Kikkoman Corporation

In this final installment in our series on the five internationally recognized flavors— sweet, salty, sour, bitter and umami—we take a closer look at umami, arguably the most complex of these, and certainly the one which is most definitive of Japanese cuisine.

The majority of dishes in Japanese cooking are based on dashi, soup stock made from konbu (dried kelp), katsuobushi (dried bonito flakes), niboshi (dried sardines) and hoshi-shiitake (dried shiitake mushrooms), and flavored with soy sauce, miso and other seasonings. Japan's tradition of making soups based on the subtle flavors of these ingredients goes back more than half a millennium, and it is these ingredients that are at the heart of umami.

The Discovery of Umami

About 100 years ago, scientists discovered that the subtle flavor of stock made with konbu derives from an amino acid called glutamine. This flavor was given the Japanese term umami, meaning "savory." Later, it was found that the essence of the flavor of katsuobushi is inosinate and that of dried shiitake is guanylate, both nucleic acids. In 1985, an international symposium on umami was held where scientific evidence was presented demonstrating that umami was the fifth basic taste, along with sweet, sour, bitter and salty. It was at this event that the Japanese word umami was accepted into the international vocabulary of taste. The taste buds that detect umami are found at the back of the tongue.

Katsuobushi and Dashi Stock

The custom of using thin shavings of katsuobushi is unique to Japan. Dried katsuobushi, made from cuts of bonito meat, is one of the hardest foods in the world. Its flavor is well-preserved within its hardened blocks and can be maintained for a very long time. Dashi made with katsuobushi flakes is made up of more than 40 nutrients, including inosinate, glutamin, peptides, sugar and organic acids. A high peptide content is said to give body or depth to a soup. The nutrients of all these ingredients are more soluble in soft water than in hard water. Dashi is therefore a complex blend of individual flavors including umami, saltiness, sourness and bitterness, and it is this intermingling that brings out its unique depth and mellowness.

Most Japanese restaurants use broths called ichiban (first) dashi or niban (second) dashi made from konbu and the dried shavings of either bonito or tuna. The konbu is steeped for 30-60 minutes in a pot of water, after which it is placed over high heat and then removed just before the water comes to a boil. Katsuobushi flakes are added immediately after turning off the heat and the liquid promptly strained.

This is ichiban dashi: the glutamin of the konbu and the inosinate of the katsuobushi combine to strengthen the umami seven to eight times, creating a fine, aromatic soup without discordant flavors. With the addition of light color soy sauce, salt and sake, ichiban dashi is used to make clear soups; seasoned with soy sauce and other ingredients, it is the basis for chawan-mushi custard and dashimaki-tamago, layered dashi omelet, as well as for dipping sauce for soba noodles.

Niban dashi is made using the same konbu and katsuobushi that were removed in making ichiban dashi. Placed in water and brought to a boil, this stock is simmered for 10 minutes, then the liquid is strained. This broth possesses ample umami drawn from the essences and amino acids remaining in the ingredients, but the aromas of the konbu and katsuobushi themselves become much stronger, so this dashi is more suitable for strongly flavored dishes such as miso soup, simmered vegetables and udon soup.

The flavor of these dashi soup stocks is enhanced further by adding soy sauce. The salt element in the soy sauce strengthens the umami taste. Standard examples of dishes made with stock seasoned with soy sauce are kabocha no fukumeni (simmered Japanese pumpkin), chikuzen ni (boiled chicken with vegetables) and niku-jaga (simmered meat and potatoes).

Healthy Dashi

Soup stock can also be made using niboshi or dried boiled fish. Niboshi are made by washing small fish, boiling them in salt water of about the same salinity as sea water and then drying them. Compared to katsuobushi, broth made with niboshi has a fishier flavor. The most popular type of niboshi are katakuchi-iwashi (anchovy), which are high in fat. Dashi made with these has a pronounced aroma of fish, and is commonly used for noodle broth and miso soup broth. Niboshi are not used solely to make broth, but are always used as an additional ingredient to augment the flavors of konbu and katsuobushi.

In Japan's Buddhist-inspired shojin ryori (vegetarian cuisine), stock is made mainly from konbu, but other ingredients include dried shiitake mushrooms or soybeans, dried gourd rind or the dried peels of vegetables. The dashi made from these ingredients is much thinner than that made from katsuobushi, so rather than using just a single ingredient, a number of them are boiled together to create a complex umami.

Some experts believe that dashi made with katsuobushi fights fatigue and stress. Certainly, given its capacity to bring out the inherent flavor of ingredients, dashi has many healthy merits in contrast to high-calorie flavorings such as butter and cream, and for this reason, dishes that reveal Japan's traditional and delicious umami are becoming more popular in the West.

Author's Profile

Takashi Yamamoto was born in Fukui Prefecture in 1944. He graduated from the Osaka University School of Dentistry. He taught at the Faculty of Dentistry at the university from 1972 -1991. Since April 1991 he has held a professorship at the Faculty of Human Sciences there. A specialist in brain science and the physiology of taste, Dr. Yamamoto is currently engaged in research on the mechanisms of taste and eating preferences.