Molds on food: How dangerous are they?

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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?

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.

Molds have branches and roots that are similar to 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.

Are Some Molds Dangerous?

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.

Are Molds Only On The Surface Of Food?

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.

Where Are Molds Found?

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.

What Are Some Common Foodborne Molds?

Molds most often found on meat and poultry are Alternaria, Asperigillus, Botrytis, Cladosporium, Fusarium, Geotrichum, Monilia, Manoscus, Mortierella, Mucor, Neurospora, Oidium, Oosproa, Pennicillium, Rhizopus and Thamnidium. These molds can also be found on many other foods.

Mycotoxins are poisonous substances 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.

Is Mushroom Poisoning Caused By Molds?

No, it is because of 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 a higher species of fungi. The term "toadstool" (from the German "Todesstuhl" - death's stool) is commonly given to poisonous mushrooms, but 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.

Are Any Food Molds Beneficial?

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, bleu, 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.