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5 December 2013 11:26 am ,
Vol. 342 ,
An animal rights group known as the Nonhuman Rights Project filed lawsuits in three New York courts this week in an...
Researchers have been hot on the trail of the elusive Denisovans, a type of ancient human known only by their DNA and...
Thousands of scientists in the Russian Academy of Sciences (RAS) are about to lose their jobs as a result of the...
Dyslexia, a learning disability that hinders reading, hasn't been associated with deficits in vision, hearing, or...
Exotic, elusive, and dangerous, snakes have fascinated humankind for millennia. They can be hard to find, yet their...
Researchers have sequenced and analyzed the first two snake genomes, which represent two evolutionary extremes. The...
Snake venoms are remarkably complex mixtures that can stun or kill prey within minutes. But more and more researchers...
At age 30, Dutch biologist Freek Vonk has built up a respectable career as a snake scientist. But in his home country,...
- 5 December 2013 11:26 am , Vol. 342 , #6163
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Soft Drink Secrets
9 November 1998 7:30 pm
When a clear, fruity soft drink called Orbitz appeared on supermarket shelves 2 years ago, consumers marveled at the dozens of tiny gelatinous spheres suspended in the liquid that spin around when the bottle is shaken. While Orbitz's manufacturer, Clearly Canadian Beverage Corp., attributes the trick to an equal density between the spheres and the liquid, a team of chemical engineers now has a more sophisticated answer. At last month's annual meeting of the Society of Rheology, scientists said the Orbitz liquid has the unusual property of being much more viscous at rest than in motion.
When he first encountered Orbitz, Skip Rochefort, a chemical engineering professor at Oregon State University, Corvallis, tested the equal density explanation by adding enough alcohol to the drink to lower the liquid's density by 20% to 30%. The beads, however, remained suspended. Puzzled, Rochefort teamed up with local high school student Jason Hower to carefully extract the spheres and test the fluid's viscosity. The two then discovered the secret to Orbitz: When the fluid is in motion, its viscosity is roughly the same as water and the balls can move freely. But at rest, the liquid's viscosity is 100,000 times higher, keeping the spheres suspended and immobile.
Rochefort explains this phenomenon by pointing to the behavior of molecules of xanthan gum and gallan gum, two of the drink's ingredients. These long molecules, he explains, bind weakly to each other to form a spiderweblike network in liquid that holds the balls in place--a phenomenon few beyond Orbitz's creators understood. But once shaken the bonds are broken and the web disintegrates, he says.
Rochefort's description is essentially correct, says Ross Clark, a rheologist from Kelco, the company that makes the Orbitz ingredients. But Orbitz really shouldn't be thought of as a futuristic fluid, he adds: "There's been a lot of fuss over what is a relatively simple material."