Bitter value

Bitterness" is a property of a chemical compound(bitter substance) that cannot be measured objectively. A measured value for the bitterness value can be found in DAB9. The DAB9 defines (according to Ph.Helv.7) the bitterness value as the reciprocal value of that concentration of a chemical compound which is just tasted in a taste test.

The bitter value is determined in comparison to a dilution series of quinine hydrochloride. It is expressed in Ph.Helv. units.1 Ph.Helv. unit corresponds to the 2000th part of the bitterness of quinine hydrochloride.
The bitterest natural substance is called amarogentine, a bitter substance from the gentian root.

In contrast to the taste qualities sweet and salty, different receptors are responsible for the perception of the quality "bitter". Since the different bitter substances always induce the same receptor responses, information is always passed on to the brain in the same form. Thus the same taste quality is always induced.

Receptors for bitter substances are also found on smooth muscle cells of the bronchial system. Their activation causes bronchodilatation.

1. Chadwick M et al (2015) Perception of bitterness, sweetness and liking of different genotypes of lettuce. Food Chem 197(Pt A):66-74.
2. Chrysanthou A et al (2016) Sensory Threshold Studies of Picrocrocin, the Major Bitter Compound of Saffron. J Food Sci 81:189-198.
3. Hayes JE et al.(2015) Quinine Bitterness and Grapefruit Liking Associate with Allelic Variants in TAS2R31; Chem Senses 40:437-443.