BATS, PAPAYAS and PAPAIN

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I envisioned this as a very short chapter until I encountered the enzyme, papain, in papayas.

LET'S HAVE THE SHORT PART FIRST.

The papaya plant grows widely in tropical countries. The ripe fruit is sweet. People like papayas and so do bats. People plant the small black papaya seeds by hand. Bats plant papaya seeds in their droppings.

LIKE THE BAT-PLANTED GUAVAS AND FIGS.

Right. That practice ensures that there are genetically valuable papaya plants growing in the wild.

Papayas are high in Vitamin C and Vitamin A. They can have a melon-like shape and some say they have a musky canteloupish taste. Papayas are so very sweet that many people enliven their taste with lemon or lime juice. Some people like to eat a few of the many black seeds along with the papaya flesh for an extra peppery zing. Not too many though! Papaya seeds in excess can have a laxative effect.

Plantations of papayas provide jobs for human beings. For example, 800 acres of papayas in Jamaica require the energies of 600 people.(5) In Hawaii management of fruit in the field; picking and sorting, accounts for nearly half of the labour costs.(2)

Papaya plants grow quickly for about 5 years and grow up to 25 feet in height. The first ripe fruit can be picked when the plant is 11 months old, and the last fruit can be reached from the ground when the plant is about 3 years old. As the plant rapidly grows taller the fruit eventually attains a height beyond human grasp.(2)

Photograph courtesy of Forest & Kim Starr (USGS)

During the two best-bearing years there might be two to four ripe fruits each week.

Picking papayas out of hand reach requires skill. If the tender skin of the fruit is scratched it will leak latex and be commercially useless except for local reduced sale.

One picking device is to acquire a supply of suction cups which are commonly seen on plumber's helpers. (2)

• Attach a cup to the end of a long bamboo pole.
• Hold the cup snugly against the bottom of the fruit.
• Thrust the pole upwards to snap the stem.
• Catch the falling fruit.

WE'VE LEARNED ABOUT THE DIFFICULTIES ATTENDING HAND-HARVESTING FRUIT BEFORE; PETAI, DURIAN AND CAROB. ISN'T THERE A MACHINE THAT CAN HELP IN HARVESTING ON A PAPAYA PLANTATION?

Yes, a hydraulic lift machine with an operator and two pickers can equal the work of 8 handpickers in the same time. There are, however, extra cost considerations. The machines are expensive. They break down. Machines require maintenance and eventual replacement.(2)

Yellow-epauletted bat; papaya planter

THIS WAS SUPPOSED TO BE THE SHORT PART. WHEN DO WE GET TO PAPAIN?

Papain is a biological enzyme contained in the latex of green papayas and other parts of the plant. Papain can make tough meat tender.

It is said that some cooks will hang a tough stewing hen among the branches of a papaya tree overnight to tenderize it. A more cautious cook will rub the meat with a piece of green papaya or add papaya plant leaves or a chunk of green papaya to the cooking pot.

In the supermarket world, a customer will buy a package of papain-based meat tenderizer.

All of the above cooks are using the protein-cleaving enzyme, papain, to make tough meat tender.

There are other plant enzymes which are tenderizers; bromelain in pineapples and ficin in figs. Papain is the most studied and most widely used of the plant enzymes.

Big fruit bat (Artibeus lituratus) papaya planter
Photograph: David Liebman, Lubee Bat Conservancy

HOW IS PAPAIN SEPARATED FROM A GREEN PAPAYA?

By hand labour. Here is one method.(2)

• Make incisions in the skin of a green papaya every four or five days.
• Collect the latex that oozes out of the cut with a bowl
  • or
• Clamp a collection collar around the stem of the plant
  • then
• Spread the collected latex on a cloth
• Dry the latex in an oven set to a low temperature
• Grind the dried latex to a powder
• Pack the powder in a container.

Yield: 1.5 pounds (.68 kilo) of papain from 1500 average sized papayas.

A papain collection collar as imagined by the illustrator

ARE THERE ANY USES FOR PAPAIN BESIDES AS A MEAT TENDERIZER?

There are many, many uses for papain from a research task as delicate as "disassociating the retina of a turtle"(3) to clearing cloudy beer.

It is also used to:(2)

• remove hair from animal hides prior to tanning
• treat wool to prevent shrinkage
• clot milk

Papain can be an ingredient in:

• Soft contact lens cleaners
• Pet food
  • reduces thickness
  • improves taste
• Toothpaste
• Cosmetics
• Detergents
• Digestive aids

Pallas' spear-nosed bat; papaya planter

There are some impressive uses of papain in medical treatments.(2)

• Removal of dead tissue from wounds such as ulcers, bedsores, burns, cysts, carbuncles and surgical wounds
• Reduction of swelling and inflammation
• Destruction of the suffocating membranes associated with diptheria
• Reduction of adhesions and swelling sometimes associated with surgery
• Treatment of ulcers, pinched nerves, slipped spinal discs
• Treatment of cancer. Although the specific action is not understood, administration of the papain enzyme can:
  • reduce the undesirable side-effects of chemotherapy and radiotherapy
  • reduce tissue inflammation (5)

Finally, if you are choking as a result of swallowing an overlarge inadequately chewed chunk of meat, papain can be administered with GREAT CAUTION to soften the obstacle.

IS THERE ANYTHING NEGATIVE ABOUT THIS MAGICAL SUBSTANCE, PAPAIN?

Yes, there is in papain the potential for arousing a violent allergy producing hives, laboured breathing, swelling of the throat, lips, face and tongue. (5)

This means that care must be exercised when papain is part of a medical treatment and when papain-based meat tenderizers are used in cooking and commercial products.

Veldkamp's dwarf epauletted bat

References:
(1)Root, Waverley 1980. Food, Simon and Schuster, New York
(2)Morton, Julia F. 1987 Fruits of Warm Climates, pages 336-346;http://www.hort.purdue.edu/newcrop/morton
(3)Sarthy P.V., Bunt, A.H., The ultrastructure of isolated glial (Muller)cells from the turtle retina. Anatomical Record, 1982, February, 202(2):275-83
(4)Professor Robert J. Lancashire,University of the West Indies,Papaya-pawpaw http://wwwchem.uwimona.edu.jm:1104/lectures/papaya.html
(5)Drug Digest Papain; http://www.drugdigest.org/DD/PrintablePages/herbMonograph/0,11475,552451,00.html
(6)Robinson, Richard, Anaphylaxis, Gale Encyclopedia of Medicine, Gale Group,publishers, December 2002

Text and illustrations by ML Alley-Crosby who thanks Dr. Bruce J. Hayward of Western New Mexico University and the Museum Mammal Collection, University of Alaska, Fairbanks, for permission to use his photograph as guidance for drawing Veldkamp's Dwarf Epauletted Bat. Thanks also to the Lubee Bat Conservancy for permission to use the photograph of Artibeus lituratus.

Thanks to Forest and Kim Starr for access to their immense photographic library of plants growing in Hawaii.

http://www.hear.org/starr/hiplants/images/index.html

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