Things you might not have known about pineapples.
Pineapples contain bromelain which breaks down protein therefore the juice can be used as a marinade or meat tenderiser.
It can also be used as an anti inflammatory agent.
As I have stated, Bromelain helps to digest protein. There is some evidence that bromelain supplements may reduce swelling, bruising, inflammation and pain after surgery and injury
Digestion

Bromelain is a popular natural digestive aid due to it's ability to digest proteins. It's used for bloating, gas and other digestive symptoms and for conditions such as irritable bowel syndrome. Bromelain is often used alone or in combination with other enzymes such as lipase, which digests fats, and amylase, which digests starch. There is little research, however, on the safety or effectiveness of bromelain for digestion.