Meat tenderizers are proteolytic enzymes or proteases, enzymes specialized in breaking the peptide bonds between amino acids found in complex proteins. Meat is held together by a complex protein called collagen, and aside from mechanical tenderization and cooking, enzymes are the only other available meat tenderizers. Meat is often tenderized before cooking, to make it less tough and more suitable for consumption.

Meat tenderizers often come in a powdered form that can be sprinkled directly on the meat. Meat tenderizers dissolve some of the sinewy connections within the meat at room temperature. If meat tenderizers are allowed to act for too long, the meat can become squishy and lose its special texture.

The most popular meat tenderizer, called bromelain, is composed of a number of protease enzymes and harvested commercially from the stems of pineapple plants, where it is concentrated. The substance can be found throughout the entire plant, but is harvested from the stems because they are usually not consumed and are therefore available to be processed. Besides being a meat tenderizer, bromelain is an excellent anti-inflammatory agent, blocking metabolites that cause swelling. It has been used effectively to treat sports injuries and swelling caused by arthritis.

Papain, extracted from the papaya, is another popular meat tenderizer. Less well-known are actinidin, from the kiwi, and ficin, from the fig. In the past, meat tenderizers were injected directly into living animals, but today this is viewed as both inhumane and unnecessary. Most ranches do not put their meat through a tenderization process, leaving that instead to the preferences of consumers in the home.

If pure meat tenderizers are put in the mouth, they cause a tingling sensation but are not especially harmful. Meat tenderizers are a common ingredient in marinades. If sprinkled on top of uncooked meat, they independently penetrate the meat within minutes.