How to Read a Turmeric Certificate of Analysis (COA)

A Certificate of Analysis (COA) is the single most important document in a turmeric purchase — it's the batch-specific proof of what you're actually buying, as opposed to general commercial descriptions. Yet many first-time importers aren't sure how to interpret every line. Here's what each parameter means and why it matters.

Curcumin content (HPLC)

This is the headline number — the percentage of curcuminoids in the sample, measured by High-Performance Liquid Chromatography (HPLC), the industry-standard analytical method. Commercial-grade turmeric powder typically ranges from 2–3% on the low end up to 6.5%+ for high-curcumin standardized lots. Extraction and pharmaceutical buyers usually specify a minimum threshold (e.g. 5%+); food and seasoning buyers often accept a broader range. Always check that the COA specifies HPLC as the test method — some suppliers quote curcumin content from less rigorous colorimetric methods, which tend to overstate the figure.

Moisture content

Expressed as a maximum percentage (typically ≤9% for turmeric powder), this measures residual water content. Higher moisture increases the risk of microbial growth and mold during storage and transit, and effectively dilutes the active curcumin content per kilogram. A COA showing moisture near or above the stated maximum is worth querying before shipment, not after.

Total ash and acid-insoluble ash

Total ash measures the mineral residue left after incineration — a general indicator of purity, since excessive ash can signal contamination with soil or extraneous mineral matter. Acid-insoluble ash is more specific: it isolates the silica/sand fraction that doesn't dissolve in dilute acid, directly indicating whether the turmeric was adequately cleaned before processing. Typical limits are ≤6.5% total ash and ≤1.0% acid-insoluble ash — a COA well outside these ranges points to inadequate post-harvest cleaning.

Heavy metals (Pb, As, Cd, Hg)

Lead, arsenic, cadmium, and mercury are tested because turmeric, like many root crops, can accumulate heavy metals from soil — a known regulatory concern, particularly for the US and EU markets which have tightened turmeric heavy-metal limits in recent years. A compliant COA states results against a named standard (e.g. EU or US Pharmacopeia limits), not just "within limits" without a reference standard — always ask which threshold was applied.

Granulometry (mesh size)

This describes powder fineness — commonly 60–80 mesh for standard turmeric powder, finer for specialty applications. Mesh size affects solubility, blend uniformity in formulations, and visual texture; it's a processing specification rather than a purity indicator, but still worth matching to your intended use.

Microbiological testing

Not always on a basic COA but standard for food-grade shipments — tests for Salmonella, E. coli, and total plate count. If your end market requires food safety certification (FSSAI, EU food law, US FDA), confirm microbiological results are included before the order ships, not after.

What a trustworthy COA looks like

• Batch or lot number that matches the physical shipment, not a generic template
• Named testing laboratory (accredited, third-party where possible — e.g. SGS, Eurofins, Spices Board-approved labs)
• Test method specified for each parameter (especially HPLC for curcumin)
• Reference standard cited for heavy metal limits (EU, US Pharmacopeia, or destination-country specific)
• Issue date close to the shipment date — an old or undated COA is not reliable evidence for a current batch

Every export lot from Crossway Global is tested at an accredited third-party laboratory, with a batch-specific COA issued prior to dispatch and shared with buyers before final payment is due.