Fruits That Ruin Jell-O and Other Gelatin Desserts

Fruits That Ruin Gelatin
Some fresh fruits contain enzymes called proteases that break apart collagen strands and prevent Jell-O and gelatin from setting.

If you add certain fruits to Jell-O or other gelatin desserts, the gelatin won’t set. Here’s a look at which fruits ruin Jell-O, why they cause a problem, and what you can do to prevent it from happening.

Fruits That Prevent Gelatin From Setting

Jell-O and other types of gelatin contain collagen. Hot water hydrates the collagen strands so they form a mesh that holds liquid in a semi-solid shape upon cooling. But, some fruits contain enzymes called proteases that break proteins like collagen. The strands are too short to form a mesh, so the gelatin doesn’t set.

Fresh pineapple is the fruit best-known for preventing gelatin from setting, but there are other ingredients to avoid adding to Jell-O. Here is a list of ingredients that ruin Jell-O and the enzyme they contain:

  • Pineapple – bromelain
  • Kiwi – actinidin
  • Papaya – papain
  • Figs – ficain
  • Pawpaw – papain
  • Mango – actinidain
  • Guava
  • Ginger root

Using Pineapple in Jell-O

You can still use pineapples, kiwis, and other fruit from the list, but first you need to inactivate the enzymes within them. Prolonged heating degrades the enzymes, so cooked or canned pineapple works in Jell-O. Freezing does not denature enzymes, so expect frozen pineapple to ruin gelatin.

Fresh Fruits to Add to Jell-O

While a few fresh fruits cause problems with Jell-O and other forms of gelatin, most fruits are fine. Enjoy adding apples, peaches, plums, oranges, strawberries, raspberries, and blueberries to your gelatin recipe. Bananas contain the enzyme actinidain, but it’s not present in high enough amounts to cause a problem.

Can You Freeze Gelatin?

Fruit enzymes aren’t the only way to ruin gelatin. Don’t freeze Jell-O or gelatin because ice crystals break the collagen matrix, too. Freezing set gelatin typically results in a half-set mess, that’s partly leathery and partly liquid. Just don’t!

Experiments With Fruit and Gelatin

Experimenting with fruit is a fun way to discover which ones contain proteases.

  • Experiment with different types of fresh fruit to see if you can tell which ones contain proteases.
  • See whether fresh pineapple affects gelatin after it has already set. Compare the effects of a ring of fresh pineapple to a ring of canned pineapple.
  • Test whether adding meat tenderizer ruins gelatin. Meat tenderizer contains proteases. Does heating meat tenderizer before adding it to gelatin inactivate it and allow gelatin to gel? Does freezing meat tenderizer before use have any effect?
  • See whether fresh pineapple causes a problem with similar products, such as agar, konjac, pectin, or carrageenan.


  • Barrett, A.J.; Rawlings, N.D.; Woessnerd, J.F. (2004). Handbook of Proteolytic Enzymes (2nd ed.). London, UK: Elsevier Academic Press. ISBN 978-0-12-079610-6.
  • Chittenden, R.H.; Joslin, E.P.; Meara, F.S. (1892). “On the ferments contained in the juice of the pineapple (Ananassa sativa): together with some observations on the composition and proteolytic action of the juice.” Transactions of the Connecticut Academy of Arts and Sciences. 8: 281–308.
  • Hale, L.P.; Greer, P.K.; Trinh, C.T.; James, C.L. (April 2005). “Proteinase activity and stability of natural bromelain preparations.” International Immunopharmacology. 5 (4): 783–793. doi:10.1016/j.intimp.2004.12.007
  • van der Hoorn, R.A. (2008). “Plant proteases: from phenotypes to molecular mechanisms.” Annual Review of Plant Biology. 59: 191–223. doi:10.1146/annurev.arplant.59.032607.092835