Fungal contamination of food may be one of the more
pervasive and serious causes of endemic disease. Fungi produce mycotoxins that
are versatile and potent causes of disease. Mycotoxins can cause acute and
chronic illnesses, induce cancer, and damage vital organs such as the liver
kidney and brain. A variety of fungi (Fusaria, Trichothecium, Cephalosporium,
etc.) may contaminate grains, in particular, and produce illness with symptoms
such as vomiting, diarrhea, headaches, chills, dizziness, and blurred vision.
Aflatoxins are produced by molds which favor nuts, corn,
millet, and figs. The Food and Agriculture Organization estimates that 25% of the world’s food crops contain aflatoxins. These
toxins may produce symptoms like loss of appetite and jaundice (hepatitis)
immediately and with repeated exposure, they are also carcinogenic. Some of these fungal metabolites are also neurotoxins that produce
tremors as a conspicuous symptom. The same fungi, which produce aflatoxin,
produce a tremorgen, known to cause "staggers" in sheep and cattle. The common
fungi, which grow on food, even in the refrigerator, are Penicillium,
Aspergillus, and Claviceps. Over 15 tremorgenic mycotoxins have been isolated
from these fungi.
Sweet potato supports a fungal growth (Fusarium
solani), especially when the tuber's surface is damaged. The fungus alters the
potatoes' metabolism, and toxic stressors are produced. Ipomeanol is one such
chemical that is liver and lung toxic. Lung disease in cattle is caused by
fungal-infected sweet potatoes. The mycotoxin ochratoxin A is a common
contaminant of foods and beverages such as beer, coffee and wine. It is produced
as a secondary metabolite of moulds from Aspergillus and Penicillium genera.
Ochratoxin A inhibits protein synthesis by competition with phenylalanine its
structural analogue and also enhances the production of oxygen free-radicals.
Its multiple toxic effects include cytotoxicity, teratogenicity, genotoxicity,
mutagenicity and carcinogenicity. OTA exposure was linked to “Balkan Endemic
Nephropathy” with a high incidence of urinary tract tumors.
In Canada 363 samples of cereal-based infant foods were
collected from the retail stores over 3 years and tested for mycotoxins. The
samples included oat-, barley-, soy-, and rice-based infant cereals, mixed-grain
infant cereals, teething biscuits, creamed corn, and soy-based formulas. Samples
were analysed for targeted mycotoxins (deoxynivalenol, nivalenol, HT-2 toxin,
zearalenone, ochratoxin A, fumonisins B(1) and B(2), and five ergot alkaloids).
Soy-based cereals (which usually contain corn) exhibited the highest incidences
of deoxynivalenol (100%), zearalenone (46%) and fumonisins (75%). Overall,
deoxynivalenol was the most frequently detected mycotoxin--it was detected in
63% of samples analysed. Survey results demonstrated the regular occurrence of
multiple mycotoxins in cereal-based infant foods
The US FDA manual on food mold and yeasts stated: “The
large and diverse group of microscopic foodborne yeasts and molds (fungi)
includes several hundred species. The ability of these organisms to attack many
foods is due in large part to their relatively versatile environmental
requirements. Although the majority of yeasts and molds are obligate aerobes
(require free oxygen for growth), their acid/alkaline requirement for growth is
quite broad, ranging from pH 2 to above pH 9. Their temperature range (10-35°C)
is also broad, with a few species capable of growth below or above this range.
Moisture requirements of foodborne molds are relatively low; most species can
grow at a water activity (aw) of 0.85 or less, although yeasts generally require
a higher water activity. Both yeasts and molds cause various degrees of
deterioration and decomposition of foods. They can invade and grow on virtually
any type of food at any time; they invade crops such as grains, nuts, beans, and
fruits in fields before harvesting and during storage. They also grow on
processed foods and food mixtures. Detectability in or on foods depends on food
type, organisms involved, and degree of invasion; the contaminated food may be
slightly blemished, severely blemished, or completely decomposed, with the
actual growth manifested by rot spots of various sizes and colors, unsightly
scabs, slime, white cottony mycelium, or highly colored sporulating mold.
Abnormal flavors and odors may also be produced. Occasionally, a food appears
mold-free but is found upon mycological examination to be contaminated.
Contamination of foods by yeasts and molds can result in substantial economic
losses to producer, processor, and consumer. Several foodborne molds, and
possibly yeasts, may also be hazardous to human or animal health because of
their ability to produce toxic metabolites known as mycotoxins. Most mycotoxins
are stable compounds that are not destroyed during food processing or home
cooking. Even though the generating organisms may not survive food preparation,
the preformed toxin may still be present. Certain foodborne molds and yeasts may
also elicit allergic reactions or may cause infections. Although most foodborne
fungi are not infectious, some species can cause infection, especially in
immunocompromised populations, such as the aged and debilitated, HIV-infected
individuals, and persons receiving chemotherapy or antibiotic treatment. “
Chemistry, Quality, Safety as an eBook
Alpha Education Books explain nutrition and the role of food choices in
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in the center column to read sample topics. The author is
Stephen J. Gislason MD
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