What "Sortex Cleaned" Means for Pulses and Spices, and How to Spec It

What optical sorting removes from pulses and spices, what it leaves behind, where it fits in a cleaning line, and how to write a cleaning specification.

This post explains what an optical sorter does to pulses and whole spices, what it cannot do, and how to write a cleaning specification that a supplier can be held to.

"Sortex cleaned" appears on almost every Indian offer for pulses, seeds and whole spices. It is useful shorthand, but it only names a process. It says nothing about the result. Two "sortexed" lots can have very different levels of foreign matter.

Where the word comes from

Sortex is a brand of optical sorting machine made by Bühler. In India, as in many origins, the brand name became the generic word for any optical sorter, much as people say "Xerox" for a photocopy. A "sortex cleaned" lot may have passed through a Bühler machine or through any of several other makes, Indian or Chinese.

What an optical sorter does

The product flows in a thin stream down a chute or belt. As it falls, cameras look at each grain or seed. Software compares what each camera sees with the settings for acceptable product. When a particle falls outside those settings, a short blast of compressed air from an ejector knocks it into a reject stream.

Machines differ in what they "see":

Colour cameras (visible light) detect discolouration: dark, stained, mouldy-looking or off-colour grains, and foreign material of a different colour.
Infrared and near-infrared sensors detect differences in composition. They help separate stones, glass, plastic and some foreign seeds that look the same colour as the product.
Shape and size detection on newer models picks out broken pieces, shrivelled seeds and odd shapes.

Throughput, number of channels and camera resolution vary a great deal between machines. So does how the operator sets the sensitivity.

What sorting typically removes

On pulses and whole spices, a well-set optical sorter will remove a large share of:

Discoloured, black, stained and immature grains
Stones, mud balls and glass that differ in colour or composition
Other grains and weed seeds of a different colour
Visibly insect-damaged or mouldy grains
Husk pieces and stalks of a contrasting colour
In some set-ups, splits from whole pulses, or hulled from un-hulled seed

What sorting does not do

This is the part buyers often miss.

It does not remove residues. Pesticide residues, ethylene oxide and other chemical contaminants are inside or on the product. Sorting does not change them. Residue compliance depends on the source lot and has to be tested in a lab.
It does not sterilise. Salmonella, E. coli and total plate count are unchanged. If you need low microbial counts, ask for steam sterilisation as a separate step.
It does not guarantee mycotoxin levels. Removing discoloured and damaged grains can lower aflatoxin or ochratoxin A, because contamination often concentrates in damaged grains. A lot can still fail a lab test. Sorting supports compliance. Only testing proves it.
It does not remove hidden insects. Eggs and larvae inside an apparently sound grain pass straight through. Fumigation or controlled storage deals with these.
It does not catch look-alikes reliably. Foreign material of the same colour, size and density as the product (some weed seeds, or a cheaper seed used as adulterant) can pass, especially on colour-only machines.
It does not fix moisture, size or dust. Those need drying, grading screens and aspiration.
It is not 100%. Every machine trades off rejection of bad material against loss of good product. A supplier can run tighter settings, or sort twice, but each pass costs yield.

Sortex is one step in a cleaning line

A typical export cleaning line for pulses or whole spices includes:

Pre-cleaner and aspirator: removes dust, light husk and chaff.
Screens or sieve grader: removes oversize and undersize material and grades by size.
Destoner (gravity separator): removes stones and heavy particles by density.
Magnet: removes ferrous metal.
Optical sorter: removes off-colour grains and remaining foreign matter.
Hand picking (for some spices and premium grades): a final visual check on a belt or table.
Metal detection at packing for retail packs.

When an offer says "machine clean", it usually means steps 1 to 4. "Sortex clean" adds step 5. Ask which steps the supplier actually runs.

How to write a cleaning specification

Replace "sortex cleaned" with numbers. A practical cleaning spec covers:

Parameter	How to state it	Example wording
Purity	% by weight of the named product	"Purity min 99.5%"
Foreign matter	% by weight, define it	"Foreign matter (stones, mud, glass, other non-product) max 0.1%"
Extraneous matter	% by weight	"Extraneous plant matter (stalks, husk, leaves) max 0.5%"
Other grains or seeds	% by weight	"Other edible grains max 0.25%"
Discoloured or damaged	% by weight or count	"Damaged and discoloured max 1%"
Insect damage	% by count	"Weevilled max 0.5% by count; no live insects"
Particle size	maximum size of any foreign object	"No foreign object above 2 mm"
Moisture	% max, with method	"Moisture max 10%"
Process	steps required	"Machine cleaned and optically sorted; metal detected at packing"

The European Spice Association's quality minima are a useful reference for spices. They include a 1% extraneous matter ceiling and a rule that no foreign object larger than 2 mm should be present. Many buyers set tighter figures for whole spices headed to grinding or retail.

Add the tests that sorting cannot replace

Pesticide residues against your market's maximum residue limits
Aflatoxins and ochratoxin A where relevant (chillies, nutmeg, some pulses)
Salmonella and microbiology for ready-to-eat use
Pyrrolizidine alkaloids for some seed spices headed to the EU
Heavy metals where your market sets limits

State who tests, at which lab, and whether the result must be in hand before loading or before payment.

Agree how you will measure

Disputes usually come from different sampling. Agree:

Sampling method and sample size per lot
Whether the pre-shipment sample is sealed and retained
An independent surveyor if the value justifies it

Before you order

Ask which cleaning steps are used, not only "sortex"
Put purity, foreign matter and damage limits in numbers
Set a maximum foreign object size
List the lab tests sorting cannot replace
Agree sampling and who holds the counter-sample

If you are buying cleaned pulses or whole spices, send us your cleaning spec, pack size and destination port and we'll come back with a written quote.