How the miracle fruit changes sour into sweet

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Pop a “miracle berry” into your mouth, and you might wonder if it was named by an overreaching marketing department. The small red fruit tastes of very little – it has a “mildly sweet tang… [like] a less flavorful cranberry”. But it’s not the taste of the fruit itself that matters. To understand why the berry gets its name, you need to eat something acidic. The berries have the ability to make sour foods taste deliciously sweet. Munch one, and you can swig vinegar like it was a milkshake, or bite lemons as if they were candy.

The secret to the fruit’s taste-transforming powers is a protein called miraculin. Now, Ayako Koizumi from the University of Tokyo has discovered just how the protein acts upon our tongues.