Science, Soup, and the Search for the Fifth Taste

Japanese soups are based on a stock called dashi, which is a very simple, clear broth. It is made by extracting the taste substances from a particular species of brown macroalgae, konbu, and flakes of fish that have been cooked, salted, dried, fermented, and smoked, known as katsuobushi. Dashi is rich in umami and is a ubiquitous, indispensable element that is central to all traditional Japanese cuisine.

Professor Ikeda’s hypothesis was that the soup must contain a substance that imparted a taste that could not be explained away as a combination of the four common basic tastes. So he set to work on the very labor-intensive, and at times probably very tedious, process of making a chemical analysis of all the ingredients found in an aqueous extract of konbu (Saccharina japonica), a species of kelp. He started with 12 kilograms of the seaweed, basically working on his own with a single laboratory assistant.