How to Tell If Cheese Has Gone Bad
There are so many varied types of cheese, it is easy to forget they are all made from essentially the same process. Some of these are very basic cheeses which can be made in minutes, others are matured for months or even years. All types of cheese are derived from milk, often in a process which requires the cheese to be acidified. Even minute changes in a cheese's production can change the flavor profile, often resulting in various levels of pungentness. Often when we wan to know whether a food is bad, we smell it. Since the process of making cheese essentially requires us to make ‘off’ milk, it is notoriously difficult to tell. Fortunately, oneHOWTO is here to show you how to tell if cheese has gone bad.
The first thing you should do is check the expiration date of the product. When you go to the supermarket to buy food, it is important that you look at the expiration date. Reputable stores will ensure no expired produce is being sold, but this is not the case with everywhere you go.
More importantly for us, we need to check the expiration date when we use the product. We also need to see for how long it has been open. Since cheese can last a relatively long time, we often open it and don't use it for an extended period. It is important to store it correctly to prevent it from spoiling. This includes cheese which has been left out of the refrigerator and exposed to air. This should not happen for longer than two hours, maximum.
Unlike many products (such as pork or chicken), we can often eat cheese past its expiration date. The cheese itself may still be good. However, it is always advisable to not eat it past expiration, just to be safe. If you are still unsure whether the cheese is bad, you can look at the methods below.
If you really want to know if cheese is fresh you can make it at home. Do so with our article on how to make cheese curd at home.
Appearance of the cheese
In many cases, you can tell a cheese is off when it has mold. Unfortunately, many different types of cheese have mold as part of their character and appearance. Such is the case with blue cheeses such as Stilton, Roquefort and gorgonzola. For this reason we will tell the difference between blue cheese and non-blue cheese:
- Blue cheese: if you want to know whether blue cheese is bad, you need to pay attention to it when you buy it. Take a look at the mold and see if it is the same color as when you bought it. When a blue cheese goes moldy, the blue veins start to turn grey and lackluster. Bad mold on blue cheese can be seen if the mold is fluffy.
- Non-blue cheese: if you see blue mold on a cheese which isn't supposed to have it, you can assume it has gone bad. However, most white or colored cheeses will develop white mold before blue mold appears, something which can be difficult to distinguish in the former.
For both blue and non-blue cheeses, a little bit of mold may not be a problem. Some sources recommend that you simply cut off the areas where the bad mold appears, then the rest of the cheese can be eaten. This is because it takes a long time in many cases for mold to spread through a cheese. If you choose to do this, it is a risk, but it is possible the remainder of the cheese is fine to eat. This is another reason why it is hard to tell if cheese has gone off.
Smell of the cheese
The smell of a cheese is another reason it can be difficult to tell if it has gone bad. Many cheeses have a strong odor which is supposed to be present. Stinking bishop is one strong-smelling cheese which comes to mind. Again, it is important to examine your cheese when you first open the packaging. When you open a cheese, give it a sniff so you can know what it smells like fresh.
If you have opened your cheese for a while and you want to know whether it has gone bad, sniff it again. If the cheese smells different to before, it means something has changed. Likely it has gone off. Although cheeses can smell very strong, they shouldn't necessarily smell putrid.
For cheeses which are not supposed to smell strongly, then changes in the odor are usually easier to determine. If these cheese have a strong smell when they shouldn't, it is best to avoid them.
If you want to learn more about spoiled food, take a look at our article on how to tell if an avocado is bad.
Texture of the cheese
Finally, the texture of a cheese can help you to know whether or not it is still good to eat. This is the method used least since most cheeses will start to smell or look bad before you notice a difference in texture. For example, a soft white cheese like a mozzarella might look the same if it has just spoiled, but its smell will likely be bad.
However, if you can't smell anything, you might need to look at the texture. If a hard cheese has gone soft or you can see it has separated, then it is more likely to be off. This is something which can happen to fresh cheese if you leave it out too long. It may start to become oily since the fat leeches out of it. For a cheese like fresh mozzarella, although it is packaged in liquid, it should still be firm. If it has started to trun slimy, it means it has gone bad.
How to make cheese last longer
Finally, we provide you a few tips you can use for all types of cheese to ensure they last as long as possible:
- Keep the cheese in the refrigerator. All type of cheese need to be kept cool, so don't leave them out overnight after a dinner party.
- Store the cheese in a suitable container. Many cheese some in plastic packaging which can be difficult to reseal. Many people just close over the opening and leave it in the fridge. It can often be knocked and the cheese exposed to air. This will dry out the cheese and often make it spoil more quickly. Keep it in a sealable container such as a Tupperware box.
- For soft cheeses such as mozzarella, ensure you keep them in the liquid it comes with. This prevents the cheese from drying out.
If you have some milk that has gone bad, you can actually make it into a cheese. To see how it's done, look at our article on how to make paneer with spoiled milk.
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