News Articles

 

Click on link

Read the latest news thanks to Google

Givaudan buys Quest
Parliament passes chemical law    The sour taste new understanding

Fat taste receptor discovery could influence food formulation

By Anthony Fletcher

11/4/2005 - The recent discovery of fat taste receptors on the tongue sheds new light on how taste buds function and could have ramifications for food makers.

Writing in the Journal of Clinical Investigation, scientist Philippe Besnard and his team from the University of Burgundy identified receptors, called CD 36, in the tongues of rodents. It is not known yet if this discovery is applicable to human tongues as well.

Experts have conventionally thought that the tongue detects five tastes - sweet, salty, sour, bitter and the savoury umami taste - but this discovery could changed the way ingredients are formulated.

For example, the salty taste is physically unique. It was recently discovered that taste receptors inside the human tongue require the shape and size of the sodium ion in order to register a salty taste, thus influencing the development of salt replacers.

In the same way therefore, the possible identification of a fat taste bud in humans – the next logical step - could help food makers develop products that satisfy consumer craving for the creamy mouthfeel and flavour that fat can give.

This would be of great interest to food makers looking to tap in on growing concerns about obesity and weight gain. In the west, about 40 per cent of all energy comes from fat consumption.

"As we gain more information regarding the function of this receptor, we may be able to devise better strategies to address the addictive potential of dietary fat," said professor Nada Abumrad of Washington University School of Medicine, writing in the in the same medical journal.

This remains to be seen however. The CD36 receptor is already known to exist in many tissues involved in fat storage, but its taste function, if it exists in humans, has not been studied. But the University of Burgundy study still represents an important breakthrough.

By knocking out the receptor in some mice so that it no longer worked, the team was able to compare the behaviour of normal mice and these ‘knock out' mice.

According to Besnard, the normal rodents showed a preference for fatty foods when offered them, yet the knock out mice did not. In addition, when the researchers put a fatty liquid onto the tongues of the normal rats, this triggered a release of fat-processing substances from the digestive organs.

This reaction did not happen in the knock out mice.

Previous research into taste has revealed that the human tongue has about 10,000 taste buds with five taste sensations: sweet, bitter, and umami, which work with a signal through a G-protein coupled receptor; salty and sour which work with ion channels.Contrary to popular understanding, taste is not experienced on different parts of the tongue. Though there are small differences in sensation, which can be measured with highly specific instruments, all taste buds, essentially clusters of 50 to 100 cells, can respond to all types of taste.

Taste buds (or lingual papillae) are small structures on the upper surface of the tongue that provide information about the taste of food being eaten.

 

Monell Chemical Senses  Newsletter

Miracle Fruit a new flavour phenomena?

 

Makes acidic drinks sweet!

A chemical that makes sour, acidic food taste wonderfully sweet may soon be flowing from a genetically altered lettuce created by scientists in Japan.

A team of researchers at the University of Tsukuba genetically engineered lettuce into a living factory capable of producing large quantities of miraculin, a protein that can fool taste buds into thinking acidic foods and liquids are actually sweet.

Miraculin works by bonding to sweet receptors on the tongue.

"Sweet receptors sit on taste buds and wait for sweet molecules to come along and set them off," explained Göran Hellekant, a miraculin researcher and professor of physiology and pharmacology at the University of Minnesota. "Normally, they can only be set off by chemicals that are legitimately sweet, but miraculin may distort their shape a bit so that they become responsive to acids, instead of sugar and other sweet things."

Miraculin's effect lasts as long as the protein is bound to the tongue, which can be up to an hour. It makes most acidic foods taste sweet, but does not improve the taste of bitter things.

The major natural source of miraculin is an African berry, Richadella dulcifica, that is often called "miracle fruit." But it is quite difficult to extract miraculin from the berries and purify it. Thus, if miraculin were to become popular as a sweetener, a better source would be necessary. As the Japanese researchers showed, adding Richadella genes to lettuce fit the bill: The scientists were able to obtain up to 40 micrograms of miraculin per gram of lettuce leaves, a tremendous amount considering the potency of the exotic protein.

Researchers have proposed using miraculin in place of artificial sweeteners, but there are a number of drawbacks. Since it is a protein, it cannot be cooked. When most proteins are heated, they denature and lose their effectiveness. Some 30 years ago, U.S. dieters could buy a pill that contained miraculin and put it in their mouth before having a meal or beverage. This would make the rest of the meal taste unbelievably sweet without any need for added sugar. Similar pills are currently sold in Japan (Japanese language website), but they are quite expensive, priced at several dollars per tablet.

"Miraculin must be taken before eating. It should not be mixed into food," said professor James Kalat of North Carolina State University's psychology department. "Back when it was possible to get miraculin tablets, my wife and I got together with another couple for a miraculin party. We used the miraculin tablets, then started trying every sour thing we could find. I remember straight lemon juice as being pretty good. I also tried vinegar and sauerkraut juice. Those did not taste good. The next morning we awakened with ulcers in our mouths, barely able to talk. Sure, these things tasted sweet, but they were still highly acidic."

Stanley Parsons, professor of biochemistry at the University of California at Santa Barbara and former editor of the journal Neurochemistry, said scientists often mass-produce exotic proteins by expressing them in bacteria, yeast or plants. They insert the gene for the protein into a host and coax the organism into making a supply. The Japanese researchers reported that others had unsuccessfully tried bacteria, yeast and tobacco before they found success with lettuce.

"It may never be successful as an artificial sweetener," said Parsons, "but it sure could make a remarkable salad."

 

Super Lettuce Turns Sour Sweet       Aaron Rowe 12.07.06