In 1907, while enjoying a soup dish made with dashi broth and kombu seaweed, Japanese chemist Kikunae Ikeda had an idea that would change the culinary world. He noticed a taste that was not sweet, salty, sour or bitter. Ikeda gave a name to this tasty taste hard to describe: umami and identified the specific amino acid that triggered it.
Scientists in Europe and the United States remained skeptical about whether umami was really a taste until a receptor on the tongue was discovered nearly a century later, in 2000. Today, most scientists and cooks they take it for granted, but interest is now growing in another taste first detected in Japan.
The most recent taste, kokumi, is even harder to describe than umami, but it is potentially just as important in understanding how and why we enjoy food. In Japanese, the term koku describes foods that have the “thick” type of mouth often imparted by fats, which English speakers might call rich. “It feels like a physical sensation,” says culinary scientist Joshua Evans. It works “by covering the mouth and becoming more intense and expanding over time.” When asked what foods koku has, Japanese cuisine experts list wild boars, adult wasps, duck eggs and aged sake, as well as slow-fermented dishes.
Koku reflects a more touch-related sensory experience, influenced by aromas and textures. Adding the Japanese suffix -my, that is, taste, highlights the specific taste detected by the tongue. The precise nature of kokumi is still the subject of much debate among sensory scientists and cooks, in part because it cannot be detected on its own; rather, it modifies other tastes and flavors.
Early research on kokumi focused on the contribution of garlic to food. In 1990, Japanese scientist Yoichi Ueda discovered that if he added diluted garlic to two types of soups, the people who ate them would describe having more sensations associated with kokumi. Subsequent research isolated amino acids in garlic that appeared to cause the effect, including glutathione.