Pineapple is a fruit that pairs well with beef, pork, chicken and some types of fish. While imparting a great deal of flavor, pineapple juice helps tenderize tough cuts of meat. The enzyme in pineapple, bromelain, digests protein, softening the tissues in meat before cooking it. The juice also imparts a rich, tart flavor to meat that many people like. The easiest way to tenderize with pineapple is to buy a fresh one and extract the juice from it by using a small kitchen appliance to pulverize it. Most juice manufacturers pasteurize the juice, a process that kills the enzymes that tenderize the protein found in meat.
Place a cutting board on a flat surface. Wash the pineapple and cut off the green top and the bottom by laying the pineapple on its side and applying pressure on the knife. Depending on how firm the pineapple is, you may need to use a back and forth motion to remove the top.
Stand the pineapple back up and use the knife to remove the skin. Remove the eyes left on the pineapple by using the tip of a paring knife or potato peeler to dig them out.
Rinse the pineapple and the cutting board. Place the pineapple bottom-end up on the cutting board and cut the sides away from the core of the pineapple, a pithy part of the fruit that has little juice.
Dispose of the center of the pineapple and cut the remaining fruit into pieces that will fit in your juicer, blender or food processor. Process the fruit pieces until you have enough juice to marinate the cut of meat you want to tenderize. If you do not have any of these appliances, you can cut the pineapple into small pieces to marinate the meat.
Put the meat you want to tenderize in a shallow pan and pour the juice or diced pineapple over the meat. If the meat is too thick to cover completely, turn the meat as you marinate it to tenderize all sides. Refrigerate until you are ready to cook. Since the acids in pineapple are strong, do not marinate the meat more than 12 hours, or the acids themselves will start to cook the meat.