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How Dangerous Is Moldy Food?

The food commonly gets spoiled because of mold. Moldy food does not look good and has a bad texture and taste and can have grayish, whitish or greenish fuzzy spots. There are some types of mold, which produces harmful toxins; and there are some types of molds which are used to produce some specific foods, such as some type of cheeses.

In this article, we will discuss about mold in food and whether it is harmful if consumed. 

What is Mold and What does it look like?

Mold is nothing but a form of fungus, which creates thread-like, multi-cellular structures. Mold is often visible to the human eye, as it grows on food, and it also changes the appearance of the food. Moldy food becomes soft and its color also changes. The actual mold looks fuzzy, fluffy and can have a dusty texture.

The mold produces spores which lends the color and is often green, black white or grey in color. Moldy food can taste like wet dirt and the smell can be “off.”

Even if the mold is seen on the surface of the food, not many know that the roots of the mold grow deep down into the food. For the mold to grow, it needs warm, moist organic matter and for this reason food is commonly the ideal environment for it.

There are about thousands of different forms of mold and they are present everywhere in the environment. Other than being present in food, mold can also be found indoors in moist places (1).

The primary purpose of food preservation methods, such as freezing, pickling and drying is done with the sole purpose to stop the mold growth along with the microbes that are responsible for spoiling the food.

Can Mold Contaminate All Types Of Foods?

Mold can contaminate and grow on almost all kinds of foods. There are some foods that are more prone to mold than others. Fresh foods having water content is more prone to spoilage by mold. Preservatives on the other hand reduce the chances of mold growth, as well as the growth of microorganisms (2). Mold can also grow during the process of production of food, such as growing, harvesting, processing or storage (2).

What are some Common Foods That Can Grow Mold?

Some of the common foods which the mold just loves to make its home are:

Vegetables, such as bell peppers, tomatoes, carrots and cauliflower.

Fruits, such as, oranges, strawberries, raspberries, apples and grapes.

Bread, especially the one which does not have preservatives in it.

Cheese, which are both hard and soft types.

Other foods which mold loves to grow on consist of nuts, meat, milk and processed foods.

What is Xerophilic Mold?

Majority of the types of molds need oxygen to live and they do not thrive if there is less oxygen. However, mold can also grow on food which airtight packed after being opened. Moisture is needed by the majority of the molds to live; however, a certain form of mold known as xerophilic mold can sometimes grow in sugary and dry environments. Xerophilic mold can also be found on dried fruits, chocolate and baked goods in some cases (3, 4, 5).

Food Contamination Can Also Occur Due To Bacteria

Along with mold, there can be invisible bacteria, which can live and grow along with the mold on the food. Food borne illnesses occur as a result of eating food contaminated by bacteria causing symptoms, such as nausea, vomiting and diarrhea. Depending on the type of bacteria, the severity of the illnesses occurs and it also depends on the amount consumed and the overall health of the person (6).

What Should You Do With The Moldy Food?

 If there is mold on food, then it is advised to discard it. Soft food contains increased moisture content, which makes it easy for the mold to grow under the surface and makes it hard to detect also. Along with mold, there can be bacterial growth also.

It is easy to remove the mold present on hard foods, like hard cheese. One can just cut the portion that has mold on it. Commonly, mold cannot easily penetrate the dense or hard food. However, if mold covers the entire food, then you should throw it away immediately.  Also, do not sniff the mold, as it can cause respiratory problems.

Moldy Foods that can be Salvaged

Given below are the food items which can still be used when the mold is removed or cut off (1):

  • Firm vegetables and fruits, such as apples, carrots and bell peppers.
  • Hard cheese, such as Parmesan and Gorgonzola.
  • Dry-cured country hams and hard salami.

When you are cutting off the mold from food, you need to cut at least one inch below and around the mold. Also, do not touch the mold directly with your knife.

Moldy Foods That Should Be Thrown Away

If there is mold on the below foods, then it should be thrown away (1):

  • Soft vegetables and fruits like, cucumbers, strawberries and tomatoes.
  • Bread and other baked goods, as the mold can easily penetrate and grow under the surface.
  • Soft cheese, such as cream and cottage cheese along with crumbled, shredded and sliced cheese.
  • Cooked food, such as meat, casseroles, grains and pasta.
  • Jellies and jam: If there is mold on these products, then it can contain mycotoxins and should be thrown away.
  • Legumes, peanut butter and nuts and other products that are made or processed without preservatives are more prone to mold growth.
  • Bacon, deli meats, hot dogs, sour cream and yogurt; if all these have mold on them, then should be immediately discarded.

Molds Can Be Good!

Molds are also used to produce food. One of the categories of molds is Penicillium and this is used in the production of various forms of cheese, such as Gorgonzola, blue cheese, Camembert and brie (2, 7).

These cheeses are safe to consume as the strains used to make them do not produce harmful mycotoxins. Other molds that are safe include koji molds, also Aspergillus oryzaea and are used for fermenting soybeans to make soy sauce. Also used to make vinegar and fermented beverages, including sake, which is a Japanese drink (8).

Point to remember is even though some types of molds are added to certain foods during the process of production to get certain effects; however, these same molds are still capable of spoiling other food products. A good example is Penicillium roqueforti is used for making blue cheese; however, it can cause spoilage if it grows in grated or fresh cheese (2). 

Mycotoxins are Produced by Mold

Mycotoxins are the toxic chemicals produced by the mold. It can cause disease and in some cases even death, depending on the duration of exposure, the amount eaten, and the health and age of the person (9).

Acute toxicity consists of gastrointestinal symptoms, such as vomiting, diarrhea and acute liver disease as well. Prolonged exposure to low levels of mycotoxins can cause immune system suppression and in some cases can even cause cancer (10, 11).

Other than ingesting contaminated moldy food, other ways to get exposed to mold is through skin contact or inhalation of mycotoxins in the environment (9). The mold growth is commonly obvious and visible to the eye; however, the mycotoxins are not visible to the human eye.

Aflatoxin is one of the most studied, most toxic and most common mycotoxins. It is a carcinogen and if ingested in high amounts can cause death. Aflatoxin contamination can be commonly seen in warm areas and is usually associated with drought conditions (12). Aflatoxin and other mycotoxins are heat-stable and it can easily survive food processing. So, it can be present in processed food also like peanut butter (10).

Contamination of Food and Crops by Mycotoxins Is a Serious Issue

Mycotoxins can be presents in foods due to contaminated crops. Mycotoxins contamination is one of a common issue faced by the agricultural industry, as mold produces mycotoxins. Around 25% of the grain crops all over the world can be contaminated with mycotoxins (11).

There are various types of crops, which can be contaminated, such as oats, corn, rice, spices, nuts, vegetables and fruits.

There are many factors that affect the formation of mycotoxins, such as droughts make the plants weak and thus make them more susceptible to infestation and damage (10, 13).

Animal products like milk, meat and eggs can also have mycotoxins if the animals consumed contaminated feed. Mycotoxins can also contaminate food during storage if the storage environment is comparatively warm and moist (11, 13).

Since it is not possible to completely prevent the formation of mycotoxins, the food industry has established different ways to monitor it. The mycotoxins levels in foods are strictly regulated in around 100 countries (12, 14, 15).

While exposure to small quantities of these toxins is possible through the diet, however, the levels do not cross the safe limits and will not cause any harm especially if the individual is healthy. Unfortunately, it is not possible to completely avoid its exposure.

Mold produces these harmful toxins under the right conditions (when the food is rotten) and when it reaches maturity.  So, the chances of you throwing away the food by the time food reaches this state to have these toxins are very high.

Does Mold Cause Allergic Reactions?

Mold can cause a respiratory allergy reaction in some individuals after they have eaten moldy food. More research needs to be done on this topic.

In some cases, individuals with allergy to mold have experienced allergic symptoms after consuming Quorn, which is a food product made from fungal proteins or mycoproteins (16, 17, 18, 19). Another cases showed a person having a serious allergic reaction after consuming bee pollen supplement, which was contaminated with the molds Cladosporium and Alternaria (20).

Another case where a teenager who was allergic to mold died after eating a pancake mix which was heavily contaminated with mold (21).

People not having allergy or sensitivity to mold are not likely to get affected if they accidentally ingest it in small quantity. 

How to Prevent Mold from Growing On the Food?

There are many ways to prevent mold growth on the food. First of all, it is important to keep the area where you store your food extremely clean, as the spores from moldy food can accumulate in the refrigerator and other storage spaces. It is also important to properly handle the food items.

Some tips to prevent mold growth in foods are (1):

  • It is important to clean your fridge using a mild disinfectant if possible every few weeks or as soon as you see it getting dirty.
  • The items used to clean the fridge, such as the sponges, dishcloths should also be kept cleaned.
  • Always keep perishable foods in a cool area: foods which will get bad fast should be kept in the refrigerator and should not be left outside for more than two hours.
  • Buy food in small quantities: always buy small quantity of food, as fresh food has a limited shelf life. Buy in small amounts and use within a few days.
  • Always keep the storage containers clean and sealed to prevent exposure to mold spores in the atmosphere.
  • Always consume the leftover food first before moving to the fresh food.
  • If you do not want to eat something in the near future, then keep it in the freezer.


Mold is naturally present everywhere in the atmosphere and if it starts to grow on food, then it causes it to rot. Mold can produce harmful mycotoxins in different kinds of food items; however, the levels of mycotoxins are tightly regulated. Exposure to small amounts to this toxin is not likely to cause any harm in individuals who are healthy. Mycotoxins only develop when the mold has matured and by that time many people would have thrown their food away.

Moldy foods should be avoided as much as possible, more so if someone has a respiratory allergy to it. Nevertheless, if someone ingests it accidentally, then it will not cause harm in most cases.


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Team PainAssist
Team PainAssist
Written, Edited or Reviewed By: Team PainAssist, Pain Assist Inc. This article does not provide medical advice. See disclaimer
Last Modified On:May 19, 2024

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