Does Miso Go Bad? Here’s What You Need to Know

Miso soup first originated in Japan, and has now not only become a staple of Japanese cuisine, but has made its way to popularity around the world. I’m a sucker for a good bowl of miso soup to start my meal!

It’s one of the most popular foods in Japan, eaten by three-quarters of the population at least once a day. Plus, over 80% of all miso paste is used to make it. With that being said, all typical Japanese households know at least one (if not several) miso soup recipes.

Along with sipping it for the taste, miso soup also contains a lot of nutritional benefits. Some potential health benefits include improved digestive health, reduced risk of cancer, lower risk of heart disease, and less severe symptoms of menopause.

In one serving of miso soup, there are 40 calories and 0 grams of saturated fat, trans fat, and cholesterol. It does, on the other hand, contain 3 grams of protein. It’s also an excellent source of Vitamin K, Manganese, Copper, and Zinc, and includes other nutrients like calcium, iron, vitamin B, and magnesium. You’ll also be sure to get some probiotics in your bowl.

Given all of these benefits, it makes sense to go out and stock up or make lots of homemade miso so that you always have some to hand! However, you may be wondering – does miso go bad?

Unfortunately, all good things must come to an end. That said, the good news is miso soup doesn’t expire as quickly as you think. Read on to learn more!

What is Miso?

Miso is a traditional Japanese seasoning produced by fermenting soybeans with salt and kōji (also known as Aspergillus oryzae, a filamentous fungus) and that’s been cultivated from rice, barley, seaweed, or soybeans.

Miso soup, on the other hand, is of course a traditional Japanese soup that consists of a dashi stock, which is mixed with softened miso paste. You can add extra ingredients like seaweed or tofu to add to the flavor. 

If we’re talking flavors, miso is distinguished as the ultimate reference point for the flavor sensation known as “umami,” aka, “essence of deliciousness” in Japanese. The taste is often described as the meaty and savory aspect that deepens the flavor. 

The miso paste combined with the broth/soup form creates a deep, savory flavor that also includes toasty, funky, salty-sweet combinations. This umami flavor is actually the base of a lot of everyday Japanese cooking. 

Does Miso Go Bad?

Yes, unfortunately, miso does go bad. However, it does not go bad as quickly as you’d think, meaning you get to savor that taste for a bit longer!

When stored correctly, miso soups are generally safe to consume for a few extra days. You can refrigerate miso, which preserves freshness for a short period of time but keeps its flavor.

Or, you can freeze miso soup and miso paste. Just keep in mind that although it will last longer, you may lose some of that texture and flavor we know and love!

How Long Does Miso Last?

If properly stored in the refrigerator, miso soups are generally safe to eat for the next three days.

As for the freezer, your miso soup can keep safe for up to 6 months. However, your container will most likely expand during storage and cause a freezer-burn layer on your miso soup. 

Miso paste, on the other hand, has a longer lifespan than once put into soup form. Typically speaking, miso paste can last indefinitely in the freezer. But for best use, try getting the most out of it for 18 months

If unopened in the refrigerator, miso paste is good for at least one year or its best by date with 3-6 months added to the lifespan. But if you open it, that’s okay too! You still get three beautiful months with the paste before it starts to turn.

Refrigerated Miso Soup2-3 days
Frozen Miso Soup6 months
Unopened Miso Paste, RefrigeratedBest-by-date plus 3-6 months
Opened Miso Paste, Refrigerated3 months
Frozen Miso PasteIndefinitely - 18 Months for best quality

How to Tell if Miso Has Gone Bad

Miso Soup

When it’s time to take your miso soup out of the freezer, check for any visible discoloration. That will be a major indication the soup has gone bad. Other signs are if your miso soup looks more cloudy than usual or has spots of mold on it. This is rare, but it’s never a bad thing to check out if you feel you have some old miso. 

Miso Paste

If you’re checking to see if the paste has gone bad, the major thing you’ll notice is that the quality will lessen and become less sweet to taste. Since paste may last indefinitely, you’ll just have to decide if the lessened flavors are worth keeping. But that can be a game-time decision.

Hot to Store Miso

Storing Miso Paste

The best method for storing an unopened package of miso paste is to put it in a cool, dark place away from light and sources of heat. You do not have to refrigerate unopened miso. This is similar to most condiments such as hot sauce or ketchup. Think about it; you purchase these at the store on the shelves and not the refrigerated aisles. Therefore, why would you need to store the paste in the fridge when you get home?

When that miso is opened, you can then reseal it tightly to make sure nothing gets through the lid. Go ahead and store that away in the fridge, or (plot twist), you can restore it in the pantry or even at room temperature. It’s also a good idea to read the label. Sometimes it will tell you to store it in the fridge once opened or put it back in the pantry. Trust the instructions.

Storing Miso Soup

When you have leftover miso soup that you’re eager to eat another day, you will put the miso soup into an airtight container and make sure it’s sealed tight.

You can then go ahead and store it in the fridge. It is also suggested that for best results, you separate the contents of the soup. For example, take out the tofu, seaweed, and green onions and put those in a separate airtight container to be added again to the broth later on.

If the miso soup is still hot when you’re done eating it, you can go ahead and let it cool at room temperature first for up to 2 hours before putting it away in the fridge. 

You can also freeze miso soup to further prolong its shelflife. All you need are freezer bags or freezer-safe airtight containers and room in your freezer! Click here for our guide to freezing miso soup.

When you have that hankering for miso soup again, you can easily reheat it, whether frozen or refrigerated. You’ll also be able to put the soup additions that you took out previously, such as the tofu and seaweed, once the soup turns back into a liquid state. 

This way, all the ingredients preserved their textures and flavors.