Mixing taste illusions: The effect of miraculin on binary and trinary mixtures

Miraculin, the extract of miracle fruit (Richadella dulcifica or Synsepalum dulcificum), is a taste-modifying protein, its effect consisting in a temporary and almost complete replacement of sour taste with sweet taste. Despite psychophysical investigations were carried out in the past, very little is known about the effect of this molecule on taste interactions. We investigated the changes induced by miraculin on the gustatory sensations evoked by isolated tastants (citric acid, caffeine, NaCl and sucrose) and by binary and trinary mixtures that included a sour tastant (citric acid). We confirmed the effects of miraculin on citric acid, both as a single tastant and in mixtures. In mixtures including a salty tastant, the "illusory sweetness" induced by miraculin significantly reduced saltiness. Variable effects were shown on the perception of bitterness, although mostly in the direction of bitterness suppression. Finally, contrary to previous results, miraculin added sweetness in mixtures that included a sweet tastant. +PRATICAL APPLICATIONS: The taste-modifying protein miraculin has been known since long time due to its surprising property of transforming sourness into sweetness. Here, we put at test the properties of miraculin in mixtures, proving that its sweetness-inducing effect has an impact also on saltiness and bitterness, provided that the mixture includes a sour tastant (citric acid). In all mixtures containing NaCl (sour-salty, sour-salty-bitter and sour-salty-sweet), saltiness was significantly reduced, suggesting a suppressive interaction between miraculin-induced sweetness and NaCl. Similarly, although less strongly, the bitterness (of caffeine) was suppressed in two mixtures out of three (sour-bitter and sour-bitter-sweet).