A tenderizer is a tool, ingredient, or preparation used to break down the tough connective tissue and muscle fibers in meat so it is easier to chew. Tenderizers fall into three broad categories: mechanical, enzymatic, and acidic.
Mechanical tenderizers are physical tools, such as meat mallets, tenderizing hammers, or needle/blade tenderizers that pierce the meat to sever fibers. Pounding or scoring meat with a mallet or the flat of a blade to improve texture is a practice found across many cuisines, though the specific tools vary by tradition.
Enzymatic tenderizers are proteins that break down collagen and muscle fibers, most commonly papain (from papayas) or bromelain (from pineapples). These enzymes are the active ingredient in commercial powdered meat tenderizers and occur naturally in marinades or rubs made with those fruits.
Acidic tenderizers, such as citrus juices, vinegar, or wine, denature protein at the meat's surface when used in a marinade. This softens the exterior but, unlike enzymatic tenderizers, does not meaningfully penetrate to tenderize deeper muscle fibers, and prolonged exposure can leave the surface mealy rather than tender.
Tenderizers are used mainly on tough cuts of meat, such as beef chuck, pork shoulder, or lamb shanks, ahead of quick, dry-heat methods like grilling or pan-searing that don't otherwise give collagen time to break down. Slow cooking methods such as braising achieve a similar effect through heat and time alone, without a separate tenderizer.
Household and commercial use of tenderizers is common wherever tough or lean cuts of meat need to be made palatable for quick cooking, from stews and pan-seared steaks to cube steak or chicken-fried steak, where mechanical tenderizing is used to prepare the meat before cooking.