Dried Shiitake mushroom




Frequently asked questions and answers

Table of Contents

Basic Information about Dried Shiitake Mushrooms

Q1.What are dried shiitake mushrooms?

Dried shiitake mushrooms are fresh shiitake mushrooms that have been dried. There are ones like those from China that are dried from shiitake mushrooms grown on sawdust and ones like those from Japan that are grown on natural logs. Although they may look similar, there is a difference between naturally grown dried shiitake mushrooms which are delicious and those that are artificially cultivated which are less tasty and less healthy.

Q2.What is the difference between dried shiitake mushrooms and fresh ones?

Dried shiitake mushrooms contain Guanylate, a Umami enhancer, which is not present in fresh shiitake mushrooms. This acid enhances the flavor of other ingredients. Drying fresh shiitake mushrooms causes their cell cores to break down. When rehydrated, the RNA inside the cores reacts with external enzymes to create Guanylate.

Q3.How much do dried shiitake mushrooms expand when rehydrated?

The size increases approximately 1.3 times, and the weight increases by about 5 times.

Q4.How are dried shiitake mushrooms grown?

In Japan, about 90% of dried shiitake mushrooms are grown on natural logs. About 70% of the country's dried shiitake mushrooms are produced in the three prefectures of Oita, Miyazaki, and Kumamoto. As log-grown shiitake mushrooms are generally cultivated without pesticides and are very perishable, producers dry them within half a day of harvesting.

Q5.What types of dried shiitake mushrooms are there?

According to the Shiitake Quality Labeling Standards (MAFF), there are mainly two types: "Donko", which are harvested before their caps have fully opened, and "Koshin", which are harvested after their caps have opened.

Q6.What is the difference between "Donko" and "Koshin"?

Donko are shiitake mushrooms harvested in a bud-like state, thick, meatier, and chewy. Koshin are shiitake mushrooms harvested after their caps have expanded, and they are characterized by a large diameter and thin leaves, making them easy to cut to match other ingredients and to rehydrate quickly.

Q7.How many types of dried shiitake mushrooms are there? Why are their prices different?

Depending on the degree of cap opening at the time of harvest, there are Donko and Koshin, which are further divided into large caps, medium caps, and small caps based on their cap diameter. In addition, there are particularly premium shiitake mushrooms such as "Hana Donko". To achieve a large cap diameter, it is necessary for the log to be large or fresh and rich in nutrients. Therefore, Donko with large caps are the most flavorful and chewy, and thus the most delicious shiitake mushrooms. They are also the most expensive. And if grown naturally also more expensive.

Q8.What is Hana Donko?

During the growth process of shiitake mushrooms, if the surface of the mushroom is not directly rained upon and dries and cracks as it grows, it becomes a Hana Donko Shiitake. If water does not directly fall on the shiitake, until the harvest, the cracked part remains white like a flower, and it is called "Hana Donko" or "Tenpaku Donko". Since they grow with less water, they have an excellent texture, and when sliced, they have a texture similar to abalone, making them top-quality.

Q9.What is the difference between forest-grown shiitake mushrooms and sawdust-grown ones?

Forest-grown shiitake mushrooms are cultivated outdoors on natural logs from trees like oak, while sawdust-grown shiitake mushrooms are grown indoors on beds made from sawdust mixed with nutrients. Although they may look similar, they differ in taste and texture, not to mention health concerns. For example, when comparing shiitake mushrooms from the same Kyushu region, the forest-grown shiitake mushrooms contain about twice as much Glutamate, a component of umami taste, and about six times more Guanylate, which amplifies the Umami of other ingredients, than sawdust-grown ones.

Q10.Are there different types of shiitake spores/spawn?

There are 5-6 main types used according to their germination temperature. Larger producers tend to use multiple types of spores to spread out the harvest time.

Q11.Aren't all shiitake mushrooms the same, no matter where they're sourced?

Differences in cultivation methods, local climates, types of logs used, and drying methods can all create differences in flavor. When producer traceability cannot be established, the taste and consistency cannot be guaranteed.

Q12.Why can the flavor of each dried shiitake mushroom differ in the same package?

If you consider "made in Japan" as a region, shiitake mushrooms from a wide range of production areas, such as Tohoku, Shizuoka, Shikoku, and Kyushu, are selected for the same shape and size, and they all go into the same bag. This is why the flavor of each shiitake mushroom differs. Kyushu is recommended because about 90% of the logs are from Japanese Sweet Oak (Kunugi) trees, considered the best for Shiitake.

Q13.Is the primary season for dried shiitake mushrooms in autumn?

In the case of log-cultivated dried shiitake mushrooms, about 80% of the annual harvest is in the spring. Since the temperature at harvest time is lower in spring than in fall, better and more thick "donko" can be harvested.

Q14.Where do the logs come from?

In Kyushu, Japanese Sweet Oak, Kunugi trees are abundant, so all the logs are secured within Kyushu. Kunugi Oak is considered the best for premium tasting and textured shiitake.

Drying Method of Dried Shiitake Mushrooms

Q1.Is your dried shiitake mushroom sun-dried?

The producers dry the mushrooms with hot air, and then, at the factory, they are further dried using far infrared drying and exposed to ultraviolet light. Historically, mushrooms were dried at high temperatures in the producing areas using firewood or charcoal. After this, they were sun-dried in the summer sunlight following the rainy season. However, due to the inconsistency of natural ultraviolet light from the sun due to weather conditions and the problem of foreign material contamination, we switched to exposing them to ultraviolet light in the factory. Also, the most important factor in the quality of dried shiitake mushrooms is to reduce the moisture content. If they absorb moisture, they have less flavor and softer texture. In our company, we further dry the mushrooms in the factory using far infrared rays to reduce the moisture content to below 9% for shipment (others usually around 12%).

Q2.How do the producers dry the shiitake mushrooms?

Log-cultivated shiitake mushrooms are completely grown without pesticides and do not keep well, so they must be dried with hot air immediately after harvesting (at 40-55°C for about 20 hours). Any other harvested shiitake mushrooms will spoil if the dryer is full, so they gather just enough to fill their dryers. This is why log-cultivated shiitake mushrooms come in various shapes and sizes. However, freshly picked and quickly dried natural shiitake at high temperatures become the most delicious mushrooms.

Q3.Wasn't it sun-dried in the past?

It is a common misconception that until recently, sun-drying was the method used to dry shiitake mushrooms. Sun drying has a disadvantage in that it is not tasty because it dries at low temperatures. Log-cultivated shiitake mushrooms easily go bad after harvesting, and the quality will gradually deteriorate if they are slowly dried in the sun. Although the strong sunlight in midsummer is good, the sunlight in spring and autumn, which is the spring harvest season, is weak and unsuitable for sun drying. However, until poly bags became available in recent years, it was difficult to store dried shiitake mushrooms for a long time, and sun-drying was necessary after the rainy season to maintain the dried state. In other words, it was not sun-drying at the production site but at the consumption site. In this case, it makes the most sense to sun-dry in the strong sunlight of midsummer, and this is written in the bible of vegan cuisine, "Tenzo Kyokun".

Q4.How can we sun-dry shiitake at home?

When the UV index (which is reported daily by the Japanese Meteorological Agency) is "strong" at 6 or more, it is the best time to dry in the sun. At this time, sun drying for even 1 hour is sufficient. Always take them out of the bag and arrange the mushrooms on a wire rack or something similar, allowing maximum air circulation so they do not overlap, with the underside of the mushroom cap facing up. The more the mushrooms are exposed to ultraviolet rays, the whiter the bottom of the mushroom cap becomes, which means that natural vitamin D has greatly increased. Once they have dried out completely, let them cool down by taking them to a well-ventilated place to remove the built-up heat, then put them in a bag or airtight container.

How to Choose and Purchase Dried Shiitake Mushrooms

Q1.Can you teach me how to choose good dried shiitake mushrooms?

Dried shiitake mushrooms with a bright yellow underside, thick, weighty, and hard with dry caps are the freshest and tastiest.

Q2.Why does the shiitake I bought smell more mushroomy than usual?

When they absorb moisture, they become a bit soft and start to smell fishy. If they absorb more moisture, the underside turns reddish-brown, and mold may grow.

Q3.How can I choose tasty dried shiitake mushrooms at the store?

Choose mushrooms in which each piece is heavy and has a full body and volume. Therefore, when you pick up a bag at the store, the bag with the least total volume and fewer pieces inside will likely contain the tastiest shiitake mushrooms.

Nutritional and Health Benefits of Dried Shiitake Mushrooms

Q1.What are the nutritional components of dried shiitake mushrooms?

You can find detailed information on the nutritional components of dried shiitake mushrooms on the website of the Ministry of Education, Culture, Sports, Science and Technology in Japan. Website


Q2.What are the health benefits of dried shiitake mushrooms?

The Five Major Benefits of Dried Shiitake Mushrooms (Shiitake Powder)


Q3.How do the nutritional components of dried shiitake mushrooms differ from those of fresh ones?

The cultivation methods for dried and fresh shiitake mushrooms greatly differ. In Japan, about 90% of dried shiitake is grown on logs, while about 90% of fresh shiitake is grown indoors on mushroom beds. When comparing the edible part per 100g of fresh (mushroom bed) and dried (log-grown) shiitake mushrooms on the Ministry of Education, Culture, Sports, Science and Technology's food composition database, it's evident that dried shiitake mushrooms are richer in amino acids. Particularly, the amino acids found in greater quantities in dried shiitake are cystine (224%), total sulfur-containing amino acids (190%), methionine (159%), glutamic acid (142%), and aspartic acid (141%).

Q4.What vitamins and minerals are contained in abundance in dried shiitake mushrooms?

The vitamins and minerals that can be labeled as "rich" are as follows, in descending order of abundance per 100g of edible portion. (Dried shiitake mushrooms, boiled )
Total dietary fiber 6.7 g
Potassium 200 mg
Niacin equivalent 2.6 mg
Niacin 2.0 mg
Pantothenic acid 0.86 mg
Iron 0.5 mg
Vitamin B2 0.26 mg
Vitamin B6 0.07 mg
Copper 0.07 mg
Vitamin B1 0.05 mg
Folic acid 35 μg
Biotin 7.0 μg
Vitamin D 1.4 μg

As we mentioned above, we use UV light to dry all of our shiitake further, which greatly increases the vitamin D content as follows: Donko variety (34 μg), Koshin variety (48 μg), and shiitake powder (79 μg).

Q5.Are dried shiitake mushrooms rich in dietary fiber?

Yes, dried shiitake mushrooms can be considered rich in dietary fiber. For each 100g of the edible portion, the fiber content is as follows: soluble dietary fiber (0.5 g), insoluble dietary fiber (6.2 g), and total dietary fiber (6.7 g).

Q6.How many calories are there in dried shiitake mushrooms?

The caloric content of 100g of the edible portion is 40 kcal.

Q7.Are dried shiitake mushrooms suitable for diabetic patients?

Yes, dried shiitake mushrooms are beneficial for people with diabetes due to the effects of dietary fiber in slowing sugar absorption, the insulin-like effects of eritadenine, the action of β-glucans from the shiitake mycelium, antioxidant properties, support a healthy diet.

Q8.What is "guanylic acid" in dried shiitake mushrooms?

Guanylic acid in dried shiitake mushrooms has the effect of closing the umami receptors on your tongue, which allows you to feel the umami flavor for a longer and stronger duration. While glutamic acid is abundant in many foods, guanylic acid is found only in a limited number of foods, and most are contained in dried shiitake mushrooms.

Q9.Do dried shiitake mushrooms contain a lot of purines?

When rehydrated, dried shiitake mushrooms increase weight by approximately five times. Therefore, the purine content is about 75.9mg/100g when rehydrated. Compared to other foods, shiitake mushrooms have a relatively low purine content.

Purine content (mg/100g) as reported in The Gout & Uric Acid Foundation's website: Tuna - 157.4 Chicken (thigh) - 122.9 Mackerel - 122.1 Salmon - 119.8 Maitake mushrooms - 98.5 Buckwheat flour - 75.9 Dried shiitake (rehydrated) - 75.9 Pork (belly) - 75.8

Q10.Do dried shiitake mushrooms cause allergies?

One of the allergic reactions to shiitake mushrooms is shiitake dermatitis. This mainly occurs when undercooked fresh shiitake mushrooms, grown on mushroom beds, are consumed, resulting in intense itching and rash, primarily on the chest, abdomen, and back. Shiitake dermatitis does not occur if the mushrooms are thoroughly cooked. Despite drying our log-grown shiitake mushrooms under high heat using a ceramic panel infrared dryer, consuming the rehydration broth raw on a daily basis can cause shiitake dermatitis within about two weeks. Therefore, please consume shiitake mushrooms after cooking them properly.

How to store dried shiitake mushrooms

Q1.How can I store dried shiitake mushrooms?

Store them at room temperature in a low-humidity area, away from direct sunlight.

Q2.Do I need to store them in the refrigerator after opening?

Storing in the refrigerator can cause condensation due to temperature changes when taken out, leading to moisture absorption. Therefore, we recommend storing them in a sealed container at room temperature in a low-humidity area.

Q3.Is there a way to make dried shiitake mushrooms last longer?

Dried shiitake mushrooms can quickly lose their flavor when they absorb moisture. Occasionally drying them under strong sunlight reduces their moisture content and increases their vitamin D content, hitting two birds with one stone.

Q4.Is it OK to use wet but not fully rehydrated dried shiitake mushrooms?

We do not recommend it.

Q5.Can dried shiitake mushrooms be frozen?

Yes, they can be frozen. However, they are prone to absorbing moisture as they return to room temperature, so it is recommended to rehydrate them directly when defrosting and not defrost slowly, like in the refrigerator.

How to rehydrate and cook dried shiitake mushrooms

Q1.How can dried shiitake mushrooms be used in cooking?

They can be used in all kinds of cuisine including Japanese, Western, Chinese, Indian, Arabic, and more.

Q2.Can you give some tips or a specific method for rehydrating?

The Umami of dried shiitake mushrooms is maximized when rehydrated at a low temperature. Therefore, it is recommended to rehydrate them overnight in the refrigerator.

"Best way to rehydrate dried shiitake for maximum flavor"

Q3.What should I do if I want to use dried shiitake mushrooms quickly?

Cutting the mushrooms (especially Koshin Dried Shiitake) while rehydrating can make them ready to use faster and still taste delicious.

"Quick and easy rehydration for dried shiitake in 20 minutes!"

Q4.How can the soaking liquid from dried shiitake mushrooms be used?

It can be used as a secret ingredient in various dishes to enhance the natural flavors and amp uo the Umamik of other ingredients. The ideal amount of shiitake mushroom soaking liquid to use is 1 tablespoon per 250ml of soup stock. The key is to use it sparingly. Guanylic acid, a umami component of shiitake mushrooms, can become bitter when used excessively. Even when using a generous amount, it's recommended that the shiitake soaking liquid make up only 1/10 of other soup stocks, such as kelp or bonito. For instance, use 50ml of shiitake soaking liquid for 500ml of soup stock. You can use more for shiitake stews, but even then, limit it to a third of the total soup stock.

Q5.Please tell me how to cook dried shiitake mushrooms easily.

Here's a simple Japanese method to cook dried shiitake mushrooms (Shiitake Nimono).

Soak them overnight in cold water in the refrigerator. Strain the soaking liquid with a tea strainer, cut off the stems of the shiitake, and place them in a pot. Bring to a boil over high heat. After boiling, reduce the heat and simmer for 10 minutes. Skim off the scum, flavor with a little soy sauce, mirin (a sweat sake, or substitute with Japanese Sake + sugar) to taste and optional Katsuo Bushi (bonito flakes), and turn off the heat to cool.

Q6.How do cooking methods differ between dried and fresh shiitake mushrooms?

The method of cooking dried shiitake mushrooms differs from fresh ones. Dried shiitake has a distinctive umami flavor that can enhance various dishes. Additionally, the soaking liquid from dried shiitake makes an excellent broth, so add it to your other dishes to up the Umami. When grilling dried shiitake, they tend to become dry compared to fresh shiitake, so techniques like steaming in foil are necessary.

Q7.Please tell me how to preserve the rehydration juice (shiitake mushroom broth) from dried shiitake mushrooms.

I recommend freezing the shiitake soaking liquid (shiitake broth) to store and use when needed. Pour it into ice cube trays or freeze it in small portions for easy use. Its strong aroma might affect other foods, so use it sparingly to improve the flavor of your foods without adding a shiitake taste.

Q8.How do you cook dried shiitake mushroom soup?

Shiitake broth exhibits a synergistic effect when combined with the Umami of meat or seafood. Adding the broth from the initial cooking stage intensifies the Umami by up to 30 times.

Q9.What are some easy recipes using dried shiitake mushrooms?

For another simple recipe using dried shiitake, try cutting the rehydrated shiitake into bite-sized pieces, add butter, and wrap in foil to steam grill. The flavor and aroma differ from fresh shiitake.

"Foil-Grilled Shiitake"

Q10.What is your best recipe using dried shiitake mushrooms?

A recommended recipe for dried shiitake is "Chikuzen-ni," a Japanese simmered dish. Compared to making the same dish with fresh shiitake, the flavors becomes more deep and balanced thanks to the Umami from the dried shiitake.

"Chikuzenni," Simmered Chicken and Vegetables

Q11.Do you have a dessert recipe using dried shiitake mushrooms?

We recommend using dried shiitake mushrooms in desserts because the umami effect gives a long-lasting sweet aftertaste. For example, Haagen-Dazs and MOW are low in additives, so if you add 1/2 teaspoon of shiitake mushroom powder to one of these high-quality vanilla ice creams and mix well before eating, you will notice that the milk flavor is richer and the aftertaste is better. It doesn't taste like shiitake mushrooms.

Using Dried Shiitake?! Miraculous Vanilla Ice Cream

Q12.What are some common mistakes people make when cooking dried shiitake mushrooms?

A common mistake when cooking with dried shiitake is insufficient rehydration. It's best to rehydrate at as low a temperature as possible to maximize the release of guanylic acid, a flavor-enhancing compound. This prevents the full flavor of the dried shiitake from being released.

Q13.Where can I find recipes for cooking with dried shiitake mushrooms?

We recommend this site.


Q14.Can I add the dried shiitake mushrooms directly to the stew and cook for about an hour without letting them soak in water?

If you are cooking a stew and add dried shiitake directly without rehydrating them, the shiitake won't be as tasty. However, it's still fine for extracting broth. You can use the tough stem of the dried shiitake like a bay leaf and add it directly to the stew. While the stem isn't eaten when the dish is finished, the guanylic acid released from the shiitake stem enhances the Umami of the other ingredients in the stew.

Q15.How are the stems used?

Shiitake stems are rich in Umami and are best used by finely chopping them. Or you can make them easier to eat by splitting them along the fibers or slicing them thinly.

Q16.Why do shiitake mushrooms sometimes become bitter when cooked?

If you cook a lot of fine shiitake mushrooms, they may become bitter. The unique Umami of dried shiitake mushrooms, guanylic acid, is a nucleic acid-based umami component, so it can be perceived as a bitter taste when the Umami is concentrated.If it is bitter, you can dilute it. You can solve this problem by diluting it with water or mixing it with other broths.

Q17.Is the white foam that appears when shiitake mushrooms are cooked scum?

You can tell by tasting it, but the white foam contains a lot of Umami. 10 minutes of cooking over low heat will remove most of the foam, so it is OK to remove the foam that remains after 10 minutes.

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