Bitter compounds are closely related to sweet compounds. Both compounds are made up of amino acids. The only difference between the two is their ability to rotate plane polarized light. Negative rotation of light (designation: "P") has the alcohol group furthest from the carbonyl group on the left hand side of the molecule. This makes the compound bitter tasting. Positive rotation of light (designation "D") has the alcohol group on the right hand side therefore it tastes sweet (Teransishi, 1981). It is very interesting to note that while sweet and bitter tastes seem so opposite, it is as simple as an analogy of someone wearing a ring on the right hand or the left hand.

Most bitter compounds are lipophilic (fat loving) and are soluble through plasma membranes which allows the compound enter the cell. This movement is called transduction. The fact that some people are unable to taste certain bitter substances (taste blindness) suggests that there is a specific transduction process for these compounds which not everyone possesses (Cagan, 1989).

For those of us who do taste bitter compounds, we can either mask the taste with other substances such as sugar or we can chemically neutralize the taste. It has been found that Sodium Chloride (standard table salt) suppresses the bitterness in some substances do to the compounds charge. For example, quinine and strychnine, which carry a positive charge, are neutralized by the negatively charged chloride ion in salt. This suppressive effect may be brought about by inhibition of an electrostatic interaction between the positive charge of the bitter substance and the negative charge on the receptor membrane (Brand 1989).

THE ESSENCE OF BITTERNESS By Teresa Garner and Phil Bopp NFM425 May 30, 1996

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Updated: Sunday, March 30, 2008.