The Grapevine

Tootsie Pop Mystery Solved: How Many Licks It Takes To Get To The Center, Based On Science

Tootsie pop commercial with Mr. Owl
It takes this many links to get to the Tootsie roll center of a Tootsie pop, and it’s a lot more than three. Time

“How many licks does it take to get to the center of a Tootsie pop?” This has been one of the confectionery world’s most puzzling questions even the wise Mr. Owl could not answer in the classic 1970 TV commercial. But now the world finally knows the licks it takes to get you to the lollipop’s Tootsie roll center, and hint: It’s more than just three, according to a recent study published in the Journal of Fluid Mechanics.

Science has answered the age-old question by identifying the complex process by which materials are shaped and ultimately dissolved as a result of surrounding water currents. "How flowing fluids generate unique shapes through erosion or dissolution is complex and fascinating," said Leif Ristroph, senior author of the study and an assistant professor at New York University (NYU) Courant Institute, according to Science Daily. Knowing this, NYU and Florida State University scientists formulated a theory for how flows cause dissolving and shrinking, which led them to find the long-sought answer to the childhood Tootsie pop question.

The researchers immersed cooked up hard candy — measuring about 2 inches — on a water current during various experiments conducted in NYU's Applied Math Lab. Shapes such as spheres and cylinders were then placed in a water tunnel that allowed for washing these shapes by well-controlled flows. The candy’s changing shape was captured using time-lapse photography to formulate a theory for how flows affect dissolving.

The findings reveal a peculiar but consistent shape emerges and then persists before eventually vanishing. This same shape or “sculpture” is seen regardless of the candy’s initial form and the speed of the water flow. Applying this theory to a lollipop, researchers found it takes an estimated 1,000 licks to get to the center, while it takes 2,500 licks to get to the center of a Tootsie pop, Time magazine reported. The difference in licks is mainly due to a Tootsie pop’s diameter size: 1.063 inches. While the Tootsie pop finding is the most impressive for those who were curious, the theory can be used for research in geology and pharmaceutical science.

A similar study from Purdue University found it takes a lot less to get to the Tootsie pop’s center. A group of engineering students used a licking machine, modeled after a human tongue, to determine the average number of licks it takes to reach the center. They also conducted a licking challenge-unassisted machine to use as a comparison. The findings revealed it took 364 licks with the licking machine, while it took an average 252 licks for each human volunteer.

Based on the wide range of results from these scientific studies, it's clear there remains a mystery when it comes to licks and reaching the Tootsie roll center of a Tootsie Pop. The only way to really know is to try it for yourself. Can you resist the temptation of biting your lollipop and tasting the Tootsie roll in the center, unlike Mr. Owl?

The world may never know.

Source: Huang JM, Moore MNJ and Ristroph L. Shape dynamics and scaling laws for a body dissolving in fluid flow. Journal of Fluid Mechanics. 2015.

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