Understanding a Matcha COA: Key Parameters Every Buyer Should Check
How to read and interpret a matcha COA. B2B guide to color values, particle size, moisture, heavy metals, pesticide residues, and microbiological limits — with a downloadable QC checklist.
A matcha Certificate of Analysis (COA) is the single most important document in any B2B matcha transaction. It is the laboratory-validated proof that the powder in the bag matches what the supplier promised — and that it is safe, legal, and fit for your market. Yet most buyers skim past it because the format looks intimidating. This guide walks you through every parameter line by line, so you can read a COA like an experienced QC manager and use it as a real sourcing tool, not just a checkbox.
1. What Is a COA — and Why It Matters
A Certificate of Analysis is an official, batch-specific test report issued by the producer (or an independent third-party lab) covering the physical, chemical, and microbiological properties of that exact production lot. It is not a marketing sheet and it is not a generic spec card — it is bound to a lot number, a production date, and a packaging date.
For B2B matcha buyers, a proper COA protects you in four ways:
- Food safety — confirms heavy metals, pesticide residues, and microbiology are within your market's legal limits.
- Customs & import clearance — EU, US, GCC, and most Asia-Pacific regulators can request the COA at the border.
- Product consistency — verifies the matcha in your container actually matches the reference sample you approved.
- Legal defense — if a downstream recall happens, your batch-level COA proves due diligence.
2. Color Values (L*, a*, b*)
Color is the first quality signal buyers notice visually, but on a COA it is expressed numerically using the CIE L*a*b* color space. Three numbers do most of the talking:
| Parameter | What It Measures | Ceremonial / Premium | Culinary / Latte | Industrial |
|---|---|---|---|---|
| L* (lightness) | 0 = black, 100 = white. Matcha falls in the mid range. | 55–65 | 50–60 | 45–55 |
| a* (red/green) | Negative = green. The more negative, the more vivid green. | −18 to −28 | −15 to −22 | −10 to −18 |
| b* (yellow/blue) | Positive = yellow. Lower b* = fresher, more vivid green. | +18 to +28 | +22 to +32 | +25 to +38 |
How to read it in practice: High-grade ceremonial matcha shows a vivid, slightly bluish green. On the report that translates to L* around 55–60, a* strongly negative (around −20 to −25), and b* in the low 20s. If a* is barely negative (say −8) and b* is high (above +35), the powder has oxidized or was shade-grown too briefly — both reduce the antioxidant profile and the sensory quality.
3. Particle Size Distribution
Matcha particle size — typically measured by laser diffraction — controls mouthfeel, foam stability, color release, and dissolution in liquid. The COA usually reports a D50 (median) and sometimes D10 / D90.
| Grade / Use | Typical D50 | What You Will Notice |
|---|---|---|
| Ceremonial (pure drinking) | 5–15 μm | Silky, no grit, stable micro-foam |
| Latte / RTD | 10–30 μm | Smooth in milk, no sinking residue |
| Culinary / baking | 30–60 μm | Visibly fine but with light texture |
| Industrial extraction | 60–149 μm | Coarser mouthfeel, faster extraction in hot water |
Anything above 149 μm (100 mesh) is no longer "matcha" by international trade definition — it is classified as "green tea powder". Some suppliers blur this line. Your COA should declare the D50, the measurement method (laser diffraction vs sieve), and the dispersing medium.
4. Moisture & Water Activity
Moisture drives shelf life, mold risk, and clumping. Two numbers matter:
- Moisture content (%) — measured by loss on drying (LOD) or Karl Fischer. Quality matcha should sit at ≤ 6.0%; premium lots often read 3.5–5.0%.
- Water activity (aw) — the water available for microbial growth. Should be ≤ 0.40 for safe ambient storage; values above 0.60 invite mold and shorten shelf life dramatically.
5. Heavy Metals (Pb, As, Cd, Hg)
Tea plants are known accumulators of heavy metals. Even with clean soil and GAP-certified farming, every shipment should be tested against your destination market's limits.
| Metal | EU Limit (Reg. 2023/915) | US FDA / Prop 65 (guidance) | China GB 2762 | GCC / SFDA |
|---|---|---|---|---|
| Lead (Pb) | ≤ 3.0 mg/kg (tea) | ≤ 1.0–3.0 mg/kg advisory | ≤ 5.0 mg/kg (tea) | ≤ 3.0 mg/kg |
| Arsenic (As) | ≤ 1.0 mg/kg | ≤ 1.0 mg/kg | ≤ 0.5 mg/kg (inorganic, tea) | ≤ 1.0 mg/kg |
| Cadmium (Cd) | ≤ 1.0 mg/kg | ≤ 0.4–1.0 mg/kg advisory | ≤ 1.0 mg/kg | ≤ 1.0 mg/kg |
| Mercury (Hg) | ≤ 0.05 mg/kg | ≤ 0.05 mg/kg | ≤ 0.05 mg/kg | ≤ 0.05 mg/kg |
These are maximum regulatory ceilings, not target values. A reliable supplier will run 50–70% below the limit, leaving headroom for accumulation during transport and storage. If your COA shows numbers sitting right at the legal line, that is a red flag — ask the supplier about their farm-level source map and historical testing data.
6. Pesticide Residues
Pesticide screening should cover the full multi-residue panel — typically 200–500 active ingredients — even if your market only enforces a subset. Different regions treat the same molecule very differently:
- EU — default MRL of 0.01 mg/kg for substances not explicitly listed.
- US — tolerances set per crop, often more lenient; some compounds banned in EU are allowed.
- China (GB 2763) — national positive list, frequently updated.
- Japan — among the strictest; positive list system with uniform 0.01 mg/kg default.
- GCC / Saudi SFDA — follows GSO limits, generally aligned with Codex.
7. Microbiological Limits
Matcha is a low-water, low-pH food, so microbial risk is limited — but not zero. The COA should report at minimum:
| Test | Typical Specification | Why It Matters |
|---|---|---|
| Total Plate Count (TPC) | ≤ 10,000 CFU/g | Overall hygiene indicator |
| Yeast & Mold | ≤ 500 CFU/g | Critical — moisture control proxy |
| Enterobacteriaceae | ≤ 100 CFU/g | Process / equipment hygiene |
| E. coli | Negative in 25 g (or < 10 CFU/g) | Fecal contamination indicator |
| Salmonella | Negative in 25 g | Zero tolerance — recalls trigger |
| Staph. aureus | Negative in 25 g | Human-handling risk |
| Aflatoxins (B1, B2, G1, G2) | EU: B1 ≤ 5 μg/kg; total ≤ 10 μg/kg | Mycotoxin from poor drying / storage |
Micro limits differ by destination: EU Regulation 2073/2005, US FDA BAM / Food Code, China GB 29921, and GCC GSO 1016 all use similar zero-tolerance language for pathogens, but the sampling plans differ. Always cross-check your spec against the regulation that applies to your shipment.
8. Optional: Bioactive Profile
Beyond safety, premium buyers often request the bioactive fingerprint — useful for product marketing claims and for matching sensory quality to price. Common line items:
Catechins
Total 8–14% of dry weight for ceremonial. EGCG typically 3–6%.
L-Theanine
≥ 1.5% for ceremonial grade; the driver of umami and calm-focus effect.
Caffeine
2.5–4.5%. Lower than coffee but consistent across grades.
Chlorophyll
Total ≥ 0.6% signals fresh, well-shaded leaves.
Amino acids
Total ≥ 3% for premium; correlates with shade duration.
Polyphenols
Total ≥ 10% — supports antioxidant label claims.
9. Red Flags vs Green Lights on a COA
🟢 Green Light
Lot number, production date, harvest year, and packaging date all present. Color a* strongly negative. D50 matches the grade. Heavy metals at < 60% of regulatory limit. Micro panel fully negative for pathogens. Issued by ISO 17025 accredited lab.
🟡 Watch
Lab not named or not accredited. Some "not detected" entries without LOD. Bioactive profile missing for a "ceremonial" claim. Two-week gap between production and COA issue date.
🔴 Red Flag
Generic COA without lot number. Heavy metals at > 90% of limit. TPC or yeast & mold above spec. Any Salmonella or E. coli positive. Moisture above 7%. Color values off-grade without explanation.
10. Buyer QC Checklist — What to Verify Before Releasing Payment
Pre-shipment Inspection Points
- COA carries a unique lot number matching the container / inner bags
- Lab name and ISO 17025 accreditation visible on the report
- Production date < 90 days from COA issue date for fresh leaf, < 180 days for stored leaf
- Color (a* ≤ −18 for ceremonial, ≤ −15 for latte) within grade promise
- Particle D50 matches the grade spec (5–15 μm ceremonial, 10–30 μm latte)
- Moisture ≤ 6.0% and water activity ≤ 0.40
- Heavy metals all ≤ 70% of your destination market's limit
- Pesticide screen ≥ 200 compounds; LOD declared per compound
- Salmonella negative in 25 g; yeast & mold ≤ 500 CFU/g
- Aflatoxin B1 ≤ 5 μg/kg, total ≤ 10 μg/kg (EU benchmark)
- Optional bioactives (L-theanine, catechins) align with grade story if marketed
- Sensory panel: color, aroma, mouthfeel match reference sample
11. Terra Matcha COA Standard
Every Terra Matcha shipment — whether a 1 kg sample or a 1,000 kg container — ships with a third-party COA from an ISO 17025 accredited lab (SGS, Eurofins, or CTI depending on the customer's destination market). Default panels include:
- Color (L*a*b*), particle size D50, moisture, water activity, ash
- Heavy metals: Pb, As, Cd, Hg
- Pesticide screen: 300+ multi-residue panel
- Microbiology: TPC, yeast & mold, Enterobacteriaceae, E. coli, Salmonella, Staph. aureus
- Aflatoxins B1, B2, G1, G2 + ochratoxin A
- Bioactive profile (L-theanine, total catechins, EGCG, caffeine, chlorophyll) — for Uji series and on request for A series
Need a specific panel for your market (USDA NOP, EU Organic input verification, GCC SFDA pre-shipment, KFDA, FSSAI)? Tell us at quote time and we will align the COA to your regulatory target — at no extra charge for standard panels.