Molds - The Good, the Bad and the Ugly

Courtesy the April 2008 newsletter of The Dr. Clark Store

and, Self Health Resource Center 1055 Bay Blvd ste A, Chula Vista, CA 91902

There are thousands of species of molds. Most of them are “bad,” but some are “good.” Alexander Fleming’s famous discovery of the antibiotic penicillin, for example, involved the mold Penicillium chrysogenum. And friendly molds are used to make certain kinds of cheeses. Roquefort, blue, Gorgonzola and Stilton cheeses have blue veins of mold throughout the cheese. Brie and Camembert have white surface molds. Other cheeses have both an internal and a surface mold. The koji molds, a group of the Aspergillus species, have been cultured in eastern Asia for many centuries. They are used to ferment the soybean and wheat mixture from which soy sauce and miso are derived.

Molds reproduce through tiny spores. Some spores can remain airborne indefinitely, and many are able to survive extremes of temperature and pressure.

Although molds grow on dead organic matter everywhere in nature, their presence is only visible to the naked eye when mold colonies form.

Common Molds

Common molds include Rhizopus stolonifer (black bread mold), Stachybotrys (appears on water-damaged building materials) and Botrytis cinerea or gray mold rot (strawberries, raspberries and other fruits). Leave a slice of bread out on the counter for a few days and Rhizopus stolonifer, black bread mold, will soon set up housekeeping. The stubborn mildew that appears so persistently on your shower walls is probably Stachybotrys. And that nice juicy peach you forgot about in the fruit basket is now playing host to a thriving colony of Botrytis cinerea.

Friendly Fungi

There are three main categories of cheese in which the presence of mold is a significant feature: soft ripened cheeses, washed rind cheeses and blue cheeses.

Soft-ripened cheeses start out firm and rather chalky in texture. They are aged from the exterior inwards by exposing them to mold. The mold may be a velvety bloom of Penicillium candida or P. camemberti that forms a flexible white crust and contributes to the gooey texture and intense flavor. Brie and Camembert, the most famous of soft-ripened cheeses, are made by allowing white mold to grow on the outside of a soft cheese for a few days or weeks.

Washed-rind cheeses are soft in character and ripen inwards like those with white molds. However, they are treated differently. Washed rind cheeses are periodically cured in a solution of saltwater brine and other mold-bearing agents, making their surfaces amenable to the reddish-orange Brevibacterium linens. The result is a pungent odor and a distinctive flavor. Washed-rind cheeses can be soft (Limburger), semi-hard (Munster), or hard (Appenzeller).

Blue cheese is created by inoculating a cheese with Penicillium roqueforti or Penicillium glaucum. The mold grows within the cheese as it ages. These cheeses have distinct blue veins and assertive flavors. Their texture can be soft or firm. Some of the most renowned cheeses are of this type, each with its own distinctive color, flavor, texture and smell. They include Roquefort, Gorgonzola and Stilton.

The not-so-nice guys

Molds are ubiquitous in nature, and mold spores are a common component of household and workplace dust. However, when mold spores are present in large quantities, they may constitute a health hazard to humans, causing allergic reactions and respiratory problems. Because of this, mold allergy has become a serious problem for many people.

Some molds generate toxic liquid or gaseous compounds, called mycotoxins. Mycotoxins are harmful or lethal to humans and animals when exposure is high enough. Serious neurological problems can result from prolonged exposure to mycotoxins. One example of toxic mold is Stachybotrys chartarum, which has been associated with sick building syndrome. Farm animals frequently suffer from mycotoxin poisoning and may die as a result. Mycotoxins resist decomposition from cooking, and remain in the food chain.

Dermatophytes are parasitic fungi that cause skin infections such as Athlete's foot and Jock Itch. Most dermataphyte fungi take the form of a mold, as opposed to that of a yeast.

Opportunistic infection by molds such as Penicillium marneffei and Aspergillus fumigatus is a common cause of illness and death among immunocompromised individuals, including AIDS victims.

Your Kitchen game plan

When you see mold on food, is it safe to cut off the moldy part and use the rest? For most foods the answer is no, according to the U.S. Department of Agriculture. Discard soft cheeses such as Brie and Camembert if they display molds that are not a part of the manufacturing process. Infected soft cheeses, such as cottage cheese, cream cheese, Neufchatel and crumbled, shredded and sliced cheeses, should be discarded. Such foods with high moisture content can be contaminated below the surface.

For hard cheeses in which mold is not part of the processing, it’s safe to remove the mold and eat the cheese. USDA recommends cutting off at least one inch around and below the mold spot. Be sure to 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.

Small mold spots can be cut off fruits and vegetables with low moisture content such as cabbage, bell peppers and carrots. Cut off at least one 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. Discard fruits and vegetables with high moisture content that can be contaminated below the surface.

Although most molds prefer higher temperatures, they can grow in your refrigerator. Check for mold in refrigerated jam and jelly and on cured, salty meats such as ham, bacon, salami and bologna. Discard jams and jellies infested with mold. The mold could be producing a mycotoxin. Hard salami and dry-cured country hams normally have surface mold. Some salamis have a characteristic thin, white mold coating that is safe to consume, but they shouldn’t show any other mold. Dry-cured country hams normally have surface mold that must be scrubbed off before cooking.

Clean the inside of your refrigerator every few months with one tablespoon of baking soda dissolved in a quart of water. Keep your dishcloths, towels, sponges and mops clean and fresh. A musty smell means they’re spreading mold around.
Keep the humidity level in the house as low as practical—below 40 percent, if possible.

Empty opened cans of perishable foods into clean storage containers and refrigerate them promptly. Don’t leave perishables out of the refrigerator for more than two hours. Use leftovers within three or four days so mold doesn’t have a chance to grow.

When you handle mold-infested foods, do not to sniff the moldy item. This can cause respiratory problems.

Bottom line: in some cases you can cut away the moldy part and use the food item—provided you know what you’re doing. But generally speaking, if food is covered with mold, discard it. If in doubt, throw it out.