Environmental Engineering Reference
In-Depth Information
High humidity and water activity (
a
w
) favor mycotoxin production; the
amounts vary with the product. Molds and most yeasts require oxygen to
grow and grow over a very wide pH range. Mycotoxins may also be resistant
to heat and dessication and can survive a range of temperatures from 14
◦
to 131
◦
F(
−
10
◦
to 55
◦
C). Ingestion of contaminated feed by farm animals
may permit carryover of toxins into meat and milk. There are about 15
types of dangerous mycotoxins. One common type, aflatoxin, is a potential
human carcinogen and is produced by the mold
Aspergillus flavus
and other
Aspergillus
species generally found in feeds and food. Aflatoxin-producing
mold growths occur over a wide range of temperatures from 53
◦
to 110
◦
F
(12
◦
to 43
◦
C), although 92
◦
F(33
◦
C) is optimum.
Aspergillus
mold has been
detected in peanuts and peanut butter, corn, figs, cereals (wheat, barley,
millet), cottonseed products, milk and milk products, and other foods that
are not properly dried and stored, thereby favoring fungus contamination and
growth on the food. The
Aspergillus
species may be airborne and inhaled,
causing aspergillosis. Compost piles are common reservoirs and sources of
infection. Fortunately, the mere presence of a mold does not automatically
mean the presence of mycotoxins. Contamination may result also before
harvest. Most fungal toxins, including aflatoxins, are not destroyed by boiling
and autoclaving.
23
Oven roasting artificially contaminated peanuts for 30
minutes at 302
◦
F (150
◦
C) or microwave roasting for 8.5 minutes can destroy
30 to 45 percent of aflatoxin B
1
.
24
Properly stored leftover foods may also
be
a
source
of
aflatoxins.
Aflatoxins fluoresce under
long-wave ultraviolet
light.
Aflatoxin causes cancer in rats and is suspected to be a cause of liver cancer
in humans. Mycotoxins can also damage the liver, brain, bones, and nerves with
resultant internal bleeding.
A concise summary of mycotoxins and some mycotoxicoses of humans and
animals is found in a report of a WHO Expert Committee, with the participation
of the Food and Agriculture Organization (FAO) of the United Nations,
25
a paper
by Bullerman, and a paper by Scott.
26
,
27
Some compounds and substances may
inhibit, stimulate, or have no effect on the growth of aflatoxins.
28
Foods (vegetables, meats, fruits, and cheeses) with abnormal mold growth
should be promptly and properly discarded.
29
The exception to this is cheese
from which mold has been
properly
removed (including mold filaments deeply
penetrating along the holes or eyes), which is considered safe to eat. For
other foods, is not safe to scrape off the mold and eat the remaining food.
Mycotoxins are not effectively destroyed by cooking. Freezing food will
prevent mold growth, but mold grows at refrigerator temperature, although at
a slower rate. The inside of refrigerators should be washed and dried regularly
to prevent mold growths and musty odors; commercial deodorants are not a
substitute for cleanliness. Some cheeses, such as Roquefort, Brie, Camembert,
and Blue, are processed with special species of molds, similar to those from
which penicillin is made, and have been consumed with safety for hundreds
of years.
30
In addition, consuming certain dairy, fruit and vegetable delicacies
