A certificate of analysis is the document importers, retailers and manufacturers rely on most, and the one most often accepted without being read. Japanese suppliers vary widely: some provide a full lab report per lot; others send a generic “typical values” sheet once a year. Knowing what a COA should contain lets you ask for the right one.
01 · Identity
First, check what the report is about
- Lot number on the COA matches the lot you are buying, and the same number appears on packaging and shipping documents
- Sample date and test date, and the harvest or milling date if given
- Laboratory: the supplier’s in-house lab, or an external accredited laboratory
- Product name and grade as on the specification
A report without a lot number is a product datasheet, not a certificate for your shipment. Both have uses; do not confuse them. Matcha supplier documents explains the difference between spec sheets, COAs and certifications.
02 · Test items
Typical test items on a matcha COA
| Category | Typical items | What to check |
|---|---|---|
| Physical | Moisture, particle size, color, foreign matter | Against your specification |
| Microbiological | Total viable count, coliforms, E. coli, Salmonella, moulds and yeasts | Method and limits stated; “not detected” with a detection limit |
| Heavy metals | Lead, cadmium, arsenic, mercury | Units (mg/kg or ppm) and limits for your market |
| Pesticide residues | Multi-residue screen | Number of compounds screened and detection limits; see pesticide residues and matcha exports |
| Radioactivity | Cesium-134/137 where requested | Requirements have relaxed in many markets; check current rules |
| Allergens / GMO | Statements rather than tests | Usually a declaration |
Not every buyer needs every item on every lot. Agree a per-lot panel and a periodic panel with the supplier and write it into the specification.
03 · Units and limits
Units, limits and detection limits
- Compare like with like: mg/kg equals ppm; μg/kg equals ppb.
- A result of “not detected” is only meaningful with the limit of detection (LOD) or quantification (LOQ) stated. “ND (LOQ 0.01 mg/kg)” tells you something; “ND” alone does not.
- The limit column on a supplier’s COA is usually the supplier’s or Japan’s limit. Your market’s limit may differ; check against it, not against the supplier’s pass mark.
- Microbiological results depend on method; make sure the method is stated when comparing labs.
A “pass” against one country’s standard is not automatically a pass against another’s. Read the number, then apply your own limit.
04 · Gaps
Common gaps and how to close them
- Typical values instead of lot results: ask for a lot-specific report at least periodically, and per lot for high-risk items in your market
- In-house only: request an external accredited lab report at agreed intervals
- Missing residue coverage: ask how many compounds the screen covers and whether it includes those relevant to tea
- No link to the shipment: insist the lot number is on the report, the bags and the invoice
- Language: Japanese-only reports are fine if you can read the numbers, but ask for an English header at least
05 · Process
Turning it into a routine
Write the agreed panel and frequency into the specification and supply agreement (see what to put in a matcha supply agreement), request the COA with the pre-shipment sample, and file it with the retained sample. If your importer or a customer audits you, that file is what they will ask for.
Our quality and documentation service reviews supplier reports against your market’s requirements and requests missing items from suppliers in Japanese.
06 · FAQ
Frequently asked questions
What is the difference between a COA and a specification sheet?
A specification sheet describes the product’s target values; a certificate of analysis reports test results for a specific lot. Both are useful, but only the lot-numbered COA tells you what was measured on the matcha you are receiving.
How often should I get a COA?
Per lot for new suppliers, strict markets or high-risk items, and periodically once a history is established. Agree the panel and frequency in the specification.
Is a Japanese-language COA acceptable?
Usually the numbers, units and methods are readable, and an English header can be requested. What matters is the lot link, the detection limits and which limits were applied.
Japan-side support
Want a supplier’s test reports checked?
Send us the COA and the specification. We check coverage against your market’s needs, ask the supplier for what is missing and confirm the lot link.
Send your requirements