How Long Does Miso Last? Can it Go Bad?

So, you’ve bought a bit of miso to make yourself the occasional portion of miso soup and now find yourself wondering how long it will last. It’s a common question. Given that miso is often sold in such large volume and each dish only requires such a small amount to flavor it, you would think that it wouldn’t go off quickly, right? Surely there aren’t millions of people out there chucking out vast quantities of miso paste because they can’t use it quickly enough? Well, it depends. It seems like there is a lot of conflicting information out there on how to store miso and for how long.

So, if you’ve found yourself looking at a tub or jar of miso that is fast approaching its sell-by date, you probably have a few questions, You may be thinking “Is this gone off?”, “How can I tell if it has gone off?”, or “Should I have stored this in the freezer?”. Thankfully, we have endeavored to trawl through the internet dispelling all of the myths related to miso. So, if that’s what you’re looking for, you’ve come to the right place!

The Best Way to Store Miso

Let’s kick this off with a positive by immediately getting into some good news. Given that miso paste is made by fermenting soy beans, it is quite a forgiving product when it comes to storing it. So, if your miso paste has gone beyond its sell-by date, it may still be totally fine. This is because of the fact that fermented food products in general are a difficult environment for bacteria to settle and thrive in. It also has a pretty high salt content which further serves to preserve it. With that in mind, let’s get into the best storage techniques for miso.

Fridge, or pantry?

There is conflicting information everywhere on the internet on this question, with no real resolution in sight. Having looked into it deeply, the reason for the debate is that technically, either one will do when the miso is unopened. Miso in this state just isn’t all that demanding. It wants to be kept away from moisture, heat, sunlight, and moisture. Once you have covered these bases, it will store quite well. So, the fridge is fine, the pantry is fine, kitchen cabinets are also fine – so long as they aren’t near a source of heat or moisture.

Opened miso

Once again, provided that the correct conditions are met regarding exposure to the elements, it doesn’t really matter whether you store it in the fridge or the pantry. We would have a preference for the fridge as you can pretty much guarantee that the temperature will always be stable. Some miso labels will urge you to put it in the fridge after opening. In these cases, we would recommend following the manufacturer’s advice. One important tip for storage is always to make sure that your miso is well sealed up before you place it back into the fridge or pantry. The fridge will have plenty of moisture circulating around it which will cause your miso to spoil very quickly otherwise. It will also prevent foreign bodies from entering your miso and infecting it.

How Long Does Miso Last?

So, now that we’ve handled the best ways to store miso paste, it’s time to get into how long it will last under those conditions. The first thing to note is that store-bought will inevitably come with a sell-by date. However, given that miso is a fermented product that is high in salt, it can preserve incredibly well if stored carefully. Because of this, it is possible that miso will retain its quality for months after the printed date if the package is unopened. Overall, it is not uncommon for miso to last for up to a year after it has first been packaged. Once opened, the miso will have inevitably had some contact with air which will accelerate its degradation. Even if you take the best imaginable care of your miso, it will only retain its quality for a maximum of 3 months afterward, or maybe 4 in exceptional cases.

Signs That Your Miso May Have Gone Off

It can be quite difficult to ascertain whether something with as strong a flavor and an aroma as miso is gone off. In most cases, when a miso paste has begun to turn, the first sign you will notice is that the underlying sweetness in its flavor will have disappeared. At this point, it will still be usable but it won’t provide the same quality of flavor as before. The chances of spoilage beyond this are relatively slim, but it can occur in some cases. The first sign of this kind of spoilage you should keep an eye out for is a discoloration of the surface of the miso. If it has darkened in color or adopted a new color entirely, it has to be thrown out. Upon opening the package, if you are instantly hit by a pungent odor, the whole package must be thrown out as it has likely been contaminated by a foreign body of some sort. The last sign of spoilage is the most obvious of them all; mold. In this case, don’t attempt to cut around the affected area to preserve the rest. Instead, discard the whole package and replace it.

Should Miso be Refrigerated?

There is no need to store miso paste in the fridge if it is unopened. Instead, the pantry or a kitchen press will do. However, once the package is opened, though it is not absolutely necessary, we would recommend storing it in the fridge from then on out.

Freezing miso

If you are unlikely to use all of your miso by the time it expires, freezing is an option that might work for you. There are a few ways to freeze miso that will ensure that it will preserve correctly and not change its flavor or texture dramatically. Our favorite way of doing this is also perhaps the most convenient. We opt to freeze it in portion sizes using an ice-cube tray. After these cubes freeze, they can then be transferred into an airtight freezer bag ready for use.

Miso Storage, Sell-by Dates, and Other Related Questions

Is miso good for you?

Given that miso is a fermented food, it actually possesses quite a few health benefits. It reportedly helps with digestion and is a good source of probiotics. However, when cooking miso you should never raise it above boiling temperature as this will kill off its live cultures.

Where does miso come from?

Miso, made from fermented soy beans, originates in Japan where it is commonly used to add an umami flavor to dishes. It is most commonly found in soups, sauces, and marinades.