Pineapple contains a plant enzyme called bromelin that breaks down proteins.
Bromelin is used in many meat tenderizers for this purpose (and that's why cooking ham with pineapple
makes it tender).
JellO packages warn you not to put pineapple chunks
into the gelatin. Jello is a protein mesh with trapped pockets of liquid; the
bromelin cuts the protein chains and keeps the gelatin from jelling properly.
Why do pineapples produce an enzyme that tenderizes meat? It's a defense mechanism. The sap of the pineapple plant contains much higher concentrations of
bromelin and can cause severe pain if eaten.
Dr. Ron Rusay has written a simple experiment
to demonstrate protein degradation's role in kitchen chemistry.
Author: Fred Senese senese@antoine.frostburg.edu