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Does miso go bad? And how long does miso paste last? Keep reading to find out everything you need to know!

If any one of us looked in our kitchen cupboards right now, I bet we would all find a collection of pastes and sauces that we bought long ago in preparation for branching out of our comfort zones, after which we promptly forgot all about those ingredients.

Does Miso go bad

In the world of culinary pursuits where every person is exploring the variety of ingredients across the globe, there are a lot of these ingredients appearing in people’s cupboards.

However, the problem with them is not the ingredients themselves, but our knowledge of them.

Even if we use them in one dish, many people are left scratching their heads about what to do with them beyond that one dish, whereas people who use these ingredients in their native culture have a bedrock of experience when cooking with them.

Of course, this happens all over the world and with many ingredients, but one of the most puzzling to a western audience is miso.

How do you use it? Is it a flavor enhancer or a foundation for a dish? And when exactly does miso go bad? That last one is the main topic of today, and we will seek to answer that question in this article.

What Is Miso?

Before we look at anything else, we need to look at just what miso is. Miso is a type of fermented soy paste that is incredibly popular in East Asia. The actual ingredients of miso are soybeans, salt, and koji, and that are the only essentials you need for miso.

Yet, the type of koji that you use changes how the miso will taste and the flavors it will give to your dishes.

So, to break it down more, koji is the key ingredient here, and it is actually a type of mold that is essential to the miso-making process. To make it, the mold culture (in the case of miso, this is Aspergillus oryzae) is added to some pre-steamed white rice.

The rice must be completely cooled before this is allowed to happen. This mold culture has been cultivated specifically for this purpose, due to the difficulties in the past of creating one from natural surroundings.

The koji will begin to break down the rice and after a while, it will be at the perfect point to add the koji to the rest of the ingredients.

Once the other ingredients are added the mixture will be left to be broken down by the koji, then it will be fermented and aged at which point you will have the perfect miso mixture.

Miso comes in a huge variety, thanks to the difference in how they are prepared, and as such you can create a massive amount of different tasting miso dishes.

The two most common varieties are white and red miso. White miso is made from boiled soybeans and is sweet and soft in the umami flavor.

Red miso is made from steamed soybeans and is left to ferment for longer, which gives it a salty and powerful umami flavor.

Does Miso Go Bad?

It is the nature of the world and the universe that eventually something will go bad, and unfortunately, that applies to miso as well. However, unlike a lot of ingredients – pastes, sauces, or otherwise – miso takes far, far longer to go off or bad than most other foods.

If you leave miso unopened in a pantry or cupboard, it will actually be fine for a surprisingly long time. All miso pastes will have the best before date on, and that best before date will normally be about 2 to 3 years after you bought it for an unopened miso pot.

Notice this is the best before date as well, meaning that miso could very well last beyond this, but it will change in texture, flavor, color, and quality over time, so be aware of that.

If you have opened your miso, then that best before date is dramatically reduced. Normally, after opening the manufacturer will advise you to eat the miso within 3 to 4 months, before the texture, flavor, color, and quality change.

If these changes don’t occur, however, then it is entirely possible to keep eating miso for up to a year after opening, just be cautious of the possible changes happening before trying some.

Another thing to point out is that opened miso can be stored in the pantry, kitchen cupboards, or in the fridge during this time without spoiling, just make sure the areas outside the fridge do not go above room temperature.

If you don’t have the space to store your miso in a cupboard or the fridge, there is a third option, which most people don’t try. You could freeze it.

Miso is perfectly fine and stable to store in the freezer, and it can mean that you can have miso for years without going out to buy more. Nonetheless, there are some things you need to do before trying this method.

The first is to separate your miso into different containers based on how much you are going to use. This is because once it is frozen, it is rock hard and difficult to take apart without defrosting it completely. The second is to make sure you only defrost it once you are ready to use it.

Re-freezing miso a second time changes the texture and flavor of the miso, which while not bad is not the best it could be either, so it is best to just make sure that you never have to freeze it again.

Benefits Of Miso

As you can see, miso keeps for an insanely long time and normally that means it shouldn’t have many benefits to eating it, thanks to the measures we take in the modern-day for shelf stability.

Yet, that is simply not the case, miso is a wonder food that has so much nutritional value it is astounding.

It is rich in proteins, calcium, iron, selenium, manganese, choline, potassium, copper, zinc, and phosphorus, making it a perfect substitute for vegans in the protein game.

Benefits Of Miso

The fact that it is a probiotic means that it is incredibly healthy for your gut, as the gut relies on good bacteria to maintain good digestion and absorption of nutrients.

Therefore, if you introduce miso to your diet, you can expect to feel much healthier just from your digestive tract.

Miso also has a large supply of B vitamins, including the elusive B12 vitamin. To find B12 in a vegetarian-based diet is very difficult, so having a cup of miso soup a day will help any new vegetarians struggling without having to turn to multivitamins.

One surprising thing about miso is that despite its high sodium levels, studies have shown that it doesn’t have much effect on the heart or organs that are normally detrimentally affected by salt.

The commonly held viewpoint by scientists is that due to the antioxidants, amino acids, and nutrients in the miso, it negates the effects that sodium normally has, but this viewpoint is yet to be proven. What we do know is that the sodium within the miso isn’t as harmful as other sources, which is great news all around.


Miso is a wonderful ingredient to incorporate into your diet. It is not only one of the longest-lasting foods that you will have in your house, but it can be one of the most delicious and nutrient-rich as well.

It is perfect for adding to soups or broths, and if you are feeling experimental, you could even make a variety of pan sauces and curries out of it.

If you have never tried miso, give it a go. Even if you can’t get it right the first time, you only need to use a bit, so there are plenty of ways to get it right in the future.

Can You Still Eat It?

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