What do soysauce and parmesan have in common ?
Flavour. The umami flavour, which was defined as the fifth basic flavour, along with sourness, bitterness, sweetness and saltiness.
The umami flavour occurs due to the presence of glutamic acid. Parmesan contains 1680 mg of glutamic acid for 100g of cheese. Soy sauce contains 782 mg for 100g (see table below).
The link between glutamate and the umami flavour was discovered by the Japanese chemist Kikunae Ikeda (1864-1936). Around the same time, the French chef Auguste Escoffier also discovered the tasty properties of glutamate, and gained success through a new sauce recipe: the renowed veal stock.
 
The fifth flavour
Democritus, Plato and Aristote were wrong. Man can definitely discern five flavours.
The gastronome Brillat-Savarin (1755-1826) used to mention an additional flavour he called « osmazome », which he linked to meat stocks. And when the French Chef Auguste Escoffier (1846-1935) created the aforementioned veal stock that upgraded so many dishes, he was simply condensing glutamate (2).
Nevertheless, umami was not acknowledged as the fifth flavour before the eighties, when science determined that the human tongue indeed had dedicated umami taste buds, as those for sweetness, saltiness, sourness and bitterness.
And it was only in the year 2000 that research finally proved that umami was due to the interaction between glutamic acid and these specific taste buds (3).
 
Best sources for the umami flavour
Food Glutamic acid (mg / 100g)

Cheese

Parmesan
Roquefort

1 680
1 280
Algae (kombu) 1608
Sauces
Fish sauce (nuoc mam)Soy sauce (shoyu)

1 370
782

Vegetables and fruits

Tomato
Green peas
Mushrooms (shiitake)
Vegetables (cabbage, asparagus, spinach)
Avocadoes

246
106
71
50
18
Seafood
Scallops
Crabs (Alaska)

140
72
Meats
Chicken
Beef

22
10
 
The discovery

In 1908, during a trip in Germany, Ikeda noticed some similarities between tomato, asparagus and cheese, all of them new to him, and the unique taste of dashi, an algae stock used in Japan to cook miso soup.

“Those who pay careful attention to their tastebuds will discover in the complex flavour of asparagus, tomatoes, cheese and meat, a common and yet absolutely singular taste which cannot be called sweet, or sour, or salty, or bitter…”
Dr. Kikunae Ikeda, Eighth International Congress of Applied Chemistry, Washington, 1912.

 

Dashi is prepared from the kombu seaweed, from which Ikeda managed to extract glutamic acid after lengthy examinations.  An amino acid, it was in fact discovered 40 years earlier by the German chemist K.H.L. Rithausen, who isolated it from wheat bran. Ikeda named it « umami », which means « tasty » in Japanese.

 

 
Glutamic acid

The umami flavour comes from the carboxylate anion of glutamic acid, a naturally occurring amino acid in protein-heavy foods like meat, cheese and mushrooms. For example, sweetness is connected to mono/disaccharides, thus leading us to starch-heavy foods; umami is connected to glutamic acid, leading us to protein-heavy foods.

The salts of glutamic acid, can be hydrolysed to produce glutamate ions. The glutamate, also known as E621, is a flavour enhancer commonly used to add the umami taste to other foods.

 

 
Umami et Koji
Soy sauce and miso soup are fermented foods in which the umami taste is strong. Fermentation is precisely what gives them this flavour, especially the Koji process.

The word « koji » both refers to the fungus Aspergillus oryzae, to the process of solid state fermentation, and to the fungus’s must, used in the traditional brewing of sake. Aspergillus oryzae produces a large diversity of enzymes: lipases, amylases and proteases. Some among the latter, release glutamic-acid  and cause the umami taste to be perceived.

(1)  Ikeda, K. (1909) New seasonings.J. Tokyo Chem. Soc. , 30,820 -836 [in Japanese].

(2)  Sweet, Sour, Salty, Bitter... and Umami, by Robert  Krulwich http://www.npr.org/templates/story/story.php?storyId=15819485

(3) Chaudhari, N., Landin, A.M. and Roper, S.D. (2000) A novel metabotropic glutamate receptor functions as a taste receptor. Nat. Neurosci., 3,113 -119

 

 
Further readings

Sweet, Sour, Salty, Bitter.. and Umami., Robert Krulwich.

NPR

The Discovery of Umami, Bernd Lindemann, Yoko Ogiwara and Yuzo Ninomiya

CHEMSE

UMAMI information center

UMAMI