Buy from a processor you have checked, against a written spec that names the adulterants you are worried about, and test a sample drawn by your own person from the actual lot. Buying whole spices rather than powder, where you can, also makes adulteration much harder to hide.
Adulteration is usually done for weight or appearance. Testing finds most of it, but only if you test for the right things on a sample the supplier did not choose.
What adulteration looks like
The methods vary by product, but they fall into a few groups.
- Added starch or flour, often in powders, to add weight.
- Added colour, to make a dull or old product look fresh.
- Extraneous seeds or plant parts that look similar to the real spice.
- Exhausted spice: material that has had its essential oil extracted, then mixed back into good product.
- Excess stalks, husk, sand or dust left in to add weight.
Why powders carry more risk
In a whole spice, a foreign seed or a stone is visible. In a powder, everything looks the same. That is why ground spices carry more risk than whole ones.
If you need powder, consider buying whole and having it ground under your control, or buy powder only from a processor whose grinding you have seen. Ask whether they grind their own cleaned raw material or buy powder from someone else.
Put it in the specification
A spec that only lists moisture and purity leaves room for many adulterants. Add parameters that reveal them. Which ones you need depends on the spice, so ask your lab for advice on the product. Our guide to writing an agri product specification covers the structure.
- Volatile oil content, which falls when exhausted spice is mixed in.
- Total ash and acid insoluble ash, which rise with sand and soil.
- Tests for starch and for added or non-permitted colours where relevant.
- Microscopy to identify foreign plant material in powders.
- A plain statement that the product is free from added colour, starch and foreign material.
Control the sample and the supplier
- Visit the plant, or have someone do it, to confirm the supplier processes the product. See how to tell a trader from a processor.
- Have samples drawn from stock and sealed by someone working for you.
- Test at an accredited lab and have the report sent to you directly.
- Test the pre-shipment lot, not only the first approval sample.
- Keep a sealed counter-sample from every shipment.
- Keep testing on repeat orders. Adulteration often appears once a buyer stops checking.
Watch the price
A quote well below the market for the same grade is a warning. Real spice at a given quality has a cost that follows the local market. If someone undercuts that cost, the difference has to come from somewhere, and it is often the product.
Compare like with like before you judge. Ask each supplier for the same grade, the same cleaning level and the same pack, so a lower quote cannot hide a lower spec.
How we help
We audit the processor's plant, write adulteration checks into the spec, and draw sealed samples from the lot for testing at an NABL-accredited lab, with the original report shared with you. Ask for a free sourcing review.