Introduction: Umami as a Taste Percept

This introductory chapter first provides a brief overview of the human sense of taste and its historic division into four basic or primary qualities, sweet, sour, salty, and bitter, each with a different nutritional function. It then describes the identification of a potential fifth basic taste, umami, typically elicited by the sodium salt of glutamic acid (MSG). Umami taste has been posited as a way to identify and motivate consumption of amino acids and protein in a manner analogous to how sweet taste is thought to identify and motivate consumption of energy-rich foods. It then briefly discusses some special perceptual characteristics of human umami taste relative to the other four basic taste qualities. These include its more subtle nature, its strong apparent tactile component, its specificity to the single amino acid glutamate, and its high concentration in human milk. It concludes that although we have recently learned much about the mechanisms and functions of umami, more remains to be discovered.