Miraculin: The sweetest miracle

Amanda Edward
25 February 2015

Above: Miracle berries (Synsepalum dulcificum) (Wikimedia Commons/Hamale Lyman)

Imagine if everything tasted sweet. Believe it or not, there is a fruit native to West Africa that can make that happen! After you consume the flavourless red berries of Synsepalum dulcificum, even the sourest foods taste sweet: limes and lemons taste like oranges and vinegar tastes like maple syrup.

Did you know? The fruit of the Asian plant Curculigo latijblia, native to western Malaysia, contains the protein cucurlin, which can also alter the taste of sour foods. Unlike miraculin, cucurlin tastes very sweet and its effects last no longer than three minutes.The effects can last for more than an hour, even if you take breaks between snacks. And the wonderful experience is all thanks to a miraculous protein called miraculin and how it interacts with your taste buds.

Taste buds and taste receptors

The surface of your tongue is made up of thousands of tiny taste buds, each one of them containing specialized proteins designed to relay (send) chemical signals to your brain. Thanks to these taste receptors, you can perceive the five main tastes—sweet, sour, salty, bitter and umami (savoury).

Contrary to popular belief, taste buds with receptors for a particular taste are not localized in a specific area of your tongue. In fact, each taste bud contains multiple receptors, so you can distinguish between different tastes anywhere on your tongue.

Miracle fruit and the key to sweet

Now, imagine if you could exclusively switch on the sweet taste receptors. That’s essentially what Synsepalum dulcificum—commonly called the “miracle fruit”—does when you eat it. The plant’s “miracle berries” contain a protein called miraculin, which was first isolated in 1968. However, it wasn’t until 2011 that Japanese researchers discovered how miraculin fits perfectly into your sweet taste receptors, like a key in a lock. But turning the key to unlock a sweet taste happens only under specific conditions.

When you eat acidic foods, miraculin acts as an agonist, activating your sweet taste receptors so a signal of intense sweetness is sent to your brain. But when conditions are neutral or slightly alkaline, miraculin acts as an antagonist (deactivator) and inhibits (blocks) other molecules that elicit a sweet response, such as the artificial sweetener aspartame, from binding.

Did you know? Only 250 mg of miraculin can be extracted from 1 kg of miracle berries. That’s the equivalent of getting about one-twentieth of a teaspoon out of a standard bag of sugar.Eating miracle berries before eating sweet foods will not amplify their sweetness, nor does it appear to have any effect on salty, bitter, or umami tastes. It is does not change the actual composition of the food you eat, only your perception of how the food tastes.

So why can’t you find such a remarkable fruit on supermarket shelves? After all, it could help diabetics who need to reduce their intake of sugary foods as well as those with medical conditions that inhibit their sense of taste.

The main problem is that it takes four years for the plant to fully mature, and even then only about 25% of shrubs actually produce fruit. It is also difficult to cultivate outside West Africa, so transportation costs would be very high.

However, scientists are attempting to genetically modify tomatoes and lettuce to express (produce) miraculin. Even better, researchers found that rats on a miracle berry diet were healthier than those on a pet food diet and reported no short-term negative effects even when the rodents consumed very large amounts. Miraculin could well turn out to be the sweetener of the future!

Learn more!

The 'Miracle' Berry That Could Replace Sugar (2014)

David Cox, The Atlantic

Report on the potential of the miraculin contained in the fruit of Synsepalum dulcificum as a sweetener.

Sweet and Sour Science (2012)

Ruth Williams, The Scientist

Report on the discovery of how miraculin unlocks sweet taste receptors.

The Tongue Map: Tasteless Myth Debunked (2006)

Christopher Wanjek, LiveScience

Explanation of why the idea that the tongue is mapped into four areas—each for a different taste—is wrong.

Molecular mechanisms of the action of miraculin, a taste-modifying protein (2013)

T. Misaka, Seminars in Cell & Developmental Biology 24

Link to abstract. Subscription required to view full text.

Production of Recombinant Miraculin Using Transgenic Tomatoes in a Closed Cultivation System (2010)

T. Hirai, G. Fukukawa, H. Kakuta, N. Fukuda & H. Ezura, Journal of Agricultural and Food Chemistry 58

Link to abstract. Subscription required to view full text.

Human sweet taste receptor mediates acid-induced sweetness of miraculin (2001)

A. Koizumi, A. Tsuchiya, K. Nakajima, K. Ito, T. Terada, A. Shimizu-Ibuka, L. Briand, T. Asakura, T. Misaka & K. Abe, Proceedings of the National Academy of Sciences of the United States of America 40

Sweet and Taste-Modifying Proteins: A Review (1996)

B. F. Gibbs, I. Alli & C. Mulligan, Nutritional Research 16

Link to abstract. Subscription required to view full text.

Characteristics of Antisweet Substances, Sweet Proteins, and Sweetness-Inducing Proteins (1992)

Y. Kurihara, Critical Reviews in Food Science and Nutrition 32

Link to abstract. Subscription required to view full text.

Miraculin, the Sweetness-inducing Protein from Miracle Fruit (1986)

J. N. Brouwer, H. Van Der Wel H, A. Francke & G. J. Henning, Nature 220

Link to abstract. Subscription required to view full text.

Scientific articles discussing research on miraculin and other taste-modifying proteins.

Research on Preservation of Synsepalum Dulcificum by Coatings (2011)

C. Liu, C. He, T. Xie, Y. Yang & T. Liang, Advanced Materials Research 239-242

Link to abstract. Subscription required to view full text.

Scientific article on coating miracle berries to help preserve them during storage and shipping.

Amanda Edward

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