Reader Brandi writes in to ask why her recent attempt to make a fresh pineapple JELL-O ring ended in disaster. Brandi, the answer is that fresh pineapple contains an enzyme by the name of bromelain which is a protein-digesting enzyme, and gelatin is a protein. Canned pineapple will work in a JELL-O mold because the heat of the canning process denatures (chemistry talk for “messes up”) the bromelain enzymes.
I know what you’re thinking. Or at any rate I know what you might be thinking. Oh hell who am I kidding, you’re almost certainly not thinking it but I needed a transition. What on earth is a protein-digesting enzyme doing in a pineapple? It’s a good question, because really, what use does a fruit have for such a thing?
The answer is that nobody really knows. One theory is that late at night when nobody’s looking, pineapples nip out to burger joints to take advantage of off-hour discounts. Another holds that the enzyme is a defense mechanism designed to kill insects that eat pineapples. Yet another posits that bromelain irritates the stomachs of animals that eat pineapples. Not enough to deter the animal completely, since fruiting plants rely on animals to spread their seeds, but enough to discourage any single one from make a pig of itself at the buffet.
There is one other very interesting idea on the subject, specifically that fruit proteases (protein enzymes) are an example of cooperative relationships between plants an animals. How so? Because proteases, when they pass into the digestive system of an animal, kill and dissolve parasites like tapeworms. And that of course is a considerable benefit for any omnivore whose insurance doesn’t cover gastrointestinal disorders. But that’s really just a guess. In truth the mystery of the meat-digesting fruit has yet to be solved.