Can you eat miso paste raw?

In this brief guide, we will answer the question, “Can you eat miso paste raw?”. We will also elaborate on the different types of miso, the health benefits of miso paste and some ways to use miso paste.

Can you eat miso paste raw?

Yes, you can eat miso paste raw. Miso paste can be used straight from the container and does not require further cooking. It is a simple fermented paste that provides an umami flavor to everything from marinades to sweet dishes. The earliest form of miso called kokusho (soybeans and grains fermented with salt) is said to have originated from ancient China or perhaps in Japan thousands of years ago (1).

You can take a tablespoonful and add it directly to salads, soups and sauces without cooking. The most typical use of miso in Japanese cuisine is miso soup. Seasonal ingredients (vegetables, seaweed, and seafood) are cooked in dashi soup stock made from dried bonito, dried kelp, or other flavoring ingredients, and a spoonful of miso paste is dissolved in the soup (1).

As miso paste is a cultured product, the best way is to add it to hot dishes once they are cooked. Heat will destroy the bacteria present in the miso paste. 

Miso paste 

Miso paste is a semi-viscous paste produced by fermenting cooked soybeans with a starter known as “malt.” The malt is produced mainly by a bacteria named Aspergillus, which is cultured on soybeans, rice, or barley grains. 

Miso pastes are also produced from cultured wheat or millet, or mixtures of various grains and beans. The color is a quite good indicator of the potency of flavor. The consistency can vary, also. Miso produced from whole grain is generally more saltish than that produced from a hulled grain.

The taste of miso is governed by peptides, amino acids, and glucose, which are resolved from protein and starch by enzymes of the fungus koji and yeast. Studies have reported that the aroma components in miso are formed by microbes, especially yeast, during the long period of aging and fermentation and that these components are the most important. One such component is 4-hydroxy-2(or 5)-ethyl-5(or 2)-methyl-3(2H)-furanone, with a sweet caramel-like aroma (2).

Different varieties of miso

Miso can be white, yellow, barley, or red. The most typical variety of miso is produced from just soybeans, but the type and percentage of raw ingredients can differ. Rice miso is made from rice, soybeans, and salt. Rice is first fermented with koji mold to produce koji, which is then used for the fermentation and maturation of soybeans. Barley miso is produced in much the same way, except that barley or naked barley is used instead of rice. Soybean miso is made from soybeans and salt using soybean koji for fermentation and maturation. Mixed miso can be any combination of rice, barley, and/or soybean miso or any miso produced using a mixture of rice, barley, and/or soybean koji (1).

White miso 

It is produced from soybeans and rice and is fermented for a maximum of 2 months. White miso is white in color and is sweet to mildly salted. It is very versatile; can be added to salads and fried vegetables.

Fermentation and maturation are greatly affected by the enzymatic activities of koji and temperature of miso. For miso production based on both enzymatic and microbial activities, the temperature is maintained between 25 and 30 °C. The length of the maturation period is determined by what type of miso produced and varies from 1 month to years (1).

Yellow miso

Yellow miso is fermented for a little more time as compared to white miso. It is mild and very versatile. This miso uses higher percentages of koji, and they are sweeter and lower in salt (5 to 7%). The maturation takes place solely through koji enzyme activities and completes within a matter of several days at around 50 °C of controlled temperature (high-temperature digestion) (1).

Red miso 

Red miso is reddish-brown in color, produced from a greater ratio of soybeans, fermented for around 3 years and more saltish and deeper in flavor. It is most suitable to use in dishes like casseroles and tomato sauces. Red salty rice miso and thin-colored salty rice miso are generally aged for about 12 and 6 months, respectively, but weak salty rice miso is aged for about 20 days (2).

Barley miso 

It is produced from barley and soybeans. It usually has a more extended fermentation as compared to white miso. It has a powerful barley scent but is still mild and a little sweet in flavor.

Because barley absorbs water very quickly, the optimal soaking time is defined for each water temperature. During soaking, barley grains swell and form hard and tight clumps that must be loosened. The barley koji making process is similar to that of rice koji except that the higher protein content of barley makes it more susceptible to bacterial contamination, higher exothermic temperature, and clumping of koji (1).

The nutritional profile of miso

Matured miso is rich in free glutamic acid, arginine, lysine, and leucine. Carbohydrates in miso are mostly starches from rice and also include polysaccharides such as arabinogalactan from soybeans. The nutritional profile of miso paste varies according to the type, due to the ingredients used. Soybean miso contains greater amounts of proteins than rice miso. Salt also varies and red salty miso contains the highest amounts (13 g in 100 g). A 15 g serving of miso provides, in average (1):

• Calories: 30
• Protein: 2 g 
• Fat: 0.9 g 
• Carbohydrate: 3.5 g 
• Iron: 0.63 mg 
• Zinc: 0.49 mg 
• Folate: 5 mcg 
• Salt: 1.37 g 

The benefits of miso paste

Supports gut health

The process of fermentation that occurs during the manufacturing of miso boosts the growth of healthy bacteria, called probiotics. These bacteria improve a variety of health problems, that include digestion and gastrointestinal health.

A recent study isolated a novel probiotic yeast (Zygosaccharomyces sapae strain I-6) from miso and e examined its effects on phenotypic changes in intestinal dendritic cells, and evaluated its anti-inflammatory effects in dextran sulfate sodium (DSS)-induced colitis. The results showed that this probiotic yeast could significantly reduce the inflammation of the intestinal cells, which could indicate the probiotic effect of miso paste (3).

Reduces the risk of certain cancers

Frequent miso intake reduces the risk of cancers, such as breast cancer, particularly in post-menopausal females. 

Miso also provides a good source of antioxidants which may also help in preventing certain cancers.

Soybeans contain isoflavones, and miso contains the biologically active aglycone forms genistein and daidzein. Genistein and daidzein may lower cholesterol and reduce the risk of breast and prostate cancers (4).

Promotes vitamin levels

It has been found that the healthy bacteria in the gut produce vitamins (mainly vitamins K and vitamin B-12) as a by-product of the metabolic process. This suggests that by improving the proportion of the gut microorganisms via the consumption of fermented foods, an indirect advantage may be improved nutritional quality.

Fermented foods also decrease toxins and anti-nutrients, like phytic acid concentration of the soybeans in miso.

In addition, although the mineral potassium is present in high quantities in soybeans, and it has been found to decrease during fermentation, miso is still considered a good source containing between 0.2 and 0.44 g/100 g. Evidence has shown that increased potassium intake reduces blood pressure and is associated with a lower incidence of stroke (4).

Enhances immune function

Being a good source of probiotic bacteria, miso supports the immune process and helps combat infections. Regular consumption of a number of fermented foods including miso may reduce the demand for antibiotic treatment when combating infection. 

Recent study discovered that an anti-bacterial metabolite produced by lactic acid bacteria in some fermented foods was able to bind to specific receptors on the surface of cells and signal the human immune system. This finding suggests that metabolites produced by microorganisms in fermented foods may be one of the ways that fermented foods provide a health benefit (4).

Supports brain health

The consumption of fermented foods has been found to improve cognitive health, which also includes anxiety and depression.

Different ways to use miso paste

Miso paste can be directly added to a variety of dishes: 

• Spread some white miso paste over grilled corn on the cob
• Add a spoonful to stir fry
• Skip the salt and mix into your favorite salad dressing 
• Mix in sauteed vegetables i.e., mushrooms, onions, and greens
• Stir some in mashed potatoes or mashed cauliflower

How to store miso?

When purchasing miso, prefer the enzyme-rich, unpasteurised, live product that will require to be kept in the refrigerator. This variety is packed with beneficial microorganisms. 

After it is opened, the consistency, color and flavor may be modified, so keep a look at it. Some can be stored for a pretty long period without any worries.

Conclusion

In this brief guide, we have provided an answer to the question, “Can you eat miso paste raw?”. We have also elaborated on the different types of miso, the health benefits of miso paste and some ways to use miso paste.

References

1. Kusumoto K-I, Yamagata Y, Tazawa R, Kitagawa M, Kato T, Isobe K, Kashiwagi Y. Japanese Traditional Miso and Koji Making. Journal of Fungi. 2021; 7(7):579. 
2. Ohata, Motoko, et al. Quantification and odor contribution of 2-furanmethanethiol in different types of fermented soybean paste miso. J agric food chem, 2009, 57, 2481-2485.
3. Okada, Y., Tsuzuki, Y., Sugihara, N. et al. Novel probiotic yeast from Miso promotes regulatory dendritic cell IL-10 production and attenuates DSS-induced colitis in mice. J Gastroenterol, 2021, 56, 829–842. 
4. Allwood, Joanne G., Lara T. Wakeling, and David C. Bean. Fermentation and the microbial community of Japanese koji and miso: A review. J Food Sci, 2021, 86, 2194-2207.