If you add certain fruits to Jell-O or other gelatin desserts, the gelatin won't set up. Here's a look at which fruits have this effect and what happens that causes them to ruin Jell-O.
Fruits That Ruin Jell-O
The fruits that ruin Jell-O contain enyzmes called proteases which break the chemical bonds that try to form between chains of protein as Jell-O or other gelatin tries to gel.
- pineapple - bromelain
- kiwi - actinidin
- figs - ficain
- papaya - papain
- pawpaw - papain
- ginger root
Only Fresh Fruit Causes a Problem
You may have had Jell-O that contained pineapple or another of the fruits on the list. This is because the enzymes in the fruit only disrupt the gelling process if the fruits are fresh or frozen. If the fruit is heated (e.g., canning or cooking) then the enzymes are permanently inactivated, making the fruit perfectly fine for making Jell-O.