Science
Tasteful colours
Bernard Dixon
Our expectations of the way something ought to taste has a real effect on the way it actually does taste. That is the remarkable implication of some new research that has been reported from the Department of Food Science and Nutrition at Colorado State University. Dr J. A. Maga, the scientist responsible for the discovery, has found that the colouring of dilute solutions of bitter, sweet, and other substances alters a person's perception of their taste.
Just as intriguing is the fact that the report appears in the first issue of a new learned journal, Chemical Senses and Flavor, which was launched last week. Usually the appearance of a new scientific periodical marks the emergence of a totally new research area. So it is, in a sense, with this one: investigations into the mechanism of taste have burgeoned in recent years, as a result of both basic scientific interest and increasing preoccupation of the food industry with the preservation and improvement of taste in packaged foods. What is unusual on this occasion is that publication of the new journal coincides with the revival of a scientific theory of taste that can be traced back as far as Aristotle.
During recent decades, many highly sophisticated explanations of taste have been devised, but all have been found wanting. Popular once more, therefore, is the venerable belief in four basic taste qualities: salty, sour, sweet, and bitter. One of the reasons why this Aristotelean theory went out of fashion was its failure to account convincingly for the full range of
The
Spectator May 25, 197) tastes as we know them. It used to be thought that, just as one can mix three primary colours to create virtually any other colour, so one should be able to simulate the characteristic flavour of, say, smoked salmon or ice cream simply by judiciously blending the four primary tastes. From a physiological standpoint, the implication of this idea is that the taste buds contain four different types of 'reception,' at sensitive cells, which are stimulated differentially ,.„ various tasty foods. Though the' evidence from the mixing 0f different tastes is still ambiguous, recent evidence does begin t.0 provide strong support for tlus explanation. We now know, f,nr example, that different parts of the tongue differ in their sensitivity t_,° the four basic tastes, while fin°. ings of a relationship between taste and chemical structure atig' gest the idea of discrete sensitivitY rather than a continuum.
' What Dr Maga has done is to 'show that, in the case of sweest' ,sour, and bitter butnot salty), 'people's expectations clearlY influence their sensation of taste He used as his research materials series of solutions, ranging frail extremely dilute to moderate' strong, of four different chemicals representing sweet (sucrose), sourd (citric acid), bitter (caffeine), an salty series w amcshlomriadde)e uta pste E i colourless form, and separatelY with '.(tasteless) red, green, °,1. yellow colouring agents addo. Young men and women were the asked to sample the liquids frtnri each series, beginning in each case with the most dilute, and record; ing the point at which they fir5 experienced the particular taste. The results were surprising, t! say the least. In most cases, til! coloured solutions needed to b` more concentrated before tbe subjects were capable of identifY" ing the specific taste — Par ticularly with sour and bitter tastes. Particular colours had Par ticular effects, thus implicating 3d psychological association of foo colours with taste. Green, Oro example, increased the threshol, at which the sweet solution coal° be tasted. Conversely, yell° colour decreased taste sensitivitY• There were several other sociations between (presumablY,' the expectation stemming fro' colour associations of particulai,, foods, and the real ability experience taste. The one exce7 tion was with saltiness. Are parently, we do not associat, saltiness with any particula' colour: none of the coloured sa,15 solutions were detected at Si nificantly different concentration, from that of the colourless control. Does Dr Maga's discovery have any practical value? PossiblY', Like the stand-up comic Wh:t makes you feel that you rritl'i laugh at his jokes, however bana,',i the food technologists coul; probably learn to exploit peoPle expectations by subtle colourinfe of food and drink. Perhaps th,,e wine trade has already learned 06 scret — in its preparation an packaging of cheap plonk.
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