Phew! Where’s the time gone?
Anyway, let’s get on with it. I’ve already discussed the primary source of bitterness in beer, so now I’ll revisit the topic of bitterness from a different view: the physiology of bitterness.
The sensation of bitterness is not well understood at all. Nearly every aspect of bitterness is shrouded in complexity, and although new research is continually expanding our level of understanding there is still a great deal to be learned. The reasons bitterness is a tricky subject to elucidate are numerous and varied. There are a wide variety of chemical compounds which are bitter, such as polyphenols, organic acids, peptides, salts, sulfimides, and acyl sugars. This variety in molecular size and shape in turn implies a variety of mechanisms of operation. There is also a huge variation in how bitterness is perceived by individuals, and these variations are largely genetic in origin. Further confounding our understanding of these mechanisms are the difficulties that arise when attempting to communicate the qualities of bitter sensations. There are no agreed upon vocabularies for describing bitterness and its qualities, so while one person may describe caffeine as having a harsh and unpleasant bitterness another person may call it medicinal and lingering. Are they perceiving the same sensation, and is there even a way to tell for sure? Yet another factor in the complexity of bitter taste is the interactions that bitter sensations have with other sensations, most notably sweetness. Certain mixtures of bitter and sweet compounds can have interesting and unexpected effects on each other, with some sensations being suppressed by the presence of other compounds. In some cases there can be a synergistic effect where the total sensation is greater than what would be expected from a merely additive effect. In this article I will explain some of the mechanisms and characteristics of bitterness as we understand it so far.