Cheese Gone Bad: What Does It Look Like?

Cheese is a dairy product and, like all dairy products, it can spoil and harbour harmful bacteria. It's important to know how to spot when cheese has gone bad to avoid health risks. There are three main attributes to look out for: smell, appearance, and taste. Firstly, spoiled cheese can smell rancid, sour, or putrid. It can also smell like spoiled milk, ammonia, or even a refrigerator or freezer. Secondly, cheese can go bad when it changes colour, develops a slimy or greasy texture, or grows mould. Finally, spoiled cheese can taste bitter, acidic, or unpleasantly sour.

Mould: if it's a blue cheese, the blue veins will turn grey. For non-blue cheeses, white or coloured mould will appear first

Mould is a common indicator of spoilage in cheese. However, it is important to distinguish between blue cheese and non-blue cheese when identifying spoilage.

Blue Cheese

Blue cheese is characterised by the presence of blue mould and veining, which gives it a distinctive flavour and appearance. The blue veins in blue cheese will turn grey when the cheese has gone bad. This colour change is accompanied by a strong ammonia smell, similar to cat urine.

Non-Blue Cheese

For non-blue varieties of cheese, the presence of any mould indicates spoilage. Initially, surface mould may appear as small white or coloured spots. If the cheese is only covered by a small amount of surface mould, it may be possible to trim off the affected area and consume the remaining cheese. However, if the entire piece is covered in thick mould, it is best to discard the cheese.

Texture: if a hard cheese has gone soft, or a soft cheese has become slimy, it's likely gone bad

Changes in texture can be a good indicator of whether or not a cheese has gone bad. It's important to note that some changes in texture may be normal for certain types of cheese. However, any sudden or unusual changes in texture can signal that the cheese has spoiled. For example, if a hard cheese has gone soft, or a soft cheese has become slimy, it has likely gone bad.

Hard cheeses like Cheddar can start to crack when they spoil due to changes in the cheese's moisture content and the growth of unwanted bacteria. As hard cheeses age, they lose moisture, which can cause them to become brittle and prone to cracking. To prevent cracking, store your cheese in a cool place with good air circulation and the right humidity conditions.

On the other hand, soft white mould cheeses like Camembert can become slimy when they spoil due to the growth of unwanted bacteria. During the cheesemaking process, the mould grows on the surface of the cheese and helps create its characteristic bloomy rind. However, if the cheese is not properly stored, other types of bacteria can grow and cause spoilage.

Additionally, if a fresh cheese like mozzarella has been left out too long, it may start to become oily since the fat leeches out of it. Fresh mozzarella should still be firm, even though it is packaged in liquid. If it has started to turn slimy, it has likely gone bad.

Smell: if it smells like spoiled milk, ammonia, or your fridge, it's probably off

When it comes to cheese, smell is one of the most important factors in determining whether it has gone bad. This is because cheese is a dairy product, and one sign of spoiled cheese is an "off" smell. Depending on the type of cheese, this scent can be similar to spoiled milk, ammonia, or even a refrigerator or freezer.

If a mild cheese like Monterey Jack or American cheese smells strong, like blue cheese or Limburger, it's time to throw it away. However, it's important to note that some cheeses are naturally pungent, and can have a strong ammonia smell even when they are still good to eat. For example, blue cheese or Camembert will have a strong ammonia smell similar to cat urine when they have gone bad. If you are familiar with the smell of a particular cheese, and the cheese you have smells like a much more concentrated version, it's probably a safe bet that it's no longer safe to eat.

Ammonia is produced by bacteria that break down the protein in cheese, and it has a strong, pungent smell similar to cleaning products or urine. While ammonia is more commonly found in aged or washed-rind cheeses, excessive amounts can indicate spoilage. In addition to the unpleasant smell, ammoniated cheese can also have a bitter or sour taste.

If you're unsure whether your cheese has gone bad, it's a good idea to smell it when you first purchase it. This way, you'll have a good understanding of how it's supposed to smell, and you'll be able to notice when something is off. However, keep in mind that some cheeses can be pungent and "off"-smelling from the start. In these cases, don't rely on smell alone and also consider the appearance and taste of the cheese.

Taste: if it tastes bitter, sour, or has an unpleasant aftertaste, it's gone bad

When determining whether a block of cheese has gone bad, one of the most important senses to rely on is your taste. If the cheese has taken on a bitter or sour taste, it's a sure sign that it's past its prime and should be discarded. Similarly, if you experience an unpleasant aftertaste after consuming the cheese, it's a clear indicator of spoilage.

Cheese is known for its diverse and complex flavors, ranging from creamy and mild to sharp and pungent. However, when cheese goes bad, the taste can become distinctly unpleasant. This is because, with time, the bacteria in the cheese continue to break down the milk proteins and fats, leading to the development of off-flavors.

A bitter taste is often indicative of the presence of excess bacteria or mold. These microorganisms can produce bitter-tasting compounds as they continue to grow and break down the cheese. A sour taste, on the other hand, can result from the production of lactic acid by bacteria. While some cheeses are intentionally sour, such as those made with bacterial cultures like yogurt, an overly sour taste can indicate excessive bacterial growth and spoilage.

An unpleasant aftertaste can also signify that the cheese has gone bad. This aftertaste might be described as rancid, metallic, or soapy. It's often caused by the oxidation of fats in the cheese, which can happen when the cheese is exposed to air for too long or if it's past its expiration date. This process is known as lipolysis, which can result in the breakdown of fats into shorter-chain fatty acids, contributing to an unpleasant flavor.

It's important to remember that the taste of cheese can vary based on factors like milk type, aging, and additives. However, when in doubt, trust your taste buds. If the cheese tastes bitter, sour, or leaves an unpleasant aftertaste, it's best to discard it to prevent any health risks associated with consuming spoiled food.

Expiry date: if it's past its expiry date, it's best to throw it out

While some cheeses can be salvaged if they've been stored past their expiration date, it's generally best to throw them out. This is especially true for soft cheeses, which tend to spoil more quickly than hard cheeses. If your soft cheese has passed its expiration date, it's best to toss it.

Hard cheeses can last 3-4 times longer in the fridge than soft cheeses since they contain less moisture and are therefore less prone to spoilage from bacteria. If stored correctly, hard cheeses like Asiago, Parmesan, Beaufort, pecorino Romano, and Cheddar can last four to six months in the fridge. However, if your hard cheese has passed its expiration date, it's still best to throw it out.

Semi-hard to semi-soft cheeses, such as Emmental, Gruyère, havarti, Muenster, Port Salut, Gouda, Edam, Jarlsberg, and Cantal, have a fridge life of about two to four weeks after the expiration date. Again, if your semi-hard or semi-soft cheese has passed this timeframe, it's best to discard it.

In general, it's important to trust your senses when determining if a cheese has gone bad. Look for any signs of mould, and use your judgement to see if the cheese smells or tastes different from when you bought it. If in doubt, it's always better to be safe than sorry and throw the cheese out. Remember, there is always more good cheese in the world!

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