The Miracle Fruit berry, when eaten, causes sour foods (such as lemons and limes) subsequently consumed to taste deliciously sweet. Native to West Africa, it utilizes a molecule called miraculin to change the shape of the sweetness receptors on our tongues, activating them to respond to acids, too. Suddenly, sour tastes register as sweet ones.
When the fleshy part of the fruit is eaten, this molecule binds to the tongue’s taste buds, causing sour foods to taste sweet. At neutral pH, miraculin binds and blocks the receptors, but at low pH (resulting from ingestion of sour foods) miraculin binds proteins and becomes able to activate the sweet receptors, resulting in the perception of sweet taste. This effect lasts until the protein is washed away by saliva (up to about 30 minutes).
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