Moldy Cheese: What's Happening And Is It Safe?

Cheese is a delicious and popular dairy product, but it can be confusing to know what to do when it gets mouldy. Mould is a type of fungus that thrives in moist areas and can be transported by water, air, or insects. While mould on most foods means it's time to throw it away, this isn't always the case with cheese. In fact, some cheeses are meant to be mouldy, like blue-veined cheeses and Brie, and it's safe to eat these moulds. However, mould on other types of cheese can indicate spoilage and may be harmful. So, what happens when cheese goes mouldy, and what should you do?

How to identify good vs bad mould on cheese

Firstly, it's important to note that mould is an integral part of the cheesemaking process. In fact, without it, we wouldn't have Camembert, Brie, or blue cheese. However, sometimes mould can go bad, and it's important to know how to identify this.

As a general rule, unwanted blue, green, white, and grey moulds are fine and can simply be cut off the cheese. However, pink, red, orange, and black moulds are not as good. If you spot any of these colours, it's best to discard the cheese entirely. Black moulds, in particular, will make the cheese taste terrible.

The softer the cheese, the easier it is for mould to penetrate and, therefore, the more contaminated it will be. Fresh, soft cheeses such as ricotta, mascarpone, and chèvre should be discarded if mould is present, as the damp environment means that the mould has likely penetrated deep into the cheese and negatively impacted the flavour. For soft cheeses like Brie or Port Salut, cut away about a quarter of an inch from any surface where mould is visible. Harder, aged cheeses, like aged Cheddar or Parmesan, can simply have the mould scraped away.

If you see white, fuzzy mould tinged with green, the flavour effect is minimal, and the mould can be safely cut away. If the cheese is mouldy and wet or smells of ammonia, it should be discarded.

To prevent mould from growing on your cheese, store it properly and eat it within a reasonable timeframe. Wrap the cheese in special cheese paper or parchment paper, label it with the type of cheese and the day you bought it, and store it in your crisper drawer or a dedicated wine fridge, which has less cold temperatures that are better for the cheese.

How to salvage mouldy cheese

It's a common misconception that cheese should be thrown away as soon as it shows any signs of mould. In reality, this isn't always necessary, and there are ways to salvage mouldy cheese. However, it's important to note that this depends on the type of cheese and the extent of the mould growth.

Firstly, it's crucial to understand that mould is an integral part of the cheesemaking process. Many cheeses, such as blue cheese and Brie, are intentionally moulded as part of their production. Therefore, finding mould on your cheese doesn't automatically mean it's unsafe to eat.

That being said, there are certain types of cheese that should be discarded if mould is present. These include any shredded cheese, Brie, Camembert, cottage cheese, cream cheese, Neufchatel, and Ricotta. For these varieties, it's best to play it safe and throw them away, as the mould can significantly alter the flavour and texture of the cheese.

However, for most other types of cheese, it is generally safe to cut off the mouldy portion and consume the rest. Hard, salty cheeses like Parmesan and aged Cheddar are good examples, as the mould roots are unlikely to penetrate deep into the cheese. Simply cut off at least an inch around and below the mould spot to ensure you remove all the roots, and the remaining cheese should be safe to eat.

If you're unsure about consuming the cheese, there are alternative ways to salvage it without eating it directly. One option is to incorporate it into a cooked dish, such as macaroni and cheese. By mixing the cheese with other ingredients and cooking it thoroughly, you can transform it into a delicious meal while mitigating any potential risks associated with mould consumption.

Another option is to create a cheese spread, such as the French Fromage Fort or Beer Cheese. These spreads are made by grinding up bits of cheese and combining them with other ingredients like garlic, olive oil, wine, herbs, or beer. This process can help mask any undesirable flavours or texture changes caused by the mould and give your old cheese a new lease of life.

The dangers of eating mouldy cheese

It is not recommended to eat mouldy cheese, even though it may not always indicate spoilage. While some types of mould are used in the cheesemaking process, mould that appears on old cheese is usually a sign of spoilage and can be dangerous to consume.

Mould is a type of fungus that thrives in moist areas. It is transported by water, air, or insects, and can invade food through root threads, with stalks rising above the food and spores forming at the ends of the stalks.

Mould can carry harmful bacteria, including E. coli, Listeria, Salmonella, and Brucella, which can cause food poisoning. Symptoms of food poisoning include vomiting, stomach pain, and diarrhoea, and in severe cases, it may even lead to death.

Some moulds can also produce mycotoxins, which are poisonous substances that can cause acute food poisoning, immune deficiency, and even cancer. The carcinogen aflatoxin, for example, has been linked to an increased risk of liver cancer.

While it is rare for mould to spread beyond the surface of hard cheeses such as Parmesan, Swiss, or Cheddar, it is still recommended to cut off at least one inch around and below the mouldy spot if you choose to consume the cheese. However, this does not apply to soft cheeses, shredded cheeses, or sliced varieties. Any signs of mould on these types of cheese mean that the entire product should be discarded, as the spores can easily contaminate the entire cheese.

Therefore, it is generally recommended to throw away mouldy cheese, especially when there are children or individuals at high risk in the household.

How to prevent cheese from moulding

Cheese is a food that is susceptible to mould, and mouldy cheese is usually the result of improper storage, handling, and the reuse of utensils. However, there are several ways to prevent cheese from moulding.

Firstly, it is important to store cheese at the proper refrigerated temperature. The ideal temperature for storing most cheeses is between 35°F and 45°F (2°C to 7°C). Keep the cheese in the refrigerator, ideally in the crisper drawer, where humidity levels are slightly higher.

Secondly, avoid using plastic wrap or airtight containers to store cheese. Cheese needs to breathe, and plastic wrap can damage the taste of the cheese. Instead, use wax or parchment paper, then loosely cover it with plastic wrap or place it in a resealable plastic bag with some air inside. Alternatively, use cheese storage paper or bags, which are designed to allow air circulation while protecting the cheese from air exposure.

Thirdly, if you have a variety of cheese types, keep them separate to prevent cross-contamination of flavours and mould spores. This is especially important with strong-smelling or blue-veined cheeses.

Fourthly, change the wrapping periodically, especially if the cheese sweats a lot, and replace the paper every time you unwrap it. Used wrapping will not provide the same breathable seal, reducing freshness.

Additionally, consider cutting large blocks of cheese into smaller portions and wrapping them individually. This will help reduce the surface area exposed to potential mould spores each time you use the cheese.

Finally, always use clean knives and hands when cutting or handling cheese to minimise the introduction of bacteria and mould spores. If possible, handle cheese with food-grade plastic gloves or plastic wrap, as even clean hands and utensils can transfer mould spores.

The best way to store cheese

When cheese goes into a mould, it's usually because of poor storage. But fear not, there are several ways to prevent this from happening!

Storing cheese correctly is important to prevent mould and maintain its quality and flavour. Here are some tips to ensure your cheese stays fresh:

• Avoid plastic wrap: Plastic wrap can suffocate the cheese, affecting its flavour. After a few days, the cheese may start to take on a plasticky taste.
• Don't wrap too tightly or too loosely: Cheese needs room to breathe. Wrapping it too tightly can cause an ammonia smell and taste. However, wrapping it too loosely can lead to dried-out, hardened cheese.
• Use cheese bags or cheese paper: Cheese bags or cheese paper are ideal as they are porous, allowing the cheese to breathe while protecting it from excess air exposure.
• Replace the paper each time you unwrap: For sweaty cheeses, replace the paper or parchment each time you unwrap it to maintain a breathable seal.
• Store soft and fresh cheeses differently: Keep soft cheeses like mozzarella, ricotta, and chèvre in their original containers. For larger pieces of mozzarella, remove them from the brining solution and wrap them in plastic, replacing the plastic each time you open it.
• Replace the brine if contaminated: If the packing solution on fresh cheeses becomes contaminated, replace it with a saltwater brine made from one tablespoon of salt dissolved in a few cups of water.
• Buy small quantities: Only buy as much cheese as you can consume in one or two sittings to reduce the risk of mould.
• Store in the vegetable drawer: Keep cheese between 35-45°F (34-38°F is ideal). Store it in the vegetable drawer or on a bottom shelf, away from the freezer, to maintain a consistent temperature.
• Use oil to prevent mould: Rub the cut faces of the cheese with olive, canola, or vegetable oil and store in an airtight container. If mould appears, it will be on the oil, which can be wiped off.
• Use airtight containers: Store cheese in airtight containers to prevent bacteria and moisture from affecting it.
• Rub with butter: Rubbing a thin layer of butter onto the cheese can help keep it fresh, especially for mature and hard cheeses like cheddar and Parmesan.
• Portion and freeze: Grate or portion the cheese and store it in the freezer to extend its shelf life. However, freezing may affect the texture and melting ability.
• Use a vacuum sealer: Cut a vacuum bag longer than the cheese block for resealing. Blot the cheese with a paper towel if there is surface moisture.
• Control moisture: Use a paper towel to control moisture around the cheese. Don't let it get too dry or too wet.
• Store in the original wrapper: Place the cheese in a rubber tub with its original wrapper to maintain freshness.
• Cut off mould: If mould appears, cut it off. Mould usually only grows on the surface, so removing 1mm of cheese is sufficient.
• Store different cheeses separately: Keep strong-smelling cheeses like blue cheese and brie away from other cheeses to prevent foreign mould growth and odour transfer.
• Keep the fridge clean: A clean fridge offers better cheese storage. Mouldy food can cause your cheese to mould faster, and a dirty fridge can harbour harmful bacteria.

Frequently asked questions