Umami: The fifth taste
Much work has been done on the mechanisms and perceptions of taste in humans and it has long been known that there are four basic tastes; sweet, sour, bitter, and salty. The work of Kukunae Ikeda at the beginning of the twentieth century set the stage for our discovery and understanding of the fifth taste – umami. Taking its name from the Japanese word for ‘delicious’ or ‘meaty’, umami is best described as a pleasant savory note that can increase the perceived flavor, and even saltiness, of foods.
Our understanding of the mechanism of perceived saltiness and umami has advanced significantly since the work of Ikeda and we now know that the presence of two key elements is necessary to maximize umami. The first of these molecules is monosodium glutamate (MSG). The presence of MSG on the tongue stimulates receptors on the surface of specific taste buds which then signals the human brain to increase saliva production. Common theory is that this mechanism is a way to prepare humans for protein digestion as meat is high in naturally occurring MSG. The second element that is key to maximizing umami is the presence of nucleotides – specifically inosinate and guanylate. Commonly referred to as I+G, the combination of MSG and I+G in foods causes a marked synergistic effect on the perception of umami, saltiness, and flavor. The evolutionary significance for our desire of umami type flavours can be exploited to meet modern consumer demands for sodium reduction and clean-label formulation.