Among the various kinds of common fruits, paw-paw has perhaps the most versatile usefulness. There is hardly any part of the paw-paw plant that is not valuable. When any part of the paw-paw plant is incised, especially the unripe fruit, a white milky substance called latex exudes. In order to preserve the plant’s life, however, it is indeed advisable to tap only the matured green fruit with the view to obtaining the best of the latex, which is then used to produce papain.
The latex so obtained is a rich source of pappain, a digestive enzyme. Crude latex contains two important proteolytic enzymes called papain and chymo-pappain. If swallowed raw, both enzyme substances are active in breaking down protein like the enzyme pepsin and rennin in the human stomach.
Pappain is generally employed in a wide variety of industries, most especially where protein is present either as a contaminant that must be completely eliminated or when only a slight alteration of the protein content is required to give the products the desired characteristics. That is why it finds tremendous application in the food industry for tenderizing meat and softening sausage casings. Moreover, it is very important in the breweries for clarifying or chill-proofing beer.
In the Health and Pharmaceutical sector, pappain is a very powerful therapy. The roots, leaves, fruits and seeds of the plant are reported to contain an alkaloid carpaine, which lowers the pulse frequency and depresses the central nervous system. In Nigeria today, cleansing facial soaps are being manufactured with pappain enzyme extract.
The medicinal potency of pappain is indeed far more reaching. Diseases like chronic and infantile diarrhoea, oesophageal obstructions, diphteria, cholera, cancer, bleeding piles, ulcers, enlarged spleen, kidney disorders, elephantiasis intestinal worms, can be cured by pappain. Furthermore, Eczema, psoriasis, ringworms and various forms of infectious diseases are also effectively treated with formulations derived essentially from pappain.
Pappain is also used in the fell mongering of sheep’s skin (i.e., for removing the hair or wool from hides in preparation for leather making), and in the leather industry for the tanning of leather. In the textile industry, woolen and raw silk fibre are similarly treated with pappain.
For the clarification of lenses and preparations for the recovery of spent film in the optics and photographic industries the product further finds profound application.
Further in the food industry, the ripe paw-paw (papaya) fruit with golden yellow-to-orange coloured pulp and mild characteristic aroma is widely used as a table fruit or in combination with other fruits as salads. The paw-paw fruit could be industrially processed into fruit bar, candy, jam, marmalade, toffee, baby foods, jelly, syrup, canned fruit juice, cereal flakes and wine.
The choice of the taste or flavour of the fruit product depends so much on the plant species. There are so many species or varieties of the plant but the most popular in Nigeria is the sunrise solo dwarf, which was introduced from Hawaii.
Paw-paw products have very wide local and international markets especially the Western and other industrialized countries of the world where the medical and nutrition sciences are advanced. The three derivatives of the product namely: raw paw-paw, fruit products and pappain have specific target markets.
International prices for each derivative are handsomely attractive, and the global demand for papain alone is estimated at over 800 tonnes currently against the global supply of approximately 500 tonnes.
Nigerian entrepreneurs are yet to join the league of big-time world suppliers despite the country’s great supply potential. Countries like the Philippines, Brazil, India, Ceylon, and Thailand have made remarkable achievements in the export of Pappain (processed latex); while African countries like Kenya, Zaire and Mozambique have succeeded in exporting the raw preserved latex(the semi-processed form).
An integrated Paw-paw project involving the cultivation of the paw-paw plant and the processing of the latex into spray-dried pappain for export and the fruit into fruit products for the domestic market can be easily set up in Nigeria.
The Plant and machinery for processing pappain consist mainly of the Mixing tank and the Spray drier. Core equipment for processing the fruit include Boiler, Grading Machine, Hydraulic Press, Vacuum Evaporator and Laboratory Equipment.
Technical assistance obtainable from Germany, India or the US could be arranged.
The best way to ensure an uninterrupted inflow of raw materials is by establishing a plantation. A suitable project site should be near this source of raw materials, taking into consideration the bulky or perishable nature of the raw products. The milky latex and the ripe paw-paw fruits constitute the principal raw materials for pappain and fruit products, respectively, while appropriate chemical catalysts and hydrolyzing agents are used for processing the latex into pappain. The process of pappain production involves tapping, filtration, and coagulation of the milky latex; then, spray-drying of the solidified latex into powder; and finally, quality control.
The activity (state of quality) of pappain may be tested in two ways:
- The first is a low-cost assay method using milk powder in which the ability of the pappain to clot the milk is tested.
- The second method involves the measurement of the amount of tyrosine released by pappain from a standard case in solution.
Consider setting up a small to medium-scale integrated plant with an annual output of about 40 tons of pappain and 80 tons of fruit products. At the price of 60 United States dollars per kg of pappain and 60 cents per kg of fruit products, an export-oriented producer could generate a total turnover of over 2 million U.S. dollars in the very first two years of being in business.
Details of the technology employed in the production of pappain and paw-paw fruit products, international market links, export procedures and documentation, plantation programme and all other relevant information, will be embodied in a comprehensive Feasibility Report for interested prospective investors.
Meanwhile, the investment profile for establishing a small-scale factory is something like this:
Pre-operational Costs 500
Land & Factory Building 7,000
Core Plant, Machinery & Equipment 35,000
Other Capital Utilities 10,000
Working Capital Requirements 5,000
Total Investment Outlay 57,500