Why is fresh pineapple not used in gelatin desserts?

Because cooking breaks down the enzyme in pineapple that causes it to not set properly. read more

Gelatin, which is a mixture of collagen proteins, solidifies when you cook it because its proteins form tangled mesh pockets that trap the water and other ingredients. After the gelatin cools, the proteins remained tangled. This results in your wiggly-jiggly gelatin dessert. The fruits listed above contain proteases, which are enzymes. read more

The enzymes in bromelain are inactivated once they have been heated to about 158° F (70° Celsius), so while fresh pineapple prevents Jell-O from gelling, gelatin made using canned pineapple (which was heated during the canning process) won't ruin the dessert. read more

Cooked or canned pineapple can be used in gelatin desserts, because the heat used in canning and cooking destroys the bromelain. More information: Go ahead and buy your fresh pineapple. Pineapple set with pure pineapple juice makes a beautiful jelly, and fresh pineapple tastes much better than canned. read more