At the supermarket, you can find all sorts of delicious Jell-O and even ones with bits of fruit in them. Jell-O is simply a brand name for gelatin, so we’ll try to refer to it as gelatin from now on. The chemical structure of gelatin is basically a mixture of peptides, or short polymers of amino acids, and proteins. Gelatin is a processed version of the protein collagen, which is found in the hooves, bones, and connective tissue of cows, horses, and pigs. The 3-D protein mesh that composes gelatin is fairly organized, and the holes of the mesh are filled with water. The result is a “jelly”-like substance, or something that is soft enough to cut yet rigid enough to hold its shape.
For desert, you might happen to want to eat a gelatin dessert with some fresh fruit. This certainly sounds delicious, but be careful about what fruit(s) you use! If you don’t want your gelatin dessert to dissolve into a puddle of colored water, don’t use pineapples, mango, or kiwi. All of these fruit contain the enzyme bromelain, which is a member of a special class of proteins called proteases. These proteins essentially eat through other proteins. Because the structure of gelatin is a protein mesh, mixing gelatin and bromelain leaves you with a soupy mess instead of an enjoyable treat.
You might even see this warning on Jell-O packets, such as the one below:
Fresh pineapples will certainly have bromelain proteins to break down the proteins in gelatin. Why not frozen ones though? Fresh frozen pineapples never lost their proteolytic abilities; the bromelain was still active, just frozen away temporarily. Canned pineapples are good though! Why? Because in their manufacturing preparation, the enzymes were denatured in order to enhance preservation. With these tips in mind, have fun making a successful and delicious jello!
Enjoy your dessert! (:
Author: Jonathan Yu