The Types of Molds You Can Eat and The Ones You Should Never Eat

Why can I safely eat a slice of Gorgonzola but if I eat any other moldy cheese, I might feel sick? They both have mold, so what's the difference? What makes some molds edible and others not? Here's everything you need to know about molds and how they affect our bodies.

What Are Molds?

In order to distinguish between gorgonzola and moldy cheese, we must first understand what this mold is that occasionally takes over our fridge and why it forms. Mold is nothing more than a mass of microscopic fungi placed next to each other: that's right, they are the "cousins" of the mushrooms we collect in the woods in autumn, but much smaller. They are all very close to each other, forming a real living aggregate that expands, eats and grows, becoming quite large and therefore visible to the naked eye… but only under two conditions: they need humidity and nourishment. If you pay attention, in fact, molds appear right on foods, which are ‘nourishment' by definition, and this happens – often – when a bit of humidity forms in the fridge.

To spread, molds use so-called “spores,” which are the reproductive cells of molds. Think of them as seeds, except that instead of staying in the ground, they travel through the air for days, months, or even years in search of the right place to germinate.

We can't see them because they are so tiny, but there could be some right now right here in front of me, flying undisturbed in this room. When they find a favorable place, they stop and sprout, forming mold.

The Different Types of Mold

There are different types of molds, some good and some bad. For example, there are molds of the genus Mucor and R hizopus that are found in fruit, rotten vegetables or spoiled bread and that, in some cases, can be harmful to our body. Then there are also molds of the genus Aspergillus or worse Stachybotrys Chartarum, capable of causing even serious respiratory problems.

And then there is it: Penicillium, the so-called good mold. So good that it has even saved millions of people. Yes, as you can guess from the name, it is the same mold that allowed Fleming, in 1928, to discover penicillin: the first antibiotic ever discovered, thanks to which it was possible to eradicate diseases once thought to be incurable. In fact, Fleming was studying bacteria at that time when he noticed something incredible. He had just returned from vacation and realized that he had forgotten one of the trays of bacteria open for all that time. The tray had been contaminated by mold and around that mold he saw that a sort of halo had formed where the bacteria did not proliferate, as if a sort of invisible shield was protecting the mold. He did 2+2 and understood that that same “invisible shield” created by that type of fungus (Penicillium notatum specifically), could also be used to keep bacteria away from human beings. Needless to say, thanks to that discovery he saved many human lives. So next time your wife or father nags you that you never put things right, remind them of Fleming and how his carelessness changed the world!

What Are "Good" Molds?

However, now it's easy for us to put 2+2 together: the mold present in Gorgonzola, Stilton or Roquefort is actually of the Penicillium genus, the same one discovered by Fleming. In particular, it is almost always Penicillium glaucum or Penicillium roqueforti (which takes its name from Roquefort cheese). The spores of these molds are inserted into the milk during the production of this type of cheese, which is called blue cheese, and in this way colonies of mold form inside them, which give it not only that typical bluish-green color, but also a soft and melting consistency. In fact, molds are able to break down the proteins in the cheese and degrade the fats, making the product irresistibly creamy, ready to be spread on a slice of bread.

Other cheeses have mold on the outside, they are bloomy rind cheeses. An example of this is Brie, whose mold is formed by the fungus Penicillium candidum, which gives the rind a whitish color. Even in this case, don't worry, the mold is harmless and the cheese can be safely consumed with the entire rind, obviously if you like it.

In most cases, blue cheeses can be safely consumed by people who are lactose intolerant. When molds are added, they attack the lactose, drastically reducing its quantity, until the cheese reaches lactose levels so low as to be harmless. In any case, I recommend that you do some test tastings and evaluate the effects and avoid consuming kilos of gorgonzola if you are intolerant: this is because, it must be said, lactose tolerance varies from person to person, so on the most sensitive individuals even blue cheeses that contain very low percentages of lactose could have some side effects.

In general, to be considered “lactose-free”, the lactose content of cheeses must be equal to or less than 0.01%.

Not Just Cheese: Other Foods With "Good" Molds

Molds are not only on cheeses, but also on other products: for example, on salami. In fact, they are absolutely necessary for the pluming, that is, the process by which molds are placed on the skin of the salami to preserve it and allow it to mature correctly. The skin will then form this whitish patina that serves to protect the product by maintaining the right balance of humidity between the inside and outside. And then there are even wines with mold: moldy wines or also called botrytized because of the name of the fungus that attacks them, Botrytis cinerea. This mold attacks the skin of the grapes, giving the wine a unique and refined flavor.

What Are "Bad" Molds?

Unfortunately, not all molds give us antibiotics or delicious cheeses. Some can give us respiratory problems, gastrointestinal disorders and even skin inflammation. Their harmfulness depends on the production of mycotoxins, which are toxic substances naturally produced by molds. One of the most common mycotoxins in food products is aflatoxin B1, produced by some molds of the Aspergillus genus, which develops in cereals, corn, peanuts and dried fruit in general. This mycotoxin has been classified as carcinogenic to humans, so prolonged exposure to it increases the risk of developing cancer, specifically liver cancer.

The problem with aflatoxins is precisely this: they do not send us to the hospital directly like when we eat a poisonous mushroom from the forest, no, they act slowly over time, causing tumors, cancer, liver and kidney problems. Exposure to this mold must therefore be reduced to a minimum. These molds are not always visible at first glance and can form in various ways, for example if food is stored poorly by the manufacturing companies or during transport, or once it reaches our pantries. Aflatoxins can also reach us through indirect routes. For example, molds can also hide inside yogurt: if the cows that produce the milk have consumed feed that in turn has been contaminated by mycotoxins.

Furthermore, the increase in temperatures and humidity linked to climate change means that aflatoxins are spreading more and more even in Europe, where they were originally less present, so they are a problem that will worsen over time. On this aspect, however, we can be quite calm because, precisely because of the danger of these mycotoxins, especially foods such as corn, feed and cereals, are carefully checked before being put on the market.

But don't think that mycotoxins are exclusive to bad molds, they are produced by all molds. In some cases even by the good molds we were talking about before. The mold Penicillium roqueforti (the one in blue cheeses), in certain conditions could for example produce a mycotoxin called roquefortine C, but it does so in minimal quantities and therefore does not cause any problems to our body.

Continuing our journey into bad molds, we cannot fail to mention Stachybotrys Chartarum, whose mycotoxins cause respiratory problems, skin inflammation, mental confusion and in extreme cases even respiratory collapse. This is perhaps one of the most dangerous molds and has a black and shiny color. More than in food, however, it spreads in the damp walls of homes and in materials rich in cellulose.

What Happens if I Eat Bad Mold?

It is true, as we have said, that molds can be very toxic but, if ingested in small quantities, in most cases nothing happens. If by chance while we are at dinner we happen to accidentally eat a piece of food with mold, don't worry, there is no need to run to the hospital to have a gastric lavage: just notice it and throw away the food.

If you consume large quantities of mold, however, it is likely that you will get a bad stomachache with vomiting and diarrhea. The real danger, I repeat, remains prolonged exposure to mold, so keep your eyes open and pay attention to the state of your walls and your pantries.