small, oval leaf — requires fine screen configuration for consistent particle size.

Coriander Leaf (Dhania Patti)

Soft, fragile leaf with high volatile oil. Distinct from coriander seed in both structure and flavour profile. Very sensitive to heat — loses characteristic fresh-herb aroma rapidly above 50°C.

Holy Basil (Tulsi)

Strong eugenol and methyl eugenol volatile oil. Both culinary and medicinal applications. Stalk is substantially harder than leaf — grade separation required before processing for premium leaf powder.

Moringa (Drumstick Leaf)

Increasingly specified for nutraceutical applications. Fine powder required (80 mesh+). High protein and iron content. Processing temperature critical — bioactive compounds degrade above 60°C.

Bay Leaf (Tej Patta)

Stiff, leathery leaf with thick central midrib. Requires different cutter configuration from soft herbs. Used in biryanis, stocks and masala blends. Midrib removal improves powder quality.

Dried Spinach / Greens

Thin, fragile leaf with high chlorophyll content. Colour is the primary quality indicator — any yellowing or browning during processing is a rejection risk. Very low processing temperature required.

OUTPUT PRODUCT FORMS
What the processing line produces

Dried herb lines produce multiple output forms from the same incoming material. Each form requires a different exit point from the processing sequence and different equipment between drying and packing.

Whole / Rubbed

Hand-rubbed or loosely broken leaf
Minimal processing — dried leaf loosely broken to reduce volume without significant size reduction. Used in retail tea and herb packs where visual leaf character is required.

Cut (Coarse)

3–8mm cut herb pieces
Cutter mill to 3–8mm with stalk separation by sifting. Standard for foodservice kasuri methi, restaurant-grade dried herbs and herb tea blends. Colour retention is critical at this grade.

Granules

1–3mm fine cut granules
Finer cut for masala blends, snack seasonings and instant food applications. Requires two-stage cutting for consistency. Sifting removes stalk fragments that create texture defects at this size.

Powder

40–80 mesh fine powder
Full powder for spice blends, health supplements and industrial food applications. The most temperature-sensitive grade — volatile oil loss at the mill is the primary quality risk. Enclosed processing and low-heat mill configuration essential.

HOW IT WORKS
The dried herb processing line, stage by stage

Green colour and volatile aroma are lost cumulatively — each stage adds heat, mechanical stress or air exposure. The line must be designed to minimise these at every step, not just at the milling stage.

STEP 1
Intake & Inspection
Moisture checked — intake moisture should be 8–12%
STEP 2
Cleaning & Aspiration
Dust, stones and foreign material removed before processing
STEP 3
Stalk Separation
Sieve or air separation to remove coarse stalks from leaf fraction
STEP 4
Pasteurization
Sub-80°C steam — microbial reduction with minimum colour impact
STEP 5
Post-Pasteurization Drying
FBD at low temperature — returns herb to target moisture
STEP 6
Cutter Mill
Clean-cut size reduction to target particle — not impact milling
STEP 7
Sifting & Grading
Grade separation — stalk fragments removed from leaf fraction
STEP 8
Blending (Optional)
Batch blending for colour or aroma specification consistency
STEP 9
Packing
Sealed packing — moisture barrier, minimised dwell time post-process
KEY QUALITY PARAMETERS
What buyers actually specify
Dried herb quality is primarily visual and aromatic — buyers specify colour grade, particle size and aroma before they specify moisture. The processing line determines all three.

Colour — Green Retention

Vivid green to olive green — yellowing = rejection
Green colour in dried herbs comes from chlorophyll, which degrades to pheophytin (yellowish-olive) when exposed to heat, acid or prolonged storage. Processing temperatures above 60°C accelerate chlorophyll degradation measurably. Buyers of premium kasuri methi, mint and curry leaf powder specify colour visually — any yellowing relative to a reference sample triggers rejection before moisture or particle size is even checked.

Aroma Intensity

Herb-specific — assessed against reference standard
Herb aroma comes from volatile compounds stored in surface glandular trichomes — the tiny oil-bearing structures on leaf surfaces. Drying temperatures higher than 60°C result in the loss of most volatile compounds in dried herbs. Impact milling at high speed compounds this by releasing oil simultaneously from thousands of cells and exposing it directly to heat at the mill chamber surface. Aroma is evaluated against a buyer's reference sample — weaker aroma than reference is a quality failure even if all measurable parameters pass.

Particle Size / Cut Specification

Coarse: 3–8mm; Granule: 1–3mm; Powder: 40–80 mesh
Herb particle size specification is application-driven. Cut grades are specified in millimetres — they are evaluated by visual inspection and mesh separation. Powder grades are specified by mesh size. For both, consistency within the specified range matters as much as the mean particle size — a broad distribution produces visible texture variation in the finished application and uneven flavour release.

Moisture Content

Specification: typically 8–10% max for cut herbs
Dried herb moisture specification is higher than for spice powders — the cell structure tolerates some retained moisture without caking risk. However, moisture above 10–12% increases microbial activity and reduces shelf life. The recommended moisture level of the process line input is around 8–12% — above this range the herb becomes tough rather than brittle and the cutter mill generates more fines and heat during size reduction.

Stalk Content

Premium grades: stalk <3% by weight
Stalk material in kasuri methi and other leaf herbs dilutes aroma, contributes woody texture and degrades the visual appearance of the powder or cut herb. Premium export grades of kasuri methi and mint specify low stalk content — which requires effective stalk separation before and after size reduction. Stalks and leaves have different hardnesses and require different screen sizes to separate after cutting, which is why multi-deck sifting is essential on premium herb lines.

Microbial Count

EU/US: Salmonella absent; TPC <10⁵ CFU/g
Field-dried herbs carry microbial contamination from soil contact and open drying. Export market microbial requirements apply to dried herbs as they do to spices. For green herbs, full HTST sterilization at 102°C+ is not appropriate — the temperature causes irreversible chlorophyll degradation and colour loss. Low-temperature steam pasteurization below 80°C achieves export microbial compliance while preserving the green colour that defines premium herb quality.

EQUIPMENT BY PROCESS STAGE
Machines MillNest deploys on this line
Dried herb processing lines are built around three principles: clean cutting over impact, low temperature throughout, and stalk-leaf separation at multiple points in the sequence.Each row below pairs a process solution with the specific equipment used in fertilizer powder applications. Click either side to go deeper.
Stage 1 — Cleaning & Stalk Separation

Foreign material removal and leaf-stalk grade separation

Dried herbs arrive with varying ratios of leaf to stalk depending on the harvesting and drying method. Stalk material processes differently from leaf in the cutter mill — it is harder and more fibrous, produces a different particle size and reduces the aroma and colour quality of the finished cut herb or powder. Aspiration at intake removes lightweight dust and foreign material. Initial sieve separation divides coarse stalk fraction from the more uniform leaf fraction before the material enters the cutter mill. For premium kasuri methi grades, this pre-separation is the step that most directly affects the finished product colour and aroma — more stalk content at this stage means lower quality at every subsequent step.
View De-Dusting & Filtration Solutions
Equipment at this stage
ASPR

Aspirator

Air separation of dust, fine foreign material and lightweight impurities before herb enters the processing line

SIFT

Vibro Sifter (pre-separation)

Coarse stalk separation from leaf fraction before cutter mill — reduces stalk content in the finished product

Stage 2 — Low-Temperature Pasteurization

Export microbial compliance with colour preservation

Green dried herbs are among the most temperature-sensitive materials in any food processing line. Full HTST sterilization at 102–122°C causes visible chlorophyll degradation — the green colour shifts to olive or yellow within the treatment time, and this colour change cannot be reversed by any downstream processing step. MillNest deploys TEMA Process B.V. steam pasteurization at temperatures below 80°C for green herb applications — below the threshold where chlorophyll degradation becomes visible, while still achieving the Salmonella absence and TPC reduction required for EU and US export compliance. Treatment time and temperature are confirmed from the actual incoming microbial count of the herb batch, not set as a fixed programme.
View Pasteurization Solution
Equipment at this stage
HTST

Natural Steam Sterilizer

Sub-80°C treatment for green herbs — export microbial compliance without chlorophyll degradation or colour loss

FBD

Fluid Bed Dryer

Post-pasteurization moisture removal at reduced air temperature — critical for green colour preservation

Stage 3 — Cutter Mill Size Reduction

Clean-cut size reduction that preserves leaf structure and colour

The cutter mill is the correct primary size reduction tool for dried leaf herbs — not the hammer mill. The MCUT’s rotating and stationary blade geometry produces a scissor-like cutting action on the leaf material, slicing through fibrous cell walls cleanly to produce a uniform particle size without the dust, fibre tearing or volatile oil release that impact milling causes in the same material. Screen aperture determines the output size — interchangeable screens allow the same mill to produce 3–8mm coarse cut, 1–3mm granule or 40-mesh powder from the same herb in successive runs with a screen change. Screen selection is confirmed by trial on the specific herb variety, as hardness and fibre content differ between kasuri methi, mint, curry leaf and bay leaf. For fine powder grades (60–80 mesh), a secondary hammer mill pass after the cutter mill may be required — at reduced speed with inter-stage cooling to protect volatile oil.
View MCUT Cutter Mill
Equipment at this stage
MCUT

Cutter Mill

Primary size reduction for all dried leaf herbs — clean-cut blade action, interchangeable screens for all output grades

MHAM

Hammer Mill (secondary, fine powder only)

Secondary fine powder pass for 60–80 mesh grades — reduced speed, inter-stage cooling after cutter mill

Stage 4 — Sifting, Blending & Packing

Grade separation and colour-standardised blending

Post-cutting sifting on a multi-deck sifter simultaneously separates on-spec cut leaf, undersize fines and oversize stalk fragments. The fines from herb cutting have lower aroma and colour intensity than the larger cut particles — their separation and routing to a lower grade or separate product stream is part of maximising the yield of premium grade material. For export contracts specifying colour against a buyer’s reference standard, ribbon blending of different crop-date batches to colour specification is standard practice on commercial herb lines. Prompt sealed packing after blending minimises re-absorption of atmospheric moisture and slows continued chlorophyll degradation in the finished pack.

View MRBL Ribbon Blender
Equipment at this stage
SIFT

Multi-Deck Vibro Sifter

Grade separation of cut leaf, stalk fragments and fines — multiple output grades from a single sifting pass

MRBL

Ribbon Blender

Crop-batch colour blending for export specification compliance — sealed discharge directly to packing

Transform Fresh Herbs into Premium-Quality Dried Products.

Preserve the natural aroma, flavor, color, and nutritional value of your herbs with our advanced drying and processing solutions. From harvesting to hygienic packaging, we ensure every step meets the highest quality standards. Partner with us to deliver consistent, market-ready dried herbs that customers trust.

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