The papaya tree is indigenous to tropical America and is cultivated throughout the tropical world and warmer parts of the subtropics. On a large scale it is cultivated in India, Sri Lanka, Tanzania, Hawaii, Florida, Phillippines, South Africa and Australia.

Harvest

A large herbaceous tree of 5–6 m height, Carica papaya is dieceous but rarely monoecious. The fruit grows to a length of 30 cm and can weigh upto 5 kg. Latex may be collected from incisions made on the full grown unripe green papaya fruit 75–90 days after fruit set. The coagulated latex lumps are collected and incisions continued at weekly intervals till latex no longer exudes. The collected lumps are shredded, dried and purified by dissolving them in water and precipitating with alcohol. Papain when purified is a greyish white hygroscopic powder.

Constituents

Papain contains several proteolytic enzymes and unlike pepsin it can act in acid, neutral and alkaline media. It has peptidase I – which can digest protein into polypeptides – a rennin-like milk-coagulating enzyme, an amylolytic enzyme and a clotting enzyme similar to pectase.