Cheese And Its Smell: When Does It Go Bad?

Cheese is a dairy product, so one sign that it has gone bad is an off smell. This can be spoiled milk, ammonia, or even a refrigerator or freezer. Some cheeses are naturally pungent, so it can be tricky to identify spoilage by smell alone. Other indicators of cheese going bad include changes in colour or texture, sliminess, oil, bloated packaging, and—of course—taste.

Smell is not the only indicator of cheese going bad

While smell is one of the main indicators of cheese going bad, it is not the only one. Each cheese ages and spoils differently, so it is important to use a combination of smell, appearance, and taste to determine whether your cheese has gone bad.

Appearance

Surface mould is natural for cheese, and small amounts of it are not a cause for concern. You can try trimming off the mouldy part of the cheese and eating the rest. However, if the entire piece is covered in thick mould, it may not be worth saving. Other appearance indicators include changes in colour, consistency, sliminess, oil, or bloated packaging.

Taste

When all else fails, you can try tasting a small piece of the cheese to determine whether it has gone bad. If the cheese tastes sour or has an unpleasant aftertaste, it has likely spoiled.

Smell

As a dairy product, cheese that has gone bad will often have an "off" smell, similar to spoiled milk, ammonia, or even a refrigerator or freezer. However, some cheeses are naturally pungent and "off"-smelling, so it is important to familiarise yourself with the smell of the cheese when you first purchase it.

Appearance can be a sign of spoilage

Discolouration is another sign of spoilage. This can occur due to oxidation or exposure to air, resulting in a slimy or sticky texture. If you notice any unusual colour changes, such as yellow or green patches, it's best to discard the cheese.

In addition to mould and discolouration, changes in the texture of the cheese can also indicate spoilage. If your cheese has become slimy or dries out quickly after being opened, it's likely to have gone bad.

It's important to note that the appearance of cheese may vary depending on the type of cheese and storage conditions. Harder cheeses tend to last longer than softer cheeses due to their lower moisture content. Proper storage, such as keeping the cheese refrigerated and wrapped tightly, can also help prolong its freshness and delay spoilage.

Taste is a reliable indicator of cheese going bad

While smell and appearance can be indicators of cheese going bad, taste is a reliable indicator. When all else fails, you might just have to try a piece of the cheese to tell if it has gone bad. If you think your cheese has spoiled and it comes down to a taste test, only taste a piece large enough to get the flavour. Taste is the one indicator that is a dead giveaway that your cheese is bad. If your cheese tastes sour or has a plain unpleasant aftertaste, you'll know your cheese is done.

In most cases, the spoilage of cheese is due to the growth of bacteria or the breakdown of proteins and fats in the cheese. This can lead to the production of chemicals like ammonia, butyric acid, and geosmin, which give the cheese an unpleasant taste.

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. Ammoniated cheese can have a bitter or sour taste. Butyric acid is produced by bacteria when they break down the fat in cheese, and it gives the cheese a pungent, rancid smell and a sour or unpleasant taste. Geosmin is produced by the bacteria used to ripen certain cheeses, and it has an earthy aroma that can be described as musty, damp, or mossy.

It's important to note that some changes in the taste of cheese may be normal for certain types of cheese. For example, blue cheeses are known for their pungent smell and taste, while washed-rind cheeses tend to have a stronger smell than taste. However, any sudden or unusual changes in taste can be a sign that the cheese has spoiled.

Hard and soft cheeses differ in how they spoil

Soft cheeses like cottage cheese, cream cheese, and other crumbled, shredded, or sliced cheeses should be discarded if you see any mould on them. However, for hard cheeses, you can simply cut off the mould and continue to eat the rest of the cheese.

To determine whether a cheese has gone bad, you can use your senses of sight and smell. If you see spots of mould on hard cheese, cut off at least 1 inch (2.5 cm) around and below those spots. If you notice an ammonia smell, this is another indication that the cheese has gone bad.

When it comes to soft cheeses, if you notice a sour milk smell or a "ripe" smell (like rotting trash) that is not characteristic of the cheese's style, it is best to throw it out.

Bacteria, yeasts and moulds are responsible for the smell of cheese

The smell of cheese, whether good or bad, is often down to bacteria, yeasts and moulds. For example, washed-rind cheeses like Époisses are rubbed down with a salt brine, liquor, or water, creating an environment that attracts certain bacteria. The most dominant and common bacteria is Brevibacterium linen (B. linens), which lends a reddish hue to the rind in addition to an austere flavour and a robust, somewhat stinky aroma.

Blue cheeses are also known for their pungency. Their dynamic flavours can range from caramel to tangy lemon or even roast beef. They are made with a culture mix containing a bit of B. linens that is added to the milk before the curd is formed, a process that is partly responsible for the strong aromas in the cheese.

Small-format goat cheeses are often ripened with Geotrichum Candidum yeasts, which impart abundant odours of sulphur along with notes of overripe pineapple or citrus fruits.

When cheese goes bad, it's usually because other moulds and bacteria have taken hold. You'll know when this happens because you'll smell a sour milk smell that's not associated with the cheese, and the taste will be off.

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