Is It Safe to Eat Moldy Bread or
Cheese?
January 10, 2015
Story at-a-glance
-
Mold on hard foods (hard cheese, firm vegetables) can be cut
off (with an inch around it), and the food safely consumed
-
Mold on soft foods (bread, fruit, and soft cheese and
vegetables) has likely permeated through the food, so it
should be discarded
-
While some mold is harmless, others can cause allergies,
respiratory problems, or may produce cancer-causing
substances called mycotoxins
By Dr. Mercola
You take a block of cheese out of your refrigerator and notice
fuzzy spots of white or green mold. Should you toss it or simply cut
the mold off? What about mold that appears on other foods, like
strawberries or bread?
The "rules" about when it's safe to eat moldy food or not vary
depending on the type of food. Generally speaking, if the food is
hard, such as a brick of cheddar cheese or a carrot, you can cut off
the moldy section (plus about one inch around it) and use the rest.
For softer foods, they should be discarded when mold is spotted
because, the fact of the matter is, mold can be quite
dangerous, and its roots can easily permeate soft foods,
contaminating areas that appear to be mold-free. Let me explain…
What Is Mold?
Mold is a type of microscopic fungi that lives on organic matter.
It's estimated that there are 300,000 or more different species of
fungi, most of which are thread-like and produce spores that can be
easily spread in air or water (or by insects). In many cases, mold
will consist of three primary parts:1
- Root threads (which can spread throughout your food and may
not be visible with your naked eye)
- Stalks rising above the food
- Spores at the end of the stalks (the spores give the mold
its color)
Some mold is perfectly safe to eat and, in some cases, even
desirable (the classic example would be cheeses made with mold, such
as blue, Brie, Camembert, and Gorgonzola). Other molds can be quite
toxic and may produce allergic reactions and respiratory problems,
or produce poisonous substances called mycotoxins.
Aspergillus mold, for instance, which is most often found on meat
and poultry (as well as environmentally), can cause an infection
called aspergillosis,2
which is actually a group of illnesses ranging from mild to severe
lung infections, or even whole-body infections.
The most serious type of aspergillosis is invasive aspergillosis,
which is when the mold invades your blood vessels and the spreads to
the rest of your body. Aspergillus allergy can result in
fever, productive cough, and worsening asthma.
With aspergillosis, you can actually grow a "fungal ball" in your
lungs, a tangled ball of fungal fiber called aspergilloma.
Aspergilloma can lead to coughing up blood (hemoptysis), wheezing,
shortness of breath, fatigue, and weight loss. Other common
foodborne molds include:
Alternaria |
Botrytis |
Cladosporium |
Fusarium |
Geotrichum |
Monilia |
Manoscus |
Mortierella |
Mucor |
Neurospora |
Oidium |
Oosproa |
Penicillium |
Rhizopus |
Thamnidium |
Grains and Nuts Are Common Sources of Toxic Mycotoxins
One of the greatest concerns regarding mold in food is the
mycotoxins that some varieties produce. One of the most researched
mycotoxins is aflatoxin, a cancer-causing poison. According to the
US Food and Drug Administration (FDA):3
"In the United States, aflatoxins have been identified in corn
and corn products, peanuts and peanut products, cottonseed, milk,
and tree nuts such as Brazil nuts, pecans, pistachio nuts, and
walnuts. Other grains and nuts are susceptible but less prone to
contamination."
Aflatoxin is said to be the most carcinogenic naturally occurring
substance known, and it is known to cause liver cancer and immune
suppression in humans. While the US FDA and the US Department of
Agriculture (USDA) monitor peanuts and field corn for aflatoxin at
high levels, there is concern about long-term exposure to low levels
of this common mold-related toxin.
According to the Food and Agriculture Organization (FAO) of the
United Nations, about 25 percent of the world's food crops are
affected by mycotoxins, including aflatoxin.4
As noted by the USDA:5
"Many countries try to limit exposure to aflatoxin by
regulating and monitoring its presence on commodities intended
for use as food and feed.
The prevention of aflatoxin is one of the most
challenging toxicology issues of present time… Aflatoxins are
considered unavoidable contaminants of food and feed, even where
good manufacturing practices have been followed."
Unfortunately, this is one type of mold toxin that you can't
detect by examining your food. There are some tips you can use to
minimize this risk, however. In the case of pistachios, for
instance, be sure the pistachios you eat come from a reliable
supplier, which dries the nuts immediately after harvest to minimize
decay.
Some California pistachio farmers are also using spores of a
beneficial fungus to displace the fungi that produce aflatoxin. This
strategy has been found to reduce aflatoxin by up to 45 percent,
without the use of chemicals.6
You can further reduce your risk by:
- Choosing in-shell pistachios (shelled pistachios are much
more likely to be contaminated with aflatoxin)
- Avoiding dyed pistachios, which may cover up staining
- Avoiding eating pistachios that have a sour taste or signs
of mold, excessive moisture, or insect damage
Mold on Food: What to Toss, What to Keep
Mold that's visible may appear to exist in contained areas on
your food – a gray furry spot here or a few green dots there.
However, beneath this visible mold are likely deep roots that may
have invaded the rest of the food. In cases where the mold is
dangerous, its toxic elements may be contained not only in these
threads but also throughout the food.
For this reason, if you see mold anywhere on a soft, easily
penetrable food, you should discard it. You may also need to toss
nearby foods that may have touched the moldy area, as mold can
spread quickly and easily, especially in produce. Moldy foods that
you throw away should be put into a small paper or plastic bags so
the mold cannot escape.
Do not attempt to sniff the moldy food to see if it's
spoiled, as this can introduce mold spores into your respiratory
tract. In the case of harder foods, it's acceptable to cut off the
moldy spot and about one inch around it (to ensure you've
removed any roots).
When doing this, be sure the knife does not touch the mold and
contaminate the area you are cutting. The USDA has compiled the
chart below to help you determine when a moldy food should be kept
or discarded.7
FOOD |
HANDLING |
REASON |
Luncheon meats, bacon, or hot
dogs |
Discard |
Foods with high moisture content can
be contaminated below the surface. Moldy foods may also have
bacteria growing along with the mold. |
Hard salami and dry-cured
country hams |
Use. Scrub mold off surface. |
It is normal for these shelf-stable
products to have surface mold. |
Cooked leftover meat and
poultry |
Discard |
Foods with high moisture content can
be contaminated below the surface. Moldy foods may also have
bacteria growing along with the mold. |
Cooked casseroles |
Discard |
Foods with high moisture content can
be contaminated below the surface. Moldy foods may also have
bacteria growing along with the mold. |
Cooked grain and pasta |
Discard |
Foods with high moisture content can
be contaminated below the surface. Moldy foods may also have
bacteria growing along with the mold. |
Hard cheese
(not cheese where mold is part of the processing) |
Use. Cut off at least 1 inch
around and below the mold spot (keep the knife out of the
mold itself so it will not cross-contaminate other parts of
the cheese). After trimming off the mold, re-cover the
cheese in fresh wrap. |
Mold generally cannot penetrate deep
into the product. |
Cheese made with mold
(such as Roquefort, blue, Gorgonzola, Stilton,
Brie, and Camembert) |
Discard soft cheeses such as Brie
and Camembert if they contain molds that are not a part of
the manufacturing process. If surface mold is on hard
cheeses such as Gorgonzola and Stilton, cut off mold at
least 1 inch around and below the mold spot and handle like
hard cheese (above). |
Molds that are not a part of the
manufacturing process can be dangerous. |
Soft cheese
(such as cottage, cream cheese, Neufchatel, chevre,
Bel Paese, etc.) Crumbled, shredded, and sliced
cheeses (all types) |
Discard |
Foods with high moisture content can
be contaminated below the surface. Shredded, sliced, or
crumbled cheese can be contaminated by the cutting
instrument. Moldy soft cheese can also have bacteria growing
along with the mold. |
Yogurt and sour cream |
Discard |
Foods with high moisture content can
be contaminated below the surface. Moldy foods may also have
bacteria growing along with the mold. |
Jams and jellies |
Discard |
The mold could be producing a
mycotoxin. Microbiologists recommend against scooping out
the mold and using the remaining condiment. |
Fruits and vegetables, FIRM
(such as cabbage, bell peppers, carrots, etc.) |
Use. Cut off at least 1 inch
around and below the mold spot (keep the knife out of the
mold itself so it will not cross-contaminate other parts of
the produce). |
Small mold spots can be cut off FIRM
fruits and vegetables with low moisture content. It's
difficult for mold to penetrate dense foods. |
Fruits and vegetables, SOFT
(such as cucumbers, peaches, tomatoes, etc.) |
Discard |
SOFT fruits and vegetables with high
moisture content can be contaminated below the surface. |
Bread and baked goods |
Discard |
Porous foods can be contaminated
below the surface. |
Peanut butter, legumes, and
nuts |
Discard |
Foods processed without
preservatives are at high risk for mold. |
Proper Food Storage Can Help Prevent Spoiled Food
After you've removed a moldy item from your refrigerator, be sure
to clean the area where it was stored (you can find
tips on how to best clean your refrigerator here). Otherwise,
you may simply re-contaminate the next food item you put in. Next,
you can drastically reduce food spoilage by learning the basics of
proper food storage. In your fridge, for instance, meat, poultry,
fish, and leftovers should be stored on the bottom shelf, where
temperatures are cold and stable.
On the other hand, the fridge door is the warmest part of the
fridge and temperatures can fluctuate significantly, so use it only
to store condiments and butter. Citrus fruits can last up to two
weeks right on the counter, while garlic and onions need to be
stored in a dark, cool pantry, where they will stay fresh for up to
four months. The life of leafy greens can be extended by as much as
three extra days if you don't wash them before putting them in your
fridge. Also keep in mind that apples, pears, and bananas release
natural ripening agents that will hasten the demise of any other
produce placed in their vicinity. For more details, I've listed
27 tips to make your groceries last longer here, which include
many tips to keep mold growth at bay:
- Store onions in old pantyhose to keep them fresh for up to
eight months (tie a knot in between each one to keep them
separate).
- Chop dry green onions and store them in an empty plastic
water bottle. Put the bottle in the freezer and sprinkle out
what you need when you're cooking.
- When storing potatoes, keep them away from onions (this will
make them spoil faster). Storing them with apples will
help keep the potatoes from sprouting.
- Store salad greens in a bowl covered with plastic wrap, and
add a paper towel to help absorb moisture. A salad spinner will
also help remove excess moisture -- a key culprit in wilting
leaves -- from your greens.
- Mushrooms should be stored in a paper bag in a cool dry
place, or in the fridge. Avoid storing mushrooms in plastic, as
any trapped moisture will cause them to spoil.
How to Reduce Mold Growth on Your Food
There are additional steps you can take to protect your food from
mold growth. When you're serving food, it's important to keep it
covered, for instance, as this helps prevent exposure to mold spores
that may be in your air. When you use jarred foods, you should also
put any leftovers into a clean storage container (don't store it
right in the same jar). It's always important to refrigerate
leftovers promptly (within two hours or less) and use up leftovers
within three to four days (this way mold won't have a chance to
grow).8
If you've got containers of food sitting in your fridge for long
enough to get moldy, you're probably not planning out your meals as
efficiently as possible. Before you go food shopping, make a meal
plan for the week. Do a thorough check of what you already have on
hand so you don't let good food go bad, and have your meals planned
so the fresh foods you buy get eaten in a timely manner (and while
they're still fresh).
Have You Considered Mold in Your Home?
While it's important to reduce and minimize exposure to mold in
your food, it's also wise to consider other sources of mold
exposure, including that in your home. As many as 40 percent of all
American schools and at least 25 percent or more of all homes are
believed to be affected by mold and microbial growth due to water
intrusion.
According to mold expert Dr. Jack Thrasher, the prevalence of
mold in America is so great he refers to it as pandemic. A musty,
mildew odor is a tip-off that you need to check your home for any
visible signs of mold. Unexplained health problems, including
frequent headaches, chronic fatigue, skin rashes, allergies, chronic
sinusitis and more may also be due to mold exposure. For more
information, please view my
interview with Dr. Thrasher below, in which he discusses the
health effects of toxic molds and bacteria in your home, as well as
his recommendations for remediation.
Copyright 1997- 2015 Dr. Joseph Mercola. All Rights Reserved.
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