Why does the enzyme in pineapples soften both steak and your tongue?

It’s summertime. Your in-laws are lounging on the back patio, the kids are splashing through the sprinkler, and you’re confidently managing the grill, flipping steaks as if you were born for it.

Before long, you stack the steaks high on a serving platter. "Dinner's ready!" you shout. Your family and friends line up, filling their plates with your famous steaks, still sizzling hot.

As your guests take their seats, you stand off to the side, eagerly watching them take their first bite, trying to read their faces. The feedback is not what you hoped for. Like a dog trying to pry a sock from your clenched fist, your guests struggle to tear off bite-sized pieces of meat. Aunt Pat is the first to speak up. As usual.

Aunt Pat grumbles, "I've had jerky that's more tender than this steak!"

As everyone turns to look at you, the chef, two things become clear: One, Pat is clearly not your favorite aunt, and two, you didn't tenderize the steak properly before cooking it.

Collagen is to blame for your tough steak. This protein forms long strands that hold the steak together. It's like the "glue" of tissue in both cows and humans, providing structure to muscle tissue. Collagen is a key component of tendons, ligaments, and other connective tissues.

­

The tenderizing process helps break down the collagen for a more enjoyable meal. You can tenderize the meat in several ways: by using a wooden or steel mallet, allowing the meat to age and naturally break down, sprinkling on powdered tenderizer, or using an electric or mechanical tenderizer. For the adventurous, some cooks even tenderize meat underwater with shock waves created by explosions.

Or, forget the explosives and use a fresh pineapple. Specifically, bromelain, an enzyme most concentrated in the pineapple’s stem. This enzyme not only breaks down the tough fibers of meat but can also irritate a human tongue. But how does it do that? Can it also dissolve your fingerprints? And why did you invite Aunt Pat to your cookout? We’ll answer at least two of these questions in the next section.

Bromelain: The Protein's Worst Enemy

Columbus first encountered pineapples in 1493, though they were not native to the Caribbean islands he visited [source: Kew]. Despite being associated with Hawaii, this spiky, sweet fruit actually originates from Brazil.

In the 1890s, scientists began isolating and studying bromelain, a natural enzyme blend of two proteases (protein-digesting enzymes) found in pineapples. They found that bromelain is highly effective at breaking down proteins like the collagen in steak and even the tissue in your tongue.

While bromelain is present throughout the pineapple, it is most concentrated in the stem. Most commercially produced pineapple is sliced, canned, or juiced, leaving behind remnants rich in this potent enzyme. This is then extracted and turned into a powder. Bromelain powder is used not only for tenderizing meat, but also for reducing inflammation, treating swelling, aiding digestion, and even managing excessive blood clotting.

Bromelain works effectively in these ways because it has the ability to break apart amino acids. Amino acids are organic compounds found in living cells. When they link together, they form peptide bonds, connecting one amino acid's amino group to another's carboxyl group. These peptide bonds create proteins, which carry out essential functions in cells, tissues, and organs.

This compound separates the vital peptide bonds that hold proteins in collagen together. Since collagen gives muscle tissue its shape, when it breaks down, the tissue loses its firmness. If meat were left for a day or two with bromelain on it, it would become so mushy that you wouldn't want to eat it. However, if used just before cooking, bromelain softens the steak, making it easy to chew while still keeping its texture intact for flavor. The heat from cooking at around 158°F (70°C) neutralizes the enzymes, halting their action once the meat is done.

But bromelain’s effects aren’t limited to steak. If you place a fresh slice of pineapple in a cup of Jell-O while it cools (after the gelatin has dissolved in boiling water), the mixture will stay liquid instead of setting into its usual gel form. This happens because bromelain breaks down the gelatin, preventing it from forming a solid structure.

So what about your tongue? Does it undergo the same process as the steak when you eat pineapple? Yes, but it doesn’t last long. Just like with the steak, bromelain starts breaking down the peptide bonds that form proteins from amino acids. The good news is that your tongue regenerates its cells, so there's no permanent harm. Once you finish the pineapple, your body metabolizes the bromelain, rendering it harmless soon after consumption.

After years of cutting and harvesting pineapples, workers' hands suffer significant wear. It was once believed that prolonged bromelain exposure could permanently erase fingerprints, but this isn't the case. Unless the finger is severely damaged, such as through a deep burn, your fingerprint will always regenerate after an injury.