Cheese's Enemy: Spoilage Timing When Left Out

How long can cheese be left out before it goes bad? The answer depends on the type of cheese. Soft cheeses with high moisture content, such as Brie, Camembert, and cream cheese, are more perishable and should be discarded if left out for more than two hours. Harder cheeses, like cheddar, Parmesan, or Gouda, have a lower moisture content, making them less susceptible to bacterial growth and spoilage. These cheeses can be left out for up to four hours and rewrapped and refrigerated if they are still in good condition. However, it is important to note that the quality and taste of cheese can deteriorate after being left out for extended periods, even if it is still safe to consume.

Soft cheeses: throw away after two hours

Soft cheeses are those that are more delicate and creamy, with a high moisture content. They are typically made from fresh curds that have not been pressed or aged. This means they are more perishable and susceptible to bacteria and spoilage. Examples of soft cheeses include cottage cheese, cream cheese, Queso Fresco, feta, mozzarella, burrata, brie, and Camembert.

Because of their high moisture content, soft cheeses are the perfect environment for bacterial growth. Therefore, soft cheeses should not be left out at room temperature for more than two hours. After this time, they should be discarded, as they will have a much higher risk of being contaminated with dangerous toxins.

The United States Department of Health recommends not keeping any perishable food out of the fridge for more than two hours. This is especially important for soft cheeses, as their high moisture content and lack of aging make them highly perishable.

If you are serving a soft cheese, it is best to let it come to room temperature first to improve its flavour and texture. This will take around 20-30 minutes. However, it is important to keep in mind the overall time that the cheese is left out for, as food that has been left out too long can be dangerous.

If you notice any signs of spoilage on your soft cheese, such as a strange smell, discolouration, or mould, it is important to throw it away immediately. Some moulds can be harmless, but others can produce dangerous toxins that can be harmful if consumed.

Hard cheeses: safe for up to eight hours

Hard cheeses, such as cheddar, Parmesan, and Gouda, can be left out at room temperature for up to eight hours before spoiling. These cheeses have a lower moisture content, which makes them less susceptible to bacterial growth and, therefore, less perishable. This longer shelf life at room temperature is also due to the aging process involved in making hard cheeses. During this process, most of the whey is removed from the curds, reducing the moisture content even further. The aging process also gives hard cheeses a distinct, crumbly texture and more complex flavors.

Hard cheeses are aged for longer periods, typically between two and 36 months, and sometimes even longer. The longer aging process also contributes to the slower growth of bacteria, making the chance of foodborne illness from consuming these cheeses extremely low. This is why hard cheeses are considered safe to consume even when left out at room temperature for extended periods.

While hard cheeses can withstand being left out for up to eight hours, it is still important to practice proper food safety and handling. After four to five hours at room temperature, hard cheeses may start to dry out and lose their optimal appearance. Therefore, it is recommended to refrigerate any leftover cheese as soon as possible to maintain its quality.

When checking if a hard cheese has gone bad, look for signs of spoilage such as mold, an unpleasant smell, a slimy surface, dark spots, dryness, cracks, or changes in texture. If any of these signs are present, the cheese should be discarded. However, if the cheese appears unchanged, it is generally safe to consume, even if it has been left out for an extended period.

In summary, hard cheeses are a safe choice for parties or gatherings where food may be left out for several hours. Their lower moisture content and longer aging process make them more resistant to bacterial growth and spoilage. However, proper food handling practices, such as prompt refrigeration, are still important to maintain the quality and freshness of these cheeses.

Bacterial growth: moisture content and age impact spoilage

The moisture content and age of cheese play a significant role in bacterial growth and spoilage.

Moisture Content

Cheeses with higher moisture content, such as ricotta, queso blanco, mascarpone, cottage cheese, cream cheese, and fresh mozzarella, are more perishable and susceptible to bacterial growth and spoilage. These cheeses have shorter shelf lives when left out and should be discarded after two hours at room temperature. Their high moisture content provides more opportunities for bacteria to grow, making them highly perishable.

On the other hand, harder cheeses with lower moisture content, such as cheddar, Parmesan, and Gouda, are less likely to support bacterial growth and can be left out for longer durations. These cheeses have a lower risk of bacterial contamination due to their reduced moisture content.

Age

The age of cheese, or the length of time it has been left out, is another critical factor in bacterial growth. Even for harder cheeses with lower moisture content, the likelihood of bacterial growth increases as they are left out for extended periods. While they can be left out for longer than softer cheeses, it is still recommended to discard them if left out for more than four hours to minimize the risk of bacterial contamination.

Combined Effects of Moisture Content and Age

The combined effects of moisture content and age significantly impact bacterial growth and spoilage. Softer cheeses with higher moisture content have shorter safe-to-consume windows when left out, typically around two hours, while harder cheeses can last a bit longer, up to four hours. However, it's important to note that the quality and taste of cheese can deteriorate even before these time frames, and it's always recommended to trust your senses and avoid consuming cheese that looks or smells unpleasant.

Signs of spoilage: smell, slimy surface, dark spots, mould

Signs of spoilage: smell

Cheese that has gone bad will have a strong, unpleasant smell. This could be rancid, sour, or ammonia-like.

Slimy surface

If the cheese feels slimy, sticky, or excessively hard, it has likely gone bad. Fresh cheddar cheese has a firm and smooth texture.

Dark spots

Discolouration is a sign of spoilage. If you notice dark spots, streaks, or patches, the cheese has likely spoiled. Avoid consuming discoloured cheese as it may contain harmful bacteria.

Mould

Mould is a tell-tale sign of cheese spoilage. Look for fuzzy or discoloured patches on the cheese's surface. Common mould colours include white, green, blue, or black. Even a small amount of mould indicates that the entire block of cheese is contaminated and should be discarded.

Storage: don't wrap hard cheese too tightly

When storing hard cheese, it is important not to wrap it too tightly. This is because cheese is a living, breathing thing, and it needs air to survive. Wrapping it too tightly in plastic wrap will suffocate the cheese, reducing its quality and flavour and shortening its shelf life.

Additionally, a tight wrapping promotes the growth of bacteria, including those not native to the cheese, which can cause food-safety issues and off-flavours. It also prevents the dissipation of natural off-odours, like ammonia, which is produced by bacteria native to the cheese. Finally, because cheese is mostly oil and fat, it can absorb flavours and chemicals from the plastic, which is not ideal.

So, what is the best way to store hard cheese? Well, at Cowgirl Creamery, they sell cheese wrapped in waxed paper, which is recommended by kitchen scientist Harold McGee. If you are worried about your cheese drying out, you can then wrap it loosely in plastic wrap or place it in a plastic bag that is not fully sealed. This method provides breathability for the cheese without drying it out.

When wrapping hard cheese, place the cheese on the paper with the cut side down. Then, pull the bottom right-hand corner of the waxed paper up over the piece of cheese and lay it flat across the top. Still holding the paper tightly over the cheese, pull the right-hand side of the paper over to the left, forming a tight crease over the pointy end of the cheese. Secure this with a small piece of tape. Take the double sheet of paper at the top of the cheese and crease it sharply so that it runs flat along the top of the cheese and meets the paper that is underneath. Fold the now-triple piece of paper back over the cheese and secure it with another piece of tape. Your cheese should now be wrapped, and you can place it in the vegetable drawer of your refrigerator.

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