Theory for the mechanism of action of “miracle fruit”

Flavor Alterations Associated with Miracle Fruit and Gymnema sylvestre

Taste and flavor (retronasal olfaction) interact in the brain. The rules of that interaction are not well understood. This study uses 2 taste modifiers that alter sweet to examine the effects on flavors. Subjects used the Global Sensory Intensity Scale to assess the aroma, sweetness, sourness, and flavor of 10 foods. As previous work had shown, miracle fruit added sweetness to acids, which secondarily reduced sourness (mixture suppression) and Gymnema sylvestre reduced sweetness in sweet foods as well as the sweetness induced by miracle fruit. In this study, multiple regression showed that both sweet and sour contribute to flavor. Gymnema sylvestre reduced the perceived sweet of predominantly sweet foods (chocolate and maple syrup) as expected; reducing the sweet, reduced the flavor. The effects of miracle fruit were complicated by its dual action: intensification of sweet and reduction of sour. Predominantly sour foods (vinegar, lemon, mustard, pickle) were sweetened by miracle fruit but any flavor enhancement associated with the added sweet appears to have been countered by the flavor reduction associated with reduced sourness. Moderately sour foods that are also sweet (tomatoes, strawberries) were sweetened by miracle fruit and thus flavor was enhanced; flavor loss through sour reduction was apparently not sufficient to counter the flavor enhancement due to increased sweet so the net result was that tomato and strawberry flavors were enhanced. The flavors of control foods (not predominantly sweet or sour [sausage, peanuts]) showed only small changes.

Plant-derived triterpenoid sweetness inhibitors

Considerable recent attention has been focused on naturally occurring compounds with taste-modifying activity, which are of potential use in both dietary sweetness management and in gaining a better understanding of the sweet taste sensation. This review summarizes information on the phytochemistry and biological activity of more than 40 triterpenoid sweetness inhibitors that have been isolated from the leaves of three medicinal plants, namely, Gymnema sylvestre R.Br. (Asclepiadaceae), Ziziphus jujuba P. Miller (Rhamnaceae), and Hovenia dulcis Thunb. (Rhamnaceae).

Effect of gymnemic acid on single taste hairs of the housefly, Musca domestica

The effect of a gymnemate salt extract (KGE) on the behavioral and neurophysiological taste responses of Musca domestica to sugar and salt were studied. After exposure of single taste hairs to KGE, the behavioral positive response to a just-suprathreshold sugar stimulus was abolished, and the neuronal firing pattern was modified in a form that ranged from a waxing and waning of impulse frequently to an abolishment of impulses. The neurophysiological response to a salt stimulus was similarly modified, although the waxing and waning of spike frequency was more rapid and firing returned to a near-control pattern sooner. Neurophysiological studies were replicated with two other fly genera. The results uniformly suggest a narcotic effect on the dendrites of taste neurons.