The word "tenderness" might make you think of candy and flowers, a special song or a romantic dinner, but in the kitchen, "tenderness" isn't quite so romantic. It describes the texture of meat. Today's A Moment of Science asks, what makes meat "tender"?
Tenderness can depend on the cut of the meat. But chemical tenderizers can give any cut a more tender texture. One popular tenderizer is papain, which comes from the papaya tree. Papain works by breaking down meat proteins using a chemical process called hydrolysis.
Meat proteins are very large molecules. In hydrolysis, hydrogen atoms and hydroxide molecules attach themselves to the larger meat protein molecules and break the large proteins down into smaller molecules. The resulting smaller meat proteins have a softer texture.
Papain's ability to break down proteins has other uses besides meat tenderizing. It is used in enzyme-cleaning solutions for contact lenses and in medicated ointments used to treat severe wounds.
Of course, there are other ways to tenderize meat without using chemicals. You can simply use a meat mallet to break down the large protein molecules by beating them into smaller pieces, but this method won't work, as papain does, on both meat and contact lenses.