Miso 味噌 Fermented Soybean Paste

Mika Oka
9 min readSep 23, 2023
READ MORE 米味噌とはどんな味噌?特徴やおすすめレシピをご紹介 | DELISH KITCHEN

Miso is a well-known ingredient in many Japanese dishes that adds that savory umami flavor without using any meat or meat broth. It is a paste crafted from fermented soybeans. This process involves mashing soybeans and blending them with salt and a culture known as koji (麹, Aspergillus oryzae). This same fungus is used in the production of sake, shochu, and rice vinegar.

But miso isn’t limited to just soup; it finds its way into various culinary applications. Japanese chefs use it to enhance sauces, dressings, and marinades, and it’s handy for pickling vegetables and meats.

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· History of Miso
· The Concept of Ichiju-Issai, The Balanced Meal
· Miso as Superfood
Salt Content
· Miso-Making Process
· Miso Types by Color
· Storing Miso
· Common Ingredients in Miso Soup
· Important Things to Know
· How to Drink Miso Soup

History of Miso

This fermented food likely traces back to around 11th century B.C. Historical records mention a monk who received miso as part of his salary, sent from Ōmi Province (modern-day Shiga prefecture).

There is also references of miso as part of nobility’s compensation. During this era, miso was a luxury reserved for the upper class and remained unfamiliar to the common people.

Miso consumption in the Heian era involved salted soybeans, dried to form a seasoning for steamed vegetables or fish. It was paired with rice or enjoyed as a salty accompaniment to sake. Additionally, miso served medicinal purposes.

As rice cultivation expanded across the country toward the end of the Heian era, miso began incorporating rice koji in its fermentation process. This shift led to the emergence of regional miso varieties using soybeans, rice, and wheat.

The Concept of Ichiju-Issai, The Balanced Meal

The concept of Ichiju-Issai originated during the Kamakura period (1185–1333) in Japan, signifying the essential elements of a balanced meal in Japanese culinary culture. This basic meal typically consists of rice, considered the meal’s foundation, accompanied by a bowl of miso soup and a side dish. Implicitly, pickled vegetables are often included to complete the ensemble.

In contemporary times, the notion of a balanced meal has evolved into Ichiju-Sansai, which translates to one soup and three dishes. This updated concept incorporates not just one, but three side dishes, often featuring fish or meat in one dish and various vegetables in the remaining two. Many homemade meals now adhere to this model. While Japan is renowned for its rice consumption, miso soup holds an equally vital place at the Japanese dining table.

Miso as Superfood

While numerous studies have explored the potential health benefits of consuming miso soup, it’s important to note that the results can vary based on factors such as race, age, ethnicity, gender, and diet. Some of the potential benefits associated with miso consumption include:

  • Enhanced Digestive Health: Miso, as a fermented food, contains probiotics similar to yogurt, sauerkraut, kombucha, and kimchi. These probiotics harbor “good” bacteria that can reduce inflammation, support healthy digestion, and fortify the immune system. In essence, miso aids your body in processing and absorbing nutrients efficiently.
  • Cardiovascular Health: Research indicates that miso soup consumption may lower the risk of fatal heart diseases. Studies have revealed a correlation between higher isoflavone levels (nutritional supplements found in legumes) and reduced risk of strokes and heart attacks, particularly in some Japanese women.
  • Cholesterol Reduction: Certain animal studies suggest that miso may contribute to lower levels of LDL cholesterol, often referred to as “bad” cholesterol. Reduced cholesterol levels are linked to a decreased risk of heart disease and strokes.
  • Cancer Risk Reduction: Miso’s rich antioxidant content can help protect cells from free radical damage, a factor associated with cancer development. Both animal and human studies have suggested that consuming miso may reduce the risk of various cancers, including lung, colon, stomach, and breast cancers.
  • Menopausal Symptom Alleviation: Soybeans, a key component of miso, offer multiple health advantages for women, including relief from hot flashes during menopause. Soy-based foods are also associated with maintaining optimal bone health and averting osteoporosis.
  • Skin Health Improvement: Miso boasts a wealth of antioxidants, such as vitamin E, isoflavones, and saponins. These antioxidants shield the body from the damaging effects of free radicals, known to accelerate aging. Additionally, miso contains linoleic acid, an essential fatty acid that promotes soft and blemish-free skin.
  • Potential Diabetes Prevention: Some studies propose that fermented soy products like miso could delay the progression of type 2 diabetes.

Salt Content

  • While miso is undeniably salt-rich, it remains a dietary staple in Japan. It’s worth noting that you don’t require a substantial spoonful of miso to craft a flavorsome miso soup or employ it as a seasoning for stir-fries. A small quantity can work wonders, the taste of miso should be subtle and does not overwhelms your palate.
  • To mitigate sodium absorption in the body, incorporating potassium-rich vegetables such as potatoes, leafy greens like spinach, various seaweeds including wakame, and bamboo shoots into your miso-based dishes can be beneficial.

Miso-Making Process

READ MORE みそ(味噌)を知る | イチビキ 公式サイト (ichibiki.co.jp)

It all begins with koji, a fungus widely employed in fermenting foods in Japan. Koji, scientifically known as Aspergillus Oryzae, plays a role similar to bacteria and mold in developing complex flavors, much like how cheese gets its unique taste. To create koji, they introduce spores into a mixture of steamed rice or a combination of rice and soybeans.

As the koji undergoes fermentation, it transforms starches into sugars and releases glutamate, the source of its umami taste. Miso, on the other hand, results from mixing koji with soybeans, rice, or barley, followed by additional fermentation to achieve various flavor intensities. Depending on the blend of rice and barley and the fermentation duration, distinct flavor profiles emerge.

Soybeans, water, salt, and the pivotal koji mold are the fundamental components of all miso types. Koji, usually derived from rice, barley, or pure soybean, serves as the catalyst for the fermentation process.

Miso Types by Color

READ MORE マルコメ 公式オンラインショッププラス糀 無添加糀美人 650g×3: みそ・缶詰 (marukome-shop.jp)

The color of miso varies based on ingredients, the amount of koji used, and fermentation time. One key factor is the Maillard reaction that occurs during fermentation and aging. This reaction involves amino acids in soybeans, rice, and wheat reacting with sugars to produce brown pigments. The longer the Maillard reaction goes on, the darker the miso becomes.

  • Red miso, also known as aka miso (赤味噌), is crafted from 70% soybeans and 30% rice or barley. The soybeans are steamed before being mixed with koji. A prolonged fermentation period of approximately 1 to 1.5 years yields a darker, robust, and salty miso (13%). Red miso boasts the highest protein content among all miso types. Its color can range from deep amber to chestnut. Red miso continues to darken with time, but its high salt content prevents spoilage.
  • Light-colored miso, also known as tanshoku miso (淡色味噌), shares a production process with white miso. Its yellowish hue results from higher salt content than white miso and an extended aging period, which promotes the Maillard reaction to a greater extent than in white miso.
  • White miso, or shiro miso (白味噌), is created from about 40% soybean and 60% rice or barley. White miso undergoes a much shorter fermentation period, typically 1 to 2 weeks. This results in a milder and less salty flavor than red miso. The yellowish beige color arises from the soybeans’ boiling process, which prevents the Maillard reaction. White miso contains the most carbohydrates among miso varieties, imparting a sweeter taste and a very smooth texture.

Based on my personal experience, if you’re new to the taste of miso, it’s advisable to start with white miso (shiro). For health reasons, I’d steer clear of yellow miso (tanshoku) due to its elevated salt content. When you’re ready to explore bolder flavors, you can experiment by combining white and red miso or simply opt for the red miso variety.

Storing Miso

For opened miso:

  • Once opened, refrigerate the miso to halt the fermentation process and prevent mold growth. Miso contains beneficial lactic acid bacteria, such as Tetragenococcus halophilus. Refrigeration helps maintain freshness.
  • After opening the miso package, wrap it with parchment paper or plastic wrap and ensure a tight seal when not in use. This prevents oxidation and exposure to air.
  • Always use clean, dry utensils when scooping out miso to avoid contamination and mold growth.

For unopened miso:

  • Store unopened miso in a cool, dry place, away from light and heat.

Common Ingredients in Miso Soup

This includes a selection of common ingredients such as tofu, wakame seaweed, Japanese radishes, and potatoes, in addition to the fundamental miso paste. It also involves dashi, a soup stock crafted from bonito or kombu seaweed.

You can use almost any ingredients in your miso soup. I used to vacuum seal the leftover from my food carving in convenient servings, storing them in the freezer for my miso soup.

Simple Miso Soup

I recommend watching a video tutorial for the basics of making miso soup. This will help you understand how to create your own miso soup using locally available ingredients. The only essential Japanese components you’ll require are dashi, miso and the strainer.

For those leading busy lives, instant miso soup and freeze-dried miso soup can be readily purchased in most Japanese supermarkets and convenience stores.

Photo by author

Important Things to Know

  • Add the miso paste to the soup stock just before serving. You can prepare the ingredients beforehand but wait until you’re about to serve the soup to include the miso paste. Avoid boiling miso soup once the miso is added, as this can result in the loss of nutrients, flavors, and aromas.
  • Avoid adding miso directly into the soup, as it may not dissolve properly resulting in miso chunks. Instead, place miso into a soup ladle. Gradually pour the dashi into the ladle and stir the miso mixture with chopsticks, until it dissolved. Consider using a miso strainer which is more convenient.

How to Drink Miso Soup

READ MORE 本物の味噌ってなに?選び方や体にいいおすすめの無添加味噌も! (kakakunara.com)

In contrast to Western customs, miso soup is typically enjoyed directly from the bowl, akin to sipping from a cup. Use your chopsticks to partake in the contents, much like you would when eating rice. When sipping the soup, cradle the bowl with both hands. For those who are right-handed, use your left hand beneath the bowl and your right hand on its side while drinking.

I’m just a humble fan who loves all things Japanese and hopes to bring a little bit of that love to you. Arigatou gozaimasu!

*This story contains affiliate links

味噌のこと|マルコメ (marukome.co.jp)
みそ(味噌)を知る | イチビキ 公式サイト (ichibiki.co.jp)
本物の味噌ってなに?選び方や体にいいおすすめの無添加味噌も! (kakakunara.com)
米味噌とはどんな味噌?特徴やおすすめレシピをご紹介 | DELISH KITCHEN
味噌のきほん|発酵調味料|みんなの発酵BLEND (hakko-blend.com)
味噌 — Wikipedia

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Mika Oka

Sharing her unique perspective on the world as a hearing-impaired autistic person with bipolar disorder despite the challenges. emikaoka.wordpress.com/home/