Scientists learn startling new truth about sugar

July 25, 2011

Flying in the face of years of scientific belief, University of Illinois researchers have demonstrated that sugar doesn't melt, it decomposes.

"This discovery is important to food scientists and candy lovers because it will give them yummier caramel flavors and more tantalizing textures. It even gives the pharmaceutical industry a way to improve excipients, the proverbial spoonful of sugar that helps your medicine go down," said Shelly J. Schmidt, a University of Illinois professor of .

In a presentation to the Institute of Food Technologists about the importance of the new discovery, Schmidt told the food scientists they could use the new findings to manipulate sugars and improve their products' flavor and consistency.

"Certain flavor compounds give you a nice caramel flavor, whereas others give you a burnt or bitter taste. Food scientists will now be able to make more of the desirable because they won't have to heat to a 'melting' temperature but can instead hold sugar over a low temperature for a longer period of time," she said.

Candy makers will be able to use a predictable time-temperature relationship, as the does in milk pasteurization, to achieve better results, she said.

Schmidt and graduate student Joo Won Lee didn't intend to turn an established rule of food science on its head. But they began to suspect that something was amiss when they couldn't get a constant for in the work that they were doing.

"In the literature, the melting point for sucrose varies widely, but scientists have always blamed these differences on impurities and instrumentation differences. However, there are certain things you'd expect to see if those factors were causing the variations, and we weren't seeing them," Schmidt said.

The scientists determined that the melting point of sugar was heating-rate dependent.

"We saw different results depending on how quickly we heated the sucrose. That led us to believe that molecules were beginning to break down as part of a kinetic process," she said.

Schmidt said a true or thermodynamic melting material, which melts at a consistent, repeatable temperature, retains its chemical identity when transitioning from the solid to the liquid state. She and Lee used high-performance liquid chromatography to see if sucrose was sucrose both before and after "melting." It wasn't.

"As soon as we detected melting, decomposition components of sucrose started showing up," she said.

To distinguish "melting" caused by decomposition from thermodynamic melting, the researchers have coined a new name—"apparent melting." Schmidt and her colleagues have shown that glucose and fructose are also apparent melting materials.

Another of Schmidt's doctoral students is investigating which other food and pharmaceutical materials are apparent melters. She says the list is growing every day.

Having disposed of one food science mystery, Schmidt plans to devote time to others. For instance, staling intrigues her. "We could ship a lot more around the world if we could stabilize it, keep it from getting stale," she said.

Or there's hydrate formation, which can make drink mixes clumpy if they're open for a while. "We've observed the results—clumping under conditions of low relative humidity—but we really don't know why it happens," she noted.

Schmidt said that new instruments are making it possible to probe some of the processes scientists have taken for granted in a way they couldn't do before.

Explore further: Researchers study how ice melts in contact with soil

More information: Four studies describing Schmidt's research have been published in recent issues of the Journal of Agricultural and Food Chemistry.

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5 / 5 (1) Jul 26, 2011
Decomposes in your mouth, not in your hand.
1 / 5 (2) Jul 26, 2011
yummy that's just what we all need, more untested chemicals in our diet from special melting. Remember popcorn workers lung? Oh yeah food science is so great, I prefer to stick with what mother nature gave us to begin with. You know, good natural organic foods that were totally ruined and now charged a premium for by big industry? What did people ever eat before these pirates got their stranglehold over our food supply? (sarcasm). Keep your fake, plastic food.
5 / 5 (1) Jul 26, 2011
...Did you, um, read the article, stealthc? Melting (or, given this information, "melting") sugar is not some diabolical exercise in food perversion carried out by mad culinary scientists; it's just another food preparation technique, and it's been used for hundreds of years. All that these researchers have done is looked more closely at the process, and figured out what's actually going on, chemically speaking, in such evil and high-tech products as caramel and granny's molasses cookies. Would you have preferred to have been left ignorant?
5 / 5 (1) Jul 27, 2011
And they are making things less dangerous by doing the cooking at lower temperatures, if you got that far Stealth. They are not making yet another fake sweetener.
5 / 5 (1) Aug 02, 2011
This makes sense if you think about it. Sugar comes from a plant and plants decompose. It makes no difference if it is in crystalline form it is still from something that was alive at one time.
5 / 5 (1) Aug 02, 2011
Who ever thinks this is a strange untested chemical did not understand the article and should not comment. ERRR DUHHHHH

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