Sourness and the Sensation of Tasting a Lemon

Sourness is illustrated by this yucky icon for taste sensations that are lemon flavoured.

Any flavor or gustatory perception that could be roughly described as acidic or caustic is called a sour taste sensation. We use words like soapy, tart, corrosive, sharp, astringent, tangy, acerbic, rancid, vitriolic, biting, vinegary etc. to identify these flavors. To make a binary description of a sour sensation compare it to tasting a lemon. Report the result using one of the following algebraic statements. If the two experiences are not comparable, then say that the sensation is not a sour sensation and express this as $\delta_{\mathit{H}}=0$ . If the sensation is like tasting a lemon, then say that it is tart. Write this as $\delta_{\mathit{H}}=+1$ . If the sensation is not like tasting a lemon, then say that it is soapy and that $\delta_{\mathit{H}}=-1$ . The number $\delta_{\mathit{H}}$ is called the sourness. These relations are mathematically expressed by

$\delta_{\mathit{H}} \equiv \begin{cases} +1 &{\text{if a sour sensation is tart }} \\ \; \; 0 &{\text{if a sensation is not sour}} \\ -1 &{\text{if a sour sensation is soapy }} \end{cases}$

Reference Constant for Sourness

The numerical constant associated with tasting a lemon has not yet been determined.