Illinois Scientists Discover Truth About Sugar

Mars' M&Ms have always had a catchy phrase "melts in your mouth, not in your hand." While the candy is quite delicious, Illinois scientists have discovered a half-truth about the melting adage.

You see, sugar doesn't melt; it decomposes. 

So says Shelly Schmidt of the University of Illinois. "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," says Schmidt, a University of Illinois professor of food chemistry.

Schmidt recently told the Institute of Food Technologists' 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 flavors 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.

Apparently Schmidt and graduate student Joo Won Lee didn't plant to refute an established rule of food science; however, they suspected something was off when they couldn't get a constant melting point for sucrose 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.

According to Schmidt, a true or thermodynamic melting material retains its chemical identity when it transitions 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."

"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.