Umami and MSG

Abstract Umami taste was first proposed by Kikunae Ikeda in the early 1900s as the taste of glutamate. His first paper described many basic aspects of umami taste that were consolidated by later studies conducted by many researchers around the world. Since his discovery of umami taste and the development of the production process for glutamate (monosodium L-glutamate, MSG), for over 100 years, MSG has been used to improve the palatability of many foods. As the production and consumption of MSG became prevalent worldwide, the safety of MSG as a food additive was questioned. Many researchers tackled this problem, resulting in MSG now being placed in the safest category of food ingredients. In contrast, establishing umami as a unique taste by taste scientists needed much time and effort. By the 1980s, the taste of glutamate had been thoroughly investigated from physiological, behavioral, and psychological perspectives, leading many investigators to conclude that umami is a basic taste much like sweet, salty, sour, and bitter. Subsequent molecular studies identified taste receptors for glutamate, which provided conclusive evidence for umami as a basic taste. This chapter aims to provide a broad understanding of umami taste, including the historical context for umami and MSG, why umami is considered a basic taste, and differences of umami taste in different regions of the tongue and across species. This chapter closes by describing some distinctive phenomena surrounding umami taste, such as its intensity and synergism, its long-lasting effects, and the salivary secretions and feelings of mouthfullness and satisfaction elicited by umami stimuli.