Understanding Miso Paste

Pretty much everyone has heard of miso soup. It’s ubiquitous at Japanese restaurants and a common starter at vegan or other eateries as well. For home dwellers, instant miso soup is now widely available, too. The more discerning cook or diner may also be familiar with miso as one of the best glazes for salmon, or other meats and veggies.

There are some things, however, that even handy home cooks may not know about miso — for instance, that it usually comes in paste form as an ingredient. Or that you can use it to give unexpected depth of flavor to chicken noodle soup, add it to pasta water for the best buttered noodles, and take your pizza sauce to the next level. Similarly, many people don’t know that miso paste is available, usually in several forms, in the refrigerated section of most larger grocery stores.

That’s a shame, because this ingredient is basically magic. Yes, you can make a bit of soup with it any time you want, but you can also use it as the base for so many delicious (and easy) recipes. If you’ve not yet familiarized yourself with this common ingredient from Asian cooking, the time to do so has come.

Miso is a fermented mash of soybeans and salt, and sometimes other grains, typically rice or barley. The mash must be inoculated with a specific type of mold, Aspergillus oryzae, known colloquially as koji. Koji is actually the basis for other fermented ingredients you’re likely familiar with, including soy sauce, rice vinegar, sake, and tamari.

In many miso recipes, the mold is present in special types of already-inoculated grain, such as rice koji. It may also be mixed with rye or barley as the foundational grain. After combining these ingredients with salt, the ingredients undergo a long fermentation period, eventually taking on the deep, rich, umami flavor that we know as miso.

A note about sweet miso: This typically refers to white miso that’s been fermented for a shorter period of time and is therefore less pungent and umami-forward, has less salt than other varieties, and is quite smooth and creamy. However, you shouldn’t interpret this as actually containing sugar or tasting sweet; it’s just much milder. You can think of the word “sweet” as how it’s used in “sweet cream” butter: not actually sweet, but not so salty.

Today, we associate miso most strongly with Japanese cuisine. Its presence in the beloved miso soup makes separating the associations hard, but in fact, miso is believed to have originated in China. Combinations of soybeans, millet, and salt crop up around the first century BCE. It wasn’t always vegetarian, either; Originally, the mixture was made with meat or fish as the base. Known as jiang, it didn’t come over to Japan until the seventh century, brought by monks. Although it is today a common enough ingredient, and certainly a more affordable one, miso was, at that time, a luxury. It was available only to religious orders and the very wealthy, sometimes even used as a salary. Moreover, it wasn’t yet used as a common base for soups and other foods, but rather as a condiment for spreading or dipping.

Over time, it became a critical food for soldiers in times of war. By the 17^th century, however, industrial manufacturing processes made miso available to commoners, and it has remained a mainstay of Japanese cooking ever since. Eventually, it made its way to Western countries in the 1970s, buoyed on a tide of health consciousness.

Miso is the result of a two-step fermentation process. First, manufacturers inoculate the rice or other grain (the “substrate”) with the Aspergillus spores and they undergo a short (about two days), but hot, fermentation process at 30 degrees Celsius, or 86 degrees Fahrenheit. This is critical for the spores to release enzymes, which then drive the second stage of fermentation, when the prepared koji is combined with other ingredients to make miso — or soy sauce, sake, and so on. Historical records indicate that this process has been around for three millennia.

In the second stage, the koji, plus soybeans and salt, goes into a vat to ferment for between two months to two years. The longer the fermentation process, the more savory the miso becomes. Importantly, miso does not get ground into a paste until after fermentation is complete. During its long stay in the fermentation jar, it stays a mash.

So far, you’ve heard a lot about miso being rich and umami … but how does this really translate to your taste buds? First, let’s tackle what it really means to be “umami.” This fifth taste has been recognized in Eastern cultures for at least a century, but was only recently added to the flavor groupings of sweet, salty, bitter, and sour in Western thinking.

Umami is a flavor that encapsulates potently meaty flavors, such as mushrooms, seaweed, and meat. It is characterized by its lasting nature and complex, but balanced, taste, as well as the way it makes your mouth water. It also coats the tongue, which leads to its long-lasting nature and is why it’s so often described as rich. Perhaps the best way to think about umami is as a meaty flavor that doesn’t actually have to involve meat. Miso brings flavors other than umami to the table, however. It is often described as earthy, savory, and salty-sweet. Funky is not out of place either.

A true discussion of the breadth and depth of miso throughout time and space is, naturally, impossible here — and that’s before you realize there are more than 1,300 varieties of the stuff, according to experts. Suffice it to say, there are tons of choices when it comes to miso, but only a few ones you’ll find at the store or through common online outlets. Classic varieties include shiro (white miso paste) — such as Fusion Select Organic White Miso Paste — , aka (red miso paste), awase (a mixture of red and white), hatcho (made without any added grains), and mugi (made with barley). 

There are different answers to why miso comes in different colors. For instance, some sources say that recipes that use white rice become white miso, and those that rely on red rice turn into red miso. Others claim that the reason for the difference in color is the length of fermentation, with the mash going from white to red to red-brown and even black, depending on how long it keeps brewing. Still, others point out differences in salt content, with more salt equating to deeper coloring. There is truth to all three of these factors — the various recipes that comprise the 1,300 varieties depend on a huge variety of factors and often come down to the prefecture where they’re made. Interestingly, the reason miso darkens is due to the same reason meat browns: the “maillard reaction.” This is a process whereby amino acids interact with sugars and turn brown.

Miso paste is not hard to find — you can purchase it in most grocery stores. It’ll be in the refrigerated section, and if it’s not there, you may find shelf-stable versions in the Asian foods aisle. If you strike out or want more options, head to the nearest Asian foods market, where you’ll surely find a much larger selection.

If you want miso that will last a little longer, you can order dry miso online. Freeze-dried red miso powder, such as the Yamasan Kyoto Uji Dry Red Miso Powder, will last for years in your cupboards if stored in an airtight container and kept away from light, heat, and moisture. These allow you to rehydrate only the quantity you need, so you don’t have to worry about using up a refrigerated product by the time it reaches its expiration date.

Miso comes in both shelf-stable and refrigerated forms. When choosing the refrigerated versions, look for a best-by date. Don’t purchase anything that has a puffy plastic lid, which could indicate that it has started to spoil. You should also look for spots of uneven coloration, which could indicate spoilage as well. Check that the package is completely sealed. With shelf-stable products, check the label to see if you need to refrigerate it after opening.

You should also make sure the ingredients list is short; miso shouldn’t have much beyond soybeans, koji, salt, and a grain (if applicable). Avoid any products that include alcohol, preservatives, stabilizers, or ingredients with names that make you scratch your head. Miso’s not that challenging to make and preserve, so any of that extra stuff is unnecessary.

It’s not hard to make miso paste at home, but it looks a little different from mass manufacturing, and it takes a long time. We’re not talking about a few weeks on the countertop, which is about how long it takes to ferment sauerkraut, or a few days, which is what you need for kimchi. Rather, as discussed earlier, miso takes many months to fully ferment, though you can start eating it after as little as three to six months if you want the sweeter, and less rich, variety. Miso can be a bit fussy, which is why some home chefs recommend starting in winter, since miso likes colder temperatures in the early months of fermentation and hot temperature later in the process. You can start any time of year, however, as long as you have a cool, dry place to store your fermenting jars.

To make miso, you will need a few ingredients: dried soybeans (such as Soymerica Soybeans), rice koji (check out Isesou Miyako Koji), and natural sea salt without any additives (e.g. anti-caking agents or iodine). The main difference between homemade recipes and manufacturing processes is that home chefs do not typically culture koji themselves, although you can certainly do so if you wish. Soak and cook the soybeans, reserving some liquid, then combine them with rice koji and salt, mash them together, and put the whole mixture in jars or other containers. Cover tightly and let it go to town. If that all sounds like a lot, well, you can of course just buy it from the store.

Now for the million dollar question: What should you do with miso paste in the kitchen? The answer to this question is almost as big as the internet, but it definitely starts with soup. Before you continue down the road of miso cookery, make sure you’ve mastered a high-quality, delicious, rich miso soup with seaweed and tofu. A good recipe usually includes green onions and possibly greens, like chard or kale, as well. Miso soup may get upgrades, such as udon noodles, boiled eggs, or beef.

Because miso has such a lovely and distinctive flavor, it stands to reason you can put it to work in many other ways as well. If you’re ready to travel a little farther afield, you can try more adventurous recipes such as miso maple salmon, mashed potatoes with garlic and miso, and pasta and ramen with miso at their base. Great with meat and meat substitutes as well, you might try miso in chicken and veggie sheet-pan bakes, marinated pork, or broiled tofu. Its rich, earthy, umami flavor profile also makes it well suited to a variety of soups, such as carrot-leek or fish chowder. Other uses for miso are as myriad as the types. You can use it to make a punchy salad dressing, stir it into the base of your braising liquids, or put it in brining liquid when making pickles.

Miso in desserts? Why, yes! Much like you might find in a salted caramel or a maple bacon donut, the saltiness of this fermented paste complements sugar, dairy, and other dessert-forward flavors quite well. There’s a reason we use salt in baking: It helps to bring out the other flavors in the cookie, cake, or ice cream. Although you might not think a basic chocolate chip cookie could be improved upon, it turns out that a bit of miso might just be what you need to round it out.

In some countries, you’ll find goodies such as macaroons or tarts made with miso. Other ideas include chocolate tarts, miso blondies, sticky toffee cakes, chocolate pudding, or miso apple Danishes. The sky’s really the limit, so if you have an idea, just google your ingredient, plus miso, and see what pops up.

However, if you want a little guidance, there are some flavors that miso pairs with better than others. These include sturdy fruits, such as bananas and apples, or winter squashes that bring an earthy flavor profile to your dish. Because miso is strong and hearty, it also pairs well with nutty flavors: think caramel, sesame, or browned butter.

Fermented foods tend to last longer due to the presence of friendly bacteria and the low-pH (acidic) environment, which discourages the growth of harmful pathogens. Because miso is fermented, it will therefore last longer in your fridge, even after opening, than a non-preserved food (it’s right there in the name, after all).

That said, how long can you actually keep miso before it spoils? It is capable of lasting months or even years after its best-by date, and may in fact taste even better over time. Eventually, though, it will discolor and smell bad, get slimy, or grow mold — all the classic signs of spoilage. If that happens, throw it out. Ditto if it starts to taste strange, even if you don’t detect the classic rotten flavor. However, know that not all pathogens create these signs, so you shouldn’t keep miso after it starts to darken, even if it smells fine. Always store your miso paste in the fridge. If you wish, you can cut out a little circle of parchment paper that is the size of the inside of the container, then place it on top of the miso to further reduce air contact.

While miso is certainly delicious, it also carries tons of health benefits, which is a big part of the reason it made the jump from Eastern to Western cultures. It packs a huge flavor punch in only a little bit of paste, given the fact that most recipes call for a tablespoon of miso or less per cup of water. For each tablespoon, you’ll only consume around 34 calories, but you’ll get a decent punch of protein (more than 2 grams) and fat. The only thing to watch out for is salt, since that same tablespoon-sized serving contains more than 630 milligrams of your daily recommended 2,300 milligrams of sodium.

Because it is fermented, miso also has tons of probiotics, which are friendly bacteria that help to keep your gut colony healthy. In addition, it carries antioxidant properties (via melanoidins and isoflavones) that may help protect cells from free radicals and, in turn, the development of certain diseases and chronic health issues.