Frederic Melton
The length of time a block of cheese remains edible without refrigeration depends on several factors, including the type of cheese, its moisture content, salt content, and acidity. Hard cheeses like Cheddar, Parmesan, and Gouda have lower moisture content and can sit out longer without spoiling, whereas soft cheeses like Brie, Camembert, and Mozzarella are more perishable due to their higher moisture content. The presence of a rind, salt content, and acidity also influence preservation. Properly stored hard cheeses can last a few hours to a week or more without refrigeration, while soft cheeses are generally recommended to be discarded if left unrefrigerated for over two hours.
| Characteristics | Values |
|---|---|
| Ideal temperature for cheese to be left unrefrigerated | 12°C (55°F) |
| Maximum time cheese can be left unrefrigerated | 2 hours |
| Maximum time if temperature is above 90°F (32°C) | 1 hour |
| Type of cheese that can be left out the longest | Hard cheese with a rind, such as Cheddar, Parmesan, Gouda, Swiss |
| Type of cheese that should be discarded if left out overnight | Soft cheese with higher moisture content, such as Brie, Camembert, Queso Fresco, Mozzarella |
| Other factors that affect how long cheese can be left unrefrigerated | Moisture content, salt content, acidity, presence of rind |
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What You'll Learn
Hard cheeses can be left out longer
Hard cheeses, such as cheddar, Parmesan, or Gouda, can be left out of the fridge for longer than softer cheeses. This is because they have a lower moisture content, making them less susceptible to bacterial growth. If left out for four hours or less, hard cheeses can typically be rewrapped and returned to the fridge. However, it is important to inspect them for signs of spoilage, such as an unpleasant smell, a slimy surface, dark spots, dryness, cracks, or mould.
Hard cheeses that have been naturally aged, such as cheddar and Parmesan, develop a hard rind as they mature. This rind acts as a physical and biological barrier, protecting the cheese from harmful moulds and bacteria. A well-formed rind on an uncut cheese makes it very difficult for spoilage to occur, even if left out of the fridge.
The safety of consuming cheese that has been left out of the fridge depends on several factors, including the type of cheese, its moisture content, salt content, and acidity. Hard cheeses with a lower moisture content, appropriate salt content (around 2% salt by weight), and a pH of 5.5 or below are less likely to spoil. Cheeses with a more acidic pH, such as cheddar, Parmesan, and Gouda, are also more resistant to bacterial growth.
Additionally, the storage conditions and temperature play a role in how long hard cheese can be left out. Cheese should be stored in a cool, dry place, ideally in wax, parchment, or cheese paper, rather than tight, non-porous materials like plastic wrap. The U.S. Department of Health recommends that cheese should not be left out at room temperature for more than two hours, and this limit reduces to one hour if the temperature exceeds 90°F (32°C).
While hard cheeses can be left out longer than soft cheeses, it is important to use your senses to evaluate their freshness. If the cheese has an unpleasant smell, unusual texture, or visible signs of mould, it is best to discard it. Properly wrapping and storing hard cheese can help extend its shelf life and prevent spoilage when left out of the refrigerator.
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Soft cheeses are more perishable
The perishable nature of cheese depends on its moisture content, salt content, and acidity. Soft cheeses, also known as fresh cheeses, are more delicate and creamy, made from fresh curds that have not been pressed or aged. These cheeses have a high moisture content, ranging from grainy textures like cottage cheese to smooth and spreadable varieties like cream cheese. The higher moisture content creates more opportunities for bacteria to grow, making soft cheeses more perishable than hard cheeses. Examples of soft cheeses include cottage cheese, cream cheese, mozzarella, burrata, feta, brie, Camembert, and fresh mozzarella.
Soft cheeses with higher moisture content that are not aged are more perishable and less likely to last unrefrigerated. The U.S. Department of Health does not recommend keeping any perishable food, including soft cheeses, unrefrigerated for more than two hours. After this time, soft cheeses should be discarded as they have a high risk of spoilage.
On the other hand, harder cheeses like cheddar, Parmesan, and Gouda have a lower moisture content, making them less susceptible to bacterial growth. Hard cheeses can sit out for longer than the standard two hours without becoming unsafe, but their quality and taste may suffer. Hard cheeses with a well-established rind are even more resistant to spoilage, as the rind acts as a physical and biological barrier to bad molds and bacteria.
The acidity and salt content of cheese also play a role in its perishability. Cheddar and mozzarella, for example, have a relatively low pH of around 5.3, making them more resistant to bacterial growth. Additionally, a salt content of 2% by weight can help preserve cheese. However, it's important to note that even with these factors in play, leaving cheese unrefrigerated for extended periods can still carry some risk of spoilage or bacterial growth.
In summary, soft cheeses are more perishable than hard cheeses due to their higher moisture content and, in some cases, lack of aging. They should be handled with care and consumed promptly to ensure food safety. Hard cheeses, on the other hand, can last longer, especially when properly stored and when a rind is present.
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Rind and acidity impact spoilage
Cheese is a beloved staple in many kitchens, but it has a limited shelf life and can quickly go bad if not stored properly. Consuming spoiled cheese can lead to foodborne illnesses, causing symptoms such as vomiting, diarrhoea, and gastrointestinal discomfort. Thus, it is important to be vigilant about the signs of spoilage to avoid these health risks.
The rind of a cheese plays a crucial role in protecting the cheese from spoilage. When cheese is aged naturally, a hard rind forms on the exterior. This rind is composed of good yeast, mould, and bacteria, which act as a physical and biological barrier to harmful moulds and bacteria. A well-developed rind can prevent the transport of harmful bacteria to the interior of the cheese, thus inhibiting spoilage. However, rindless cheeses are more susceptible to mould growth, which can then spread to the inside of the cheese.
The acidity of cheese, measured by its pH level, also has a significant impact on spoilage. A pH level of 7.0 is considered neutral, with lower pH levels indicating higher acidity. Cheese with a pH below 5.5 is considered fairly acidic. Examples of acidic cheeses include cheddar and mozzarella, with a pH of around 5.3, and Havarti, with a pH of about 5.5. These acidic cheeses, when properly salted, are less prone to bacterial growth due to their lower moisture content.
On the other hand, "rind-ripened" cheeses like Muenster and Brie have a much higher pH, often above 6.0 when mature. These cheeses tend to have softer centres due to reduced acidity. While the rind initially protects them, once cut, they become very susceptible to spoilage. The higher pH creates an environment conducive to the growth of unwanted bacteria and mould, which can rapidly lead to food safety concerns.
Additionally, the pH of the brine solution used in cheese preservation is crucial. Adjusting the pH of the brine to between 5.0 and 5.3 has a preservative effect, reducing the risk of surface defects like soft rinds. This is because lower pH levels in the brine coincide with higher lactic acid content in the cheese, inhibiting bacterial growth.
In conclusion, the rind and acidity of cheese play crucial roles in inhibiting spoilage. A well-developed rind acts as a protective barrier, while proper acidity levels deter the growth of harmful bacteria. However, when these defences are compromised, spoilage can occur rapidly, leading to potential food safety hazards. Therefore, it is essential to monitor the condition of cheese and practise proper storage methods to prevent spoilage and ensure the safety of consumers.
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Proper storage increases shelf life
Proper storage is key to extending the shelf life of cheese and preserving its quality, flavor, and texture. Here are some tips to ensure your block of cheese remains in good condition for as long as possible without refrigeration:
Firstly, understand that cheese is a living food that continues to age and develop even after purchase. Therefore, creating the right environment for each type of cheese is essential. Temperature and humidity play crucial roles in cheese storage. Maintaining a consistent, cool temperature is important as fluctuations can impact the texture and flavor of the cheese. Ideally, your refrigerator should be set below 40°F (4°C) to inhibit bacterial growth. If you don't have access to refrigeration, a cool, dark place like a cellar can also work, especially for harder, more acidic, and well-rinded cheeses.
Secondly, control humidity levels. Too much moisture encourages mold, while too little dries out the cheese. Hard cheeses with low moisture content are generally more forgiving in this regard, as they are less prone to mold and bacterial growth.
Thirdly, avoid using plastic wrap to cover your cheese. Plastic can trap moisture, promote bacterial growth, and cause sweating or condensation on the cheese surface. Instead, opt for materials that allow the cheese to breathe and facilitate gas exchange. Cheese paper, a combination of wax and polyethylene-coated thick paper, is ideal. It resists condensation and allows the cheese to mature without taking on off-flavors.
Additionally, only slice the cheese when you need to use it. Slicing increases the surface area exposed to possible contamination, oxidation, and dehydration, reducing the shelf life. Also, remember to inspect your cheese regularly. If you spot any mold, cut off at least 1 inch (2.5 cm) around and below the affected areas, and the rest of the cheese should still be safe to consume.
By following these proper storage techniques, you can significantly increase the shelf life of your block of cheese, even without refrigeration, while maintaining its quality and flavor.
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Freezing cheese for later use
Cheese was invented long before refrigeration as a method of preserving milk. Hard and semi-hard cheeses like cheddar, Swiss, brick cheese, and blue cheese can be frozen, but softer cheeses with higher moisture content are less suited to freezing. Freezing cheese will also likely affect its texture and quality, making it drier and crumblier. Therefore, frozen cheese is best used for cooking rather than serving as a table cheese.
If you do decide to freeze your cheese, there are several steps you can take to ensure the least loss of quality. Firstly, portion the cheese into quantities you are likely to use in one go. For large blocks of cheese, do not freeze more than 1 pound (500 grams) per portion. Cheese can also be grated or sliced before freezing. Then, wrap the cheese in wax, parchment, or cheese paper, and place it in an airtight ziplock bag or container to prevent dry air from getting into the cheese and causing freezer burn. Finally, freeze the cheese as rapidly as possible to at least -9 °F (-23 °C) to prevent the formation of large, disruptive ice crystals.
Frozen cheese should be thawed in the refrigerator at 32–34 °F (0–1 °C) for 7–8 hours per 1 pound (500 grams) of cheese. Like any food, cheese that has been frozen and thawed should not be refrozen. While frozen cheese will technically stay safe indefinitely, it is best to use it within 6 to 9 months for the best quality.
It is important to note that cheese can be kept at room temperature for a long time if it has a rind. A fairly acidic, well-salted cheese with a good rind can sit happily at room temperature for a very long time (at least a week, maybe more). At 12 degrees C (55 F), it can last pretty much forever without going off.
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Frequently asked questions
The US Department of Health recommends that perishable food, including soft cheese, should not be left out of the fridge for more than two hours. Hard cheeses can be left out for up to four hours and rewrapped and put back in the fridge.
To keep cheese fresh, wrap it tightly in wax paper or parchment paper, then place it in a plastic bag or airtight container. This prevents it from drying out while allowing it to breathe.
Yes, cheese can spoil if left unrefrigerated for too long. The safety window depends on the type of cheese, primarily its moisture content and whether it is fresh or aged.
Signs of spoilage include a bad smell, slimy surface, dark spots, dryness, cracks or mould. If you see spots of mould, cut off at least 1 inch (2.5 cm) around and below the areas and enjoy the rest.
Hard, aged cheeses such as Cheddar, Parmesan, Gouda, and Swiss can be left out of the fridge for longer periods without spoiling. This is because they have a lower moisture content, making them less susceptible to bacterial growth.
