Bitter about the cold

Taste is not only a ploy food manufacturers use to trick you into buying more stuff, it’s also a clever evolutionary adaptation that helps you tell whether something is nutritious or poisonous. But it also turns out to be sensitive to temperature, in rather unexpected ways.

Twelve years ago, scientists from Yale University discovered the phenomenon of thermal taste, in which heating parts of the tongue cause a sweet sensation, and cooling other parts generates a salty or sour taste, all without any food being present (Cruz A & Green BG 2000, “Thermal stimulation of taste”, Nature, vol. 403, no. 6772, pp. 889-892 [PDF 325 KB]).

Although certain people seem to be more susceptible to this than others, more recent research has shown that all of us are likely to find the intensity of tastes changing with temperature (Bajec MR, Pickering GJ & DeCourville N, “Influence of stimulus temperature on orosensory perception and variation with taste phenotype”, Chemosensory Perception, published online 11 May 2012, DOI: 10.1007/s12078-012-9129-5).

Bitter flavours of gin and tonic or, say, a particularly hoppy beer, are likely to be more intense when chilled (photo by Kyle Flood, via Wikimedia Commons)

Garry Pickering and colleagues from Brock University in Canada tested sweet, sour, bitter and astringent flavours at temperatures of 5 °C and 35 °C, with 74 volunteers that included so-called ‘thermal tasters’, i.e. those known to be susceptible to the temperature phenomenon, so-called ‘super tasters’, i.e. those with especially sensitive palates, as well as so-called ‘normal people’.

All three groups reported an effect of temperature on taste. Sour and astringent flavours were stronger at the higher temperature, but curiously bitterness was brought out by the cold. Sweetness though seemed to be independent of temperature.

The practical applications to gastronomy are still to be explored, but molecular mixologists are sure to benefit.

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