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Science Demonstration of
Enzyme Bromelain
Why Fresh Pineapple Cannot Be Used in Jell-O
Denaturing an Enzyme
Enzymes are primarily made of proteins, large organic molecules with distinct three-dimensional shapes. The shape of enzymatic proteins is important in allowing the enzyme to work properly, because the place on the enzyme where the substrate binds to the enzyme (the active site) fits like a lock and a key. If the shape of the active site (the lock) changes, the substrate that the enzyme alters (the key) won’t fit.
Deactivating an enzyme by changing its shape is called denaturation.
Article Summary: Have you even tried to make Jell-O with fresh pineapple in it? If so, you've been disappointed. Here's why, with a simple classroom demonstration for teaching about enzymes.
Science Demonstration of the Enzyme Bromelain
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Bromelain Experiment: Container on left is Jell-O made with canned pineapple (gelatin is set). Container on right is Jell-O made with fresh pineapple (gelatin is liquid).
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The effect can be achieved several ways, including:
- exposing the enzyme to high temperatures
- changing the pH
- non-competitive inhibition, where another chemical binds to the enzyme, changing the shape of the active site
Fresh Pineapple and Jell-O™
Jell-O™ is made of gelatin, a processed version of a structural protein called collagen, found in the skin and bones of animals. Although Jell-O™ is sometimes eaten plain, fruit can also be added. When that fruit is fresh pineapple,the Jell-O™ will not solidify.
Pineapple contains the enzyme bromelain, which can digest collagen protein. Adding fresh pineapple to Jell-O™ allows the bromelain to break down the gelatin’s collagen, and the Jell-O™ will not set upon cooling.
If instead of fresh pineapple, canned is used (cooked as part of the canning process), the bromelain is denatured by the heat and cannot facilitate the breakdown of collagen. Using canned pineapple allows the gelatin to firm and set.
Page last updated:
1/2016
