Sortex cleaning means running pulses or millets through an optical colour sorter after they have been machine cleaned. Cameras view each seed as it falls, and air jets blow out any seed or particle whose colour or shade differs from the good product.
"Sortex" began as a brand name, but in the Indian trade it now means colour-sorted in general. A sortex-cleaned lot usually has higher purity than a lot that was only machine cleaned.
What a colour sorter removes
- Discoloured, black or stained seeds.
- Seeds damaged by insects, mould or heat, where the damage shows on the surface.
- Stones, mud balls and glass that differ in colour from the product.
- Seeds of other crops and weed seeds that look different.
- Immature or shrivelled seeds with a different shade.
What it does not remove
That is why sortex cleaning comes after mechanical cleaning, not instead of it. Sieves, aspirators, de-stoners and gravity tables remove what is different in size or weight. The sorter then removes what is different in colour. The two steps are compared in machine-cleaned versus sortex-cleaned.
- Defects inside the seed, such as a weevil hidden in an intact kernel.
- Foreign seeds or stones of the same colour and size as the product.
- Moisture problems, mould inside the lot or mycotoxins that are not visible.
- Pesticide residues.
- Older crop that looks similar to new crop.
Pulses and millets are different
Pulses such as chickpeas, moong and tur are large enough for sorters to work well, and the colour contrast between good and bad seeds is often clear.
Millets are very small. Sorting them needs machines set up for small seeds, and output is slower. Some millets also vary in natural colour, so the sorter must be tuned not to reject good seed. Ask whether the processor has sorted your type of millet before.
The setting also affects yield. A sorter tuned tightly rejects more good seed along with the bad, which raises the processor's cost. That is why a sortex-cleaned grade usually costs more, and why a cheap "sortex" offer deserves a closer look.
How to specify it
The full set of processing steps is in whether suppliers can clean, sort and polish pulses to your spec.
- Write "sortex cleaned" in the spec, and also set numerical limits for foreign matter, damaged and discoloured seeds.
- Ask how many passes the lot goes through, as a second pass can raise purity.
- Ask to see the sorter running on your lot, not a demonstration on another product.
- Test the finished lot, because the word "sortex" alone guarantees nothing.
How we help
We confirm at the plant that your lot is actually colour sorted and check the result against your purity limits before packing. Ask for a free sourcing review to find processors with the right sorting equipment for your pulse or millet.