CHEM215 Lecture Notes - Lecture 21: Aflatoxin B1, Aspergillus Flavus, Tetraodontidae
Lecture 21 – Food Toxicology 2
Endogenous toxins in animal foods:
• Puffer fish toxins: powerful toxin tretrodoxin found in organs of puffer fish,
mostly liver and ovaries. All 120 species of puffer fish make this toxin. Puffer fish
is considered a delicacy in Japan, so non-toxic parts of it are consumed - muscles
and testes. Normal levels are up to 0.3 g/kg.
Lethal dose of this toxin is 1.5 - 4 mg.
Toxicity —> blocks the movement of Na+ across nerve membranes. Leads
complete paralysis and respiration failure within 6-24 hours.
There is no cure for this - regular fatalities occur in Japan.
• Histamine: At 10˚C or above, a reaction occurs in mackeral, tuna and sardines,
producing histamine from histidine via an enzymatic decarboxylation reaction.
Occurs when fish that has been killed has not been stored properly, and gets above
10˚C. If fish it not stored at refrigerated temperatures, it builds up histamine.
Histamine is also found in cheese and spoiled meats.
High doses of histamine can trigger an allergic reaction in sensitive individuals —>
causes headaches, palpitations, gastric problems, skin flushes (erythema).
Legal level of histamine in fish (to sell it ) is 200mg /100g flesh.
Mycotoxins - aflatoxins in cereal:
• Mycotoxins are toxins that come from fungi - a number of different moulds such
as Aspergillus flavus.
• Fungus can grow on cereal crops, and these fungi produce aflatoxins, which are
very toxic molecules. The most potent aflatoxin is aflatoxin B1, which is a very
potent liver carcinogen. 10-15 ppb of aflatoxin B1 in diet of lab animals induces
tumour formation.
• Grains and toxins must be monitored very carefully to avoid growth of these
aflatoxins.
• The only difference between aflatoxin B1 and B2 is that B1 has an extra double
bond.
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Endogenous toxins in animal foods: puffer fish toxins: powerful toxin tretrodoxin found in organs of puffer fish, mostly liver and ovaries. All 120 species of puffer fish make this toxin. Puffer fish is considered a delicacy in japan, so non-toxic parts of it are consumed - muscles and testes. Lethal dose of this toxin is 1. 5 - 4 mg. Toxicity > blocks the movement of na+ across nerve membranes. Leads complete paralysis and respiration failure within 6-24 hours. There is no cure for this - regular fatalities occur in japan: histamine: at 10 c or above, a reaction occurs in mackeral, tuna and sardines, producing histamine from histidine via an enzymatic decarboxylation reaction. Occurs when fish that has been killed has not been stored properly, and gets above. If fish it not stored at refrigerated temperatures, it builds up histamine. Histamine is also found in cheese and spoiled meats.
