May 30, 2008
Researchers Create Bubbles That Last Up To A Year
U.S. researchers announced that they have created bubbles capable of lasting up to a year"”a finding that could greatly improve many consumer and industrial products.
Bubbles account for the airy texture in foods and cosmetic products, but smaller bubbles are more likely to pop due to gas pressure and surface tension.
But researchers at Harvard University have added a sugary coating to bubbles making them last up to 12 months at a time.
They said the idea came from a lecture by Dr. Rodney Bee, a chemist with the Anglo-Dutch company Unilever, who had been looking for a way to improve the texture of light ice cream.
Bee showed a slide of a special formation of extremely tiny bubbles he made during his research using a simple kitchen mixer.
The bubbles had tiny hexagon shapes all over their surface, resembling soccer balls, and were a micrometer in size (1-millionth of a meter).
Howard Stone, a Harvard professor, called Rodney's bubbles "extraordinary". "Small bubbles on that scale never last because of surface tension"”they instantly disappear."
Stone soon bought a kitchen mixer and Harvard University graduate engineering student Emilie Dressaire and colleagues began experimenting.
Dressaire mixed simple sugars and water that, whipped together, formed a foam with a crystalline structure that protected the bubbles from popping.
"The bubbles are fairly happy in it. We were able to keep them for a year," Dressaire said.
A coating made from sucrose stearate"”molecules that form armor around the bubbles"”kept them from popping.
"The lifetime is so long, which is the interesting part for industry," she said.
"The bubbles could be modified for other uses, including fortifying personal care products or as contrast agents for ultrasound imaging," said Dressaire.
The study received funding from Unilever, the popular maker of such foods as Hellmann's mayonnaise and Skippy Peanut Butter.
The bubbles could also be used to replace fat molecules in food products, such as ice cream.
The research was published in the journal Science.