Documentation & responsible buying
Reading a Matcha Certificate of Analysis
A certificate of analysis (CoA) is a laboratory report on one specific batch: what was measured, by which lab, with which method, and with what result against a limit. A CoA only tells you something about your stock if the batch on the report matches the batch you received, the lab is competent for that test, and the date is recent enough to be relevant. This guide walks through the typical sections and gives you a checklist for reading one when a supplier sends it.
What a CoA is, and what it is not
A CoA reports measurements. It is not a specification sheet, which describes what a product is meant to be, and it is not a certificate in the sense of a scheme certificate, which says a business is inspected against a standard. The word "certificate" in the name can mislead; the value lies entirely in the lab, the method and the batch link.
Not every supplier commissions batch analyses, and not every batch has one. Which documents to ask for in the first place is covered in what buyers can request from a matcha supplier.
Typical sections
Layouts vary by laboratory, but a usable CoA contains most of the following.
| Section | What it should show | What to check |
|---|---|---|
| Laboratory details | Name, address, accreditation body and number | Is the lab named? Is accreditation stated and checkable? |
| Report number and date | Unique report ID, date issued, date of analysis | Is it dated? Is it recent relative to the batch? |
| Client and sample | Who submitted it; product name; sample description | Does the product name match what you buy? |
| Batch or lot identification | Batch or lot number of the sample tested | Does it match the batch on your delivery or paperwork? |
| Sampling information | Who took the sample, when, and how | Was it sampled from the batch, or sent in by the client? |
| Parameters tested | The list of what was measured | Are the parameters relevant to your question? |
| Methods | Method reference for each parameter | Is each method named? |
| Results | Measured value with unit | Are units given? Are "below detection" results shown with the limit? |
| Limits or specification | The limit the result is compared against | Which limit: legal, customer, or supplier's own? |
| Accreditation marking | Which tests are within the lab's accredited scope | Are the tests you care about inside that scope? |
| Signature or authorisation | Name and role of the person releasing the report | Is it authorised, not a draft? |
How to judge the laboratory
Accreditation and scope
Testing laboratories can be accredited to ISO/IEC 17025, the international standard setting out general requirements for the competence of testing and calibration laboratories. ISO notes that accreditation bodies use it as the criteria for assessing labs (ISO). Accreditation is granted for a defined scope: specific tests, on specific materials, with specific methods.
That scope is the important part. A lab can be accredited for some tests and not others. Look for a mark or note on the report showing which results fall within the accredited scope, then check the accreditation body's public register if the result matters to your decision.
Independence
Note whether the report comes from an external laboratory or from a supplier's in-house lab. Both can be useful, but for anything you would repeat to a customer or inspector, an external report with a clear accreditation reference carries more weight.
Batch match and date
This is where most CoAs fail as evidence.
- Batch match: the batch or lot number on the report should match the batch you received. A CoA for a different batch tells you about that batch only. If your bag does not show a batch number, ask the supplier how the report links to your delivery.
- Date of analysis: compare it with the production or delivery date. An old report for a long-sold batch does not describe current stock.
- Sample description: check the product name is the same product, not a related grade or a blend.
Reading results without overreaching
A result describes the sample tested under the method stated. It does not describe every bag, and it does not support a marketing claim on its own. In particular, a CoA showing a substance below a detection limit does not entitle you to make a "free from" claim on your menu. If you are thinking about claims, read how to verify a scheme claim and its certificate first; scheme claims depend on certification, not on a single test.
Watch for these warning signs, several of which also appear in red flags when buying bulk matcha:
- No laboratory name, or no accreditation reference
- No batch or lot number, or one that matches nothing you received
- No date, or a date years before the batch you bought
- Results without units or methods
- A report that looks edited, cropped or retyped
- The same report sent for every batch
CoA reading checklist
Use this each time you receive a CoA.
- [ ] Laboratory named, with accreditation body and number
- [ ] Tests you rely on fall within the accredited scope
- [ ] Report number, issue date and analysis date present
- [ ] Product name matches the product you buy
- [ ] Batch or lot number matches your delivery or paperwork
- [ ] Each parameter has a method, a result with unit, and a limit
- [ ] It is clear which limit is used (legal, customer or supplier)
- [ ] Report is signed or authorised
- [ ] Filed with the delivery record for that batch
Recording the CoA
File every CoA against the delivery it relates to, so you can find it from a batch number or a delivery date. A simple batch log is described in traceability and batch records.
Asking Yumi
Which documentation is available can differ by product and batch, for Ceremonial Barista Matcha as for Ceremonial Matcha. Rather than assume a CoA exists, ask us which documentation is available for the current batch through the contact page, and say what you need it for so we can answer precisely.
Next step
Save the checklist into your QA file and use it for every supplier report you receive. If you are evaluating Yumi, contact us with your documentation questions before your first order.