In 1907, the Japanese chemist Kikunae Ikeda had an insight that would change the culinary world while enjoying a bowl of soup with dashi sauce and kombu seaweed. He notices a taste that is not sweet, salty, sour or bitter. Ikeda gave this difficult-to-describe savory taste a name – umami – and identified the specific amino acid it causes.
Scientists in Europe and the US remained skeptical whether umami was really a taste until a receptor for it was discovered on the tongue almost a century later, in 2000. Today, it is taken for granted by most scientists and chefs, but the interest is now growing in a different flavor that was first detected in Japan.
The newer flavor, kokumi, is even harder to describe than umami, but it may be just as important to understand how and why we like food. In Japanese, the term koku describes foods that have the kind of mouthful “thickness” that is often transmitted by fats – which English speakers can describe as rich. “It feels like a physical sensation,” says culinary scientist Joshua Evans. It works “by covering the mouth, becoming more intense and lengthening over time. When asked about food that has koku, Japanese food experts cite wild pigs, adult wasps, duck eggs and stale things, as well as long-tasting and fermented dishes.
Koku reflects a sensory experience that is best associated with touch, influenced by aromas and textures. Add the Japanese suffix -mi, which means taste, emphasizes the specific taste detected by the tongue. The exact nature of kokumi remains the subject of much debate among sensory scientists and chefs, in part because it cannot be detected in the palate alone; it rather changes other tastes and flavors.
The earliest kokumi research 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 soup, people who ate it would describe having more sensations related to kokumi. Subsequent research has isolated amino acids in garlic that appear to cause the effect, including glutathione.