Vol. XV. No. 379. 



THE AGRICULTURAL NEWS. 



359 



THE PREPARATION OF COMMERCIAL 



PAPAIN. 



Recent enquiries coucerning the production of papain 

 have made it desirable to reproduce the following article 

 which first appeared in the Agricultund News, Vol. I, No. 1; — 



The preparation of crude papain is a comparatively easy 

 matter, provided that attention is paid to certain matters of 

 detail. 



COLLECTIN<; THE MILK. 



The juice, or milk, which forms the starting point is 

 procured by making a scratch or shallow incision in the skin 

 of the fruit of the papaw while in a green condition. It is 

 desirable to employ a bone or wooden knife, like a paper- 

 kuife, for the purpose. The milky fluid rapidly exudes and 

 may be caught in a cup held beneath tlip fruit. After a time 

 the flow diminishes and the liquid coagulates in the neigh- 

 bourhood of the incision: this is carefully removed by means 

 of the bone or wooden knife and placed in the cup with the 

 milk already collected. The fruit is not removed from the 

 tree, and it may be subjected to the operation of tapping 

 several times at intervals of two or throe days. 



It is es,sential that no iron knife, or iron utensils, should 

 be brought into contact with the milk. Wood or bone should 

 be employed, and the milk should be collected in earthen- 

 ware basins or cups, or in glass vessels, and not in tins, 

 which are sure to blacken it. 



After collecting, the jui«e soon becomes coagulated and 

 then should be in the form of a snow white curd, possessing 

 a somewhat pungent, but not putrid, smell. It speedily 

 decomposes if not rapidly dried, and, when decomposing, 

 emits a most unpleasant odour. It is necessary then that 

 drying should be effected as speedily as possible. When 

 cocsideraWe quantities are being prepared, the collection of 

 the juice or milk should be undertaken in the early morn- 

 ing, and the drying .should begin before mid-day. This 

 ensures that by evening the material is in a sufHciently dry 

 condition to keep without deterioration until the following 

 moraing when the drying can be completed. 



DRYING THE MILK. 



The drying may be effected in several ways. In dry, 

 hot weather the coagulated milk may be placed in thin layers 

 on sheets of glass and exposed to the sun. This, however, is 

 rarely satisfactory on a large scale, and it is best to adopt 



stretching brown linen 

 like those, used for f ram 

 suitable size to suit the 



A small American 

 a drying stove (Fig. 1) 

 brick, a chamber about 

 long (the.se dimensions 

 the amount of material 



"11 light wooden frames, somewhat 

 !iig school slates: these may be of any 

 drying apparatus employed. 



fruit drier will answer very well, or 

 may be constructed by building, in 

 3 feet high, 3 feet wide, and 6 feet 

 can be changed in accordance with 

 to be dealt with). This is open at 



Fig, 1. Elevation. 



some form of drying apparatus. Drying is well effected by 

 spreading the coagulated milk on drying frames made by 



Fig. 2. Sectioi* along the line xx of Fig. 1. 



Figs. 1 & 2. Diiying stove, fob the i-eeparation 

 OF papain. 



(A). Ojiening across whicli tlie drying tr.ays are supported. 

 (B). Iron plate. (C). Fire grate. (D), Chiiiinej'. 



the top. About a foot fro«i the top the chamber is divided 

 horizontally into two compartments by a sheet of iron (B), 

 and below this division a small fire grate (C) is constructed; 

 at the opposite end from the grate a chimney (D) is placed to 

 lead the smoke from the lower compartment (Fig. 2). In 

 order to obtain an even heat in the upper compartment, 

 it is well to spread a layer of sand, 1 or 2 inches 

 thick, over the iron plates. The frames carrying the 

 coagulated milk are placed on the top of the chamber, so aa 

 to form a lid or cover to the opening (A^, when heal from 

 the iron plate drives oti" the moisture at a low temperature. 



It is important that the temperature at which drying is 

 effected shall be as low as possible. Any overheating 

 destroys the active principle, so that a carelessly prepared 

 product may be useless. In practice the temperature is 

 kept as low as is consistent with getting the substance 

 dried before decomposition sets in; if this can be done 

 without the temperature of the tray being raised above 

 100" F. so much the better. 



As the substance becomes dry it shrinks considerablj 

 in bulk. The contents of several trays may now be emptied 

 into one, and the drying continued. The trays emptied are 

 ready to receive another day's supply of fresh material. 



Drying must be continued until the substance is crisp 

 and in such a condition that it can be reduced to a fine 

 powder without any difficulty being experienced from 

 stickiness. The dried material should be ground to a fine 

 powder, when the resulting product should be a white o» 

 cream-coloured powder with a characteristic, but not putrid, 

 smell. The powder should be packed in tins or bottle.s, and 

 carefully preserved from contact with the air. Grinding is 

 easily effected in a mill of the type commonly employed 

 for grinding coffee: when grinding it is desirable to have the 

 papain slightly warmed. 



