No single test proves ashwagandha powder is root only. The usual approach combines microscopy, a chromatographic fingerprint compared with authenticated root, and a look at the withanolide profile, since leaf is generally richer in withaferin A.
Testing should be backed by checks at the mill. Seeing the raw roots, and the absence of leaf, tells you a lot.
Why leaf gets mixed in
Leaf is cheaper and easy to collect at harvest. Adding it can raise a total withanolide result while changing the product. Stems and aerial parts can also enter through careless cleaning. Root only is what most buyers and labels claim, so a mixed product is a compliance and trust problem.
The risk is highest with powder. Once root and leaf are milled together, they cannot be separated, and a small share of leaf is hard to see. That is why checks before milling matter as much as tests afterwards.
Tests that help
Ask the lab which tests they can do for this purpose and how they interpret them. Methods vary between labs. See what HPTLC is and botanical identity testing.
- Visual and colour check: root powder is usually creamy beige to light brown. A green tint suggests leaf.
- Microscopy: a trained analyst can see leaf structures such as hairs, stomata and leaf tissue that root does not have.
- HPTLC fingerprint: the sample is run alongside authenticated root and leaf reference material. Extra bands typical of leaf are a warning.
- HPLC withanolide profile: a high withaferin A share relative to other withanolides can indicate leaf.
Checks at the supplier
- Visit the mill and see the roots before milling. Leaf in the store is a warning.
- Ask for photos or a sample of the raw root lot used for your order.
- Check whether the mill also processes leaf, and how lines are cleaned between products.
- Ask for the supplier's own identity tests on each lot.
- Keep a retained sample of each shipment for later testing.
Put it in the contract
State root only, the botanical name and the identity test that will be used for acceptance. Agree what happens if a lot fails, including replacement or refund. A written spec makes a claim far easier. Our guide on using your own lab results to reject a shipment explains how to make results count.
Warning signs
- Root powder offered with a total withanolide figure far above other suppliers.
- A greenish or uneven colour in the powder.
- A supplier who will not show the raw roots or the mill.
- Certificates that do not name the plant part.
- Large price gaps that the supplier cannot explain by grade or season.
- Identity results on the brochure, but none for your lot.
How Creston & Co helps
We inspect the root stock at the mill, draw samples ourselves and have identity and withanolide profiles tested at NABL-accredited labs before shipment. Start with a free sourcing review.