By Mark Brown, Wired UK

Popping a squishy red miracle berry into your mouth is almost like hacking your taste buds. For up to an hour, the juices coat your tongue and previously sour foods like lemon and vinegar magically taste deliciously sweet.

[partner id="wireduk" align="right"]The berry and its plant (Richardella dulcifica) grows in West Africa. While the local population has been using its miraculous properties for centuries, it was only in 1968 that the all-important protein miraculin was extracted and sold in tablets. They're now available the web and often feature in "taste tripping" parties where brave souls dine on pickles and limes.

However, the exact mechanism that miraculin uses on your taste receptors, allowing it to magically turn sour into sweet, has been a mystery to science for almost four decades. Until now, that is, as a team of researchers from the University of Tokyo – headed by Keiko Abe – has uncovered the miracle berry's secrets.

The researchers used a system of cultured cells that let them test human taste receptors at various levels of acidity and alkalinity. They found that miraculin binds strongly to the sweet taste buds (specifically hT1R2-hT1R3) but – unlike sugar or aspartame – doesn't activate them at a neutral pH. Introduce acid, though, and the protein shifts shape in a way that "turns on" the taste bud, creating a sensation of ultra-sweet that drowns out the sour.

When the sour, acidic food is swallowed, the miraculin returns to its old inactive shape and remains firmly bound to the sweet receptor for about an hour or so, lying in wait for another acidic treat.

The miraculin also toys with sweet, sugary food in interesting ways. Drop a load of aspartame after popping a miracle berry tablet and the miraculin represses your sweet receptors, making sweet foods taste bland. But in a slightly more acidic environment, the receptor's response skyrockets, making aspartame taste sweeter than ever though possible.

Miracle berries could have applications outside of novelty culinary events. "We are interested in a large-scale production of miraculin because it has a good, sucrose-like taste and combines a non-caloric property, since developing a safe sweetener for anti-diabetes and anti-obesity uses is of pressing importance," Abe told Nature News.

Indeed, in Japan the berry is popular among dieters. In the US, though, the FDA's decision that the miracle berry is an "additive" doomed it to further testing and an upstart miraculin commercialization firm – Miralin Company – folded in the 70s.

Image: Tony Rodd/Flickr*

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Source: Wired.co.uk

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