Cheese Gone Bad: What's That Smell?

Cheese is a dairy product, so one of the signs that it has gone bad is an off smell. Depending on the type of cheese, this scent can be of spoiled milk, ammonia, or even a refrigerator or freezer. The smell of spoiled cheese is often described as rancid, sour, or putrid. It can also be pungent and acrid, smelling like ammonia, or rancid and vomit-like, with a strong, pungent smell similar to cleaning products or urine.

Spoiled cheese can smell like spoiled milk, ammonia, or a refrigerator

Spoiled cheese can smell like a range of unpleasant things, depending on the type of cheese and the stage of spoilage. One of the most common indicators of cheese gone bad is an "off" smell, similar to spoiled milk. This is due to the growth of bacteria or the breakdown of proteins and fats in the cheese. If you are familiar with the scent of your cheese when fresh, you will be able to notice when something is off.

Another common smell associated with spoiled cheese is ammonia, which is produced by bacteria breaking down the protein in the cheese. Ammonia has a pungent smell, similar to cleaning products or urine. Aged or washed-rind cheeses may naturally have an ammonia scent, but excessive amounts can indicate spoilage. These cheeses may also have a bitter or sour taste when they have gone bad.

Rancid and vomit-like smells can also indicate that your cheese has spoiled. This is due to the presence of butyric acid, a short-chain fatty acid produced by bacteria when they break down the fat in the cheese. Butyric acid is commonly found in soft, creamy cheeses like Brie, which have a higher moisture content and are more prone to spoilage.

Musty and mouldy smells can also be a sign of spoiled cheese. This is often caused by a compound called geosmin, which is produced by the bacteria used to ripen the cheese. Geosmin has an earthy aroma and is also responsible for the smell of damp soil after rain. Improper storage can lead to excessive geosmin production, resulting in an overwhelming musty smell.

In addition to these common indicators, spoiled cheese may also smell like a refrigerator or freezer. This is because cheese is a dairy product, and when it spoils, it can take on an "off" smell similar to other spoiled dairy products. Therefore, it is important to trust your senses and discard the cheese if it smells unpleasant or differs significantly from its usual odour.

A spoiled cheese smell can be described as rancid, sour, or putrid

The smell of spoiled cheese is often the result of bacterial growth or the breakdown of proteins and fats in the cheese. Ammonia, a common chemical found in aged or washed-rind cheeses, is produced by bacteria breaking down the proteins in the cheese. Butyric acid, another chemical that can be present in spoiled cheese, is produced by bacteria breaking down the fats, resulting in a pungent, rancid smell.

In addition to the smell, visual indicators of spoiled cheese include mould growth, discolouration, and a slimy or greasy texture. Spoiled cheese may also exhibit signs of browning, particularly in varieties such as Gouda and Parmesan. This browning is caused by a complex reaction between reducing sugars and amino acids from the breakdown of protein in the cheese.

The texture of the cheese can also provide clues to its freshness. Hard cheeses like Cheddar may start to crack due to changes in moisture content and bacterial growth. Soft cheeses like Camembert can become slimy due to the growth of unwanted bacteria.

It is important to note that not all mould on cheese indicates spoilage. Some types of cheese, such as Stilton or Brie, are intentionally inoculated with moulds to achieve specific flavours or textures. However, uncontrolled mould growth may produce spores and toxins that can make the cheese unsafe to consume.

To prevent spoilage, it is recommended to buy only the amount of cheese that can be consumed within a week and to store it properly, with soft cheeses like Brie and Camembert kept in the fridge in their original packaging, and harder cheeses stored in a sealed container or wrapped in wax paper.

Ammonia is a common chemical in off cheese, smelling like cleaning products or urine

Ammonia is one of the most common chemicals found in off cheese, and it is produced by bacteria breaking down the protein in the cheese. It has a pungent, acrid smell that is similar to cleaning products or urine. This smell is often described as rancid, sour, or putrid.

Ammonia is more commonly found in aged or washed-rind cheeses, where it can be a natural by-product of the cheesemaking process. However, excessive amounts of ammonia indicate spoilage. Aged cheeses, in particular, may still be good to eat after their best-by date, but excessive ammonia is a sign that the cheese has gone bad.

In addition to the unpleasant smell, ammoniated cheese can also have a bitter or sour taste. This is a sign that the cheese has spoiled and should be discarded. The presence of ammonia, along with a breaking down of the rind and colourful tufts of mould, are universal signs of a spoiled cheese.

To prevent cheese from spoiling, it is important to buy only the amount of cheese that can be consumed within one week. Store cheese properly, with soft cheeses like Brie and Camembert kept in the fridge in their original packaging, and harder cheeses stored in a sealed container or wrapped in wax paper. Consume cheese quickly, especially once the package has been opened. It is also important to handle cheese properly, using clean utensils and washing hands thoroughly before cutting.

By following these guidelines, you can ensure that you are consuming safe and delicious cheese.

Butyric acid is another chemical in spoiled cheese, with a pungent, rancid smell

Butyric acid, also known as butanoic acid, is a chemical compound found in spoiled cheese. It is characterised by its pungent and rancid odour, reminiscent of vomit, gone-off milk, or rancid butter. This unpleasant smell is a tell-tale sign of cheese spoilage and can be quite off-putting, even in small amounts.

Butyric acid is a short-chain fatty acid produced when bacteria break down fats in cheese. It is commonly associated with soft, creamy cheeses like Brie, which have a higher moisture content and are more prone to spoilage. However, it can also be found in small amounts in some aged cheeses, such as Parmesan. The presence of butyric acid in excessive quantities indicates that the cheese has gone bad.

The odour of butyric acid is difficult to ignore and can linger for extended periods. It is detectable by the human nose at extremely low concentrations, making it nearly impossible to miss. The sensitivity to this odour is believed to be an evolutionary adaptation, as the smell often indicates the presence of harmful substances.

In addition to its pungent smell, butyric acid can also give cheese an unpleasant sour taste. This unpleasant combination of smell and taste is a clear indication that the cheese is no longer safe for consumption and should be discarded.

While butyric acid is certainly not desirable in cheese, it does have some interesting uses. For example, it can be used to create molecules called esters, which have pleasant fruity scents, such as apple-pineapple or apricot-pear. These esters are then used as additives in food and perfumes. Additionally, butyric acid helps prevent salmonella bacteria from taking hold in poultry and is used as an additive in chicken feed.

Spoiled soft goat and sheep cheeses tend to smell yeasty

Soft goat and sheep cheeses are known to have pungent flavours and smells. However, when they spoil, they tend to smell yeasty. This is due to the growth of bacteria or the breakdown of proteins and fats in the cheese.

The smell of spoiled cheese can vary depending on the type of cheese and the stage of spoilage, but it is often described as rancid, sour, or putrid. In terms of taste, spoiled cheese can be bitter, acidic, or unpleasantly sour. It is important to note that even the stinkiest cheese has been cultured and aged in very controlled conditions, and a pungent cheese will still taste pleasant to a connoisseur. When cheese has gone bad, it will taste overly bitter or sour, or have a musty quality to it, like drinking water from a mouldy pipe.

The spoilage of soft goat and sheep cheeses can be attributed to a variety of factors, including improper storage, the age of the milk used, and the separation of male and female goats during breeding season. Freshness is crucial, as the older the goat milk is when it is processed, the goatier the cheese will taste. Additionally, during breeding season, male goats produce strong-smelling hormones that can affect the taste of the milk and the resulting cheese if the male and female goats are not separated.

To prevent spoilage, it is recommended to buy only the amount of cheese that can be consumed within one week and to store the cheese properly. Different types of cheese require different storage conditions. Soft cheeses like Brie and Camembert should be stored in the fridge in their original packaging, while harder cheeses can be stored in a sealed container or wrapped in wax paper.

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