Miracle fruit - formally known as Synsepalum dulcificum - is a red berry that is native to West Africa. It was first described in 1725 when French explorer Chevalier des Marchais saw villagers in West Africa eating the berry before a meal of gruel and palm wine.
A botanist with the U.S. Department of Agriculture brought it to U.S. in the 1960s.
In 1968, scientists isolated the active protein in the berry that makes things taste sweet. Because it has a miraculous way of changing sour to sweet, the protein was named miraculin. When the fruit is consumed, the miraculin in the berry binds to your tongue's taste buds. The receptors on a person's taste buds identify sour, sweet, savory and bitter tastes. Normally, your sour receptors would begin firing if you were eating a lemon. But under the influence of miraculin, the sweet receptors on your taste buds begin signaling and suppress the sour tastes. Miraculin rewires the sweet receptors temporarily to make them identify acids as sugars.
The taste of the berry itself has been likened to a less flavorful cranberry. However, the pulp packs a big punch. To experience the full effect, the berry's pulp should remain in your mouth and be spread all over your tongue for about a minute.
Once you have done this, miraculin changes the taste of sour foods to sweet. The effect will last about an hour. The taste of sweet foods tastes about the same, if not overly sweet.
Miraculin is a protein, so heat will destroy the effect. Therefore, the berry cannot be cooked and heated foods will not taste any differently than they would otherwise.
Saliva eventually washes the miraculin away and your tastes return to normal.