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Why Does Pineapple Ruin Jell-O?


Bromelain is the chemical that keeps gelatin from gelling.

Bromelain is the chemical that keeps gelatin from gelling

Dean Belcher/ Photodisc/ Getty Images

Question: Pineapple and Jell-O

Have you heard that adding pineapple to Jell-O or other gelatin will prevent it from gelling? It's true. The reason pineapple prevents Jell-O from setting is because of its chemistry.

Answer: Pineapple contains a chemical called bromelain, which contains two enzymes capable of digesting proteins, which are called proteases. Jell-O and other gelatins get their structure from links formed between chains of collagen, which is a protein. When you add pineapple to the Jell-O, you break the links as fast as they form, so the gelatin never sets up. 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.

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