Dashi is basically the backbone of Japanese cooking—the foundation that holds up so many dishes. Think of it as the BASE, that you find in everything from miso soup and ramen, to udon, soba, and simmered veggies. It’s impossible to imagine Japanese food without dashi. Honestly, when I’m walking around Tokyo, I can sometimes smell it wafting out of tiny izakayas or corner fish shops, and it just feels like a comforting hug in the air. My Japanese husband always says something like, “Oh, this dashi is so good,” before happily slurping his soba noodles.

This got me curious: what’s dashi to start with and what is behind that comforting flavor, scientifically speaking?

The name “dashi” (出汁) literally means “the soup that comes out,” and it’s known for delivering that mysterious fifth taste—umami. People talk about umami all the time now, but it was actually discovered by a Japanese doctor, Kikunae Ikeda, back in 1908. He found that the key substance in kombu kelp was glutamic acid, which gives that deeply savory taste. From that moment on, umami became recognized around the world, and we learned that other foods—like tomatoes, Parmesan cheese, and certain other veggies—also have high levels of glutamic acid. It turns out, that signature “comfort taste” isn’t just in Japan; it’s a global flavor.

The Origin of Dashi

The origins of dashi date back to Japan’s ancient Jomon period (roughly 14,000–300 BCE), when people first began using earthenware pots and fire to cook. They boiled ingredients like nuts, fruits, mushrooms, fish, shellfish, and game meat until softened, and in the process discovered that the resulting cooking liquid added depth and flavor to their meals. This realization—where the flavors extracted from various ingredients transformed simple water into something richer—is believed to have planted the very first seeds of what would eventually become dashi stock.

Later, during the Kamakura period (1185–1333), a written reference to what may have been an early form of dashi appears in the text “Chuujiruiki” (中汁記). The mention of “tashi soup” suggests that by this time, a recognizable concept of extracting savory essence from ingredients had taken hold. Over centuries, the practice became more refined, eventually evolving into the modern form of dashi we know today—an indispensable, umami-rich base that underpins the entire landscape of Japanese cuisine.

By the Edo period (1603–1868), references to “dashi” were common in culinary writings. Ryori Monogatari, Japan’s first practical cookbook, even mentions a “second dashi,” showing that cooks were refining their techniques. Kelp (konbu) was clearly noted as a key ingredient at this time. Although konbu and dried bonito first appeared in Nara period documents, they were only recorded as offerings to the Imperial Court, not as cooking ingredients. By the Edo era, though, both konbu and bonito were firmly established as essential elements of dashi-making.

Kombu Road Hokkaido -> Osaka

Regional differences in dashi production naturally emerged due to the variety of local ingredients. The dashi used in Hokkaido differs from that in Osaka, Tokyo, and Okinawa.

During the Edo period (1603–1868), the development of Hokkaido (then called Ezo) and the rise in kelp production led to new uses for kelp. Surrounded by oceans, Hokkaido became a major kelp supplier. In the latter half of the 17th century, Edo merchant Kawamura Zuiken established the Nishikigoi route( as seen in the photo), an extension of the Kitamae-bune shipping network, which transported kelp and seafood from Ezo to Kyoto, Osaka, and eventually Edo. This distribution network became known as the "Kombu Road", spreading kelp consumption throughout Edo, Kyushu, and the Ryukyu Islands.

As dashi grew more popular, regional differences solidified. In Kansai (Osaka, Kyoto), kelp became the main dashi ingredient, while in Kanto (Tokyo), bonito flakes (katsuobushi) took center stage. Two key factors explain this difference. First, the distribution process of kelp: since higher-quality kelp was sold early in Osaka, leftover kelp was sent to Edo, resulting in limited use of premium kelp in the Kanto region. Second, water quality played a role. Kansai's soft water (low mineral content) is ideal for extracting flavor from kelp, while Kanto’s harder water made it more difficult to draw out the umami, leading to the preference for bonito-based dashi.

These regional distinctions in dashi flavors were established during the Edo period, when large-scale cargo transportation connected Japan’s regions, enabling local tastes and cooking techniques to evolve in unique ways.

Types of Dashi

These are the main types of dashi found in the Japanese Cuisine. Each of the below can be used alone or in combination, but since each has a unique taste profile, they are considered distinct types of dashi.

1. Katsuobushi (dried bonito flakes)
   
   Katsuobushi, or dried bonito flakes the one dancing on top of the takoyaki as many have seen, is one of the essential ingredients for making dashi stock. It’s made by salting, drying, and fermenting bonito fish, then shaping it into a hard, wood-like block, which is later shaved into thin flakes.
   

   

   Katsuo dashi is believed to have originated in the Muromachi period (1400s).The first written record of "katsuobushi" appears in the "Tanegashima Kafu" (1513), a genealogical record of the Tanegashima clan, who ruled what is now Kagoshima Prefecture. This is significant since Kagoshima, particularly Makurazaki City and Ibusuki City, remains Japan's top producer of katsuobushi today. The appearance of "katsuobushi" in a document from Kagoshima reinforces the idea that katsuo dashi had been used in Japan since the 1400s.

   Compared to shiitake mushroom dashi and kelp (kombu) dashi, katsuobushi dashi was developed later because its production required more advanced processing techniques, like drying, smoking, and fermentation.

1. Kombu (Kombu Dashi)
   
   Kombu is a type of edible seaweed (kelp) that is rich in glutamic acid, a key component of umami flavor. Is believed to have originated between the Kamakura (1185-1333) and Muromachi (1336-1573) periods, with the earliest documented reference appearing in "Teikin Orai", written in the late 1300s. This educational text, widely used in temple schools during the Edo period, includes a reference to makonbu from Uga (near modern-day Hakodate, Hokkaido), which was valued as a dashi ingredient and was particularly popular in Kyoto. Since "Teikin Orai" was written in the late 1300s, it's believed that kombu dashi was already in use by the early 1300s.

   The waters off Hokkaido, Japan's northernmost island, provide the ideal environment for kombu cultivation. Cold water, shallow depths (5-8 meters), and nutrient-rich conditions allow kombu to thrive. It takes about two years for kombu to mature for harvest, which occurs between July and September, with harvesting dates set annually. Harvesters traditionally use long wooden poles with hooks to detach the kombu from the seabed. Once harvested, kombu is laid on rocks to sun-dry. On a hot summer day, drying can be completed within 4 to 5 hours. After drying, the kombu is taken indoors, where its shape is adjusted, and it’s prepared for shipment. Some kombu is also subjected to a process called kuragakoi (cellar conservation), where it is stored to enhance its flavor and reduce its distinctive seaweed odor. This maturation process produces kombu with deeper umami and a smoother taste.

   

   Types of Kombu
   There are five main types of kombu, all produced in different areas of Hokkaido:

   1. Rishiri Kombu – Clean, refined flavor; often used for high-end kaiseki cuisine.

   2. Rausu Kombu – Rich, bold umami flavor; used for flavorful soups and stews.

   3. Naga Kombu – Thick, robust kombu; used for everyday home cooking.

   4. Hidaka Kombu – Softer and easier to cook; used in home-cooked dishes, simmered foods, and rolls (kobumaki).

   5. Makonbu – The most highly regarded kombu; produces a clear, refined dashi, especially popular in Kyoto cuisine.
      

   

2. Shiitake mushrooms (Shiitake dashi)
   
   Shiitake dashi is made from dried shiitake mushrooms, which contain guanylic acid, a powerful umami component. This guanylic acid works synergistically with the glutamic acid found in other dashi ingredients like kombu, resulting in a more intense umami flavor. This combination is often used to create a rich, savory broth for plant-based dishes.
   
   The origins of shiitake dashi can be traced back to the Kamakura period (1185–1333). The earliest known reference appears in "Tenzo Kyokun" (1237), written by Dogen, a monk who founded the Soto sect of Zen Buddhism. While in China, Dogen encountered a Tenzo (a Zen temple cook) from Sichuan province who asked, “Do you have any shiitake mushrooms on board?” This moment highlights the knowledge that shiitake mushrooms could be used to make a flavorful dashi.

   When Dogen returned to Japan, he brought back not only Zen Buddhist teachings but also new culinary methods from Chinese temple cuisine, which became the foundation for shojin ryori (Buddhist vegetarian cuisine). Since monks avoided meat, they relied on dashi made from plant-based ingredients like shiitake mushrooms and kombu to create rich, savory flavors that could mimic the taste of meat. While the events in "Tenzo Kyokun" occurred in 1237, it's believed that shiitake dashi became established in Japan later, around the mid-1200s.
   
   Shiitake dashi is a versatile stock that enhances the flavor of many Japanese dishes, including: Clear soups (osuimono), Simmered dishes (nimono), Udon and soba noodles and Chawanmushi (savory egg custard). Since shojin ryori prohibits the use of meat or fish, shiitake dashi became an essential element in temple cuisine, where it was used to add richness and depth to simple vegetable-based dishes.

The Umami Science Behind Dashi

In 1908, Japanese chemist Kikunae Ikeda discovered umami, the fifth taste alongside sweetness, sourness, saltiness, and bitterness. His research on kombu (kelp) revealed that its savory flavor came from glutamic acid, leading to the creation of Ajinomoto (MSG) as an affordable seasoning to improve nutrition. Inspired by Dr. Miyake Hiizu’s paper on umami’s role in digestion, Ikeda aimed to create a widely accessible umami seasoning.

In 1913, Ikeda’s student, Dr. Shintaro Kodama, discovered that inosinic acid was the umami compound in bonito (katsuobushi). Due to production challenges and Kodama's early death in 1923, inosinic acid wasn't commercialized until the 1960s. Around the same time, Dr. Akira Kuninaka of Yamasa Research Institute identified guanylic acid as the umami compound in shiitake mushrooms. These three components — glutamic acid (kombu), inosinic acid (bonito), and guanylic acid (shiitake mushrooms) — became known as the three major umami components.

A key discovery was the synergistic effect, where combining umami compounds (like glutamic and inosinic acids) produced a much stronger taste. This concept, long known to chefs, was later scientifically confirmed. The discovery of umami receptors on the tongue further validated umami as a distinct taste. Today, umami is a global culinary concept, present in cookbooks, chemistry texts, and kitchens worldwide.

References

1. Traveling Food Lab - The Story of Dashi

2. Mizu Style - Understanding Dashi

3. Ninben Blog - The Essence of Dashi

4. Umami Info - What is Dashi?

5. Noriben Haretoke - Exploring the World of Dashi

6. Hyoutan Kyoto - Differences in Kanto and Kansai Dashi