Patrick Oconnell
Cheese is a staple in many households, but it can be tricky to determine whether it has gone bad. Cheese is a perishable food that can spoil and harbour harmful bacteria, and consuming spoiled cheese can lead to foodborne illnesses. The answer depends on the type of cheese, how it was stored, and what you're smelling or seeing. There are three main attributes to look out for when determining if your cheese has gone bad: smell, appearance, and taste. If you're unsure, it's best to err on the side of caution and discard any cheese that you suspect has gone off.
| Characteristics | Values |
|---|---|
| Type of cheese | Harder cheeses like cheddar, Parmesan, or Gouda can be left out of the fridge for longer than softer cheeses like mozzarella or cream cheese. |
| Storage | Cheese should be stored in a dry place, such as under a glass bell, to prevent mould. |
| Vacuum-sealed | Vacuum-sealed cheeses can be stored in the refrigerator for a long time. |
| Expiry | Cheese should be consumed by the date on the label or within a few days of purchasing it. |
| Appearance | Spoiled cheese may have mould growth, discolouration, or a slimy or greasy texture. |
| Smell | Spoiled cheese may smell like rancid milk, ammonia, or vinegar. |
| Taste | Spoiled cheese may taste sour or have an unpleasant aftertaste. |
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What You'll Learn
How to identify bad cheese
Cheese is a perishable food product that continues to mature after purchase, so it can be tricky to distinguish between proper maturing and spoilage. The key tools for determining whether cheese has gone bad are your senses, especially sight, smell, and taste.
Appearance
Mould is a well-known sign of cheese spoilage. However, it's important to distinguish between voluntary and involuntary mould. Many blue cheeses and flowery-rind cheeses are impregnated with Penicillium, a type of controlled mould, so the presence of this mould is normal. If you spot mould other than Penicillium on a soft cheese, it's recommended to discard the entire cheese. For hard cheeses, you can cut out the mouldy section and the surrounding area, but only if the mould hasn't spread to the entire cheese.
In general, any significant colour change in cheese can be a sign that the cheese has spoiled. While this may not necessarily mean that the cheese is unsafe to eat, its flavour and texture will be sub-optimal. A gritty rind does not necessarily indicate spoilage, but if the rind is excessively gritty and slimy, it's best to discard the cheese.
Smell
Cheese should only be stinky if it's supposed to be. If it smells like rancid milk or ammonia, it's best to discard it. An ammonia smell can indicate that the cheese has been wrapped up too long and was unable to breathe, but it doesn't necessarily mean the cheese has gone bad.
Taste
If you're still unsure about the quality of the cheese, take a small nibble. If it's abnormally sour or off-tasting, it's past its prime. Taste is the one indicator that can be a dead giveaway that your cheese is bad.
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Storing cheese to prevent spoilage
Storing cheese correctly is important to prevent spoilage and avoid the health risks associated with consuming spoiled cheese. Here are some tips to help you store your cheese to prevent spoilage:
Storage Location
Keep cheese in a dry place, such as under a glass bell. Avoid damp environments as mould develops more easily in these conditions, and softer cheeses with higher moisture content are more susceptible to mould growth.
Storage Container
Use an airtight container to prevent unwanted mould growth.
Storage Temperature
Store cheese in the refrigerator, ideally in the deli drawer. Hard cheeses, such as cheddar and Parmesan, can be kept at room temperature for longer than soft cheeses, but all cheeses should be refrigerated to prolong their freshness. Soft cheeses should be consumed within two weeks of purchase, while hard cheeses can last six to eight weeks in the fridge.
Packaging
Vacuum-sealed cheeses can last longer in the refrigerator and often come with best-by dates. However, don't confuse this with an expiration date.
Appearance
When purchasing cheese, check its appearance for any signs of spoilage. Surface mould is natural for some cheeses, and you can simply trim it off if the cheese below looks clean and exhibits no other signs of spoilage. However, if the entire piece is covered in thick mould, it's probably not worth saving. Other appearance indicators include discolouration, such as fading or darkening, a change in texture, and any signs of sliminess, oil, or bloated packaging.
Smell
Smell your cheese when you first purchase it to familiarise yourself with its normal odour. A significant change in smell is often an indicator of spoilage. Spoiled cheese may emit an off" smell, such as spoiled milk, ammonia, or a refrigerator-like odour.
By following these storage tips, you can help prevent cheese spoilage and ensure you're consuming safe and delicious cheese.
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What to do with spoiled cheese
It is important to identify spoiled cheese and know what to do with it. Spoiled cheese often experiences changes in colour, with the original yellow or orange hue fading. In extreme cases, it can turn black or blue. The presence of mould spots on the surface is a clear indication that the cheese has gone bad. Mould, such as mildew, can grow on cheese if it becomes contaminated and the conditions support mould growth. This mould is typically white, green, or black. Spoiled cheese may also emit a toxic ammonia-like odour or start to smell like a barnyard. It may also cause the insides of your mouth to tingle or burn.
If you notice any of these signs, it is important to discard the cheese immediately. Do not consume spoiled cheese as it can potentially harbour mould that is dangerous when ingested. According to the USDA, mouldy foods can cause allergic reactions and respiratory problems. If the mould has met the right conditions, it can produce mycotoxins, a poisonous substance that can make you very ill. In addition, mouldy foods can also harbour dangerous bacteria such as Listeria, Salmonella, and E. Coli, which can cause food poisoning.
However, if you have leftover cheese that is still within its expiration date, there are creative ways to use it before it goes bad. You can combine different types of cheese to make cheese spreads, mixed grilled cheese sandwiches, or dishes like mac and cheese, frittata, or a vegetarian version of Bolognese. You can also use cheese rinds to add flavour to soups and broths.
If you are feeling adventurous, you can even try making your own cheese at home using spoiled milk. While it may not taste as good as cheese made with fresh milk, it is possible to create a rudimentary form of cheese, such as cottage cheese, from slightly soured or spoiled milk. The process involves concentrating and changing the proteins (caseins) and fats in milk, driven by the actions of microbes. However, it is important to note that spoiled milk can develop unpleasant-smelling compounds, and the taste of the cheese may be affected.
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Safe ways to freeze cheese
Freezing cheese is a great way to preserve it and reduce waste. However, it's important to note that not all cheeses freeze well, and the texture of the cheese will change even after it is defrosted.
Hard cheeses like Cheddar, Monterey Jack, and Parmesan hold up best in the freezer. Soft cheeses such as Camembert and Brie, as well as Ricotta and Cottage Cheese, can still be frozen but their texture will suffer. Cream cheese can be frozen too, but it may separate upon thawing. In this case, you can whip it to improve its texture. Blocks or large hunks of cheese are ideal for freezing. If they are unopened, freeze them in their original packaging. If they have been opened, grate or cut the cheese into smaller cubes, then place them in a resealable plastic bag with as much air removed as possible. You can also wrap cut cubes of cheese in cling film and then place them inside another freezer-proof bag.
When freezing cheese, it's important to reduce its contact with oxygen. You can use a vacuum sealer, which will eliminate contact with surrounding air and allow the cheese to be frozen for the longest time. If you don't have a vacuum sealer, you can use parchment paper followed by aluminum foil. Tightly wrap the cheese in parchment paper and then in aluminum foil to keep everything in place while freezing.
Once you have prepared and packaged your cheese, it's important to label it with the date of freezing. Frozen cheese can be kept in the freezer for up to 3 months, although harder cheeses like Parmesan can last a bit longer. It's best to use frozen cheese within 6 to 9 months for the best quality. When you're ready to use the frozen cheese, thaw it slowly in the fridge overnight. Do not refreeze cheese that has been previously frozen and thawed, as it will become overly crumbly and the flavor will not be as good.
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Recipes to use up old cheese
There are numerous recipes that can help you use up old cheese. Here are some ideas:
Mac and Cheese
This classic comfort food is a great way to use up any leftover cheese you have. You can use a variety of cheeses, such as French Mimolette, aged Dutch Gouda, American Vella dry Jack, or a mixture of different cheeses. For an extra crispy touch, top the mac and cheese with toasted breadcrumbs.
Cheese Sandwiches
Toasted cheese sandwiches, also known as grilled cheese or toasties, are an excellent way to use up leftover cheese. You can use a variety of cheeses, such as cheddar, Gruyère, or a combination of different cheeses. For an extra indulgent treat, try making a melting fondue sandwich.
Cheese Dips
Cheese dips are versatile and can be used as an appetizer or snack. You can use leftover cheese to make a warm, cheesy dip with caramelized fennel and Brie, or a smooth and creamy dip with cheddar, perfect for chips or vegetables.
Omelettes and Frittatas
Omelettes and frittatas are quick and easy meals that can be made with leftover cheese. You can use any type of grated cheese you have, such as cheddar, Gruyère, or Parmesan. Add some vegetables, and you have a nutritious and tasty dish.
Potato Dishes
Potatoes and cheese are a match made in heaven. Use leftover cheese to make potato wedges, or stuff baked potatoes with cheese and bacon for a hearty meal. For a more elegant option, try making luxury potato skins with Brie and truffle.
Soups and Stews
Adding leftover cheese to soups and stews can enhance their flavour. You can use Parmesan rinds to add a rich, cheesy flavour to a vegetable soup or stew. Alternatively, create a creamy soup with leftover cheeses such as Camembert, Brie, Swiss, blue cheese, and goat cheese, along with leek broth, white wine, and crushed garlic.
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Frequently asked questions
There are three main attributes to look out for when determining if your cheese has gone bad: smell, appearance, and taste. If your cheese has taken on a rancid milk smell, or has a bitter or sour taste, it has likely gone bad. Other signs include discolouration, a slimy or greasy texture, and mould growth.
Cheese is a perishable food, and it can spoil and harbour harmful bacteria, so it's important to know how to store it properly. To conserve your cheese for as long as possible, keep it in a dry place, for example, under a glass bell. Hard cheeses can be kept in the refrigerator for six to eight weeks, while most soft cheeses need to be eaten within two weeks of buying them.
Consuming spoiled cheese can lead to foodborne illnesses, with symptoms including vomiting and diarrhoea. If you accidentally eat cheese that's gone bad, be sure to stay hydrated and get plenty of rest. If your symptoms persist or become severe, seek medical attention.
