Papaya scraping machine

A gravity-fed papaya skin scraping machine 10 is disclosed, comprising a rotating scraper drum 20, an inclined feed plate 60 above the drum, a conveyor belt assembly 40 above the drum to hold papaya slices 11 down on rotating rods 21 in the drum, a pulp, seed, and juice collection hopper 100 beneath the drum, and a discharge plate 80 which catches skins coming off of the drum. The pulp and seeds are subsequently separated in a finisher, free from the bitter latex taste left by prior art methods of removing the skins.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to fruit processing machinery and 
specifically to a papaya scraping or peeling machine. 
2. Description of the Prior Art 
Papaya puree was traditionally produced by chopping the whole fruit and 
screening the pulp out from the skin and seeds. However, that process 
yielded bitter tasting puree. It is preferable to peel the skin off and 
remove the seeds unbroken. As hand-peeling is laborious there has been a 
need to mechanize the process, which is difficult because the more 
regularly shaped papayas are sold fresh leaving irregular shapes for puree 
production. A papaya scraper built by Angara et al. was described in the 
December 1969 issue of the Transactions of the American Society of 
Agricultural Engineers at pp. 745-751. It comprised two feeder belts, a 
puree collection hopper, and a rotating scraper drum holding alternating 
round rods and wedge-shaped blades parallel to its axis. Papayas were 
sliced into thirds and placed face down on the first belt, which carried 
them to the downward-facing second belt. Friction of the second belt held 
the papaya skin as the flesh and seeds were scraped away by the drum and 
deposited in a puree collection hopper. The momentum of the skins carried 
them beyond the collection hopper. That machine was modified as described 
by Brekke et al. in Research Bulletin 170 of the Hawaii Agricultural 
Experiment Station at the University of Hawaii. The modified machine used 
all round rods, to reduce seed breakage, but the pulp and seeds were only 
loosened from the skins, and had to be separated later by a centrifuge. 
Because papaya skins contain bitter tasting latex, steaming or "blanching" 
the whole fruit before processing was necessary to coagulate the latex and 
prevent it from exuding from cuts in the skin while the skins were mixed 
with the pulp. 
The supply of and demand for papaya puree have continued to increase, for 
example in Costa Rica, making necessary a more satisfactory peeling 
machine. 
SUMMARY OF THE INVENTION 
It is therefore an object of this invention to provide a method and 
apparatus for cleaning, and as rapidly as possible separating, the skin 
and seeds of irregularly shaped papayas from their pulp. Other objects are 
to provide a method in which it is not necessary to blanch the papaya 
first and in which the peeled skin pieces exuding latex are kept from 
mixing with the pulp. These objects are attained by providing a feed plate 
on which sliced papayas are placed face down to slide by gravity onto a 
rotating scraper drum. Rods forming the drum wall scrape out the papaya 
pulp and seeds while a conveyor belt above the rods slows movement of the 
skins. The pulp and seeds fall through the drum rods into a collection 
hopper below for removal to, and separation of seeds by, a finisher. The 
skins are swept by the conveyor belt onto a discharge plate.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Immature papaya has pale, hard flesh which is difficult to remove. The 
flesh becomes soft and yellow from the seeds outward as it ripens, which 
it must do before it is suitable for processing into puree. Mature fruit 
is washed, inspected, trimmed, and cut into halves or thirds before having 
the pulp scraped out by this invention. 
Referring to FIGS. 1 and 2 the papaya scraper 10 comprises a drum 20, a 
conveyor belt assembly 40, a feed plate 60, a discharge plate 80 and a 
puree collection hopper 100. The scraper is supported on a stand 50. The 
sliced papaya 11 is placed flesh side down on feed plate 60, and slides by 
gravity down to conveyor 40, which comprises supply axle 41 at its upper 
end, take-up axle 42 at its lower end, and belt 45 around the axles. Belt 
45 and axles 41 and 42 are preferably 63 centimeters wide. When wet, belt 
45 must have a high enough coefficient of kinetic friction against papaya 
skin to withstand the shear force of the rods 21 moving through the papaya 
pulp. Corrugated rubber and floor-mat rubber are suitable for belt 45. The 
papaya 11, prevented by side walls 62 from falling off the sides of plate 
60, slides off the lower edge 61 of the plate onto scraper drum 20. The 
larger pieces fall with, and the smaller pieces without, the urging of 
belt 45. Scraper drum 20 comprises an axle 24, preferably at least 63 
centimeters wide, and, mounted on axle 24, two end disks 23 preferably 
having radii of 20.6 cm. Disks 23 each have a circle of holes near their 
periphery, anchoring scraping rods 21. Round stainless steel rods 21 are 
used in the preferred embodiment, although variations of the shape and 
materials are possible. 
The papaya falls off the end 61 of plate 60 into a space between rods 21 
and belt 45 which is larger than the usual thickness of a papaya slice 11. 
The papaya is pulled by drum 20 onto belt 45, which, though moving in the 
same downward direction as rods 21, is moving less swiftly and holds the 
papaya skin back. In the preferred embodiment the tangential speed of drum 
20 is 4.3 meters per second (9.65 mph) which is four times the linear 
speed of belt 45. The conveyor belt axles and the drum axle 24 are 
supported by end plates 51 and 52, and driven by conventional motors and 
reduction gears, not shown. As papaya slice 11 approaches the rod 22 
momentarily closest to the belt 45, the face of the papaya is scraped off. 
The distance between belt 45 and rod 22 should be 0.15 to 0.25 inches, or 
somewhat greater than the 0.06 inch typical maximum thickness of a papaya 
skin. Springs 44 hold cylindrical bars 43, parallel to axles 41 and 42, 
behind the face of belt 45 to maintain the papaya at a fairly constant 
pressure against rods 21. The scraped out pulp, seeds and juice fall 
through the rotating rods and drum, to be collected by hopper 100. The 
hopper, shown separately in FIG. 3, extends around the lower part of the 
scraper inside stand 50 and between the feed plate edge 61 and discharge 
plate edge 81. The pulp and seeds are removed from hopper 100 by tap 101 
to a finisher, not shown, for separation. In the finisher, paddles force 
the pulp and juice, but not the seeds, through a screen. Hopper 100 also 
has a hinge 103 holding a door 102 which may be opened for cleaning. 
Friction between belt 45 and the papaya skins carries them over the 
parallel edge 81 of discharge plate 80. Plate 80, which is not found in 
the prior art, prevents the pieces of peel, which exude latex, from 
falling into the hopper and, while awaiting separation, giving the puree a 
bitter taste. The skins are channeled by side walls 82 and slide off to be 
disposed of. 
A rinsing system including a pressurized water supply, a pipe 90 and water 
sprayers 91 is preferably provided to keep papaya juice from accumulating 
and drying on belt 45, and making the belt dirty and sticky. The spray 
also dislodges any skins sticking to the belt. 
With the drum rotating at 200 rpm single papaya slices can be processed in 
two seconds, and slices can be placed on the feed plate end-to-end or even 
side-by-side, depending on the width of drum 20 and belt 45. 
A preferred embodiment has been illustrated in detail, modifications and 
adaptations of which will occur to those skilled in the art. Such 
modifications and adaptations are within the spirit and scope of the 
present invention, as limited only by the following claims.