Science, Tech, Math › Science Fruits That Ruin Jell-O and Other Gelatin Desserts Jell-O, Fruits, and Enzymes Share Flipboard Email Print Pineapple is the main fruit known to ruin gelatin, but other fruits also prevent gelling. laymul, Getty Images Science Chemistry Chemistry In Everyday Life Basics Chemical Laws Molecules Periodic Table Projects & Experiments Scientific Method Biochemistry Physical Chemistry Medical Chemistry Famous Chemists Activities for Kids Abbreviations & Acronyms Biology Physics Geology Astronomy Weather & Climate By Anne Marie Helmenstine, Ph.D. Chemistry Expert Ph.D., Biomedical Sciences, University of Tennessee at Knoxville B.A., Physics and Mathematics, Hastings College Dr. Helmenstine holds a Ph.D. in biomedical sciences and is a science writer, educator, and consultant. She has taught science courses at the high school, college, and graduate levels. our editorial process Facebook Facebook Twitter Twitter Anne Marie Helmenstine, Ph.D. Updated May 08, 2019 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. Key Takeaways: Fruits That Ruin Gelatin Some fresh fruits prevent Jell-O and other types of gelatin from gelling.These are fruits that contain high levels of proteases. Proteases are enzymes that break chemical bonds in proteins, such as collagen in gelatin.Pineapple, kiwi, papaya, mango, and guava are examples of fruits that cause a problem.Heat inactivates proteases, so cooking fruit before adding it to gelatin prevents any issue. Canned fruit has been heated, so it is also acceptable for use in gelatin desserts. 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 - bromelainkiwi - actinidinfigs - ficainpapaya - papainpawpaw - papainmangoguavaginger 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. Jell-O's versatility enabled it to be used in a wide variety of old fashioned recipes you won't believe people actually ate.