Molds are microscopic fungi that live on plant or animal matter. No one knows how many species of fungi exist, but estimates are tens of thousands 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:
- A 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 in the wind.
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. Some molds cause allergic reactions and respiratory problems. Some common household molds produce “mycotoxins,” poisonous chemicals that can cause sickness and even death.
Contaminants in Food and Grain
Molds grow on the surface of food, but they also grow into the food. 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, mycotoxins may have spread throughout the food.
Mycotoxins are 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 times.
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.
Molds are Everywhere!
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.
Common Foodborne Molds
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 leftovers, fruits and vegetables, almost all grains and many other foods.
While most molds prefer warmer temperatures, some 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.
Minimize Mold Growth
- 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 white cleaning vinegar (baking soda does not kill mold). Rinse with clear water and dry. Scrub visible mold (usually black) on rubber casings. (bleaches out mold’s appearance, but doesn’t kill it).
- Keep dishcloths, towels, sponges, and mops clean and fresh. A musty smell means they’re spreading mold around. Discard these items, as mold cannot be cleaned from porous materials.
- Keep the humidity level in the house below 40%.
Edited from www.usda.gov; Food Safety Fact Sheet.