In brief
Mycotoxins are secondary metabolites of certain moulds (especially the genera Aspergillus, Penicillium and Fusarium) that can form during improper drying or storage of plant raw materials. In kratom, analytical practice mainly monitors aflatoxins and ochratoxin A. The limits are set by Commission Regulation (EU) 2023/915.
What mycotoxins are
Mycotoxins are low-molecular-weight organic compounds that moulds produce in response to stress or as part of a competitive strategy. In plant raw materials they represent a serious contaminant because:
- they are heat-stable - they cannot be degraded by boiling or ordinary heat treatment,
- they have high toxicological potential even at microscopic concentrations,
- their presence is uneven - within a single batch, concentrations may fluctuate locally by orders of magnitude,
- they are not visually detectable - contamination without visible signs of mould is possible.
The main classes
Aflatoxins
A product of the moulds Aspergillus flavus and Aspergillus parasiticus. Four variants are monitored in analytical practice:
- aflatoxin B1 - the most toxic; the IARC has classified it in Group 1 (human carcinogen),
- aflatoxin B2 - a structural analogue of B1,
- aflatoxin G1, aflatoxin G2 - less toxic variants.
For assessment, both the B1 value alone and the sum B1+B2+G1+G2 are stated.
Ochratoxin A (OTA)
A product of moulds of the genera Aspergillus and Penicillium, especially Aspergillus ochraceus and Penicillium verrucosum. It is monitored in all dried plant raw materials, especially in products with longer storage.
Others (less relevant for kratom)
Zearalenone, fumonisins and deoxynivalenol are primarily monitored in cereals and are not usually a dominant problem in kratom.
Formation during drying and storage
Mycotoxins in kratom typically form:
- during slow drying in the rainy season, when leaf moisture stays above 15 % for several days,
- during improper fermentation without control of temperature and humidity,
- during storage in unsuitable conditions (damp, fluctuating temperature, contaminated bags),
- during long transport in unventilated containers.
Prevention is always more effective than subsequent analysis - which is why proper logistics and storage throughout the chain from plantation to seller are important.
Limits under EU 2023/915
Commission Regulation (EU) 2023/915 sets the following limits for plant raw materials (indicative; the specific classification of kratom in Czech legislation depends on the PML regime):
- Aflatoxin B1: 2.0 μg/kg (for most plant raw materials and spices),
- Sum B1+B2+G1+G2: 4.0 μg/kg,
- Ochratoxin A: 10-20 μg/kg depending on the type of raw material (spices 15 μg/kg, dried fruit 10 μg/kg).
These limits are based on EFSA's pharmacological assessment and are uniform across the EU.
Frequently asked questions
What is the limit for aflatoxin B1?
Under EU Regulation 2023/915, typically 2.0 μg/kg for plant raw materials and spices. Some specific categories may have a different limit.
Can mycotoxins be destroyed by boiling?
No. Aflatoxins and ochratoxin A are heat-stable and cannot be degraded by ordinary heat treatment (boiling, drying). Prevention lies in preventing their formation, not in subsequent degradation.
How often is testing done?
The standard is a test for each batch of input raw material and for each batch packed for distribution. The periodicity is part of the distributor's record-keeping obligation.
What is the difference between visible mould and a mycotoxin?
Mould is a living organism; a mycotoxin is its chemical product. A mycotoxin may be present even after visible mould has been removed. Conversely, visible mould does not always produce a mycotoxin (it depends on the species and the conditions).
References
- Commission Regulation (EU) 2023/915 on maximum levels of certain contaminants in food.
- EFSA Panel on Contaminants in the Food Chain (2020). Risk assessment of aflatoxins in food. EFSA Journal, 18(3), 6040.
- IARC Monographs on the Evaluation of Carcinogenic Risks to Humans, Volume 100F (2012). Aflatoxins.
