Moldy Cheese: Is it Safe to Eat?

Aditi Shenai

May 12, 2022

Cheese is a standard dairy product that comes in many different types. It consists of the solid (fats and proteins) part separated from milk. Though many kinds of cheese, they all follow the same basic preparation procedure. Making cheese starts with milk, and in the end, after separating solids and water, it goes through an ageing process to make the final cheese product. There are several questions about the ageing process and whether aged cheese and moldy cheese are safe to eat. 

Often in the process of preparing cheese, the microorganisms used are bacteria. However, in some cases, such as Roquefort, Camembert, brie, or blue cheese, the organisms used are specific types of mold (or fungus).

Mold can grow on any food, including cheese. There are many reasons for the cheese to mold—one of the most common being nutrition. Cheese has a lot of nutrition in it for mold to grow. In addition, there are many ways to keep mold off the cheese, such as soaking the cheese with salty water, which dries out the rind of the cheese and makes it less attractive for mold to grow.

However, mold and bacteria are often confused as the same, but they are not. Most cheeses do not mold, but the ones that do mostly have either white, blue or green penicillium mold.

What is Mold?

Mold is one of several types of fungus. In contrast to other types of fungus such as yeast or mushrooms, the distinguishing feature of mold is its growth in the form of multicellular filaments known as hyphae. 

The mold life cycle begins when a spore (a reproductive fungal cell) lands on a food item or otherwise in a condition where it can start to grow. Once it has grown in size, the hyphae form to cover parts of food visibly. This network of hyphae gives the mold its popular mycelium texture. 

Mold is, at its core, a type of fungus. The decomposition of food items colonised by mold often results in a foul smell. Therefore, many molds are dangerous for consumption, and you should not consume things that have grown mold.

However, not all molds are harmful; some molds like penicillium have medicinal uses. The first antibiotic, penicillin, was obtained from penicillium.

Moldy Cheese: The Causes

Cheese can mould due to a variety of reasons. Since mould spores are airborne and present almost everywhere, they need the right conditions to grow and develop into visible mould. 

In addition, cheese is moist and rich in nutrients, which makes up for an ideal growth environment for molds. However, mold usually doesn’t develop in a refrigerator since it lacks the perfect warm temperature required to grow. 

However, given enough time, an unclean refrigerator may still lead to moldy cheese. Furthermore, mold spores are essentially just ‘seeds’ of mold; they, on their own, are not harmful in the quantities generally present in the air. But once grown, they can produce toxins that are dangerous for human consumption. 

Moldy Cheese: How Safe is it for Consumption?

Molds are just one specific type of fungus, that produce toxins that are dangerous to humans during the decomposition of food items, like many other fungi. In addition, mycelium’s commonly observed visible texture can often penetrate deep into food items and pose a risk even when it seems that the mold is surface only.

In softer varieties of cheese, such as cottage cheese and cream cheese, the network of mold roots can easily penetrate and establish growth deep within the cheese. This network is often unrecognisable to the human eye. However, it is still as toxic to humans as the surface level mold is. 

In the more rigid varieties of cheese, such as cheddar cheese, the mold cannot establish itself deep within as quickly as soft cheese. Therefore, you can cut away the moldy part of the hard cheese and eat the rest of it. It often doesn’t cause any issues as the rest of the hard cheese usually doesn’t have molds. However, if a hard cheese has a mold patch growing on it, cut 1 inch deep into the cheese away from the mold patch, and you can save the remaining cheese to eat. 

Some culinary methods use moulds to prepare a particular variety of cheese as all forms of mould are not harmful. The microorganisms used to prepare these cheeses are moulds that do not produce toxins and are otherwise safe for human consumption. 

Usually, you can easily distinguish such moulds in some varieties of cheese. However, such sorts of cheese can still grow harmful mould on them. Therefore, if you suspect a dangerous type of mould has grown on cheese, discard it. 

Main Types of Mold prepared Cheese

1. Soft-ripened

Soft ripened cheese is known for its smooth and thin rind (the outside texture). The mould is often sprayed onto the cheese surface, allowing it to mature from the outside and give it its characteristic rind. Brie and Camembert are the most famous examples of this category of cheese.

2. Washed-rind

Similar to soft-ripened cheese, washed-rind cheese also has a soft outside texture. It is prepared by periodically ‘washing’ the surface of the cheese with saltwater or another mould-bearing agent. Washing the cheese helps it ripen inwards and gives it its characteristic smell and texture. Sometimes the softer variety of washed-rind is called smear-ripened cheese. 

Brick cheese, Limburger, and Munster are some common examples of washed-rind cheese.

3. Blue Cheese

Preparation of Blue Cheese occurs by injecting specific types of penicillium mould during the early phase of cheese when it’s loose. Often the cheese is spiked during the initial manufacturing phases to allow oxygen access deep within the interior. Spiking gives the blue cheese its distinctive blue colour and flavour. 

Roquefort, Gorgonzola, and Stilton are some common examples of blue cheese.

Health Risks of Moldy Cheese

1. Mycotoxin Exposure

Mycotoxin is a set of related toxins produced by fungi. Some studies have shown that chronic exposure to mycotoxins can lead to cancer, liver damage, or immune suppression. Aflatoxin is a well-known toxic substance produced by a fungus, known to be highly poisonous and can cause severe liver damage during acute exposure.

Other toxic substances such as Ergot Alkaloids directly cause human Ergotism. This disease causes painful spasms and requires immediate medical care.

2. Food Poisoning

Moldy cheese can contain many different types of toxins. Acute exposure to some toxins can lead to food poisoning. The symptoms usually start with nausea and drowsiness and may gradually develop into lasting diarrhoea. 

Suppose you suspect you have consumed mouldy cheese and suffer from nausea, vomiting, or diarrhoea, it is essential to get medical treatment.

3. Mold Allergy

Mould exposure can be dangerous to everyone. However, some people are more sensitive to atmospheric allergens, and mould spores can trigger allergic responses. Notably, people with asthma should take extra care while handling mouldy substances. Also, some studies show that mould exposure can lead to worse symptoms.

4. Presence of Other Harmful Microorganisms

The environment that allows mould growth is also ideal for other microorganisms such as bacteria to grow. In addition, harmful bacteria such as E. coli and Salmonella may also colonise the food and the mould. Such microorganisms can cause serious health problems, and hence you should not consume items that are doubtful of having mould.

Health Benefits of Cheese

1. Rich Protein Source

Cheese is an excellent source of proteins. Often, people following a vegetarian diet find it difficult to maintain an adequate protein intake; cheese provides a good source of proteins. The higher protein content is directly related to the fact that cheese contains the fat and proteins part of the milk separated from the water.

2. Enhances Bone Development

Many milk products contain high calcium content, and cheese is one of them. Cheese is very high in calcium and phosphorus and critical minerals required for bone development. Moreover, inadequate calcium intake results in the body using the calcium from bones, weakening them. Therefore, cheese consumption helps in maintaining a healthy intake of calcium.

3. Improves Immunity

Some studies show that the probiotic nature of cheese helps enhance the immune system, which enables people to fight off any infections and other diseases easily. 

4. Lowers Cholesterol

Cholesterol is associated with many heart diseases. Therefore, people generally assume that anything high in fat may increase their cholesterol levels. Some studies have found that cheese intake is associated with lower cholesterol levels. The high calcium content present in cheese results in less fat absorption by the body.

How to Prevent Cheese from Being Moldy

Keep Your Fridge Clean

Mold spores are everywhere, but if you keep your fridge clean, cheese has less chance of getting spores from harmful molds that might release them in your fridge. In addition, keeping your fridge clean also prevents other microorganisms from colonising leftovers or other foods.

Consume Cheese Early

Mold spores need time to grow and produce toxic substances. So if you consume the cheese early, you give less chance for the mold to kick in and spoil your cheese.

Do Not Wrap Cheese in Plastic Wrap

Avoid covering or wrapping cheese in a plastic wrap as it seals in all the moisture and other substances inside of it. The higher moisture content is ideal for mould growth. Moreover, plastic may start to release its flavour into cheese if left for more extended periods.

Handle the Cheese in a Clean Way

It is best to cut and slice cheese in a clean environment. Slicing or cutting the cheese in a dirty area or with dirty utensils risks exposure to harmful microorganisms. Therefore, using a clean cutting board and knife while handling the cheese is essential to prevent mould exposure.

The Bottom Line

Cheese is a popular dairy item, and it has many different varieties. Though some cheeses use moulds that are safe for human consumption, if you are not sure, it is best to throw away any cheese that has grown mould after being purchased. 

Toxins found in mould can be hazardous. Health risks of exposure to lousy mould include food poisoning, allergic reaction, and long-term risks of diseases such as cancer. Since not all moulds are harmful, cheese varieties obtained from moulds, such as blue cheese, have significant health benefits. However, you should always consult a medical professional to evaluate your food options. 

Storing the cheese in a cool and dry environment can help prevent mould growth. Therefore, keeping cheese in the fridge and maintaining good cleanliness in your kitchen area is essential to avoid mould in the first place. Lastly, If you notice mould on a softer variety of cheese, it is best to discard it. However, often in more hard types of cheese, it is okay to slice away the bad parts of cheese and consume the rest of it. 

Frequently Asked Questions (FAQs)

Q. Will moldy cheese hurt you?

A. Moldy cheese can contain harmful bacteria and toxins produced by molds. However, types of cheese that use safe molds for preparation, such as blue cheese, are safe to consume for healthy adults. 

Q. What should I do if I eat moldy cheese?

A. If you ate a harder variety of cheese with the mold part cut away, you might need not worry. Mold usually doesn’t penetrate deep into harder cheese. However, softer types may pose some risks, such as food poisoning. However, if you experience any side effects after consuming moldy cheese, seek medical attention immediately. 

Q. Why does cheese mold in the refrigerator?

A. Mold spores are everywhere, and if given enough time, mold spores can grow even inside the refrigerator. Ideally, mold requires hot and humid conditions to grow, but given enough time, such as in a fridge, mold can grow in cold places too. 

Q. Is mold on blue cheese okay?

A. Yes, blue cheese uses a type of mold known as penicillium. This mold is safe for human consumption, and in fact, the first antibiotic was a derivative of penicillium. However, if the mold has started to grow after you have purchased the blue cheese, it might indicate that it is a harmful type of mold. Therefore, it is best to discard such cheese. 

Q. Does all cheese have mold?

A. No, Many kinds of cheese use bacteria and other agents in the preparation process. Only specific varieties of cheese, such as blue cheese, are prepared with a mold. 

Q. Will a little mold on bread hurt you?

A. Often, eating a little bit of moldy bread won’t harm you. However, sometimes it can cause serious health issues. If you face the side effects of consuming such bread, seek medical attention. 

Q. Can eating mold cause diarrhoea?

A. Yes, eating mold can lead to food poisoning and diarrhoea. Therefore, it is best to seek medical attention if you feel you have been poisoned by eating mold. However, there are safe varieties of mold, too, such as those used to make blue cheese but do not assume any mold growing on its own on cheese is safe for consumption. Often, such mold is harmful for consumption. 

Q. Will I get sick if I accidentally ate moldy bread?

A. Chances are low if you consume insufficient quantities of such bread, but sometimes eating moldy bread can lead to serious health issues. It is best to discuss this with a medical professional before the symptoms worsen. 

Q. Can you cook mold out of food?

A. Technically, most molds cannot survive cooking temperatures. However, many molds produce toxins that do not break down even under high temperatures. Consumption of such toxins can lead to sickness. Therefore, it is best to discard any mold-containing food items. 

Q. How long does it take for the cheese to mold?

A. It depends on the variety of the cheese. Different cheeses mold differently. Cheese with higher moisture, such as cream cheese, can mold within two or three weeks, whereas more rigid varieties of cheese, such as Parmesan, can take up to 10 months to mold.

About the Author

M.Sc in: Dietetics and Applied Nutrition from Manipal University. Worked: All over India and have been involved in helping set up nutrition departments in start ups. Interested in lifestyle based nutrition. Mantra: A healthy lifestyle isn't a choice to be made or discarded, it's a way of life!

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