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Questions and Answers
Ochratoxin C (OTC) is known to be hydrolyzed to generate Ochratoxin B (OTB).
Ochratoxin C (OTC) is known to be hydrolyzed to generate Ochratoxin B (OTB).
False (B)
Chronic exposure to ochratoxins can lead to immune suppression and cancer in the liver.
Chronic exposure to ochratoxins can lead to immune suppression and cancer in the liver.
True (A)
The USFDA has established a tolerable daily intake (TDI) of 14 ng/kg body weight for ochratoxins.
The USFDA has established a tolerable daily intake (TDI) of 14 ng/kg body weight for ochratoxins.
False (B)
Ochratoxicosis is associated with the consumption of ochratoxins, affecting primarily the kidneys and liver.
Ochratoxicosis is associated with the consumption of ochratoxins, affecting primarily the kidneys and liver.
The EU maximum limit (ML) for ochratoxin A in nutmeg is set at 10 μg/kg.
The EU maximum limit (ML) for ochratoxin A in nutmeg is set at 10 μg/kg.
Ochratoxin A is the least abundant isoform of ochratoxins.
Ochratoxin A is the least abundant isoform of ochratoxins.
Aspergillus ochraceus has both sexual and asexual forms of reproduction.
Aspergillus ochraceus has both sexual and asexual forms of reproduction.
Ochratoxins can be produced by saprotrophic fungi.
Ochratoxins can be produced by saprotrophic fungi.
The chemical structure of ochratoxins consists solely of an isocoumarin nucleus.
The chemical structure of ochratoxins consists solely of an isocoumarin nucleus.
Exposure to ochratoxins only occurs through direct contact with the fungus.
Exposure to ochratoxins only occurs through direct contact with the fungus.
Ochratoxin B lacks a covalently bound chlorine atom that is present in Ochratoxin A.
Ochratoxin B lacks a covalently bound chlorine atom that is present in Ochratoxin A.
Contamination from ochratoxins can occur both before and after harvesting of crops.
Contamination from ochratoxins can occur both before and after harvesting of crops.
The optimum growth temperature for Aspergillus ochraceus is higher than 30ºC.
The optimum growth temperature for Aspergillus ochraceus is higher than 30ºC.
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Study Notes
Aspergillus Toxins
- Ochratoxins are produced by the fungus Aspergillus ochraceus.
- Aspergillus ochraceus grows best at 25°C and produces a variety of toxins, including ochratoxins, through sexual and asexual reproduction.
- Aspergillus ochraceus is a saprotrophic and pathogenic fungus that can contaminate food and animal feed.
- Ochratoxins can contaminate food and animal feed during pre-harvest and post-harvest stages.
- The most prevalent ochratoxin is Ochratoxin A (OTA), which is a potent toxin known for its carcinogenic and nephrotoxic properties.
- Ochratoxins can affect humans through consumption of contaminated food, animal products, and water.
- Direct contact with Aspergillus ochraceus in water-damaged buildings can also pose a health risk.
Ochratoxin Structure
- Ochratoxins are composed of two parts: an isocoumarin nucleus and an L-phenylalanine molecule connected by an amide bond.
- L-phenylalanine is critical for the toxic and carcinogenic activities of ochratoxins.
- Several isoforms of ochratoxins can be produced with Ochratoxin A (OTA) being the most abundant and toxic isoform.
- Ochratoxin B (OTB) lacks the chlorine atom present in OTA.
- Ochratoxin C (OTC) is an acetyl derivative that rapidly hydrolyzes to generate OTA.
Ochratoxin Toxicity
- Ochratoxins have toxic effects on both animals and humans.
- Dogs and pigs are especially vulnerable to the effects of OTA.
- The lethal dose (LD50) of OTA varies across species, with dogs and neonate rats exhibiting the highest sensitivity.
- Ochratoxicoses, diseases caused by ochratoxin consumption, primarily target the kidneys and liver.
- Ochratoxin A (OTA) can bind to DNA, leading to the formation of adducts in various organs, including the kidneys, liver, and brain.
- Chronic exposure to ochratoxin A leads to kidney and liver cancer, immune suppression, and other health issues.
- Acute exposure to high levels of ochratoxin A can be fatal.
Ochratoxin Regulations
- In 2006, the European Food Safety Authority established a "tolerable weekly intake" (TWI) of 120 ng/kg body weight for ochratoxin A.
- This translates to a tolerable daily intake (TDI) of 14 ng/kg body weight.
- The estimated tolerable dosage in humans ranges from 0.2 to 4.2 ng/kg body weight.
- The US Food and Drug Administration (FDA) has no official regulations around ochratoxins, but they consider a TDI of 5 ng/kg body weight.
- Regulations around ochratoxin A levels in food vary between countries, with the EU setting maximum limits (ML) for certain food products.
- For instance, the EU limits ochratoxin A levels to 15 µg/kg in nutmeg, ginger, pepper, and turmeric, and to 20 µg/kg in chili and paprika.
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