So you’ve bought a few packets of miso to make miso soup or use in ramen noodles. You’ve tried a few recipes, but for some reason miso dishes weren’t on your regular menu.

Now you’re left with a jar that is nearing its expiration date. That leads us to wonder: how long does miso paste last?

Or maybe you’ve just opened a packet of miso and aren’t sure how to preserve it for the long term. You’ve checked a couple of websites and found conflicting information. Some say miso can be kept at room temperature, while others urge you to refrigerate it. And you don’t really know who to trust. The same happens with the expiration and deterioration of the paste.

If you want to know more about miso storage, expiration, and spoilage, keep reading. In this article, I not only cover the basics, but I also share some links to producer websites where you can read about miso in more detail.

How long does the miso last?

You can keep miso for a long time because it is a fermented food product with a lot of salt. Some companies put an expiration date on the label because it is required by law in their country. In other countries, that date is not necessary, which is why sometimes you can’t find it on the packaging.

If the expiration date is listed on the label, you can easily assume that the unopened miso will remain at its highest quality for at least a couple of months after that date. If only the production date is listed, the pasta will maintain its quality for at least one year.

After that period, the pasta will not go bad or anything like that, but it can degrade a bit in terms of quality and become less sweet in flavor. This is because the miso is alive and is still fermenting, albeit very slowly.

Once you open the package, the downgrade process speeds up a bit. Generally, the pasta should retain its best quality for about 3 months after opening the package.

That, of course, does not mean that it will break down after 4 months or half a year. But at a certain point, you might notice some subtle flavor differences between the paste you have and the fresh miso. However, if the quality of the paste is good enough to use, you can continue to use it.

Please note that the above periods are only for the best quality. Properly stored miso will last much longer with fairly good quality.

How do you know if the miso is bad?

If you notice any classic signs of deterioration, such as mold, discoloration, or a bad smell, throw the pasta away.

Like I said before, miso can keep for a long time, so the chance of it going bad is minimal. However, over time the quality of the pasta degrades slightly and at some point you may decide to throw it away for quality reasons.

Smell it good and decide if it’s good enough or not. If you’re not sure, you can eat a small amount before making your final decision.

How to preserve miso

In terms of storage, miso is actually quite similar to tabasco. You should store an unopened packet of miso in a cool, dark place, away from light and heat sources. The pantry is the best place, but a kitchen cabinet will also work. Just make sure it’s not near the stove, as temperature fluctuations can alter the flavor of the pasta. It is not necessary to refrigerate unopened miso.

Once the package is opened, make sure that it is always tightly closed when not in use.

As for where the open miso should be stored, there are two options. The refrigerator is the best place because miso preserves its quality better at low temperatures. However, pantry or even room temperature in many cases is also suitable for long-term storage. If the label doesn’t tell you to refrigerate the pasta after opening it, feel free to store it in the pantry.

Last but not least, always use clean utensils when scooping out the batter for miso soup (for example, with tofu) or ramen noodles, or any other dish that calls for it.

Although fermented soybeans and salt are not an ideal environment for foreign bacteria to live, microbial contamination is still a possibility. And it’s super easy to avoid it simply by always using clean spoons.