MOLD IN AND ON FOODS
Fungi, including mold and yeast, range from microscopic mildew
to large mushrooms. Molds are capable of growing any where there
is moisture, some kind of "food," and air if the temperature is
right. Some molds and yeast are integral parts of food products
such as cheese, soy sauce, and bread. Molds have been used for
the production of beneficial drugs such as penicillin and
streptomycin. But some molds produce mycotoxins (fungal toxins)
which can be extremely harmful to human health, even in small
amounts. Some mycotoxins can survive for a long time in food;
most are not destroyed by cooking. Mold growth on crops and in
foods causes tremendous economic impact worldwide.
The main body of a mold plant consists of threads or mycelium,
also known as "roots" that invade the food. The stalk, the
portion above the food, produces spores (seeds), and gives color
to the mold. Spores spread the mold from one place to another
through the air. Molds which have spread their "root" threads
deeply inside a food can be very dangerous because toxin is
generally produced around these roots. Molds grow primarily in
warmer humid environments but they can tolerate colder
temperatures encountered in refrigeration storage. They can
withstand much more salt and sugar than bacteria; that is the
reason why one can find mold growth in refrigerated jams and
jellies (high sugar content), and on cured salted meat such as
bacon, ham and salami. Mold growth in foods can consume the acid
(change the pH) which in turn may promote bacterial growth. In
home canned-foods, a high-acid product can become a low-acid
product which is more at risk of pathogenic (illness-causing)
bacterial spoilage. Home-canned products which show signs of
mold growth should be discarded. Cooking does not destroy
mycotoxins, so it will not make moldy foods safe.
Aflatoxin, produced by the Aspergillus group of molds, occurs
mostly in peanuts, corn, and their products; it has been called
the most potent carcinogen in laboratory animals. Other
mycotoxins (such as ochratoxin A and deoxynivalenol) are produced
by the Fusarium molds and have been found in cereals made from
corn and rice. Do not consume moldy or shriveled peanuts. Throw
away the entire box of corn meal, cake mix, or other grain flour-
based product if any mold has developed.
Home-made jam and jellies covered with paraffin wax are likely
to support mold growth. The use of paraffin allows contamination
of jelly by mold spores in the air in the moments between pouring
the jellies into the jar and covering the jelly with hot
paraffin. As paraffin cools, it shrinks and tends to pull away
from the side of the jar. This allows spore contamination at the
edges of the jelly. Air bubbles in the hot paraffin can also
break as the paraffin cools and create tiny holes in the hot wax
seal allowing mold growth to begin. Jelly jars should be
presterilized by boiling for 10 minutes before jelly is poured
into the jars. Presterilization allows the filled jars to be
processed submerged in boiling water for only 5 minutes in
boiling water bath. If the jars are not presterilized, then the
filled jars must be processed for 15 minutes.
There are several ways to minimize the mold growth in the
refrigerator and kitchen. Clean the inside of refrigerator every
few months with 1 tablespoon of baking soda dissolved in a quart
of water. Rinse with clean water and dry. Black mold spots on
the rubber gaskets of the refrigerator can be cleaned with 3
tablespoons of bleach in one quart of water. Don't purchase
fresh food in large quantities if you cannot consume it quickly.
Don't sniff moldy items; the spores can cause respiratory
problems. Moldy food should be put in paper or plastic bags for
disposal in a covered trash can so that animals and children
cannot get into it.
If the food shows even a tiny mold spot, follow these guide
lines:
1. Hard or firm foods with tiny mold spots can be trimmed; cut
away the area around the mold (at least an inch) and rewrap
in clean wrap. Make sure that knife does not touch the
mold.
2. Soft foods such as cheese slices, cream cheese, sour cream
and yogurt should be thrown away.
TOSS:
Soft Cheeses, (Mozzarella Brie)
Sour Cream, Yogurt, Cottage
Bacon, Hot dogs, Sliced lunch meats
Meat pies
Opened canned ham
Most left-over food
Bread, Cakes, rolls, flour, pastry
Peanut butter
Juices, berries
Jam, Jellies, Syrups
Cucumbers, Tomatoes
Spinach, Lettuce, other leafy vegetables
Bananas, Peaches, Melons
Corn-on-the-cob
Stored nuts, whole grains, rice
TRIM:
Hard Cheese (Cheddar, Swiss)
Bell Peppers, Carrots, Cabbage
Broccoli, Cauliflower, Brussels Sprouts
Garlic, Onions
Potatoes, Turnips
Zucchini
Apples, Pears
Federal monitoring of food and forage crops is done
continuously by the FDA. Products which are prone to mold growth
and toxin production do not reach the grocery store, but once the
product reaches home one should be extremely careful to keep the
product safe so that molds do not grow.
M. Susan Brewer, Ph.D., R.D.
Specialist, Food Safety