Good meat tenderizers improve the flavor of meat by releasing the bonds that hold tough protein fibers together. Tenderizing mallets and machines break meat fibers with mechanical force. Enzyme-based tenderizers use chemical action to separate the peptide and collagen bonds between amino acids.
Enzyme tenderizers employ basic biochemistry to begin the digestion process before meat cooks. Powdered enzymatic meat tenderizers often include bromelain from pineapples and papain from papayas. The juices from these fruits also function as a tenderizing marinade.
Mechanical tenderizing works by striking the meat with the spiked face of a hand-held mallet. People also use "blading” and “needling” machines to tenderize meat in large-scale processing plants. Consumer Reports recommends cooking all machine-tenderized meats beyond medium-rare due to the increased risk of E. coli.