Pineapples are intriguing plants. Contrary to what you might think, they don’t actually grow on a pineapple trees! Pineapples come from pineapple plants, which are bromeliads: spiky plants that grow on the ground.
Pineapples contain the protein-digesting enzyme called bromelain. Bromelain is also used as a meat tenderizer. In fact, some people are very sensitive to the enzyme and find that it makes their lips and tongue sore. This is because the bromelain is working to tenderize your tongue! Don’t worry—once it gets to your stomach, there shouldn’t be much of a problem.
Gelatin is made out of animal proteins, particularly collagen. When you add water to the gelatin, long chains of protein form, making an invisible protein “spaghetti”. Water gets trapped in the middle of these long chains, turning what should be a liquid into a semi-solid.
Since pineapple bromelain digests proteins, when the pineapple meets the gelatin, it begins to eat away at it. The long protein chains collapse, making everything watery again.
Try adding papaya, kiwi fruit, or figs to gelatin. Do you end up with the same problem? Here’s a hint: These plants also contain protein-digesting enzymes!