MIXING TASTE ILLUSIONS: THE EFFECT OF MIRACULIN ON BINARY AND TRINARY MIXTURES ANTONELLA CAPITANIO, GIULIANA LUCCI and LUCA TOMMASI 1 Department of Neuroscience and Imaging, University of Chieti, Chieti I-66013, Italy 1 Corresponding author. TEL: +39-(0)871-3554210; FAX: +39-(0)871-3554163; EMAIL: luca.tommasi@unich.it Accepted for Publication October 13, 2010 doi:10.1111/j.1745-459X.2010.00321.x ABSTRACT Miraculin, the extract of miracle fruit (Richadella dulcifica or Synsepalum dulcifi- cum), is a taste-modifying protein, its effect consisting in a temporary and almost complete replacement of sour taste with sweet taste. Despite psychophysical investi- gations were carried out in the past, very little is known about the effect of this mol- ecule 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 percep- tion 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). INTRODUCTION Foods are complex gustatory matrices, whose sensory attributes can be understood by studying in the laboratory how single tastants combine perceptually with each other in controlled mixtures. Although we know much about the per- ception of isolated tastants and how it relates to gustatory physiology, less is known in this respect about binary and trinary interactions among tastants. Investigating the sensory experience (and its physiological counterpart) induced by combining two or three tastants offers however interesting clues for understanding the principles underlying the gusta- tory system, as interactions among tastants produce unpre- dictable effects of enhancement and suppression, often depending on the level of concentration of the tastants involved (Bartoshuk 1975; Lawless 1986; Keast and Breslin 2002). To give a few examples, at low intensities, the effect of sweet in binary mixtures with other basic taste qualities is variable. At medium and high intensities, sweet is instead gen- erally suppressive of other basic tastes (Stevens 1995; Stevens and Traverzo 1997). Salt enhances sweetness at low concen- trations and has variable effects through the moderate con- centration range, whereas sweetness suppresses salty taste at moderate intensities (Keast and Breslin 2002). At medium Journal of Sensory Studies ISSN 0887-8250 54 Journal of Sensory Studies 26 (2011) 54–61 © 2011 Wiley Periodicals, Inc.