The science of LOLLIPOPS: Scientists reveal that it takes 2,500 licks to reach the centre of an average lolly


Scientists at New York University claim it takes 1,000 licks per cm of candy

  • They placed lollipops of different sizes and shapes into slow moving water
  • They took time lapse photographs as the lollipops dissolved in the flows
  • Each lollipop developed the same shape with a flat back and domed front
  • They claim their results can be used in industry and to explain rock erosion

Most children have tried to tackle an entire lollipop without crunching it, but few have succeeded.

Now scientists have managed to calculate quite how long it takes to achieve such a feat - and it's a lip-smacking 2,500 licks.

By placing a variety of boiled sweets into flows of water, researchers were able to watch how they dissolved over time.

They calculated that it would take around 1,000 licks of the tongue to dissolve 1cm (0.4 inches) of candy.

This means that the average Chupa Chups lolly - which measures around 2.5cm (one inch) in diameter - would take about 2,500 licks to dissolve.

Dr Leif Ristroph, a mathematician at New York University's Courant Institute of Mathematical Sciences who led the study, said lollipops also tend to be sculpted into similar shapes by the flow of liquid like saliva over the surface.

He said: 'We find that different initial geometries are sculpted into a similar terminal form before ultimately vanishing.

'How flowing fluids generate unique shapes through erosion or dissolution is complex and fascinating.

'As a whimsical application, this scaling allows us to address the following long-standing question: "How many licks does it take to get to the centre of a lollipop?".'

Dr Ristroph and his colleagues placed candy lollipops ranging from 1 cm to 10cm (0.4-4 inches) into flows of water moving between 0.22mph and 2.2mph.

The researchers used simple candy shapes such as spheres and cylinders, monitoring how they dissolved using time lapse photography.

They found that regardless of the initial shape of the candy and the speed of the water, it formed consistent shapes over time with about 1cm dissolving each hour.

The back of the lollipop, closest to the stick, flattens relatively quickly while the front stays dome shaped and any irregularities are smoothed away.

The front and back faces then slowly grow closer together as they dissolve away.

Writing in the Journal of Fluid Mechanics, the scientists said that turbulence created at the back of the lollipop helps to dissolve the back and make it flat.

While the action of a tongue on the candy may also alter the way a candy dissolves, the scientists say that reliably measuring this as it happens will be difficult.

Their findings do also have some serious applications with dissolution of materials being an essential process in many chemical and pharmaceutical industries.

It could also help to explain some of the processes that occur during erosion of rocks by rivers and the sea.