Detecting Bad Parmesan Cheese: What To Look For

Parmesan cheese is a hard, dehydrated cheese with a long shelf life. It is safe to eat for a long time if stored properly, but how can you know when it's gone bad?

Storage methods

Parmesan cheese is a hard cheese with a relatively long shelf life, especially when stored properly. Here are some storage methods to keep your Parmesan cheese fresh for as long as possible:

Refrigerate

The refrigerator is the best place to store Parmesan cheese, specifically in the coldest part, such as the bottom drawer or the crisper drawer. When stored in the refrigerator under the right conditions, an unopened package of Parmesan can last for several months beyond its expiration date. Once opened, Parmesan can last for about 4 to 8 weeks. It is recommended to consume the cheese within 3 to 4 days if it has been defrosted in the refrigerator, and immediately if it has been thawed in the microwave or cold water.

Seal Tightly

To extend the shelf life of Parmesan cheese, ensure that it is well-sealed. For an opened package, you can wrap the original packaging tightly in plastic wrap or aluminium foil. For even better results, wrap the cheese first in wax, parchment, or wax paper, and then cover it with plastic wrap before refrigerating. If you are storing a small piece of Parmesan, you can place it in a Ziploc bag, removing as much excess air as possible before sealing.

Use Airtight Containers

To maintain the quality of Parmesan cheese, it is essential to store it in an airtight container or resealable bag in the refrigerator. This will help to prevent the cheese from drying out and protect it from absorbing odours from the refrigerator. For grated or shredded Parmesan, consider using a vacuum-sealed bag or a container with a tight lid.

Freeze

Yes, you can freeze Parmesan cheese! It is recommended to grate the cheese first and then store it in an airtight container or freezer bag. Freezing extends the cheese's life but may alter its texture, making it crumbly once thawed. However, it is still perfect for melting or sprinkling over dishes.

Store Alone

It is best not to mix Parmesan cheese with fresh produce. Instead, dedicate one of your refrigerator's crisper drawers specifically for cheese storage.

How to identify spoilage

Parmesan cheese is a hard cheese with a relatively long shelf life, lasting several weeks to months when stored correctly. However, it can still go bad, so it's important to know how to identify spoilage.

Firstly, familiarise yourself with the original colour, texture, smell, and taste of the cheese when you first open it. This way, you'll be able to tell if something has changed over time.

Spoiled parmesan will typically change colour, becoming darker or taking on a grey or yellowish hue. It will also develop a harder texture and may have mould on the surface, which can be white or green. If you notice any mould on hard cheeses like parmesan, it's generally safe to cut off the affected portion, plus at least an inch around and below it, and the rest of the cheese should still be usable. However, if the mould is green, this is an obvious sign of spoilage, and the cheese should be discarded.

In addition to visual cues, use your sense of smell. Parmesan has a strong smell when fresh, but it shouldn't smell mouldy or sour. If it does, it's likely gone bad and should be thrown away.

Taste can also be an indicator. If the parmesan tastes sour or mouldy, it's not worth the risk, and you should dispose of it, as with most cheeses that have gone bad.

For grated parmesan, check the "best-before" date and look out for a spongy texture, which indicates spoilage.

Shelf life of grated parmesan

Grated parmesan cheese is a convenient option for those who want to use the cheese right away without having to grate it themselves. When it comes to the shelf life of this variety of parmesan, there are a few factors to consider.

Firstly, it is important to distinguish between refrigerated and unrefrigerated grated parmesan. Unopened unrefrigerated grated parmesan can last for about 12 to 18 months at room temperature, while unopened refrigerated grated parmesan should last for about a week beyond its "use-by" date.

Once the package of grated parmesan is opened, it should be stored in the refrigerator to maintain its quality. Opened unrefrigerated grated parmesan will retain its best quality for about 10 to 12 months in the refrigerator, while opened refrigerated grated parmesan should be consumed within 3 to 5 days for the best quality, and up to 7 days for acceptable quality.

To further extend the shelf life of opened grated parmesan, it can be frozen. Frozen grated parmesan will maintain its best quality for about 18 months, but it may lose some of its texture and flavour. Therefore, it is best suited for cooked dishes such as sauces, soups, and casseroles.

It is important to inspect grated parmesan for any signs of spoilage. The best way to determine if grated parmesan has gone bad is to smell and look at the cheese. If the cheese develops an off odour, flavour, or appearance, or if mould appears, it should be discarded. Additionally, for shredded parmesan, a change in texture can indicate spoilage. If the shredded parmesan feels spongy or wet, it should be discarded.

Eating mouldy parmesan

It is not advisable to eat mouldy food, including mouldy cheese. However, some people choose to cut off the mouldy parts of hard cheeses, like Parmesan, and eat the remainder. This is because hard cheeses are less susceptible to mould due to their low water content. Nevertheless, mould can still penetrate hard cheeses, so it is important to cut off a significant amount of cheese surrounding the mouldy area.

If you do choose to eat mouldy Parmesan, it is important to note that the cheese will not taste the same as it is supposed to. The mould will have altered the flavour and texture of the cheese.

It is also worth noting that, while mould on Parmesan cheese is usually not dangerous, certain types of mould can be harmful. For example, Aspergillus niger, a dark black-grey mould, can be harmful if consumed.

If you are unsure whether the Parmesan is safe to eat, it is always best to err on the side of caution and discard it. This is especially important if the cheese is soft or moist, as mould can penetrate these types of cheeses more easily.

In addition, if you are handling mouldy cheese, it is important to be cautious and avoid touching the mould with your hands or utensils. Mould can spread easily, so it is crucial to cut off the mouldy portion carefully and clean any utensils or surfaces that come into contact with the mould.

Finally, it is worth mentioning that the best way to avoid mouldy Parmesan is to store it properly. Parmesan cheese should be wrapped tightly and kept refrigerated at all times. When properly stored, Parmesan cheese can last for about 4 to 6 weeks in the refrigerator.

Freezing parmesan

Parmesan cheese can be frozen, and this is a good way to prolong its storage time. However, freezing parmesan can change its texture and cause it to lose its signature crumbliness, making it harder to grate.

To freeze parmesan, it is recommended to grate the cheese first and then place it in an airtight container or a heavy-duty freezer bag. You can also freeze parmesan in wedge form, but it may be more difficult to grate after freezing. If freezing a wedge, wrap the cheese tightly in a freezer bag, aluminium foil, or freezer wrap.

When it comes to defrosting parmesan, it is best to do so slowly and carefully. Take the parmesan out of the freezer and place it in the fridge to defrost slowly for several hours, or even up to a day for larger blocks. It is not recommended to refreeze parmesan, as this can affect the texture.

Frozen parmesan is best used in cooked dishes, such as pasta, soup, or casseroles, rather than eaten raw as the texture will be different from fresh parmesan.

Frequently asked questions