papain Proteolytic enzyme from the juice of the pawpaw (Carica papaya) used in tenderizing meat; sometimes called vegetable pepsin. The enzyme is obtained as the dried latex on the skin of the fruit by scratching it while still on the tree, and collecting the flow. In the tropics meat is often tenderized by wrapping in pawpaw leaves.

The rate of reaction is slow at room temperature, increasing to maximum activity at 80 °C and rapidly inactivated at higher temperatures; hence, papain continues to tenderize the meat during the early stages of cooking.

pa·pa·in / pəˈpā-in; -pī-/ • n. a protein-digesting enzyme obtained from unripe papaya fruit, used to tenderize meat and as a food supplement to aid digestion.

papain A protein-digesting enzyme (see protease) occurring in the fruit of the West Indian papaya tree (Carica papaya). It is used as a digestant and in the manufacture of meat tenderizers.