Food Safety While Hiking, Camping & Boating

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Some molds cause allergic reactions and respiratory problems. And a few molds, in the right conditions, produce “mycotoxins,” poisonous substances that can make people sick. When you see mold on food, is it safe to cut 

off the moldy part and use the rest? To find the answer to that question, delve beneath the surface of food to 

where molds take root.

What Are Molds?

Are Some Molds 

Dangerous?

Molds on Food: Are They Dangerous?

Molds are microscopic fungi that live on plant or animal matter. No one knows 

how many species of fungi exist, but estimates range from tens of thousands 

to perhaps 300,000 or more. Most are filamentous (threadlike) organisms and 

the production of spores is characteristic of fungi in general. These spores can 

be transported by air, water, or insects.

Unlike bacteria that are one-celled, molds are made of many cells and can 

sometimes be seen with the naked eye. Under a microscope, they look like 

skinny mushrooms. In many molds, the body consists of: 

•	 root threads that invade the food it lives on, 

•	 a stalk rising above the food, and 

•	 spores that form at the ends of the stalks. 

The spores give mold the color you see. When airborne, the spores spread the 

mold from place to place like dandelion seeds blowing across a meadow.

Molds have branches and roots that are like very thin threads. The roots may 

be difficult to see when the mold is growing on food and may be very deep in 

the food. Foods that are moldy may also have invisible bacteria growing along 

with the mold.

Yes, some molds cause allergic reactions and respiratory problems. And a few 

molds, in the right conditions, produce “mycotoxins,” poisonous substances 

that can make you sick. 

No, you only see part of the mold on the surface of food — gray fur on 

forgotten bologna, fuzzy green dots on bread, white dust on Cheddar, coin-size 

velvety circles on fruits, and furry growth on the surface of jellies. When a food 

shows heavy mold growth, “root” threads have invaded it deeply. In dangerous 

molds, poisonous substances are often contained in and around these threads. 

In some cases, toxins may have spread throughout the food.

Molds are found in virtually every environment and can be detected, both 

indoors and outdoors, year round. Mold growth is encouraged by warm and 

humid conditions. Outdoors, they can be found in shady, damp areas or places 

where leaves or other vegetation are decomposing. Indoors, they can be found 

where humidity levels are high.

Molds form spores which, when dry, float through the air and find suitable 

conditions where they can start the growth cycle again.

Are Molds Only on the 

Surface of Food?

Where Are Molds Found?

Food Safety Information

United States Department of Agriculture

Food Safety and Inspection Service

USDA Meat & Poultry Hotline

1-888-MPHotline

(888-674-6854)

The Food Safety and Inspection Service (FSIS) is the public health agency 

in the U.S. Department of Agriculture responsible for ensuring that the nation’s commercial supply of meat, poultry, and egg products is safe, wholesome, and correctly labeled and packaged.

USDA Photo
What Are Some Common 

Foodborne Molds?

What Are Mycotoxins?

Molds most often found on meat and poultry are Alternaria, Aspergillus, 

Botrytis, Cladosporium, Fusarium, Geotrichum, Monilia, Manoscus, 

Mortierella, Mucor, Neurospora, Oidium, Oosproa, Penicillium, Rhizopus and 

Thamnidium. These molds can also be found on many other foods.

Mycotoxins are poisonous substances produced by certain molds found 

primarily in grain and nut crops, but are also known to be on celery, grape 

juice, apples, and other produce. There are many of them and scientists are 

continually discovering new ones. The Food and Agriculture Organization 

(FAO) of the United Nations estimates that 25% of the world’s food crops are 

affected by mycotoxins, of which the most notorious are aflatoxins. 

Aflatoxin is a cancer-causing poison produced by certain fungi in or on foods 

and feeds, especially in field corn and peanuts. They are probably the best 

known and most intensively researched mycotoxins in the world. Aflatoxins 

have been associated with various diseases, such as aflatoxicosis in livestock, 

domestic animals, and humans throughout the world. 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. The U.S. Food 

and Drug Administration and the USDA monitor peanuts and field corn for 

aflatoxin and can remove any food or feed with unacceptable levels of it.

No, it is due to the toxin produced by the fungi, which are in the same 

family as molds. Mushroom poisoning is caused by the consumption of 

raw or cooked mushrooms, which are higher-species of fungi. There is no 

general rule of thumb for distinguishing edible mushrooms from poisonous 

toadstools. The toxins that cause mushroom poisoning are produced naturally 

by the fungi. Most mushrooms that cause human poisoning cannot be made 

safe by cooking, canning, freezing, or any other processing. The only way to 

avoid poisoning is not to eat poisonous mushrooms.

Yes, molds are used to make certain kinds of cheeses and can be on the 

surface of cheese or be developed internally. Blue veined cheese such as 

Roquefort, blue, Gorgonzola, and Stilton are created by the introduction 

of P. roqueforti or Penicillium roqueforti spores. Cheeses such as Brie and 

Camembert have white surface molds. Other cheeses have both an internal 

and a surface mold. The molds used to manufacture these cheeses are safe 

to eat. 

While most molds prefer warmer temperatures, they can grow at refrigerator 

temperatures, too. Molds also tolerate salt and sugar better than most other 

food invaders. Therefore, molds can grow in refrigerated jams and jelly and 

on cured, salty meats — ham, bacon, salami, and bologna.

What is Aflatoxin?

How Does the U.S. 

Government Control 

Aflatoxins?

Is Mushroom Poisoning 

Caused by Molds?

Are Any Food Molds 

Beneficial?

Why Can Mold Grow in 

the Refrigerator?

Molds on Food: Are They Dangerous? Molds on Food: Are They Dangerous?

Food Safety Information 2
Cleanliness is vital in controlling mold. Mold spores from affected food can 

build up in your refrigerator, dishcloths, and other cleaning utensils. 

•	 Clean the inside of the refrigerator every few months with 1 

tablespoon of baking soda dissolved in a quart of water. Rinse with 

clear water and dry. Scrub visible mold (usually black) on rubber 

casings using 3 teaspoon of bleach in a quart of water. 

•	 Keep dishcloths, towels, sponges, and mops clean and fresh. A musty 

smell means they’re spreading mold around. Discard items you can’t 

clean or launder. 

•	 Keep the humidity level in the house below 40%. 

Examine food well before you buy it. Check food in glass jars, look at the 

stem areas on fresh produce, and avoid bruised produce. Notify the store 

manager about mold on foods!

Fresh meat and poultry are usually mold free, but cured and cooked meats 

may not be. Examine them carefully. Exceptions: Some salamis — San 

Francisco, Italian, and Eastern European types — have a characteristic thin, 

white mold coating which is safe to consume; however, they shouldn’t show 

any other mold. Dry-cured country hams normally have surface mold that 

must be scrubbed off before cooking.

Yes, molds can thrive in high-acid foods like jams, jellies, pickles, fruit, and 

tomatoes. But these microscopic fungi are easily destroyed by heat processing 

high-acid foods at a temperature of 212 °F in a boiling water canner for the 

recommended length of time. For more information about processing homecanned foods, go to the National Center for Home Food Preservation at: 

www.uga.edu/nchfp/

•	 When serving food, keep it covered to prevent exposure to mold spores 

in the air. Use plastic wrap to cover foods you want to stay moist — fresh 

or cut fruits and vegetables, and green and mixed salads. 

•	 Empty opened cans of perishable foods into clean storage containers and 

refrigerate them promptly. 

•	 Don’t leave any perishables out of the refrigerator more than 2 hours. 

•	 Use leftovers within 3 to 4 days so mold doesn’t have a chance to grow.

Buying small amounts and using food quickly can help prevent mold growth. 

But when you see moldy food: 

•	 Don’t sniff the moldy item. This can cause respiratory trouble. 

•	 If food is covered with mold, discard it. Put it into a small paper bag 

or wrap it in plastic and dispose in a covered trash can that children 

and animals can’t get into. 

•	 Clean the refrigerator or pantry at the spot where the food was 

stored. 

•	 Check nearby items the moldy food might have touched. Mold spreads 

quickly in fruits and vegetables. 

•	 See the attached chart: “Moldy Food: When to Use, When to 

Discard.” 

Don’t Buy Moldy Foods

How Can You Protect 

Food from Mold?

How Should You Handle 

Food with Mold on It?

How Can You Minimize 

Mold Growth?

Molds on Food: Are They Dangerous? Molds on Food: Are They Dangerous?

Food Safety Information 3

Must Homemade ShelfStable Preserves be 

Water-Bath Processed?
Moldy Food: When to Use, When to Discard

Luncheon meats, 

bacon, or hot dogs

Hard salami and drycured country hams

Cooked leftover meat 

and poultry

Cooked casseroles

Cooked grain and 

pasta

Hard cheese (not 

cheese where mold is 

part of the processing)

Cheese made 

with mold (such 

as Roquefort, blue, 

Gorgonzola, Stilton, 

Brie, Camembert)

Soft cheese(such as 

cottage, cream cheese, 

Neufchatel, chevre, Bel 

Paese, etc.) 

Crumbled, shredded, 

and sliced cheeses (all 

types)

Yogurt and sour 

cream

Jams and jellies

Discard 

Use. Scrub mold off surface.

Discard

Discard

Discard

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 crosscontaminate other parts of the 

cheese). After trimming off 

the mold, re-cover the cheese 

in fresh wrap.

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).

Discard

Discard

Discard

Foods with high moisture content can be contaminated 

below the surface. Moldy foods may also have bacteria 

growing along with the mold. 

It is normal for these shelf-stable products to have 

surface mold.

Foods with high moisture content can be contaminated 

below the surface. Moldy foods may also have bacteria 

growing along with the mold.

Foods with high moisture content can be contaminated 

below the surface. Moldy foods may also have bacteria 

growing along with the mold.

Foods with high moisture content can be contaminated 

below the surface. Moldy foods may also have bacteria 

growing along with the mold.

Mold generally cannot penetrate deep into the product.

Molds that are not a part of the manufacturing process 

can be dangerous.

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.

Foods with high moisture content can be contaminated 

below the surface. Moldy foods may also have bacteria 

growing along with the mold.

The mold could be producing a mycotoxin. Microbiologists 

recommend against scooping out the mold and using the 

remaining condiment.

Molds on Food: Are They Dangerous? Molds on Food: Are They Dangerous?

Food Safety Information 4

 FOOD HANDLING REASON
Food Safety Questions?

 FOOD 

Fruits and vegetables, 

FIRM (such as cabbage, 

bell peppers, carrots, etc.)

Fruits and vegetables, 

SOFT (such as cucumbers, 

peaches, tomatoes, etc.)

Bread and baked goods

Peanut butter, legumes 

and nuts

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 crosscontaminate other parts of the 

produce).

Discard

Discard

Discard

Small mold spots can be cut off FIRM fruits and 

vegetables with low moisture content. It’s difficult for 

mold to penetrate dense foods.

SOFT Fruits and vegetables with high moisture content 

can be contaminated below the surface. 

Porous foods can be contaminated below the surface.

Foods processed without preservatives are at high risk 

for mold.

Moldy Food: When to Use, When to Discard

(continued)

Molds on Food: Are They Dangerous?

The USDA is an equal opportunity

 provider and employer.

Revised August 2013

Call the USDA Meat & Poultry Hotline

HANDLING REASON

FSIS encourages the reprint and distribution of this publication for food safety 

education purposes. However, USDA symbols or logos may not be used separately to 

imply endorsement of a commercial product or service. 

AskKaren.gov

FSIS’ automated response 

system can provide food safety 

information 24/7 

and a live 

chat during 

Hotline 

hours.

Mobile phone users

can access m.askkaren.gov

Send E-mail questions to MPHotline.fsis@usda.gov. PregunteleaKaren.gov

If you have a question 

about meat, poultry, 

or egg products, call 

the USDA Meat and 

Poultry Hotline 

toll free at 

1-888-MPHotline

(1-888-674-6854).

 The hotline is open Monday 

through Friday from 10 

a.m. to 4 p.m. ET (English or Spanish).

Recorded food safety 

messages are available 24 hours a day. 

Check out the 

FSIS Web site at 

www.fsis.usda.gov