What is ochratoxin A?
Ochratoxin A (OTA) is a common mycotoxin produced primarily by molds of the genera Aspergillus (particularly Aspergillus ochraceus) and Penicillium (especially Penicillium verrucosum).
Chemically, ochratoxin A is a chlorinated isocoumarin derivative linked to the amino acid L-phenylalanine. This structural feature allows OTA to interact with proteins in biological systems and interfere with their function.
Where is ochratoxin A found?
OTA can be detected in a wide variety of foods:
- Grains and grain products (wheat, barley, rye, oats)
- Coffee (green coffee and roasted coffee)
- Wine and grape juice
- Beer
- Spices (e.g., paprika)
- Nuts and dried fruits
- Cocoa and chocolate
- Pork (due to contaminated feed)
Penicillium verrucosum is a significant contaminant in grain storage, particularly in cooler, temperate climates.
Health Risks Associated with Ochratoxin A
Ochratoxin A is a potent nephrotoxin (kidney-damaging) and exhibits other toxicological properties:
Main Effects
- Kidney damage (chronic nephropathy)
- Liver toxicity
- Immunosuppression
- Neurotoxic effects
- Teratogenic effects (harm to the unborn child)
Chronic exposure
- Balkan Endemic Nephropathy (BEN) – a chronic kidney disease in Southeast Europe associated with OTA
- Urothelial carcinomas (cancer of the urinary tract)
- Impaired kidney function
The IARC classifies ochratoxin A as Group 2B (possibly carcinogenic to humans).
Special factors in coffee and wine
Coffee
OTA forms mainly during post-harvest processing:
- Problem: Wet processing with insufficient drying
- Critical phase: Storage of green coffee at high humidity
- Roasting can reduce OTA by 10–30%
Wine
OTA can form during various stages of production:
- Vineyard: Infection of the grapes (especially with Botrytis)
- Storage: Contaminated barrels or inadequate hygiene
- Fermentation: Can partially break down OTA (depending on yeast strains)