It is traditional Turkish ice cream, known as Maras dondurma.
When prepared with the right ingredients and care, it becomes so elastic and pliable that Kirshenbaum says people have been photographed jumping rope with it.
“It’s like pulling taffy,” he says.
The two unusual Turkish ice cream ingredients, salep and mastic, probably contribute to the ice cream’s mysterious elasticity because they both contain polymers.
The main polymers in salep are glucomannans, which are chains of sugar units, and in mastic there are poly-beta-myrcene polymers.
Johnson, from Kirshenbaum’s lab, admits that you can make the ice cream without mastic, but she says that the dried resin gives it more stretchiness.
And some Turkish ice creams are stretchier than others, says Kirshenbaum.
Similarly, ice creams typically found here in the United States can have different consistencies depending on the amount of milk fat and protein, gums used as stabilizers, or other ingredients, says Karen Schmidt, a dairy science researcher at Kansas State University.