To tenderize meat, you can choose from three main methods: mechanical, enzymatic and thermal tenderization. For mechanical tenderizing, pound the meat with a mallet to break up the tough connective tissues. This method also breaks down the fibers of the meat, leaving it thinner and flatter than it was originally.
While mechanical tenderizing works well for dishes such as chicken fried steak or wienerschnitzel, which use thin and tender cuts as the star of the dish, it isn't as ideal for producing a great steak or meat on the grill.
Enzymatic tenderizing relies on special molecules that help break the collagen in the meat down quickly without interfering with the integrity of the meat itself, leaving you with tender, flavorful meat. Adding fruits such as kiwi, papaya or pineapple to the marinade provides the enzymatic action necessary for tenderizing tough cuts of meat. The bromelain in pineapple can make the meat mushy if it's left marinating too long, so use pineapple only for quick marinades. Kiwi contains actinidin, which breaks the tough tissues down without leaving the meat mushy. Add 1 to 2 tablespoons of pureed kiwi to each cup of marinade.
Thermal tenderizing relies on the slow application of heat to break the collagen in the meat down to optimize the texture. This works best for meat that contains plenty of collagen, such as brisket, chuck roasts or ribs.