It's summer. The in-laws are gathered around your back patio, the kids are running through the sprinkler and you're proudly working the grill, flipping steaks like a pro.
Soon, you pile the steaks high onto a serving plate. "Come and get it!" you call out. Your family and friends file by, loading their plates with your signature steaks, still sizzling.
As the guests take their seats, you stand back and watch as they take their first bite, carefully gauging their reactions. The news isn't good. Like a dog trying to pull a tube sock out of your clenched fist, your guests tug and strain at their meat, unsuccessfully trying to tear off bite-size pieces. Aunt Pat is the first to complain. Always.
"I've had beef jerky more tender than this steak!" Aunt Pat grumbles.
As all eyes fall on you, the chef, two things become apparent. One, Pat isn't your favorite aunt, and two, you failed to properly tenderize the steak before cooking it.
You can thank collagen for your tough steaks. These long strands of protein hold the steak together. Collagen essentially acts as the "binding" of the tissue in vertebrates like cows and people, providing muscle tissue with its structure. Collagen is a primary component of tendons, ligaments and other connective tissues.
The tenderizing step breaks down this structural binding for your eating enjoyment. You can achieve this effect in several ways. Beating it with a wood or steel tenderizing-mallet or carefully aging the meat so that its natural enzymes break down the muscle tissue pose two options. In addition, you can sprinkle on some powdered meat tenderizer or pierce the meat with an electric or mechanical tenderizer. Adventurous cooks can even place the meat underwater and tenderize it with shock waves produced by underwater explosives.
Or, you can set aside the explosives and use a fresh pineapple, specifically an enzyme found most abundantly in the pineapple's stem: bromelain. Not only will bromelain degrade the meat's tough fibers, it can also eat away at a human tongue. How does it do this? Can it dissolve your fingerprints, too? Why did you invite Aunt Pat to your cookout? Find out the answers to at least two of these questions in the next section.
Bromelain: Enemy of Proteins Everywhere
Columbus first laid eyes on a pineapple in 1493, although pineapple wasn't native to the Caribbean islands where they met [source: Kew]. Though commonly thought of as a traditional Hawaiian food, the sweet, spiky fruit originally hails from Brazil.
In the 1890s, researchers began isolating and studying bromelain, a natural mixture of two proteases (protein-digesting enzymes) found in pineapples. They discovered that bromelain is quite effective at dividing proteins such as the collagen in steak, as well as in your tongue.
Although bromelain is found in every part of the pineapple, it's most plentiful in the stem. Most commercially grown pineapple is sliced, canned or juiced. The remains are rich with this corrosive substance, which is then extracted. Powdered bromelain is used for tenderizing meat, as well as treating inflammation, swelling, indigestion and even excessive blood clotting.
Bromelain works in these capacities due to its ability to separate amino acids. Amino acids are organic compounds within living cells. Amino acids join by forming peptide bonds, a link that connects one amino acid's amino group with the carboxyl group of another amino acid. When amino acids join through peptide bonds, they form proteins. These proteins then carry out numerous functions in the structure and operation of cells, tissues and organs.
The compound separates the all-important peptide bonds that link the proteins in collagen. Since the collagen gives the muscle tissue its shape, once it's broken down, the muscle tissue begins losing firmness. If you left meat for a day or two covered with bromelain, it would be noticeably mushy, so much so that you wouldn't want to eat it. When used shortly before cooking, however, bromelain efficiently softens the steak for chewing, but leaves it firm enough to enjoy its taste. The enzymes are neutralized by heat of about 158 degrees Fahrenheit (70 degrees Celsius), so they stop working once cooked.
Pineapple's secret ingredient works on more than just steak though. If you place a fresh slice of the fruit inside a cup of Jell-O as it cools (the final step after dissolving powdered gelatin into boiling water), the solution will remain liquid, instead of "gelling," as it normally would. This is because bromelain breaks down gelatin, leaving it unable to hold a structural form.
But what about your poor tongue? Is it subject to the same degradation that steak is when you eat pineapple? Yes, but not for long. The process for "tenderizing" your tongue is the same as in the steak -- the bromelain begins to separate the peptide bonds that build amino acids into proteins. The good news is that your tongue regenerates these cells, so you won't be left with permanent damage. Once you have consumed the pineapple (or bromelain), your body begins metabolizing it and soon renders it harmless.
After years of harvesting and cutting pineapples, workers' hands undergo great damage. It was once thought that bromelain exposure gradually erased fingerprints, but this isn't true. Unless the finger itself is essentially destroyed through severe burning, for example, your fingerprint will always return after a hand injury.
If all this talk of pineapple and steak leaves you hungry for more, explore the links on the next page.
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More Great Links
- American Cancer Society. "Bromelain." June 26, 2007. (July 30, 2008) http://www.cancer.org/docroot/ETO/content/ETO_5_3X_Bromelain.asp?sitearea=ETO
- Cancerweb. "Proteases." Dept. of Medical Oncology, University of Newcastle upon Tyne. Nov. 14, 1997. (July20, 2008) http://cancerweb.ncl.ac.uk/cgi-bin/omd?proteases
- Duke, James A. "Handbook of Energy Crops." Purdue University; Center for New Crops & Plants Products. 1983. (July 30, 2008) http://www.hort.purdue.edu/newcrop/duke_energy/Ananas_comosus.html
- Gustavson, Paul K.; Richard J. Lee; George P. Chambers; Morse B. Solomon and Brad W. Berry. "Tenderizing meat with explosives." American Physical Society, Shock Compression of Condensed Matter Meeting, June 24-29, 2001. June 2001. (July 30, 2008) http://adsabs.harvard.edu/abs/2001APS..SHK.H1047G
- KEW, Royal Botanic Gardens. "Pineapples and other Bromeliads." (July 23, 2008) http://vegmad.org/ksheets/pineapple.html
- Kress, Henriette. "Pineapple. Ananas sativa." Excerpt from "The Dispensatory of the United States of America, 1918." Joseph P. Remington, Horatio C. Wood et al., eds. http://www.henriettesherbal.com/eclectic/usdisp/ananas.html
- "Tenderizing Meat." Allied Kenco. (July 30, 2008) http://www.alliedkenco.com/catalog/popup_text.php/fld/howto/tbl/howtos/key/25