Curcumin, curcuminoids, assay method and the difference between a number on a label and a number you can trust. A buyer's primer.
Walk through any supplement trade show and you will see "Curcumin 95%" on a dozen stands. It sounds simple, but the number hides a few things every formulator and brand owner should understand before they buy — because not every 95% is the same 95%.
Curcuminoids, not just curcumin
The "95%" almost always refers to total curcuminoids — a family of three compounds: curcumin itself, demethoxycurcumin and bisdemethoxycurcumin. A standardised turmeric extract is concentrated and assayed so that total curcuminoids reach a guaranteed figure, commonly 95%. If your specification cares about curcumin alone versus total curcuminoids, say so up front, because the assay and the price both move with it.
The method is half the spec
A percentage means little without the method behind it. Reputable extracts are assayed by HPLC, which separates and measures each curcuminoid precisely. Cheaper material is sometimes quoted on a UV/spectrophotometric basis, which can read higher and looser. When you ask for 95%, ask "by HPLC" in the same breath, and expect a Certificate of Analysis for the actual batch — not a generic spec sheet.
- Total curcuminoids vs curcumin — define which you mean
- Assay by HPLC, with a per-batch CoA
- Heavy metals to USP <232>/<233>, and residual solvent limits
- Extraction solvent and whether a bioavailability form is needed
- Microbial and pesticide screening for your market
Plain 95% or a bioavailability form?
Plain curcumin is poorly absorbed on its own, which is why you will see it paired with black-pepper piperine, or sold as branded bioavailability forms. There is nothing wrong with plain 95% curcuminoids — it is the workhorse for capsules and tablets — but if your product claim leans on absorption, decide that at the formulation stage so the right material is sourced.
The honest part
The figures you see on a catalogue are standard reference data. The real Certificate of Analysis varies a little with the batch and the season's raw material — that is normal and honest. What matters is that the spec is agreed in the contract and confirmed on the CoA for the lot you actually receive. A supplier who writes the number down and tests against it is worth more than one who quotes the highest figure in the room.
Tip: Ask for the CoA and a retained sample from the same batch you buy. If you ever need to defend a label claim, you want the paperwork and the material to match.
Frequently asked questions
When you say 95% curcumin, what does that actually mean?
It means 95% total curcuminoids by HPLC, which is the sum of curcumin, demethoxycurcumin (DMC) and bisdemethoxycurcumin (BDMC) — not curcumin alone. The exact split is indicative and is confirmed on the Certificate of Analysis for each batch.
Do you test by HPLC or UV?
We report the 95% figure by HPLC, which separates and quantifies the three curcuminoids individually; UV tends to over-read because it cannot distinguish them. Every batch CoA carries the HPLC assay.
What about heavy metals?
Heavy metals are tested at an accredited/NABL lab against USP <232>/<233> limits, and the results appear on the per-batch CoA. Curcumin from raw turmeric warrants this check, so we do not skip it.
Do you offer a bioavailability form with piperine?
Yes, we can supply plain 95% curcuminoids or a bioavailability-enhanced version with black pepper extract (piperine, typically standardised 95-98%). Any finished-product or absorption claim is the buyer's responsibility under local regulation; we provide the analytical data, not health claims.
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