Researchers uncover secrets of 'miracle fruit'

Sep 27, 2011 by Bob Yirka report
Photo of Miracle berry (Hamale Lyman/Wikipedia)

(PhysOrg.com) -- Though not very well known in the United States, at least until the past few years, the miracle fruit is a cranberry like fruit that has the unique property of being able to make acidic or bitter foods taste sweet. And while the protein that makes this possible has been known for quite a while, just how exactly it did its trick has been a mystery; until now. A team of Japanese and French researchers working together have solved the puzzle and have published the results of their efforts in the Proceedings of the National Academy of Sciences.

Miracle fruit, the berry of the Synsepalum dulcificum plant, grows naturally in West Africa and the locals there have long known of its sweetening properties. Pop one of the little berries in the mouth and for an hour, foods like pickles, beer, grapefruit or lime, taste like sweet versions of their former selves. More recently, the effects of the miracle fruit have been popularized by flavor-tripping parties, so named because of the odd sensational resemblance to the effects of hallucinogens. Or as Keiko Abe, one of the team leads, reports, the effect is rather magical.

To get to the bottom of how the miracle fruit performs its magic, the team grew in a dish that were engineered to produce sweet . They then applied a chemical that caused the to light up when activated. Next, they applied miraculin, the protein in miracle fruit that is responsible for the sweetening effects. After that they added different substances with different and found that the miraculin had three distinct impacts on the . At low levels there is little effect, at medium levels the miraculin boosted response and at high levels the receptors were activated on their own.

This all happens, the researchers say, because the miraculin protein changes shape when exposed to acids. The higher the level, the more it changes shape. And because the protein binds very strongly to the receptors in the human tongue, those changes in shape change the way the receptors react when acids are introduced into the mouth. The bottom line is, the higher the pH level in a substance, the sweeter it tastes to the person doing the tasting.

The end result of this research might be the introduction of a whole new kind of artificial sweetener, either as an ingredient, or as an additive by users wishing only to sweeten ordinary foods. And now that the effects of miraculin are better understood, researchers will next try to see if they can create it from scratch rather than having to rely on Mother Nature to grow it for them.

Explore further: Factor in naked mole rat's cells enhances protein integrity

More information: Human sweet taste receptor mediates acid-induced sweetness of miraculin, PNAS, Published online before print September 26, 2011, doi: 10.1073/pnas.1016644108

Abstract
Miraculin (MCL) is a homodimeric protein isolated from the red berries of Richadella dulcifica. MCL, although flat in taste at neutral pH, has taste-modifying activity to convert sour stimuli to sweetness. Once MCL is held on the tongue, strong sweetness is sensed over 1 h each time we taste a sour solution. Nevertheless, no molecular mechanism underlying the taste-modifying activity has been clarified. In this study, we succeeded in quantitatively evaluating the acid-induced sweetness of MCL using a cell-based assay system and found that MCL activated hT1R2-hT1R3 pH-dependently as the pH decreased from 6.5 to 4.8, and that the receptor activation occurred every time an acid solution was applied. Although MCL per se is sensory-inactive at pH 6.7 or higher, it suppressed the response of hT1R2-hT1R3 to other sweeteners at neutral pH and enhanced the response at weakly acidic pH. Using human/mouse chimeric receptors and molecular modeling, we revealed that the amino-terminal domain of hT1R2 is required for the response to MCL. Our data suggest that MCL binds hT1R2-hT1R3 as an antagonist at neutral pH and functionally changes into an agonist at acidic pH, and we conclude this may cause its taste-modifying activity.

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User comments : 19

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Mabus
Sep 27, 2011
This comment has been removed by a moderator.
medcegblog
5 / 5 (10) Sep 27, 2011
Apparently Bob Yirka, the author of this article, did not pass General Chemistry. Throughout this article, the author makes the mistake of thinking higher pH means higher acidity. Completely False!

The bottom line is, the LOWER the pH level in a substance, the sweeter it tastes to the person doing the tasting.
PaulRC
not rated yet Sep 27, 2011
good catch med
Doug_Huffman
1 / 5 (6) Sep 27, 2011
The bottom line is, the LOWER the pH level in a substance, the sweeter it tastes to the person doing the tasting.
This, your statement, is true only after use of MCL. In general, low pH/acidic substances taste sour, indeed, the word in Germanic languages is säure.
krundoloss
1 / 5 (4) Sep 27, 2011
Why dont they use this to make bitter foods with higher PH taste better, then people would eat them, increasing the PH of thier body and reducing or eliminating cancer. (This is based on the assumption that cancer cannot thrive in an Alkaline environment.)
ScottSalley
2 / 5 (4) Sep 27, 2011
I don't believe the foods you eat have *any* effect on the pH of your body. Even a slight change in pH of your blood can be deadly.
that_guy
not rated yet Sep 27, 2011
Yeah, I would like to point out that even though the author of the article mangled his acids and bases, this fruit, as he correctly points out, makes both acidic and bitter (Sigh, he should have said base) foods taste better. It works at both ends of the spectrum.

It is really cool, and I'm not sure why it hasn't caught on here - the japanese love to play with this thing.

While I am ok with semi-sweet beer or pickles, I'm not sure if I like the idea of using this fruit on regular beer or pickles. Sounds like it would taste like pickles dipped in sugar.

Edit: @ scott: why are you going to put such an ignorant comment out here? The way your body metabolizes food can cause a change in the PH in your blood.

@Krundoloss: look up acid forming and base forming foods. PH level before it is eaten is not a direct indicator of how it will affect the body. For example, citrus is a base forming food, while coffee is acid forming.
that_guy
not rated yet Sep 27, 2011
PS - Scott is right about a fairly small ph change in the blood can be deadly. The body tends to regulate it with a 'safe' range. and krundoloss is partially right about the acidic or basic (in a narrow range) nature of our blood chemistry and it's relation to cancer.

If your blood ph is too high (From eating sweets or red meats) you are more prone to cancer. Once the cancer has started growing, I'm not sure how effective it would be.

Krundoloss, instead of taking this circuitous route to combat cancer have less acidic blood, you could eat:

brocolli, cabbage, cucumber, peppers, onions, pumpkins, radishes, tomatoes, lettuce, shitake mushrooms, bean sprouts, grapes, grapefruit, oranges, peaches, lemons, strawberries, tangerines, almonds, tofu...etc...etc...etc.

Many of those are acidic before they are digested.

The best range for our blood is between 7 and 8.
LariAnn
1.7 / 5 (6) Sep 27, 2011
This all happens, the researchers say, because the miraculin protein changes shape when exposed to acids.


This is true according to my experience with the miracle fruit, as I both grow it and have tried it. Alkaline substances (bases) do not seem to produce the effect, only acids. The author just got confused about "higher" levels when he should have stated "higher acidity". The abstract describes the effect correctly, so the error does not originate in the paper.

Robert_Wells
2.3 / 5 (3) Sep 27, 2011
Sweet!


you mean, Bitter!

or Sour!
AlexCoe
1.5 / 5 (8) Sep 27, 2011
As a recovering cancer patient this would be a miracle! Since many of the chemo drugs change the the tastes of most everything, especially the sweet sensations this would certainly help get my ability to eat some things back again. It would be interesting to see if it would help counteract the platinum based drugs ability to make the tongue taste everything as metallic and spiky.
Montrealmma
5 / 5 (2) Sep 27, 2011
Not to be confused with beans. That's the MUSICAL fruit.
hush1
1 / 5 (3) Sep 27, 2011
Aside from the impressive display scientific acuity and scrutiny (kudos) within the commentary thread here, the downside is the exploitation of African land and people.

The largest of U.S. food industries is all over this. The monetary interests and demands staggers the imagination.
Africa's people are not aware they have no voice if plantation vs. synthetic 'herstellung' is cheaper.

There is no negative impact. No downside. For Africa.
An no effort too great or small to make the above assertions fact.
Apaquin
5 / 5 (2) Sep 27, 2011
It is really cool, and I'm not sure why it hasn't caught on here - the japanese love to play with this thing.

big sugar and fake sugar companies claim miracle fruit is unsafe and have prevented it from being used on a large scale. But I'm sure its just a coincidence that sweetener companies are vehemently opposed to the use of a new sweetener that might cut into their profits.
kaasinees
1 / 5 (4) Sep 27, 2011
Its funny how shamans, traditional chinese medicine etc. already know this was a miracle fruit a long time ago ;]
Parsec
1 / 5 (1) Sep 28, 2011
The Ph of blood is highly buffered. This means that if acidic compounds are added (more CO2 for example forming Carbolic Acid), or base compounds are added (diet? not sure how this can happen), the blood chemistry (to a point) will absorb the extra cations and anions to keep the blood at basically the same Ph.
Au-Pu
1.7 / 5 (6) Sep 28, 2011
parsec is correct our body has a variety of regulatory systems that maintain all our systems within acceptable tolerances.
When any of those systems fail we have an illness.
Rather than being concerned about sugar we should see this as a possible replacement for phenylalanine which IS potentially dangerous. Before G. D. Searle obtained authorisation to use this as an artificial sweetener it had been trialed by Monsanto as a potential chemical weapon. It failed because it had no knock-down capacity. Searle bought it and it took them something in the vicinity of 15 years to get the FDA to approve it. They had to resort to having their CEO appointed as Director of the FDA to get it approved.
Ever since they have laughed all the way to the bank each and every day
They call it Nutrisweet, Aspartame and possibly a few others.
Excessive consumption can potentially create problems. It all depends upon its rate of metabolism.
Doug_Huffman
1 / 5 (4) Sep 28, 2011
This means that if acidic compounds are added (more CO2 for example forming Carbolic Acid),...
Carbolic acid? Uhh, no! Carbolic acid is phenol C6H5OH. Might you mean carbonic acid H2CO3? Carbolic acid is generally considered toxic.
Imagine
1 / 5 (2) Sep 28, 2011
Every one seems to be up in arms about the ph comments in the article. Here is the part of the article I am concerned with "And now that the effects of miraculin are better understood, researchers will next try to see if they can create it from scratch rather than having to rely on Mother Nature to grow it for them".

Wonder what poisonous chemicals they will make it out of. So, after they figure out how to make this stuff artificially; how long before it causes cancer?

Why can't they just grow the stuff, refine it, and sell it? My guess is, cause if they can make it from chemicals, they can make it cheaper and, sell it for a whole lot more money; just like they do with sweat and low (and any other chemical sweetener).

Maybe they want to put a copywriter on it and, get rich off you. How long till the plant is made illegal to own?

Why can't they just do something safe and, natural for the consumer, for a change?
1n10spirit
not rated yet Sep 28, 2011
There they go again. Big pharma and/or AG companies taking away a potentially profitable cash crop from those who truly need it!!!