How to Qualify a Peppermint Supplier: A Scored Checklist

The Diagnostic Test

Before the scoring framework, run this. It costs one email.

Ask for: "peppermint leaf extract powder, standardised to menthol 40%, by GC."

As explained in our buyer's guide, this specification is physically incoherent — menthol is volatile and drying removes it, so no genuine leaf extract carries it at those levels.

This is the most informative single exchange available on this ingredient, and it happens before you have committed anything.

Three Disqualifying Red Flags

1. Quotes an impossible specification without comment. See above.
2. Cannot fingerprint species against other Mentha. Rosmarinic acid occurs throughout the Lamiaceae, so a supplier relying on assay has no species control — and cornmint is a far larger, cheaper crop.
3. Applies a generic botanical total-ash limit to mint leaf. Indicates they do not know their material; mint leaf runs characteristically high on total ash, and acid-insoluble ash is the informative figure.

The Scoring Framework

Weighted to 100 points. Product-class comprehension carries 20 — a category that exists only for this ingredient, and only because the confusion is so pervasive.

1. Product-Class Comprehension — 20 points

2. Species Identity — 25 points

The last row is a comprehension check. A supplier who volunteers that M. arvensis is the usual substitution risk is engaged with the actual trade; one who has not considered it is relying on their own suppliers' honesty.

3. Assay and Composition — 20 points

4. Ash Logic and Contaminants — 20 points

Pesticide screening earns its weight: mint is grown as a large-scale agricultural crop, predominantly for the oil trade, under commercial agricultural practice. The residue question is live rather than theoretical.

5. Grade Capability and Terms — 15 points

Interpreting the Score

Apply a floor across sections 1 and 2 combined: below 25 of 45, decline. Those two sections cover the only two things that genuinely go wrong with peppermint — wrong product class and wrong species.

The Sample Stage

• Smell it. The most useful check on this ingredient. A genuine leaf extract is mildly minty. Strongly aromatic powder indicates oil-loading rather than extraction.
• Dissolve it. The leaf extract should dissolve in water. An oil-loaded powder disperses but leaves an oily film or clouding.
• Check the CoA states product class and menthol. Absent on the sample, absent on bulk.
• Ask for the fingerprint chromatogram, not just the assay number.
• Check colour. Light green to off-white; unusually pale suggests bulking, though allow for light-faded stock.
• Did they ask what format you are making? The whole peppermint purchase turns on that, so a supplier who does not ask is not advising you.

First-Order Protocol

1. Nominate an independent laboratory — Eurofins, SGS or Intertek — with species fingerprinting in the scope, not rosmarinic acid alone. An independent assay would be satisfied by cornmint.
2. Ask for menthol independently as a product-class confirmation.
3. Verify pesticide residues against EU MRL on first order.
4. Retain a sealed, dated sample, stored dark given the colour sensitivity.
5. Re-verify at batch three, then annually, and on any change of growing region — mint fields can drift between Mentha species over time.

SV Botanica declares the product class on every peppermint batch, confirms species by HPLC fingerprint against authentic Mentha × piperita reference material, reports menthol by GC, and applies the ash logic appropriate to mint leaf. Buyer-nominated third-party pre-shipment testing is welcome. See the product page, the buyer's guide, or adulteration and authenticity.