BATS, PAPAYAS and PAPAIN

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)

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)

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

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.

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.

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.

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; at www.drugdigest.org, Search for "papain"
(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.