A whote bowl of marshmallows.

Do Marshmallows Go Bad?

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It’s a marshmallow world in the winter … at least it is at my house on the annual Family Cookie Day where we mix, cut, and bake dozens of cookies and sweet treats. We begin stocking up on baking basics, chocolate chips, almond bark, marshmallows (and more) weeks in advance. But if I pick up a bunch of marshmallows on sale, how long do they last, do marshmallows go bad? 

I’ve got all the answers for you here so your cookie day (or just a warm cup of hot cocoa) will be a fluffy delight, rather than a hard – or SLIMY situation. 

What Are Marshmallows Made of?

Originally, marshmallows were made using the sap of the marshmallow plant (Althaea officinalis), which grows in marshy areas – which is where it got its name. This plant’s sap has natural thickening properties and was originally used for its medicinal qualities, particularly as a remedy for sore throats.

The traditional process involved extracting the sap from the marshmallow root and mixing it with sugar and egg whites. This mixture was then whipped to create a fluffy confection.

Over time, as the production of marshmallows became more industrialized, manufacturers started replacing marshmallow root sap with gelatin. 

Gelatin provided a more consistent and reliable way to achieve the fluffy texture characteristic of modern marshmallows. This greatly simplified the production process, making it easier to mass-produce.

Today, the majority of marshmallows you’ll find in stores do not contain any actual marshmallow plant extract. Instead, they are made using sugar, water, and gelatin.

Top view of about a dozen marshmallows  arranged randomly on a wood table.

How Long Do Marshmallows Last After The Expiration Date?

When stored properly, marshmallows can last for quite some time. Their shelf life depends on several factors, including the best-before date, how they are stored, and the type of container used.

How Long Do Marshmallows Last Unopened?

Typically, unopened bags can last 6-8 months past the date printed on the package. This can stretch up to a year if they are stored in a cool, dry place away from direct sunlight.

Do Marshmallows Go Bad Once Opened?

Once opened, marshmallows should be used within 3-4 months for the best quality when stored at ideal circumstances.

Do Marshmallows Go Bad or Expire?

Yes, marshmallows do expire. While they have a pretty long shelf life due to their high sugar content, (which acts as a preservative) they are still susceptible to spoilage over time, especially if not stored properly. So if you’re stockpiling snacks for the zombie apocalypse, skip the marshmallows.

Marshmallows typically come with a “best by” or “use by” date. While they may not necessarily be harmful to eat after this date, their quality and freshness will diminish. The key to lengthening the shelf life of marshmallows is to keep them away from moisture and heat, stored in an airtight container.

A sealed package of marshmallows with the best by date clearly featured.

Can You Use Old Expired Marshmallows?

I would strongly recommend against it, but you can actually get away with using expired marshmallows in certain situations. While the “best by” or expiration date on the packaging is more about quality than safety, it’s important to inspect them carefully before using them. 

Quality vs. Safety: While expired marshmallows might not make you sick if they don’t show signs of spoilage, their quality in terms of taste and texture could be less-than-ideal. I’m talking hard and rubbery or even slimy. Yes, slimy.

Marshmallows that have hardened or become very chewy are stale. While stale marshmallows aren’t necessarily harmful, their texture and taste are compromised (and isn’t that part of what you’re counting on them for?) They won’t perform as well in recipes where their soft, fluffy texture is crucial.

If you’re using the marshmallows in a recipe where they’ll be melted (like in hot chocolate), you might get away with using slightly stale ones. However, for recipes where texture is important (like as a topping or in a marshmallow salad), reach for only fresh marshmallows.

How Do You Tell If Marshmallows Are Bad or Have Spoiled?

Marshmallows have a few telltale signs that they have spoiled. If you do a vibe check on an old bag and notice any of the following, don’t risk it. Throw them out. 

  • Change in Texture: Fresh marshmallows are soft and fluffy. If they become hard, excessively sticky, or slimy, it’s a sign they have gone bad.
  • Discoloration: Any change in color, such as yellowing or browning, can indicate things have turned for the worst. Marshmallows should typically be white or retain the color they were when purchased (if they were colored).
  • Odor: A noticeable funky or sour smell is a clear indicator that the marshmallows are no longer good to eat.
  • Mold Growth: If you see any mold on any of the marshmallows, they should be thrown out. The whole package needs to go – not just the obviously moldy ones.
  • Change in Taste: If the marshmallows pass the visual and smell tests, a small taste can help confirm their freshness. If they taste off or stale, it’s best not to consume them.

If the marshmallows are discolored, have spots of mold, or smell bad, throw them away. No exceptions. 

A white bowl of marshmallows.

Do Marshmallows Really Mold?

Yes, marshmallows can mold, although it’s not very common due to their low moisture – high sugar concentration. Mold growth usually occurs under certain conditions:

  • Moisture Exposure: If marshmallows are exposed to moisture or stored in a humid environment, they can become damp, creating an environment for mold growth.
  • Extended Storage Time: Over a long period, especially if the storage conditions are not ideal, marshmallows may start to degrade, increasing the chances of mold growth.
  • Contamination: If marshmallows come into contact with other foods that have mold or are handled with unclean utensils or hands, they can become contaminated and eventually develop mold.

While mold growth on marshmallows is relatively rare compared to other food items, it’s important to check for any signs of it, especially if your marshmallows have been stored for a long time or under less than ideal conditions. 

If you do find mold on your marshmallows, it’s best to discard the entire package, as mold can spread throughout even if it’s not visible on every piece.

How to Store Marshmallows to Keep Them Fresh

These fluffy treats are wonderfully shelf-stable despite their high water content, thriving best in a cool, shadowy spot.  Refrigeration can introduce moisture, leading to sticky or hard marshmallows. Stick to room-temperature storage unless your home is overly warm. 

Storing Unopened Bags

Store unopened bags of marshmallows in a dark, cool, dry place. A pantry or a kitchen cabinet away from heat sources is the perfect spot. Surprisingly, marshmallows can melt even in a cool home when sitting in a strong sunbeam, leaving you with a bag of goo rather than puffy sweetness.

Storing Opened Bags

If you’ve got an opened bag of leftover marshmallows, first put them in an airtight container to keep them from absorbing moisture or odors. A resealable zip-top bag can work well if you squeeze out as much air as possible before sealing. 

Even in a container, marshmallows can absorb odors, so store them away from strongly scented foods or substances.  The last thing you want is onion-flavored marshmallows. 

Another reason to keep your marshmallows stored in airtight sealed containers is so they don’t attract ants or other bugs who would love nothing more than the sugary goodness of a marshmallow. And will quickly tell their ten thousand ant friends about it. 

If you notice any small holes or openings in your packaging, it’s likely been snacked on by bugs and belongs in the trash bin. 

Marshmallows arranged on a wood table with a jar of marshmallow fluff out of focus in the background.

Do Marshmallows Go Bad In The Fridge

Marshmallows typically don’t “go bad” in the refrigerator in the sense that they will be unsafe to eat, but refrigeration tends to affect their texture and overall quality.

They can absorb moisture from the refrigerator environment. This extra moisture can make them sticky and gooey, or even cause them to develop a slimy texture, (ew!) which is something no one wants.

The cold temperatures of a refrigerator can also cause marshmallows to become hard and lose their soft, fluffy texture. Plus, when you take them out of the fridge, condensation can form, leading to texture changes.

The fridge should be a last resort, only if your kitchen is extremely warm or humid and other storage options are not viable.

How Long Do Marshmallows Last In The Fridge?

If you are going with the refrigerated route, your marshmallows in unopened packaging can last for 3-4 months in the fridge. Since they are sealed, they are less likely to absorb moisture or odors from the fridge.

Once opened, if marshmallows are stored properly in an airtight container or resealable bag, they can last for 2-3 months in the fridge. It’s important to be sure they’re protected from moisture and other food odors.

Despite these timelines, it’s always a good idea to check the marshmallows for signs of spoilage before using them. While refrigeration can extend their shelf life, remember that they may get weird. For the best results, a cool, dry pantry is usually the best storage option.

A ziptop bag of marshmallows.

Can You Store Marshmallows in the Freezer?

Yes! Storing marshmallows in the freezer is a fantastic idea, especially if you want to keep that marshmallow goodness around for longer. (Or if you like to keep your home tropical-hot like my husband’s grandma who won’t let the thermostat dip below 85).

Use an airtight container or freezer bag to prevent freezer burn and moisture contamination. If using a bag, try to remove as much air as possible before sealing it.

If you think you’ll only need a few marshmallows at a time, consider freezing them in small portions. This way, you only thaw what you need, preserving the freshness of the rest.

Freezing Affects Texture Slightly 

While freezing does a good job of preserving marshmallows, you may notice a change in texture once they’re thawed. They might be a bit softer than fresh marshmallows, but they’re still great for cooking and baking.

Remember, frozen and thawed marshmallows work best in cooked or baked recipes, as their altered texture after freezing might be noticeable in recipes where they are used as is.

Defrosting Marshmallows

Defrosting marshmallows is a simple. Just take them out of the freezer and toss them on the countertop at room temperature. This is the easiest and gentlest way to thaw them, preserving their texture.

Allow the marshmallows enough time to thaw completely. Depending on how many you’re thawing, this could take anywhere from a few minutes to an hour. 

It might be tempting to rush the process along (much like my husband when I’m getting ready for date night), but speeding things up will only cause stress and possibly melting(down). So resist that urge!

Direct heat (like a microwave) can make marshmallows melt or become overly sticky.

If the marshmallows seem a bit damp after thawing (which can sometimes happen due to condensation), you can pat them dry gently with a paper towel or leave them to air out for a bit. This helps restore their normal texture.

If your marshmallows have stuck together during freezing, gently pull them apart after they’ve thawed a bit. They are more flexible when slightly thawed, reducing the risk of tearing them.

Once thawed, it’s best to use your marshmallows relatively quickly. They’re at their best when fresh (same), even post-freezing.

Before using the thawed marshmallows, give them a quick quality check. If they smell and look fine, they’re ready to be the star in your hot chocolate, s’mores, or baking recipes. 

Does Marshmallow Fluff Expire?

Yes, Marshmallow Fluff does expire. Although it tends to last a long time due to its highly processed nature and high sugar content (remember it acts as a natural preservative). Generally, an unopened jar of Marshmallow Fluff can last for several months to a year when stored at room temperature in a cool, dry place (like a pantry or cabinet). 

Once opened, it should be eaten within a few months for the best quality. It’s important to check the expiration date on the package and look for any suspicions of spoilage before eating that rogue jar in the back of your cabinet. 

Marshmallows arranged on a wood table with a jar of marshmallow fluff in the background.

Can You Eat Expired Marshmallow Fluff?

Firstly, I can tell you that if you’re looking for ‘ehhh it’s probably fiiiiiiiine’ – you’re in the wrong place. I am notoriously picky about food, leftovers, and anything even close to its expiration date. With that in mind, eating expired Marshmallow Fluff isn’t recommended, even by general food safety guidelines.

It can absolutely go bad, especially if it’s been stored improperly or for a very long time past its expiration date. If your Marshmallow Fluff has expired, check it for signs of spoilage like an off smell, discoloration, or mold growth.

Even if it looks and smells fine, it’s important to consider the potential degradation of quality and taste. Eating expired food can sometimes lead to foodborne illness, and no one wants to spend a holiday weekend locked in the bathroom. 

The risk with high-sugar products like Marshmallow Fluff is generally lower compared to perishable foods. However, to be on the safe side, it’s best to avoid eating expired food products, including Marshmallow Fluff.

How Do I Fix Marshmallows That Have Stuck Together?

If your marshmallows have stuck together in one big blob, it’s probably because they’ve been exposed to moisture. However, there are a few things you can try to separate them and restore some of the fluffiness you’re hoping for:

  • Powdered Sugar or Cornstarch: Roll the sticky marshmallow blobs in powdered sugar or cornstarch. Both can absorb the excess moisture and prevent the marshmallows from sticking. Gently shake them in a bag or a container with the powdered sugar or cornstarch until they’re coated, then separate them with your fingers.
  • Freezing: If the marshmallows are really sticky, try freezing them for a few minutes. Once they are cold, it might be easier to pull them apart. After separating, let them come back to room temperature before using them.
  • Air Them Out: Sometimes, just leaving them out in a dry, airy space for a little while can help. The surface moisture can evaporate, making the marshmallows less sticky and easier to separate.

These methods can help in separating the marshmallows, but if they’ve become too sticky or have other signs of spoilage like mold or an off smell, it’s better to throw them out. Also, once marshmallows have become sticky, they might not return completely to their original texture.

Can I Use Old Marshmallows?

I highly recommend not using old marshmallows, or marshmallows that have any of the signs of spoilage we’ve covered here. It’s always best to pop by the store to grab another bag rather than risk getting sick or ruining a batch of your signature peanut butter fudge. 

A detail of a bowl of marshmallows on a wood table.

Are 2 Year Old Marshmallows Safe?

You’re really digging deep in the freezer or pantry, huh? While 2-year-old marshmallows stored under peak ideal conditions might still be safe to eat, their quality and taste are very likely compromised.

Check for any signs of spoilage and consider how the old marshmallows might affect the dish you’re using them in. If in doubt, it’s safer (and more delicious) to opt for a fresh bag.

Final Thoughts

So, there you have it, your ultimate guide to all things marshmallow! Whether you’re gearing up for a Cookie Day to remember or simply enjoying a cozy night with a steaming cup of hot cocoa, understanding the ins and outs of marshmallow care can elevate your sweet experience. 

Remember, the secret to marshmallow longevity is all about keeping them cool and dry. After all, nothing beats the delightful, airy puff of a perfectly fresh marshmallow melting into your treats.

About Author

Tia Goodnight

Hey! I'm Tia, and I started this site to bring you the best information on all things kitchen so you can enjoy and elevate your everyday life.

I love trying new techniques and tools, living for the thrill of pulling off a new skill. On weekends you'll find me at the local farmer's markets or hosting friends and family for an evening of yard or card games and delicious food.

If you're looking for honest, real-world advice on all things kitchen and cooking, you're in the right place!