Scientists take the pop out of tiny bubbles
CHICAGO (Reuters) - The trouble with tiny bubbles is they pop, but U.S. researchers have made bubbles that last as long as a year -- a finding that could improve many consumer and industrial products, they said on Thursday.
Bubbles lend an airy texture to foods, cosmetics and other products, but the smaller the bubble, the more likely it is to shrink and pop, succumbing to gas pressure and surface tension.
By adding a sugary coating, Harvard University graduate engineering student Emilie Dressaire and colleagues reported in the journal Science that they made bubbles that could last up to 12 months.
They got the idea from a talk given in 2005 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 were a micrometer in size, which is 1-millionth of a meter. On their surface were scores of tiny hexagon shapes, making them resemble soccer balls.
"Small bubbles on that scale never last because of surface tension -- they instantly disappear. What Rodney showed on that screen was extraordinary," said Dressaire's Harvard professor, Howard Stone, in a statement.
Stone bought a kitchen mixer for his lab and Dressaire went to work.
She concocted a syrupy mixture of simple sugars and water. When whipped, that 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 in a telephone interview.
The bubbles have a coating made from sucrose stearate, molecules that form an armor around the bubbles.
"The lifetime is so long, which is the interesting part for industry," she said.
Dressaire said the bubbles could be modified for other uses, including fortifying personal care products or as contrast agents for ultrasound imaging.
They also could be used to replace fat molecules in food products, such as ice cream.
Unilever maker of such foods as Hellmann's mayonnaise and Skippy Peanut Butter, funded the study.
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