Papain's protease activity is also used to tenderize meat.
Papain is a sulfhydryl protease enzyme derived from pineapples and papayas (Carica papaya). Papain is used in a wide variety of enzymatic formulations, and as a digestive aid is sometimes called "vegetable pepsin".
As any enzyme, papain is often expressed in units of activity. Common unit types include: FCC or N.F. units, milk-clotting units (MCU), gelatin-digestion units (GDU) or casein digestion units (CDU). Papain is listed in both the N.F. and U.S.P.
Severe irritation to the skin is not uncommon when used topically.