Despite the multitude of flavors that we taste in our everyday foods, humans actually only detect a few distinct taste sensations- bitter, sour, salty, sweet and umami. While I had heard of the other taste sensations before, I was unfamiliar with umami, a distinct savory taste sensation translated from Japanese as “delicious flavor”. The sensations sweet and umami have evolved in humans in order to recognize nutrients. These sensations are catalyzed by T1R1, T1R2, and T1R3, three G-protein-coupled receptors. In contrast, the bitter sensation has evolved as a sort of survival mechanism, a way to prevent the ingestion of toxins. It is controlled by about thirty G-protein-coupled receptors, T2Rs. While a large plethora of toxic chemicals cause the bitter sensation, humans are not able to differentiate between them. Scientists have yet to discover the details of how salty and sour sensations function, though it is suggested that they are caused by direct cell-entry of Na+ and H+.
Some scientists previously believed that these five sensations function using an across-fibre pattern. This means that either individual TRCs are tuned to multiple sensations, or that while TRCs are tuned to single sensations, the fibres carry multiple sensations. However, studies on rats and mice have suggested that the umami, sweet, salty, bitter and sour sensations are separated into groups of specific receptors- the TRCs and the fibres are tuned to single specific sensations. Reading about the distinct taste sensations made me to ponder how humans react to different foods, and in turn how we decide what is “edible” and what is “delectable”. Similarly, I thought about how chefs choose to combine these distinct flavors and how different combinations succeed while others do not. For example, I considered the simple combination that makes up a classic tequila shot- tequila, lime, and salt. The salty sensation and sour sensation are used to cover the strong taste of tequila and to make it more palatable.