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Carica papaya L.

Caricaceae
Papaya

Source: James A. Duke. 1983. Handbook of Energy Crops. unpublished.

  1. Uses
  2. Folk Medicine
  3. Chemistry
  4. Toxicity
  5. Description
  6. Germplasm
  7. Distribution
  8. Ecology
  9. Cultivation
  10. Harvesting
  11. Yields and Economics
  12. Energy
  13. Biotic Factors
  14. References

Uses

Papaya is cultivated for its ripe fruits, favored by tropical people, as breakfast fruit, and as an ingredient in jellies, preserves, or cooked in various ways; juice makes a popular beverage; young leaves, shoots, and fruits cooked as a vegetable. Latex used to remove freckles. Bark used for making rope. Leaves used as a soap substitute, are supposed to remove stains. Flowers eaten in Java. Papain, the proteolytic enzyme, has a wealth of industrial uses. It has milk-clotting (rennet) and protein digesting properties. Active over a wide pH range, papain is useful in medicine, combatting dyspepsia and other digestive orders. In liquid preparations it has been used for reducing enlarged tonsils. Nearly 80% of American beer is treated with papain, which digests the precipitable protein fragments and then the beer remains clear on cooling. Papain is also used for degumming natural silk. But most of the papain imported in the U.S. is used for meat-tenderizers and chewing gums. Also used to extract the oil from tuna liver. Cosmetically it is used in some dentifrices, shampoos, and face-lifting preparations. Used to clean silks and wools before dying, and to remove hair from hides during tanning (Duke, 1984b). It is also used in the manufacture of rubber from Hevea (Morton, 1977). Recently, the FDA has cleared chymopapain for intradiscal injection in patients with documented herniated lumbar intervertebral discs whose signs and symptoms have not responded to conservative therapy over an adequate period of time (FDA Drug Bull. 12(3): 17-18). Fruit and seed extracts have pronounced bactericidal activity against Staphylococcus aureus, Bacillus cereus, Escherischia coli, Pseudomonas aeruginosa, and Shigella flexneri (Emeruwa, 1982).

Folk Medicine

The juice is used for warts, cancers, tumors, corns, and indurations of the skin. Sinapisms prepared from the root are also said to help tumors of the uterus. Green fruit said to be ecbolic. Vermifugal seeds said to quench thirst. Leaves poulticed onto nervous pains and elephantoid growths. Roots said to cure piles and yaws. In Asia, the latex is smeared on the mouth of the uterus as ecbolic. The root infusion is used for syphilis in Africa. Leaf smoked for asthma relief in various remote areas. Javanese believe that eating papaya prevents rheumatism. Dietary papaya does reduce urine acidity in humans. Flowers have been used for jaundice. Experimentally papaya is hypoglycemic. Inner bark used for sore teeth. Latex used in psoriasis, ringworm, and prescribed for the removal of cancerous growths in Cuba. (Duke, 1984b). Latex used locally as antiseptic. Seeds considered alexeritic, abortifacient, counter-irritant, emmenagogue, and anthelmintic. Infusion of roots said to remove urine concretions. Young leaves, and to lesser degree, other parts, contain carpain, an active bitter alkaloid, which has a depressing action on heart. Plant is strong amoebicide. Latex, used as dyspepsia cure, is applied externally to burns and scalds (Reed, 1976).

Chemistry

Per 100 g, the green fruit is reported to contain 26 calories, 92.1 g H2O, 1.0 g protein, 0.1 g fat, 6.2 g total carbohydrate, 0.9 g fiber, 0.6 g ash, 38 mg Ca, 20 mg P, 0.3 mg Fe, 7 mg Na, 215 mg K, 15 ug beta-carotene equivalent, 0.02 mg thiamine, 0.03 mg riboflavin, 0.3 mg niacin, and 40 mg ascorbic acid. Ranges reported for the ripe fruit are 32-45 calories, 87.1-90.8 g H2O, 0.4-0.6 g protein, 0.1 g fat, 8.3-11.8 g total carbohydrate, 0.5-0.9 g fiber, 0.4-0.6 g ash, 20-24 mg Ca, 15-22 mg P, 0.3-0.7 mg Fe, 3-4 mg Na, 221-234 mg K, 710-1050 ug beta-carotene equivalent, 0.03-0.04 mg thiamine, 0.03-0.05 mg riboflavin, 0.3-0.4 mg niacin, and 52-73 mg ascorbic acid. Per 100 g, the leaves are reported to contain 74 calories, 77.5 g H2O 7.0 g. protein, 2.0g fat, 11.3 g total charbohydrate 1. 8 g fiber, 2.2 g ash, 344 mg Ca, 142 mg P, 0.8 mg Fe, 16 mg Na, 652 mg K, 11,565 ug beta-carotene equivalent, 0.09 mg thiamine, 0.48 mg riboflavin, 2.1 mg niacin, and 140 mg ascorbic acid, as well 136 mg vitamin E. Leaves contain the glycoside, carposide, and the alkaloid, carpaine. Fresh leaf latex contains 75% water, 4.5% caoutchouc-like substances, 7% pectinous matter and salts, 0.44% malic acid, 5.3 papain, 2.4% fat, and 2.9% resin. Per 100 g, the seeds are reported to contain 24.3 g protein, 25.3 g fatty oil, 32.5 g total carbohydrate, 17.0 g crude fiber, 8.8 g ash, 0.09% volatile oil, a glycoside, caricin, and the enzyme, myrosin. The fatty oil of the seeds contains 16.97% saturated acids (11.38% palmitic, 5.25% stearic, and 0.31% arachidic) and 78.63% unsaturated acids (76.5% oleic and 2.13% linoleic). The seeds yield 660-760 mg BITC (bactericidal aglycone of glucotropaeolin benzyl isothiocyanate), a glycoside, sinigrin, the enzyme myrosin, and carpasemine. Flath and Forrey (1977) identified 106 volatile components in papaya. Fermentation with brewer's yeast and distillation yielded 4% alcohol, of which 91.8% was ethanol, 4.8%.methanol, 2.2% N-propanol, and 1.2% unknown (non-alcohol) (Sharma and Ogbeide, 1982).

Toxicity

Externally the latex is irritant, dermatogenic, and vescicant. Internally it causes severe gastritis. Some people are allergic to the pollen, the fruit, and the latex. Papain can induce asthma and rhinitis. The acrid fresh latex can cause severe conjunctivitis and vesication. According to Morton (1977) the latex will digest tissue and cause sores under rings and bracelets, while it has been used internally for malicious poisoning. Mitchell and Rook (1979) report a yellowing of the palms and soles caused by eating papaya. Anaphylaxis is reported in about 1% of cases of chymopapain injections.

Description

Erect, fast-growing, usually unbranched tree or shrub, 7-8 m tall, with copious latex, trunk about 20 cm in diameter, soft, leaves clustered near top of plant, alternate, long-petiolate, blade suborbicular, to 80 cm long, palmately 7-11-lobed; lobes glabrous, toothed, flat; plants dioecious in nature, some monoectous cultivars; flowers aromatic, male in drooping axillary panicles to 80 cm long, with a 5-toothed green calyx and 5-toothed cream to yellow corolla; stamens 10; female flowers solitary or cymose in axils or below leaves, with 5 yellow nearly free petals to 5 cm long; ovary with 5 stigmas; fruit a large yellow to greenish-orange berry, oblong to nearly globose or pyriform, about 7.5 cm long and bitter in wild types, up to 45 cm long, with flesh 2.5-5 cm thick, sweet, juicy and of orange color in cultivars; seeds numerous in central cavity, rounded, blackish, about 0.6 cm in diameter, each enclosed in a gelatinous membrane (aril). About 8,000 seed/lb (ca 17,500 seed/kg). Fl. and fr. nearly continuous all year.

Germplasm

Reported from the Middle American Center o f Diversity, papaya, or cvs thereof, is reported to tolerate drought, high pH, insects, laterites, mycobacteria, slope, and virus (Duke, 1978). Papaya trees differ from each other in that some are either male (staminate) or female (pistillate), whereas others are perfect, having both male and female flowers on same plant. When the sexes are separate, fruits set on the female plant only when pollen is carried from male plants. One male tree is needed for each 25 or so female plants, but one cannot determine the male trees until they flower, about 12 months after germination. In perfect-flowered cvs, seed is more likely to come true than in pistillate plants. The papaya industry in Hawaii is based on the cv 'Solo', which probably originated in Barbados (Malo and, Campbell, s.d.) Fruits are about 15 cm long 5 and 10 cm wide, weighs from 400-450 gm and is pear-shaped. Some hermaphroditic cvs are 'Fairchild (no. 745)', 'Graham', 'Kissimmee', 'Betty', and 'Bluestem'. (2n = 18, 36)

Distribution

Native to Central America, papaya has been carried throughout the tropics, where it is extensively cultivated, and as far north and south as 32° latitude. Almost weedy in some areas of tropics.

Ecology

Ranging from Warm Temperate Dry to Moist through Tropical Very Dry to Wet Forest Life Zones, papaya is reported to tolerate annual precipitation of 6.4 to 42.9 dm (mean of 42 cases = 19.2), annual temperature of 16.2 to 26.6°C (mean of 42 cases = 24.5), and pH of 4.3 to 8.0 (mean of 33 cases = 6.1). Papaya is a tropical plant, killed by frost; does not tolerate shade, waterlogging, or strong winds, and may require irrigation in dry regions. It recuperates very slowly from serious root or leaf injury (Malo and Campbell, s.d.). Grows best below 1,500 m in well-drained rich soil of pH 6-6.5.

Cultivation

Seeds retain their viability for 2-3 years when kept air-dry in airtight containers. Seeds may be sown in coldframes or boxes during January or in the open in March. Early planting is much to be desired to make a vigorous plant before the beginning of following winter. Seeds germinate in 2-3 weeks. When 2 or 3 true leaves have formed, seedlings should be transplanted, spacing them 5-7.5 cm apart in seedbed. When plants are 7.5-10 m tall, they can be set in their permanent places in the field. Usual planting distance is about 3-4 m apart each way, giving about 1750 trees to the hectare. In selecting plants for field planting, the more vigorous growing plants are usually the males and may be safely discarded except for a few. By planting 2 or 3 plants in a hill, there is a chance for further selection and elimination of excessive males when first flowers appear, about one male plant to each 25 or so females is sufficient. Transplants must be watered and shaded. Mulch gives much better results than clean culture, keeping down weeds, preserving moisture, shading the soil from hot summer sun, and preventing the burning out of humus and nitrates in the top soil layer. Heavy applications of stable manure or commercial fertilizers can often be used with profit. Attempts at grafting and rooting shoots have not been successful on a commercial scale.

Harvesting

Trees from seed sown in early spring should fruit the following winter and continue to bear some fruit nearly every month in the year thereafter. Bloom to maturity is 5-8 months. Average life of a papaya grown under Florida conditions is 2 or 3 years, but trees may live in the wild 25 years or more. Yield declines after the first few years. All inferior and wild male trees in a region should be destroyed so that their pollen cannot fertilize blossoms of trees from which seed is to be selected. Seed for new plantings should be saved from perfect-flowered plants whenever possible. For fresh fruit, they are harvested just as yellowing commences. Fruits should be twisted gently, the harvester wearing cotton gloves so as not to bruise fruit surface. On trees where fruits are not crowded, fruits are cut off with a knife. Fruit should be placed directly in a picking tray that is well padded on sides and bottom with shredded paper or other soft material. The blossom end is more resistant to bruising and so fruit should be packed with this end down. Since papayas are injured by chilling, they should be kept at about 7°C with relative humidity of 85-90%, and may be kept for 7 to 21 days under these conditions. They should be ripened at 21-26.5°C as needed for marketing. Papain is harvested, like opium, by tapping the unripe fruits. Latex drips into a suitable container and is sun dried or oven dried at 55 to 60°C. The Same fruits are tapped in different cuts at weekly intervals. Tapped fruits are ultimately edible, so that both fruit and latex are harvested.

Yields and Economics

Trees produce about 50% of their papain yield in the first year, 30% in second year, and 20% in third year. Yields range 70-130 kg/ha. If this represents 5% of the latex, the latex yields are close to one MT/ha/yr. Morton recounts yields of 20-25 kg dried papain per hectare in the first year; 90-100 in year 2, 60-90 in year 3, 30-40 in year 4, and 20 or less in year 5. She equates 1 kg crude papain with 5 kg fresh latex. A tree may bear 30-150 fruits per year, each weighing up to 9 kg. Up to 34,000 kg marketable fruit per ha is a credible yield, but yields of 100 MT fruit are reported (Duke, 1978). Murthy and Natarajan (1982) report that on fertile soils 'Honey Dew' will yield ca 100 MT/ha fruit (with 1750 bearing trees/ha) the first year, 85 the second, and 75 the third. Previously Sri Lanka and presently Uganda and Tanzania are the principal producers of papain. United States is the principal importer of papain, using it mainly for meat tenderizers, beer treatment, chewing gum, and textile and tanning industry. United States imports about 340 tons of crude papain, valued at $2 million. In the tropics the papaya is used for many purposes, and wherever it is grown, is a stable food. Nearly all of Florida crop is used in homes or sold in local markets. Hawaii is the main producer for mainland United States. In 1968, produced 11,775 tons from 830 acres. Many manufactured products are made, especially papaya juice and concentrate.

Energy

Sharma and Ogbeide (1982) discuss alcohol production in their paper, "Pawpaw as a Renewable Energy Resource for the Production of Alcohol Fuels." I would urge an analysis of the copious latex as a hydrocarbon source, the hydro-8 carbon to serve as a byproduct, following extraction of papaine and its relatives. Green fruits, after tapping for latex, were once discarded but can be used to product pectin (ripe fruits do not contain pectin) (Murthy and Natarajan, 1982). Seeds, if considered waste, might be utilized instead for a possible hydroponic or aeroponic production of latex, papain, pectin, as well as energy.

Biotic Factors

The papaya fruit-fly (Toxotrypana curvicauda) is a serious pest in some areas, so that bagging fruit while still quite small is the only means for protecting it. This most important insect pest in Florida, punctures the rind of fruit to lay eggs. Use of bags is only feasible in small plantings; in commercial plantings, selection of another area at least 2 miles from old plantations or wild stands usually gives protection for a few years. Papaya whitefly (Trialeurodes variabilis), hornworms and corn earworms (Heliothis zea) may also be pests. In Florida, the papaya webworm Romalopalpia dalera, produces webs around the fruits and stems therein (Malo and Campbell, s.d.). Soil used for seedbeds should be absolutely free from nematodes that cause root knot. Nematodes isolated from papaya include: Butlerius singularis, Criconemella curvata, Helicotylenchus concavus, H. dihystera, H. erythrinae, H. cavenessi, H. microcephalus, H. pseudorobustus, Remicycliophora penetrans, Hoplolaimus pararobustus, H. seinhorsti, Meloidogyne arenaria, M. incognita,, M. i. acrita, M. javanica, M. thamesi,, Peltamigratus nigeriensis, Pratylenchus coffeae, P. zeae, Rotylenchlus reniformis, Scutellonema clathricaudatum, Tylenchorhynchus annulatus, Xiphinema insigne, X. americanum. Fungi reported on papaya include: Alternaria tenuis, A. tenuissima, Armillaria mellea, Ascochyta caricae, Aspremisporium caricae, Asterina caricarum, Botrydiplodia caricae, B. papayae, B. theobromae, Cephaleuros mycoidea, C. virescens, Cercospora caricae, C. mamanois, C. papayae, Choanephora americana, C. cucurbitarium, Cicinnobolus cesatii, Cladosporium herbarum, C. sphaerospermum, Colletotrichum capsici, C. caricae, C. gloesporioides, C. papayae, Corticium solani, Corynespora cassicola, Curvularia carica-papayae, Dendryphiella interseminata, Didymella sp., Diplodia cacaoicola, R. papayae, Erysiphe cichoracearum, Fuligo cinerea, Fusarium bulbigenum, F. equiseti, F. lateritium, F. scirpi, F. solani, F. stilboides, Gloeosporium papayae, Glomerella cingulata, Guignardia caricae, Helminth rium papayae, Leveillula taurica, Macrophoma sp., Macrophomina phaseoli, Macrosporium commune, Mycosphaerella caricae, Myrothecium roridum, Nectria haematococca, Oidium caricae, O. indicum, Ovulariopsis papayae, Penicillium digitata, Periconia byssoides, P. pycnospora, Phaeoseptoria papayae, Phomopsis papayae, Phyllosticta papayina, P. caricae-papayae, P. sulata, Phymatotrichum omnivorum, Phytophthora cactorum, P. cinnamomi, P. palmivora, P. parasitica, Pucciniopsis caricae, Pythium aphanidermatum, P. butleri, P. complectans, P. debaryanum, P. gracile, P. indicum, P. irregulare, P. muriotylum, P. oligandrum, P. rostratum, P. spinosum, P. splendens, P. ultimum, P. vexans, Rhizoctonia solani, Rhizopus nigricans, R. stolonifer, Sclerotium rolfsii, Sphaceloma papayae, Sphaerostilbe repens, Stachybotrys kampalensis, Stilbella proliferans, Vermicularia dematium. Bacillus papayae and Pseudomonas carica-papayae also attack papaya. Viruses isolated from papaya include: Bunchy-top, Cucumber mosaic, Ringspot, Waialua virus, Yellow crinkle and Leaf-curl (Ag. Handbook 165, Reed, 1976). Papaya mosaic is spread by aphid, Myzus persicae.

References

Complete list of references for Duke, Handbook of Energy Crops
Last update July 3, 1996