Papain production
Practical Action
1) Papain is potentially dangerous: prolonged contact will damage the skin of workers'
hands. In some cases it may cause allergic reactions.
2) The market for papain in Europe is shrinking as alternative chemicals are found. Papain
may be banned from some foods - such as beer - in the near future.
3) Low grade (sun-dried) papain has a much smaller market than higher quality spray-dried
papain (see below). A thorough market survey should be made to ensure that the product
can be sold.
4) Plantations of papaya trees are needed for economical production. Merely collecting
latex from the fruits of a few trees in home gardens is not a viable activity.
Papain: source and uses
Papain is in the dried latex obtained from the papaya fruit (Carica papaya L). It is the protease
most commonly used in the food processing applications mentioned above. Other important
proteases ficin, obtained from figs, and bromelain, which is obtained from pineapple.
In addition to its relevance to the food industry, papain is also used in the pharmaceutical
industry for medicines, such as in preparation of vaccines, or for the treatment of hard skin.
Papain also has veterinary applications such as in the de-worming of cattle, and is used in the
tanning of leather, in the paper and adhesive industries, and in sewage disposal. Medical
research uses papain for plastic surgery on cleft palates.
Methods of collection and extraction
Papain is obtained by cutting the skin of the unripe - but almost mature - papaya before
collecting and drying the latex which flows from the cuts. The fruit should be tapped some time
during the morning (a period of high humidity). The lower the humidity levels, the lower the flow
of latex.
Two or three vertical cuts (except the first cut, see below) 1-2mm deep are made, meeting at the
base of the fruit. The incisions are made using a stainless steel razor blade set into a piece of
rubber attached to a long stick. The blade should not protrude more than about 2mm as cuts
deeper than 2mm risk juices and starch from the fruit pulp mixing with the latex, lowering
quality.
Fruits should be tapped at intervals of about 4-7 days. For the first tapping, it is usually
sufficient to make only one cut. On subsequent tappings, the two or three cuts are spaced
between earlier ones (as explained above).
After about 4-6 minutes the flow of latex ceases. A dish is used to collect the liquid; it is then
scraped into a polythene-lined box with a close fitting lid. The box should then be stored in the
shade. Using a close fitting lid and keeping the box in the shade reduce the reactions which
cause loss of enzyme activity.
Foreign matter such as dirt and insects should be kept out of the collected latex. Any secreted
latex adhering to the fruit should be carefully scraped off and put into the collecting box.
However, dried
latex should not be mixed with fresh latex, as this lowers the quality.
When handling fresh latex, care should be taken to ensure that it does not come into contact
with skin: it will cause burning. Neither should the latex come into contact with heavy metals
such
as iron, copper or brass, as it causes discolouration and loss of activity. Pots, knives and
spoons should only be used if made from plastic or stainless steel. Fresh latex does not keep well
and should therefore be dried to below 5% moisture as soon as possible. This gives it a dry and
crumbly texture.
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