Geekery

Jelly experiment

Posted on 01. Jun, 2009 by Jake in Experiments

Dave Ansell, kitchen scientist, explains the science of jelly.

His experiment is pretty straightforward: make some jelly, according to the manufacturers instructions and add a bunch of fruit. Leave to set.
Among the fruits they used were fresh and tinned pineapple. The jelly containing fresh pineapple didn’t set properly, while the tinned pineapple jelly set just fine.

This experiment is fun, but hardly spectacular.

The interesting bit is in the explanation.

How does jelly set? Jelly is made of strands of protein molecules, which become entangled when they cool. This surrounds the water to produce solid, if wobbly, jelly.

But some fruit contain enzymes which break down proteins. Our own digestive systems break down proteins in a similar way. These enzymes break down the protein fibers in the jelly into strands that are too short to tangle properly and to allow the jelly to set.

The canned pineapple, however, has been heated to preserve it (by killing any germs inside the tin). The heat also denatures the enzymes, making the canned pineapple suitable for jelly use.

Check out Ansell’s protease & pineapple illustrations to better understand the process.

In a future experiment, I will be adding large quantities of vodka to the jelly and then consuming the finished product. This is purely in the interests of science, and is recommended only for professionals. Do not try this at home, unless you really want to.

Tags: jelly experiment, jelly science