The papaya is a small tropical tree with a straight stem marked by scars where leaves have fallen directly from it. Papayas do not have branches. The papaya fruit is pear-shaped with a bright golden-yellow skin. The flesh of the fruit is a brighter orange-yellow, juicy and silky smooth, with a sweet and sour flavor. The shiny gray or black seeds in the interior of the fruit have a peppery taste and are edible, although they are usually discarded. The papaya is an extraordinarily useful plant. In the tropics around the world papaya is the breakfast fruit, served either green or ripe. The juice is a popular beverage, and the leaves and young stems are steamed and served as a vegetable. The fruit yields an enzyme, papain, best known as a digestive aid but most commonly used to "clear" freshly brewed beer. The latex is used as a freckle remover, and the seed has antibacterial action against Bacillus cereus, Escherischia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Shigella flexneri. The leaves have been used as a substitute for soap, and for dressing wounds.
Constituents

The leaf contains beta-carotene, calcium, carpaine, fats, flavonols, niacin, papain, tannins, and vitamin C (in higher concentration in the leaf than in the fruit). The leaf, unlike the fruit, is not a source of the protein-dissolving enzyme papain, but the latex (sap) in the leaf stem is. Papain remains in leaf preparations that have been dried over low heat, but it may be destroyed in products that are dried at high heat.