Everything you need to know about papaya cultivation, growth and production. Learn about:- 1. Introduction to Papaya 2. Climate and Soil Required for Growing Papaya 3. Propagation 4. Sowing Time 5. Field Preparation and Planting 6. Weed Control 7. Manuring and Fertilization 8. Harvesting and Postharvest Management 9. Grades, Sizes, Packaging and Storage 10. Varieties 11. Uses.
Contents:
- Introduction to Papaya
- Climate and Soil Required for Growing Papaya
- Propagation of Papaya
- Sowing Time of Papaya Seeds
- Field Preparation and Planting of Papaya
- Weed Control of Papaya
- Manuring and Fertilization of Papaya
- Harvesting and Postharvest Management of Papaya
- Grades, Sizes, Packaging and Storage of Papaya
- Varieties of Papaya
- Uses of Papaya
1. Introduction to Papaya:
Papaya is the common name for the family Caricaceae. The representative genus is Carica. The common papaya is classified as Carica papaya. Four genera and about 30 species are placed in this family of dicots. They characteristically have palmately lobed or compound leaves; small, unisexual flowers; and separate male and female plants (dioecious). All parts of the plants contain milky latex in special latex-producing cells. It is native to the New World, but its exact origin is unknown.
The papaya may represent the fusion of two or more species of Carica native to Mexico and Central America. Today it is cultivated throughout the tropical world and into the warmest parts of the subtropics. The importance of papaya in the world’s economy is demonstrated by its wide distribution and substantial production in tropical countries. It has long been known and cultivated in home gardens because it is one of the few fruits which throughout the year.
The name papaya is widely recognized, however, it has been corrupted to kapaya, kepaya, lapaya or tapaya in southern Asia and the East Indies. In French, it is papaye (the fruit) and papayer (the plant), or sometimes figuier des Iles. Spanish-speaking people employ the names melón zapote, lechosa, payaya (fruit), papayo or papayero (the plant), fruta bomba, mamón or mamona, depending on the country. In Brazil, the usual name is mamao. When first encountered by Europeans it was quite naturally nicknamed tree melon.
Sometimes it is referred to as a tree. The plant is properly a large herb growing at the rate of 6 to 10 ft (1.8-3 m) the first year and reaching 20 or even 30 ft (6-9 m) in height, with a hollow green or deep-purple stem becoming 12 to 16 in (30-40 cm) or more thick at the base and roughened by leaf scars.
The leaves emerge directly from the upper part of the stem in a spiral on nearly horizontal petioles 1 to 3 ½ ft (30-105 cm) long, hollow, succulent, green or more or less dark purple. The blade, deeply divided into 5 to 9 main segments, each irregularly subdivided, varies from 1 to 2 ft (30-60 cm) in width and has prominent yellowish ribs and veins. The life of a leaf is 4 to 6 months. Both the stem and leaves contain copious white milky latex.
The 5-petalled flowers are fleshy, waxy and slightly fragrant. Some plants bear only short-stalked pistillate (female) flowers, waxy and ivory-white; or hermaprodite (perfect) flowers (having female and male organs), ivory-white with bright-yellow anthers and borne on short stalks; while others may bear only staminate (male) flowers, clustered on panicles to 5 or 6 ft (1.5-1.8 m) long. There may even be monoecious plants having both male and female flowers.
The fruit (melon-like) is commonly spherical to cylindrical in form, is 75 to 500 mm or even more in length. In general character it strongly resembles a muskmelon. The very juicy flesh is deep yellow or orange to salmon-coloured and about 25 mm thick. Along the walls of the large central cavity are attached the numerous round, wrinkled black seeds.
The unripe fruit contains a milky juice in which is present a protein-digesting enzyme known as papain, which greatly resembles the animal enzyme pepsin in its digestive action.
The papaya fruit is slightly sweet, with an agreeable musky tang, which is more pronounced in some varieties and in some climates than in others. Fruits from bisexual plants are usually cylindrical or pyriform with small seed cavity and thick wall of firm flesh which stands handling and shipping well. In contrast, fruits from female flowers are nearly round or oval and thin-walled. In some areas, bisexual types are in greatest demand. In South Africa, round or oval papayas are preferred.
Dioecious papayas have male and female flowers on different plants. This means that both male and female plants are needed for fruit production.
Gynodioecious papayas, more commonly called bisexual lines, have trees that can be female or bisexual. Bisexual flowers have both male and female parts within the same flower and can be self-pollinated.
The sex of a papaya plant cannot be determined until it starts to flower. Growers plant more plants than they need to allow for the removal of unwanted plants at flowering.
Pollination:
If a papaya plant is inadequately pollinated, it will bear a light crop of fruits lacking uniformity in size and shape. Therefore, hand-pollination is advisable in commercial plantations that are not entirely bisexual. Bags are tied over bisexual blossoms for several days to assure that they are self- pollinated.
The progeny of self-pollinated bisexual flowers are 67% bisexual, the rest being female. Plants from female flowers crossed with male flowers are 50-50 male and female. Bisexual flowers pollinated by males give rise to 1/3 female, 1/3 bisexual and 1/3 male plants.
2. Climate and Soil
Required for Growing Papaya:
Papaya is a tropical plant that grows best in warmer climates. It can be grown successfully in warm, frost-free locations in coastal regions. It also grows well in the mild subtropical regions of the country up to 1,000 m above mean sea- level. Cool winter conditions gives slow growth.
Frost-free sites are essential, as papaya plants are susceptible to frost damage. Soil temperatures below 15°C will limit growth. The temperature of the locality influences the type of flowers and fruit that are formed on a tree.
Wind reduces growth and fruit set, damages leaves and blemishes fruit. Protection from damaging south-easterly, westerly and northerly winds is essential. Windbreaks are recommended for all farms.
Papayas perform best on deep, well-drained soils with high organic matter. Papaya can also be grown in calcareous and stony soils provided with heavy dose of organic manures. Most soil types are suitable but avoid heavy clay soils. A topsoil depth of 1 m is preferred for optimum growth and production, with a minimum depth of 0.5 m essential to avoid waterlogging. It grows well in deep, rich, alluvial soils on banks and deltas of big rivers of India. Soils with high pH (8.0) and low pH (5.0) should be avoided.
3.
Propagation of Papaya:
1. By Seeds:
Papayas are generally grown from seed. Gynodioecious varieties breed true-to- type and are preferred by commercial growers. Germination may take 3 to 5 weeks. It is expedited to 2 to 3 weeks and percentage of germination increased by washing off the aril. Then the seeds need to be dried and dusted with fungicide to avoid damping-off, a common cause of loss of seedlings.
Well- prepared seeds can be stored for as long as 3 years but the percentage of germination declines with age. Dipping for 15 seconds in hot water at 70 °C and then soaking for 24 hrs in distilled water after removal from storage will improve the germination rate. If germination is slow at some seasons, treatment with gibberellic acid may be needed to get quicker results.
To reproduce the characteristics of a preferred strain, air-layering has been successfully practiced on a small scale. All offshoots except the lowest one are girdled and layered after the parent plant has produced the first crop of fruit. Later, when the parent has grown too tall for convenient harvesting the top is cut off and new buds in the crown are pricked off until offshoots from the trunk appear and develop over a period of 4 to 6 weeks.
These are layered and removed and the trunk cut off above the originally retained lowest sprout which is then allowed to grow as the main stem. Thereafter the layering of offshoots may be continued until the plant is exhausted.
Rooting of cuttings has been practiced in South Africa, especially to eliminate variability in certain clones so that their performance can be more accurately compared in evaluation studies. Softwood cuttings made in midsummer rooted quickly and fruited well the following summer. Cuttings taken in fall and spring were slow to root and deficient in root formation.
In recent years, the potential of rapid propagation of papaya selections by tissue culture is being explored and promises to be feasible even for the establishment of commercial plantations of superior strains.
Efforts have been made to determine the sex of seedlings in the nursery, Indian scientists making colorimetric tests of leaf extracts have had 87% success in identifying seedlings as female; 67% in classifying males/bisexuals grouped together.
4. Sowing Time of Papaya Seeds:
The seedlings are raised in nursery-beds or in pots or polythene bags. The seeds are sown 1 cm deep in rows and 10 cm apart. The beds should be covered with fine compost or leaf-mould. Light watering should be done with water-can in the morning. About 250-300 g seeds are sufficient for a hectare.
For protection, nursery-beds should be covered with polythene sheet or dry paddy straw. Insecticides dusting will protect the seedlings against insect pests. To protect the seedling with damping off disease the seeds should be treated with 0.1% Monosan (phenyle mercury acetate), Ceresan, Agrosan or Thiram dust before sowing.
The nursery-beds should also be treated with 5% formaldehyde solution before sowing. If disease appears in the nursery, Bordeaux mixture (1%) or copper oxychloride (0.2%) should be sprayed.
The seedlings raised in polythene bags stand transplanting better than those raised in seed-beds. Perforated polythene bags of 20 cm x 15 cm size of 150-200 gauge can be used as a container. Polythene bags are filled with a mixture of farmyard manure, soil and sand in equal proportion. Four to five seeds are sown in each bag. After germination only three seedlings are retained. Generally 15-20 cm tall seedlings become ready for planting in about two months.
5. Field Preparation and Planting
of Papaya:
A well-drained upland should be selected for cultivation. Plants are sensitive to strong winds. In open and high-lying areas should be avoided. In India, Co. 1 and Co. 2 and ‘Solo’ are set on 6 ft (1.8 m) centers; Coorg Honey Dew and Washington on 8 ft (2.4 m) centers. The seedlings are planted in pits of 60 cm x 60 cm x 60 cm size.
The pits are dug about 15 days before in summer. The manure should be thoroughly mixed with the soil which has been excavated from the pit, the mixture of the soil and FYM is returned to pit and packed to a level which brings the top of the seedling plant to 1-2 cm. Pits should be filled with top soil along with 20 kg farmyard manure, 1 kg neem or karanj cake and 1 kg bone-meal or fish-meal.
The spacing of 1.4 m x 1.4 m or 1.4 m x 1.6 m is best- suited for papaya Pusa Delicious under subtropical condition of Bihar. Spacing of 1.6 m x 1.6 m gives highest yield of fruits as well as papain in Tamil Nadu. A closer spacing of 1.2 m x 1.2 m for Pusa Nanha is adopted for high-density orcharding, accommodating 6,400 plants/ha.
Transplanting is best done in the evening or on cloudy, damp days. On hot, dry days, each plant must be protected with a leafy branch or palm leaf stuck in the soil. Except for Coorg Honey Dew and ‘Solo’, the plants are set out in 3’s, 6 in (15 cm) apart in enriched pits. Tall and vigorous varieties are planted at greater spacing, while medium and dwarf ones at closer spacing.
After flowering, one female or hermaphrodite plant is retained, the other two removed. But one male is kept for every 10 females. Coorg Honey Dew and Solo are planted one to a pit and no males are necessary. Watering is done every day until the plants are well established, but overwatering is detrimental to young plants. Double rows of Sesbania aegyptiaca are planted as a windbreak.
Proper care should be taken to save the seedlings in the field especially against insect pests and heavy rainfall in early state. In frost-prone areas, they should be protected with small thatches or polythene structure. Some extra seedlings reserved in the nursery may be utilized for gap filling.
For sequential and intercropping Papaya + tobacco intercropping in north Bihar is ideal. Intercropping should not be done when flowering and fruiting starts. Intercropping leguminous crops after non-leguminous ones, shallow- rooted crops after deep rooted ones are beneficial.
6. Weed Control
of Papaya:
Weeds grow very fast in papaya fields and use most of the applied nutrients. For removal of weed deep hoeing in recommended during first year to check weed growth. Hoeing should be avoided in rainy season or after fruiting because plants are shallow-rooted.
Overgrowth of weeds should be avoided because it will cause water-logging. Weeding should be regularly. Fluchloralin or Alachlorin or Butachlorine @ 2.0 g/ha as pre-emergence 2 months after transplanting will control all weeds for 4 months.
Removing Unwanted Male Plants:
It is necessary to keep 10% male plants in papaya orchards for good pollination. After flowering extra male plants should be removed. The hermaphrodite plants produce good-quality fruits and should not be confused with male plants.
Weaker and diseased plants should be uprooted, after ensuring 1 plant/pit. Earthing-up should be done 30 cm in radius around the plants on or before the onset of monsoon. It will help to avoid waterlogging and plant will stand erect.
7. Manuring and Fertilization
of Papaya:
Papaya needs heavy doses of manures and fertilizers. Basal dose of manures should be in the pits, 200-250 g each of N, P2O5 and K2O are recommended for getting high yield. Application of 200 g N is optimum for fruit yield but papain yield increases with increases in N up to 300 g.
A dose of 250 g N, 250 g P and 500 g K/plant is recommended for papaya Corg Honey Dew under Bangalore conditions, while 200 g each of N, P and K in split doses in the first, third, fifth and seventh month is recommended for papaya Co 1 under Coimbatore conditions.
Deficiency of lime and B has often been observed in papaya orchards. Spraying of 0.5% zinc sulphate (twice) and one spray of Borax (0.1%) may be done depending upon the nutrient status of soil.
Optimum soil moisture is essential for growth, yield and quality of fruits. The installation of constant drip irrigation (12 gals per day) has made possible papaya cultivation on mountain slopes on the relatively dry island of Maui which averages 10 in (25 cm) of rain annually.
Water stress or low moisture soil condition causes shifting of floral sex shifts towards female sterility and results in low yield. But over-irrigations cause root-rot disease. The number of irrigations depends upon soil type and weather conditions of the region. Protective irrigation is required in the first year of planting.
In the second year when its plants are laden with fruits, irrigation at fortnightly interval in winter and at 10 days interval in summer is needed from October till May. Water irrigation may be done using sprinkler or drip irrigation system. Papaya plants should be protected from water-logging. Even 24 hr stagnation with water may kill the well-established plants.
Papaya can also be grown in big pots (75 cm x 40 cm). Seedlings at the age of 10-15 cm may be planted in pots during October-November. At least 2-4 plans in each pot should be planted. Organic manures plus a dose of chemical fertilizers containing N (50 g), P (50 g) and K (75 g) should be applied as topdressing. Chemical fertilizers should be applied after flowering.
8. Harvesting and Postharvest Management
of Papaya:
In the usual papaya plantation, each plant may ripen 2 to 4 fruits per week over the fruiting season. Healthy plants, if well cared for, may average 34 kg of fruit per plant per year, though individual plants have borne as much as 136 kg.
Papaya flavor is at its peak when the skin is 80% colored. For the local market, in winter months, papayas may be allowed to color fairly well before picking, but for local market in summer and for shipment, only the first indication of yellow is permissible. While picking fruits from the tree, care must be taken that they are not scratched, and are free from any blemishes, otherwise these are attacked by fungus and start decaying during marketing.
On ripening, fruits of certain varieties turn yellow while some of them remain green. When the latex ceases to be milky and become watery, the fruits are suitable for harvesting. The fruits must be handled with great care to avoid scratching and leaking of latex which stains the fruit skin.
Change of skin color from dark-green to light-green with some yellow at the blossom end (color break). Papayas are usually harvested at color break to ¼ yellow for export or at ½ to ¼ yellow for local markets. Flesh color changes from green to yellow or red (depending on cultivar) as the papayas ripen. A minimum soluble solids of 11.5% is required by the Hawaiian grade standards.
Papayas picked ¼ to full yellow taste better than those picked mature- green to ¼ yellow because they do not increase in sweetness after harvest. Uniformity of size and color; firmness; freedom from defects such as sunburn, skin abrasions, pitting, insect injury, and blotchy coloration; freedom from decay.
Optimum Temperature – 13 °C (55 °F) for mature-green to ¼ yellow papayas
10°C (50°F) for partially-ripe ( ¼ to ½ yellow) papayas 7°C (45°F) for ripe (> ½ yellow) papayas
Optimum Relative Humidity – 90-95%
Responses to Ethylene Production:
Exposure to 100 ppm ethylene at 20 to 25°C (68 to 77°F) and 90-95% relative humidity for 24-48 hours results in faster and more uniform ripening (skin yellowing and flesh softening, but little or no improvement in flavor) of papayas picked at color break to ¼ yellow stage.
Responses to Controlled Atmospheres (CA):
1. Optimum CA 3-5% O2 and 5-8% CO2
2. Benefits of CA include delayed ripening and firmness retention.
3. Postharvest life potential at 13 °C (55 °F)- 2-4 weeks in air and 3-5 weeks in CA, depending on cultivar and ripeness stage at harvest.
4. Exposure to O2 > levels below 2% and/or CO2 levels above 8% should be avoided because of the potential for development of off-flavors and uneven ripening.
Fruits can be held at 29.64°C and high atmospheric humidity for 48 hours to enhance coloring before packing. Standard decay control has been a 20-minute submersion in water at 49 °C followed by a cool rinse. In India, dipping in 1,000 ppm of aureofungin has been shown to be effective in controlling postharvest rots.
In Philippine trials, thiabendazole reduced fruit rot by 50%. In 1979, Hawaiian workers demonstrated that spreading an aqueous solution of carnauba wax and thiabendazole over harvested fruits gives good protection from postharvest diseases and can eliminate the hot-water bath.
Fruits that have had hot water treatment and EDB fumigation and then have been stored in 1.5% oxygen at 55 °F (13 °C) for 12 days will have a shelf life of about 3 ½ days at room temperature. Fruits that have had hot water treatment when ¼ colored, followed by irradiation at 75-100 krad, and storage at 2-4% oxygen and 60°F (16°C) for 6 days will have a market life of 8 days. Those held for 12 days will be saleable thereafter for 5 days.
The fruit yield of papaya varies widely according to variety, soil climate and management of the orchard. On an average each plant of improved varieties bears 30-45 fruits, weighing 40-75 kg in one fruiting season. On an average, yield of 60-75 tonnes/ha maybe expected in a season from an orchard or papaya.
9.
Grades, Sizes, Packaging and Storage of Papaya:
The fruits are best packed in single layers and padded to avoid bruising. The latex oozing from the stem may irritate the skin and workers should be required to wear gloves and protective clothing.
The most common package size is a 4.5 kg carton, larger 10 kg. Store from 7 to 13 °C with 90 to 95% RH. At 7 to 10 °C, storage-life is limited by chilling injury, while at 10 to 13 °C ripening occurs slowly. Papaya fruit at color- turning (break) stage can be stored at 7 °C for 14 days and will ripen normally when transferred to room temperature. Ripe, full color, fruit can be held for > 1 week at 1 to 3 °C.
10. Varieties
of Papaya:
A large number of varieties are cultivated and have great variability in size, quality and other characteristics. As a matter of fact many of these are not real varieties since these cannot be relied upon to reproduce the parental characters in all their progenies.
Kapoho Solo or Puna Solo, Waimanalo (formerly ‘Solo’ Line 77), Higgins (formerly Line 17A), Wilder (formerly Line 25), Hortus Gold (a South African cultivar), Bettina and Petersen (long-standing cultivars in Queensland, Australia) Improved Petersen are some of the varieties of the world.
In Western Australia, after trials of 9 cultivars Hybrid No. 5, Petersen, Yarwun Yellow, Gold Cross, Goldy, Hong Kong, Guinea Gold, Golden Surprise and Sunnybank. The other varieties are Campo Grande, Tocaimera, Zapote, Solo (from Colombia), Betty, Bettina and 43-A-3 (from Brazil) and Hortus Gold (from South Africa).
In India, papaya breeding and selection work has been carried on for over 30 years beginning with 100 introduced strains and 16 local variations.
1. Burliar Long:
It is prolific, bearing as many as 103 fruits the first year, mostly in pairs densely packed along the stem down to 18 in (45 cm) from the ground. Seedlings are 70% females and bloom 3 months after transplanting.
2. Co 1 and Co 2:
These were developed at Tamil Nadu Agricultural University. Both are dioecious and dwarf, the first fruits being borne 3 ft (1 m) from the ground. ‘Co. 1’ is valued for eating fresh; ‘Co. 2’ is grown for table use and for papain extraction. The fruits are of medium size-3.3 to 5.5 lbs (1 ½ – 2 ½ kg), with yellow, sweet flesh.
3. Co 3:
It is a gynodioecious variety with tall, vigorous trees. The fruits are medium-sized, with high sugar content and red coloured flesh. This is preferred for desert.
4. Co 4:
It is a dioecious variety with medium-tall, vigorous trees. There are purple tinges on the stem, petiole and leaf. It is suitable for home- gardening.
5. Co 5:
It is a selection from Washington variety, cultivated mainly for papain production. It yields 1,500-1,600 kg/ha of dried papain.
6. Co 6:
A selection from Pusa Majesty, it is dioecious having dwarf stature. It produces large-sized fruits. It is recommended both for papain and dessert purposes.
7. Coorg Honey Dew:
It is a well-known cultivar. It is a selection from Honey Dew at Chethalli Station of the Indian Institute of Horticultural Research. There are no male plants; female and bisexual occur in equal proportions. The plant is low-bearing and prolific. The fruit is long to oval, weighs 4.4 to 7.7 lbs (2-3 ½ kg); has yellow flesh with a large cavity, and keeps fairly well.
8. Pant 1:
Its plants are dioecious providing medium-sized fruits. It is recommended for tarai area in Uttar Pradesh.
9. Pink Flesh Sweet:
It is a selection with excellent-quality fruits. Fruits are medium-sized with pink flesh. The TSS is 12-14° Brix. It is a good dessert variety.
10. Pusa Delkious (Pusa 1-15):
It is a medium size; flesh deep-orange, of excellent flavor; female and hermaphrodite plants; high-yielding.
11. Pusa Dwarf (Pusa 1-45):
The fruits are oval of medium size. Plant is dwarf; begins bearing fruit at 10 to 12 in (25-30 cm) above the ground. It is in much demand for home and commercial culture; suitable for high- density plantings.
12. Pusa Giant (Pusa 1-45 V):
It is with large fruits, suitable for marketing ripe, or green for use as a vegetable, also for canning. Plant dioecious, fast- growing; tall; trunk thick, wind-resistant.
13. Pusa Majesty (Pusa 22-3):
It is round, of medium size; flesh yellowish, solid; keeps well and ships well; vinis resistant; hermaphrodite plants higher-yielding than the female.
14. Pusa Nanha:
An extremely dwarf variety, it is suitable for kitchen gardens, pot and roof-top cultivation. This is ideal for high-density orcharding.
15. Sunrise Solo:
This is a gynodioecious variety having pink flesh and good taste.
16. Taiwan:
This is also gynodioecious variety with blood-red coloured flesh and good taste.
17. Washington:
It is popular in Bombay, has dark-red petioles and yellow flowers. The fruits are of medium size with excellent, sweet flavor.
11. Uses of Papaya:
i. Food Uses:
Ripe papayas are most commonly eaten fresh, merely peeled, seeded, cut in wedges and served with a half or quarter of lime or lemon. Sometimes a few seeds are left attached for those who enjoy their peppery flavor but not many should be eaten. Firm-ripe papaya may be seasoned and baked for consumption as a vegetable. Half-ripe fruits are sliced and crystallized as a sweetmeat. Papaya juice and nectar are prepared from peeled or unpeeled fruit and are sold fresh in bottles or canned.
Unripe papaya is never eaten raw because of its latex content. Raw green papaya is frequently used in Thai and Vietnamese cooking. Even for use in salads, it must first be peeled, seeded, and boiled until tender, then chilled. Green papaya is frequently boiled and served as a vegetable.
Young leaves are cooked and eaten like spinach in the East Indies. Mature leaves are bitter and must be boiled with a change of water to eliminate much of the bitterness. Papaya leaves contain the bitter alkaloids, carpaine and pseudocarpaine, which act on the heart and respiration like digitalis, but are destroyed by heat.
Papaya seeds contain 18 amino acids in descending order of abundance, glutamic acid, arginine, proline, and aspartic acid in the endosperm; and proline, tyrosine, lysine, aspartic acid, and glutamic acid in the sarcotesta.
A yellow to brown, faintly scented oil was extracted from the sundried, powdered seeds of unripe papayas at the Central Food Technological Research Institute, Mysore, India.
The papaya is regarded as a fair source of iron and calcium; a good source of vitamins A, B and G and an excellent source of vitamin C (ascorbic acid).
Carotenoid content of papaya (13.8 mg/100 g dry pulp) is low compared to mango, carrot and tomato. The major carotenoid is cryptoxanthin.
The latex of the papaya plant and its green fruits contains two proteolytic enzymes, papain and chymopapain. The latter is most abundant but papain is twice as potent. In 1933, Ceylon (Sri Lanka) was the leading commercial source of papain but it has been surpassed by East Africa where large-scale production began in 1937. The latex is obtained by making incisions on the surface of the green fruits early in the morning and repeating every 4 or 5 days until the latex ceases to flow.
The lanced fruits may be allowed to ripen and can be eaten locally, or they can be employed for making dried papaya “leather” or powdered papaya, or may be utilized as a source of pectin. Because of its papain content, a piece of green papaya can be rubbed on a portion of tough meat to tenderize it. Sometimes a chunk of green papaya is cooked with meat for the same purpose.
One of the best known uses of papain is in commercial products marketed as meat tenderizers, especially for home use. A modern development is the injection of papain into beef cattle a half-hour before slaughtering to tenderize more of the meat than would normally be tender.
Papain has many other practical applications. It is used to clarify beer, also to treat wool and silk before dyeing, to de-hair hides before tanning, and it serves as an adjunct in rubber manufacturing. It is applied on tuna liver before extraction of the oil which is thereby made richer in vitamins A and D. It enters into toothpastes, cosmetics and detergents, as well as pharmaceutical preparations to aid digestion.
Papain has been employed to treat ulcers, dissolve membranes in diphtheria, and reduce swelling, fever and adhesions after surgery. With considerable risk, it has been applied on meat impacted in the gullet. Chemo-papain is sometimes injected in cases of slipped spinal discs or pinched nerves. Precautions should be taken because some individuals are allergic to papain in any form and even to meat tenderized with papain.
In tropical folk medicine, the fresh latex is smeared on boils, warts and freckles and given as a vermifuge. In India, it is applied on the uterus as an irritant to cause abortion. The unripe fruit is sometimes hazardously ingested to achieve abortion.
Seeds, too, may bring on abortion. They are often taken as an emmenagogue and given as a vermifuge. The root is ground to a paste with salt, diluted with water and given as an enema to induce abortion. A root decoction is claimed to expel roundworms. Roots are also used to make salt.
The leaf also functions as a vermifuge and as a primitive soap substitute in laundering. Dried leaves have been smoked to relieve asthma or as a tobacco substitute. The dried leaf infusion is taken for stomach troubles in Ghana and they say it is purgative and may cause abortion.
The extracts of ripe and unripe papaya fruits and of the seeds are active against gram-positive bacteria. Strong doses are effective against gram-negative bacteria. The substance has protein-like properties. The fresh crushed seeds yield the aglycone of glucotropaeolin benzyl isothiocyanate (BITC) which is bacteriostatic, bactericidal and fungicidal. A single effective does is 4-5 g seeds.
Papaya harvesters develop skin irritation due to fresh latex. The pollen of papaya flowers develops severe respiratory reactions in sensitive individuals. Thereafter, such people react to contact with any part of the plant and to eating ripe papaya or any food containing papaya, or meat tenderized with papain.