The amazing miracle fruit: How it makes sour stuff taste sweet

Ever tasted the miracle fruit? I haven’t, but I really want to. You chew it around in your mouth and for the next hour, sour stuff like lemons taste really, really sweet.

Now researchers in Japan and France have figured out how the fruit plays this trick on us. It involves, not surprisingly, the sweet taste receptor that resides in the membrane of taste bud cells.

Normally, sugars bind to the sweet-taste receptor, as do artificial sweeteners like aspartame, saccharine and sucralose (Splenda). Scientists knew what ingredient in the miracle fruit does this weird thing to our senses: a protein in the fruit dubbed miraculin. But they didn’t know how miraculin acted.

Here’s how the team, reporting in this week’s Proceedings of the National Academy of Sciences, figured it out.

First, they genetically engineered human cells in a dish to carry the sweet taste receptor on their membranes.

Next, they exposed the cells to miraculin and let things sit awhile.

They acidified the solution in which the cells were bathed -- much as the saliva in your mouth would be acidified if you bit into a pickle or chewed on a lemon slice. Now they could see that the sweet-taste receptors became active.

If they didn¿t first add miraculin, acid didn’t stimulate the receptors. And when the pH was neutral or alkaline, nothing happened either. (Other experiments conducted by the group narrowed down precisely what part of the sweet-receptor was involved in miraculin’s sweet- taste trickery.)

The miracle fruit comes from the West African plant Richadella dulcifica. Read more about it at a website that devotes itself to explaining a different protein each month (it appears to have missed a few, but who am I to judge?)

And there’s avery nice description of the new experiment as well as the miracle fruit’s history at the�Not Exactly Rocket Science¿ blog of British writer Ed Yong.

Finally, as a special treat, here’s a video of chef Homaro Cantu demonstrating how you make a cookie with no sugar that tastes super sweet after you¿ve primed your taste buds with the miracle fruit.