How long can cheese stay out?

In this brief guide, we will answer the query, “How long can cheese stay out?” and will discuss how cheese is made?

How long can cheese stay out?

Cheese staying out period depends upon cheese types. Soft cheese can stay out for 2 hours before it becomes bad to use, while hard cheese can stay out for 8 hours.

What is cheese?

The Food and Agriculture Organization of the United Nations (FAO) gave the following definition: ‘Cheese is the fresh or matured product obtained by the drainage (of liquid) after the coagulation of milk, cream, skimmed or partly skimmed milk, butter milk or a combination thereof’. This definition does not allow for whey cheeses nor does it allow for cheeses made by the newer processes. A second definition was added for whey cheese: ‘Whey cheese is the product obtained by concentration or coagulation of whey with or without the addition of milk or milk fat’ (1).

Cheese is formed by mixing milk with a starting culture of bacteria to sour the milk, as well as an enzyme to form solid lumps called curds, which leave behind a protein-rich liquid known as whey. It is then necessary to remove the whey and age the curds for weeks, months, or even years before they can be used as cheese. Cheese is made by adding salt and other flavorings to milk.

Can cheese go bad?

So, can cheese go bad if you leave it out? At least 7,500 years ago, people began manufacturing cheese, in the rich agricultural area known as the ‘Fertile Crescent’ situated between the rivers Euphrates and Tigris in Iraq (c. 6000-7000 BC) (1). On the other hand, mechanical refrigeration has only existed for around 150 years. So, it’s evident that chilling isn’t an essential part of the manufacturing or preserving of cheese. The today cheese industry provides the following cheese products: extra hard, semi-hard, hard, semi-soft, and soft, hard, which have different moisture content and processing methods and therefore, according to variety and storage, the shelf-life varies from 4-5 days up to 5-10 years (1).

The maturing period, in which freshly formed blocks of cheese are held at temperatures ranging from 50 to 59 degrees Fahrenheit, is one of the most critical in the cheesemaking process. Many kinds of cheese are left out in the open for weeks, months, or even years at a time. This maturing process is vital to the production of high-quality cheese, not a detriment. The fermentation of carbohydrates and nitrogenous compounds in milk or curd by microorganisms is a basic activity in the cheese process. During maturation, the so-called stater culture containing lactic acid bacteria act in the milk components, lactose (the milk sugar), proteins and lipids degrading them and release precursors of compounds responsible for the flavor and aroma of the product. It will also acidify the cheese, increasing its shelf life, when compared to milk (1). 

But we need to be clear about what “bad” means. Food deterioration occurs when bacteria alter the food’s quality; food poisoning occurs when hazardous bacteria proliferate in or on the food’s surface, which may cause illness if consumed. The starter culture is an intentionally added bacteria or a mixture of different species of bacteria, which are able to give the final product its desired characteristics. However, during the manufacturing, unintentional contaminations with invasive bacteria or molds can occur, due to unappropriated handling or low-quality of the ingredients (1). Is it possible for the cheese to become a victim of this?

And the truth is, it’s probably not going to happen. In the United States, almost all cheese is prepared from milk that has been pasteurized to remove any microorganisms that may pose a health risk. That implies that eating cheese will not make you ill. Illness-causing germs aren’t going to emerge in your cheese if you leave it out for days.

So, we’re left with just plain old dishonesty. Food deterioration, like food poisoning, is caused by bacteria, however, the germs are different. Bacteria that cause food deterioration alter the food’s color, taste, texture, fragrance, and so on, making it less appealing. You won’t get ill from these rotting germs. They’re not germs, they merely make your meal unappetizing.

Water and oxygen deprivation is the most prevalent and oldest method of food preservation. Bacteria that cause food deterioration to die without water or oxygen.

Because cheese is made by squeezing out most of the water, the germs that cause food deterioration cannot readily thrive in cheese. Mold, a kind of fungus that may develop even in the refrigerator, is the most prevalent cause of cheese degradation. However, soft cheese is a high moisture cheese and may be contaminated by bacteria as well. Pseudomonas spp. can be a cause of cheese deterioration in cottage cheese. In soft, mold-ripened cheeses, the pH increases during ripening, which increases the growth potential of coliform bacteria (2). 

Food illness and food spoilage aren’t much of a concern with cheese, thus it’s safe to consume. If you leave your cheese out at room temperature, it will lose its flavor and texture owing to drying and the loss of its fat.

Soft vs. Hard Cheese: Which is better?

Over-refrigerating cheese is a common mistake made by many of us in the cheese-consuming community.

The fat content of cheese ranges from 20 to 40 percent, depending on the kind. The taste, fragrance, and texture of fat are all altered when it is refrigerated. Serving brie at room temperature rather than in the refrigerator results in a more supple and flavorful cheese. If cheeses like cheddar and Swiss are kept too cold, they may become crumbly, tasteless, and dry.

Soft cheeses contain at least 61% of moisture and a fat content ranging from 10 to 60%. They can be ripened with bacteria, such as Linburger from Belgium, Tilsiter from Germany or Monterey from USA; ripened with mold, such as the french Brie and Camembert cheeses; or they can be unripened, such as cream cheese and cottage (1).

Hard cheeses contain 44 to 59% moisture and 40 to 60% fat. They can be hard with eyes, such as the Emmental from Switzerland and the Gruyere from France; and hard without eyes, such as Cheddar and Leicester from the UK or Provolone from Italy (1).

The semi-hard cheeses contain 53 to 63% moisture and 25 to 50% fat. They can be normal semi-hard like Edam or Gouda from The Netherlands; or semi-hard internally ripen with molds, such as Stilton from the UK, Gorgonzola from Italy or Blue Cheese from the USA (1).

Cheese that has been refrigerated may be used in recipes such as casseroles and grilled cheese sandwiches. It’s best to let the pricey cheeses remain at room temperature for at least an hour before serving to ensure that they retain their taste, fragrance, and texture.

To what extent is cheese perishable?

Soft cheeses may be left out for up to four hours, while hard cheeses can be left out for up to eight hours. Further, the fat will begin to leak from the cheese, giving it an oily look and changing its texture. Again, this is based on the assumption that the room temperature is typically 70 degrees Fahrenheit.

It’s not as absurd as it seems to say that cheese should not be refrigerated at all if it is stored in a cool spot, away from direct sunlight, and eaten within a day or two after being purchased.

Aside from keeping food and beverages cool, refrigerators are excellent at removing moisture from the air. The reason is that, if you store your cheese in the refrigerator, it will dry out and lose quality more quickly than if you wrap it in parchment paper and keep it cold and dark in your basement.

There are several exceptions. It’s best to keep fresh cheeses like ricotta and cottage cheese refrigerated at all times.

However, if your residence is chilly, matured cheeses may be left out for many hours or perhaps a day. If you can’t consume it all in a day, it should be stored away in the fridge. Cheeses like Brie and Camembert, as well as semi-firm cheeses such as Monterey Jack, cheddar, and Swiss as well as hard cheeses like Parmesan and Romano, are all examples of the “bloomy-rinded” kind. Most people keep their houses at 59 degrees Fahrenheit, which means that the fridge is a good place to store food.

In general, opened soft cheeses last in the refrigerator at 40-45 F for about 2 weeks. After that, there is a risk of mold growth. Check the label’s use-by date for storage information about specific cheeses. Unopened refrigerated hard cheeses last about 2-4 months; if opened they last about 1 month. Sealed and opened hard cheeses last even longer in the freezer, about 7 months, if they are tightly sealed from oxygen (3).

Other FAQs about Cheese that you may be interested in.

What goes with cauliflower cheese?

How to make string cheese?

What does asiago cheese taste like?

Conclusion

In this brief guide, we answered the query, “How long can cheese stay out?” and discussed how cheese is made?

References

1. Robinson, R.K., Wilbey, R.A. (1998). A brief history of cheese. In: Cheesemaking Practice. Springer, Boston, MA. 
2. Doyle, Michael P. Food Microbiology and Food Safety. Serie: Foodborne. 2009.
3. Cheese. The Nutrition Source. University of Harvard.