Food Toxicology 2(2+0)

Lesson 15 : Fungal Mycotoxins

Trichothecenes

Patulin C7H6O4

• Penicillia, Penicillium expansum
• Penicillium claviforme
• Penicillium urticae
  

Some Aspergilli

• Grow on fruits (rots)
• Toxic to some bacteria
• Used to be “antibiotic”: Clavicin, Claviformin etc
• Unstable to alkaline but stable in acid condition
• LD50 15-35 mg/kg body weight
• Stable at pasteurization temperature but fermentation of apple juice eliminates this toxin or addition of vitamin C

During 1913, Russians near Siberia experienced extreme food shortage and were forced to eat grains of wheat, millet, and barley that had been left outside during the winter. The melting snow increased the moisture content, which favored mold growth and resulted in a large outbreak of mycotoxicosis. The disease, referred to as alimentary toxic aleukia (ATA), reached epidemic proportions and was found to be related to the infection of grains by Fusarium species. ATA causes atrophy of the bone marrow, agranulocytosis, necrotic angina, sepsis, and death. The disease is manifested in three stages:

1. mouth and throat inflammation, gastroenteritis and vomiting;
2. an asymptomatic second stage when immunodepression sets in;
3. a fatal stage of pinpoint skin hemorrhages and necrotic ulcers over various parts of the body.

The acute effects of toxicity are usually neurological, but the chronic effect of toxicity is characterized by massive necrosis of the GI tract, producing inflammation,hemorrhages, and leukopenia.

Trichothecenes are the primary mycotoxins produced by Fusarium. Acute toxicity (LD 50) is between 50 and 70 mg/kg. Toxin levels of contamination can be generally high (>1 to 20 ppm) in barley, oats, sorghum, rye, and safflower seeds. Some non trichothecenes mycotoxins are also produced by Fusarium, the most important one being Fumonisins.

Corn is the major staple associated with mycotoxin; in a 1990–1991 survey, 124 retail samples of corn-based human food from the U.S. and Africa contained significant amounts of fumonisin B1 and B2. High rates of human esophageal cancer have been associated with corn exposures, Fusarium growth in feed grains can be a significant problem and feeding such grains to livestock can effect their health.