Tree nuts are a high-scrutiny category: they're stored a long time, traded globally, and tested against tight mycotoxin and residue limits that differ by market. This guide is the testing side of chestnut buying — what to demand, what the numbers mean, and how to spot a COA that doesn't actually cover the lot it claims to.

Why Chestnuts Get Tested Hard

Dried tree nuts are a known aflatoxin-risk matrix, and chestnuts' high moisture at harvest (before drying/grading) demands controlled handling. Markets respond with mandatory testing: the EU runs systematic border sampling; Japan and Korea set their own limits; Middle East markets increasingly align with Codex. A shipment that fails at the border is destroyed or returned — at the importer's cost.

Pesticide Panels by Market

Key differences: the EU (Reg 396/2005) sets low MRLs across hundreds of actives; Korea's MRL system (positive list since 2019) is similarly strict; Japan's positive list system tolerances differ on specific actives; the US EPA tolerances run generally higher. The practical rule: specify the destination market on the COA request — a panel tested against the wrong market's limits is wasted paper. Require the full multi-residue screen (300+ compounds), not a cherry-picked short list.

Aflatoxin Limits

Typical limits for total aflatoxins in tree nuts: EU 4 µg/kg B1 / 10 µg/kg total (with lower B1 limits for direct consumption); US FDA action level 20 µg/kg total; Japan 10 µg/kg; Codex 10 µg/kg for ready-to-eat. Quality suppliers test each production lot and hold COAs; ask for the trend across the season, not a single cherry-picked result.

Sampling That Survives

Aflatoxin contamination is spotty — a few bad nuts in a ton. That's why official methods take large aggregate samples (10-30 kg, ground and homogenized). A COA from a 500g grab sample is statistically meaningless. Require: aggregate sampling per lot, ISO 17025 lab, and results tied to the lot code on your packing list.

Reading a COA Critically

  • Lot code matches your packing list (the #1 mismatch source)
  • Test date is after the lot's packing date
  • Lab is accredited for the specific method, not just "ISO 17025" generically
  • Results are listed per compound with the market's limit alongside
  • Round numbers everywhere ("all <LOD") with no LOD values stated — ask for LODs

Our lab protocol covers EU, Japan, Korea, and US panels per lot, with results archived against lot codes. Request a sample COA pack.

Frequently Asked Questions

What is the aflatoxin limit for chestnuts in the EU?

For chestnuts for direct consumption: 2 µg/kg aflatoxin B1 and 4 µg/kg total at EU retail stages per current EU rules; processing-bound lots follow related limits. Confirm the applicable stage with your customs broker.

How big should an aflatoxin sample be?

Aggregate samples of 10-30 kg, ground and homogenized — single small grab samples are statistically meaningless for spotty mycotoxin contamination.

Can I use one COA for all markets?

No. MRL systems differ (EU vs Japan vs Korea positive lists). Ask for testing against your destination market specifically, on the full multi-residue panel.