Bromelin in Pineapples

In its natural state pineapple contains bromelin, an enzyme which breaks down protein. It is similar to the enzyme papain (made from papaya), which is used commercially as a meat tenderizer. The enzyme in the pineapple is so abundant and powerful that plantation and cannery workers have to wear rubber gloves to avoid their hands being eaten away. Meat marinated in fresh pineapple juice is not merely tenderized but likely to fall apart. Its activity is also responsible for the fact that a jelly made with fresh pineapple juice and gelatin will not set unless a gelling agent such as agar-agar is added. Bromelin is quickly destroyed by heating, so cooked or canned pineapple and juice have no active effect.