Method for cracking walnuts and recovery of nut meat therefrom

An improved method and apparatus for the cracking of walnuts (30) is provided, and particularly Eastern black walnuts, wherein the surfaces of the shells (32) of the walnuts (30) are first altered to present compression zone(s) (132, 134), and the walnuts (30) are then cracked by subjecting the shells (32) thereof to opposed compressive forces serving to crack the shells (32) while leaving nut meat kernels intact. Preferably, the walnut shells (32) are sanded adjacent the opposed upper and lower ends (34, 36) thereof to present the zones (132, 134), with subsequent compression cracking of the shells (32), leaving a substantial fraction of the internal nut meat intact.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention is broadly concerned with an improved method and 
apparatus for cracking of walnuts (especially Eastern black walnuts, 
Juglans nigra) and recovery of nut meat therefrom. More particularly, the 
invention is concerned with the method and apparatus which increases not 
only the gross yield of nut meat, but also gives appreciably more of 
valuable large nut meat kernels, as opposed to smaller, comminuted nut 
meat fragments. Broadly, the invention involves altering the surface 
configuration of walnut shells and thereafter cracking the surface-altered 
walnut shells by subjecting them to compressive forces; this serves to 
crack the hard walnut shells while leaving a greater proportion of the 
internal kernels intact. 
2. Description of the Prior Art 
Eastern black walnuts are an important food item in American society. Black 
walnut kernels contribute considerably to the flavors of candy, ice cream 
and bakery products. They can also serve as a dietary supplement which is 
rich in phosphorus, iron, and vitamins B.sub.1 and A. Accordingly, black 
walnut meat is a premium food product commanding a relatively high price. 
Black walnuts are one of the most difficult nuts to crack among all 
hard-shelled nuts. There are basically three directions from which 
compressive, cracking pressure can be applied: (1) end-to-end along the 
longitudinal axis; (2) side-to-side across the narrowest lateral 
dimension; and (3) side-to-side along the widest lateral dimension. 
However, black walnuts vary in size and the large number of species makes 
it difficult to uniformly treat and handle the nuts for maximum yield of 
meat. 
Cracking and shelling machines for black walnuts became available in about 
1935, but the industry did not become firmly established until about 1945. 
These machines generally include a pair of hard metallic cracking rolls 
which receive the walnuts and crack the shells thereof during passage 
between the rolls. Thereafter, the mixed cracked shells and nut meat 
kernels are passed through a series of rollers with saw-like teeth, which 
separate the nut meat from the shells. The nut kernels are then sorted and 
graded and are ready for packaging. 
A persistent problem with existing processing equipment is the relatively 
low yield of nut meat which can be obtained. Generally speaking, from 220 
pounds of black walnuts a commercial sheller may expect slightly more than 
15 pounds of saleable top grade kernels, giving a yield of about 7%. 
Current commercial yields of nut meat range from about 6.5-9.5% by weight 
wet basis, whereas the theoretical yield from black walnuts is 
approximately 21.5% by weight wet basis. 
Additionally, current commercial shelling methods tend to produce an 
inordinately high percentage of small pieces, as opposed to the most 
desirable and valuable fancy large pieces. At current prices, small nut 
meat pieces are sold at retail at approximately $2.00 per pound, whereas 
the fancy large pieces are sold at about $5.00 per pound. 
There is accordingly a decided need in the art for an improved method and 
apparatus for commercial scale shelling of black walnuts and recovery of 
nut meats, wherein both the gross yield and the percentage of large 
kernels are increased. 
SUMMARY OF THE INVENTION 
The present invention overcomes the problems outlined above, and provides 
an improved method and apparatus for cracking of walnuts in order to 
enhance the recovery of nut meat therefrom. Broadly speaking, the surfaces 
of the shells of walnuts are first altered to present thereon at least one 
compression zone, whereupon the altered walnuts are cracked by subjecting 
them to opposed compressive forces at the compression zones and at points 
substantially opposite the compression zones. The surface alterations in 
accordance with the invention serve to distribute compressive forces 
during cracking in order to permit cracking of the shells while leaving 
portions of the nut meats thereof intact. Thereafter, the nut meats can be 
readily recovered from the cracked walnuts in enhanced yield. 
In preferred forms, a pair of compression zones are created on each walnut 
shell, and specifically at the top and bottom regions thereof, by abrading 
the walnuts to present opposed, flattened zones. The walnuts are then 
subjected to compressive cracking forces, typically by means of a pair of 
shiftable plates. This serves to crack the surrounding walnut shells, 
leaving (in the ideal form) a central shell column with four large, 
substantially intact kernels disposed about the column. These kernels can 
then be readily stripped from the shell column in good yield. 
In alternative forms, only a single compression zone can be formed on the 
walnut shells, specifically at the top thereof in the region of the 
characteristic natural fault line. Thereafter, the walnuts are placed upon 
a compression plate presenting an upstanding, elongated protruding element 
presenting a sharp, walnut shell-engaging edge, with the natural fault 
line being transverse to the longitudinal axis of the edge. An opposed, 
shiftable compression plate is then used to engage the opposite end of the 
walnut shell, which serves to crack the nut into four quadrants, each 
including a shell segment and an attached nut meat kernel. In this form of 
the invention, the walnut quadrants are then subsequently treated by 
surface abrading the opposed ends of each shell segment, and compressing 
the quadrants at these regions to separate the nut meat kernels. 
In a still further embodiment, the walnut shells may be cut or sawed 
substantially along the length of the natural fault line to a depth of up 
to about 2 cm and a length of up to about 3 cm. Thereupon, the cut walnuts 
are placed between a pair of opposed compression plates, with one plate in 
engagement with the cut region and the opposite plate engaging the bottom 
of the walnut. Displacement of the plates serves to crack the shells, 
leaving the nut meat kernels readily recoverable.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Turning now to the drawings, and particularly FIGS. 1-3 and 10, a typical 
Eastern walnut 30 is illustrated. The walnut 30 includes a very hard, 
coarse woody outer shell 32 as well as a top 34 and opposed bottom 36. The 
top 34 (FIG. 2) has a characteristic, elongated natural fault line 38 
therein whereas the bottom 36 typically presents a somewhat peaked tip 
region 40. As best seen in FIGS. 2, 3 and 10, the walnut is somewhat oval 
in cross-section presenting major and minor axes. Internally (FIG. 10) the 
walnut shell 32 presents central column segments 42 with four nut meat 
kernels 44, 46, 48, and 50 disposed about the column segments 42 and 
interconnected by a central bridge section 52 (FIG. 8). 
The most preferred walnut shelling apparatus 54 is schematically 
illustrated in FIG. 11 and includes an incoming nut hopper 56, nut 
orienting means 58, conveyor 60, cracking station 62 and 
collection/separation apparatus 64. 
In more detail, the hopper 56 is designed simply to receive incoming 
walnuts and to feed these to conveyor 60 and orienting means 58. The 
orienting means may be simply a station where the nuts are manually 
oriented on conveyor 60, or automated means of conventional nature can be 
used for this purpose. The conveyor 60 is an endless belt 61 trained 
around rollers 66, 68 and presenting successive nut-receiving compartments 
70 defined by spaced apart sets of upstanding projections 72 along the 
length of the belt 61. As illustrated in FIGS. 12 and 13, the orienting 
means 58 and conveyor 60 serve to place individual walnuts 30 within 
corresponding compartments 70 with the walnuts being on their sides and 
with the upper and lower ends 34, 36 thereof adjacent the side marginal 
edges of belt 61. 
The cracking station 62 is positioned adjacent the end of conveyor 60 
remote from hopper 56. The cracking station includes an uppermost 
nut-shifting assembly 74 adapted to move the individual nuts 30 through 
the station. To this end, the assembly 74 includes a pair of depending, 
shiftable, nut-engaging fingers 76, 78 operatively mounted on an 
uppermost, elongated track 80. As illustrated in FIG. 14, the fingers 76, 
78 are operable to grip individual nuts 30 for passage through cracking 
station 62. 
The station 62 beneath assembly 74 includes a pair of elongated, laterally 
spaced apart and shiftable base plates 82, 84. Each of the opposed base 
plates 82, 84 is provided with a pair of spaced apart slots 86, 88, the 
latter being adapted to receive corresponding guide pins 90 and 92 mounted 
on underlying supports 94, 96. In this fashion, the base plates 82, 84 can 
be shifted toward and away from each other by conventional means (not 
shown), in order to accommodate nuts of various sizes. 
The inlet end 98 of station 62 includes a pair of upstanding gauge plates 
100, 102 respectively secured to the base plates 82, 84. In addition, each 
base plate 82, 84 supports a corresponding rotary sander 104, 106 
downstream of the associated gauge plate, with each of the sanders 
including a motor 108, 110 and a sanding wheel 112, 114. Finally, each 
base plate 82, 84 also supports downstream of each sander a nut 
compression assembly 116, 118. Each of these includes a selectively 
actuatable piston and cylinder assembly 120, 122 respectively having an 
extensible piston rod 124, 126 and an innermost, shell-engaging 
compression plate 128, 130 coupled to each piston rod. 
The collection/separation apparatus 64 is adapted to receive shell 
fragments and nut meat kernels derived from cracking in station 62. This 
apparatus has been only schematically depicted, inasmuch as conventional 
means can be used for such collection and separation. To give but one 
example, the usual separation roll assemblies used in prior art shelling 
devices can be employed in this context, or for that matter, the shell 
kernels may be manually separated from the shell fragments. 
The operation of the preferred shelling apparatus 54 will now be described, 
with reference to FIGS. 11-15, and also FIGS. 1-9, the latter showing in 
greater detail the configuration of the walnuts at each succeeding 
processing stage. In particular, nuts properly oriented and conveyed on 
belt 61 first enter inlet 90 of station 62, whereupon the nuts are 
individually grasped by the fingers 76, 78 and moved into position between 
the gauge plates 100, 102, so as to permit positioning of the components 
of cracking station 62 relative to the individual nut. Specifically, the 
base plates 82, 84 are moved inwardly or outwardly relative to each other 
until the gauge plates 100, 102 lightly contact the corresponding upper 
and lower ends 34, 36 of the individual nut. Such base plate movement also 
serves to simultaneously position the sanders 104, 106 and nut compression 
assemblies 116, 118, as will be readily understood from a study of FIGS. 
14 and 15. 
In the next step, the fingers 76, 78 are shifted rightwardly as viewed in 
FIG. 14 until the nut is positioned between the sanding wheels 112, 114. 
At this point, the motors 108, 110 are activated and the ends 34, 36 of 
the nut are abraded to present respective, flattened compression zones 
132, 134 on the ends of the nut shell. These compression zones are 
illustrated in FIGS. 5 and 6, where it will be observed that the natural 
fault line 38 is still visible after this sanding operation. Generally 
speaking, the compression zones should have a diameter of up to about 3 
cm, and more preferably from about 1-2 cm. 
After the sanding operation is completed, the fingers 76, 78 are again 
shifted rightwardly to place the nut between the shell-engaging 
compression plates 128, 130. The piston and cylinder assemblies 116, 118 
are then activated in order to move the plates 128, 130 into compressive 
engagement with the flattened zones 132, 134 on the walnut shell. The 
maximum total displacement of the plates 128, 130 is up to about 4 mm, 
more preferably from about 2-3 mm. The rate of movement of the plates 
should be relatively slow, typically from about 1-60 mm/min. The inward 
movement of the compression plates 128, 130 serves to crack the walnut 
shell and permit subsequent collection of the nut meat kernels. Ideally, 
the shells will crack and fall away from the nut meat kernels, leaving 
only the central column sections 42 and the flattened ends of the shell, 
with the nut meat kernels 44-50 in place. It will of course be understood 
that this ideal cracking may not always occur, owing to variations in 
individual nut shell sizes, thicknesses and hardness. 
After the surrounding nut shell has been cracked (see FIGS. 7 and 15), the 
shells and the nut meat kernels drop by gravity into the 
collection/separation apparatus 64. At this point, the nut meat can be 
conventionally separated, graded and collected as explained previously. 
Attention is next directed to FIGS. 16-21 which illustrate another shelling 
apparatus 136, broadly including a whole nut orienting conveyor 138, 
initial cracking station 140, nut quadrant orienting conveyor 142, and 
secondary nut quadrant cracking and nut meat recovery station 144. 
In more detail, in the present embodiment it is contemplated that starting 
walnuts will initially be manually or machine sanded to present a single, 
flattened compression zone 146 at the top 34 of the nut in the area of 
natural fault line 38. These nuts are then placed onto the whole nut 
orienting conveyor 138 which serves to right the individual nuts and 
deliver them in a properly oriented condition to initial cracking station 
140. Specifically, the conveyor 138 includes an elongated bottom wall 148 
together with a side mounted, powered conveyor chain 150 supporting a 
plurality of spaced apart metallic, somewhat V-shaped nut pullers 152. In 
addition, the initial portion of the bottom wall 148 spaced from station 
140 is provided with a roughened surface 154 analogous to sandpaper. The 
remainder 156 of the bottom wall 148 presents a smooth metallic surface 
leading to the station 140. 
The initial cracking station 140 includes a stationary bottom plate 158 
including an elongated, upstanding protrusion 160 presenting a sharp 
shell-engaging knife edge 162. Further, an opposed piston and cylinder 
assembly 164 is positioned above plate 158 and includes an extensible rod 
166 supporting an upper shell-engaging compression plate 168. The purpose 
of the initial cracking station 140 is to separate the starting nuts into 
individual quadrants which are then delivered for subsequent processing. 
The quadrant orienting conveyor assembly includes an inlet hopper 170 
positioned beneath the initial cracking station 140 to receive the nut 
quadrants, with a lowermost, angularly oriented conveyor 172 positioned at 
the lower end of the hopper 170 for receiving quadrants therefrom. The 
conveyor 172 (see FIG. 20) includes a pair of obliquely oriented side 
plates 174, 176 which cooperatively form a somewhat V-shaped configuration 
with a bottommost space 178 between the plates 174, 176. A powered belt 
180 having a plurality of spaced apart, upstanding, quadrant-engaging pins 
182 secured thereto is located beneath the side plates 174, 176, with the 
pins 182 extending upwardly through the space 178 and between the side 
plates. As in the case of bottom wall 148, the side plates 174, 176 at the 
lower regions thereof are provided with abrasive, sandpaper-like upper 
surfaces 184, whereas the remainder of the side plate upper surfaces 
upstream of these roughened surfaces and leading to the secondary cracking 
station 144 are smooth. 
The secondary station 144 includes a nut quadrant receiver 186, along with 
cracking and recovery apparatus 188 similar to cracking station 62 
described previously. The quadrant receiver 186 is best illustrated in 
FIG. 21, and includes an elongated arm 190 presenting an outermost, 
V-shaped in cross-section section 192. The arm 190 supports a pivotally 
mounted hold-down finger 194 adjacent the section 192. Finger 194 is 
movable by means of a small piston and cylinder assembly 196 having the 
base 198 thereof pivotally secured to the arm, and with the outer end of 
the piston rod 200 thereof pivotally coupled with finger 194. In addition, 
the arm 190 is movable between a first nut quadrant-receiving position 
depicted in bold lines in FIG. 21 to a downwardly pivoted and inwardly 
displaced nut quadrant delivery position illustrated in phantom. The 
receiver 186 is designed to receive properly oriented nut quadrants from 
the outlet end of conveyor 142, and to successively deliver these 
quadrants to the secondary station 144. 
Secondary station 144 as indicated is very similar to cracking station 62. 
In particular, the station 144 includes successive gauging, sanding and 
compression devices 202, 204 and 206, as well as a dual-finger conveyor 
208 for shifting individual nut quadrants through these in-line devices. 
It will be understood in this respect that the devices 202-206 initially 
gauge each individual quadrant, sand the opposed, pointed ends thereof to 
present compression surfaces, and thereafter exert compressive forces on 
the sanded surfaces to facilitate ultimate separation of the nut meat from 
the shell quadrants. 
In the operation of apparatus 136, previously sanded walnuts having the 
flattened compression surfaces 146 are placed within initial orienting 
conveyor 138, with each of the nuts being picked up by a successive nut 
puller 152. As the nut pullers move the nuts along the length of the 
roughened surface 154, the nuts are turned until, when the nuts reach the 
smooth surface 156, they are all oriented with the previously flattened 
surface 146 facing downwardly. In addition, the nuts are oriented, because 
of their general oval cross-section, with the major axis of the nut being 
generally aligned with the longitudinal axis of the conveyor 138. 
The oriented nuts are then delivered to the initial cracking station 140 
and specifically with the surface 146 of each nut atop the knife edge 162 
of stationary plate 158. This positioning is illustrated in FIGS. 17-18, 
where it will be observed that the knife edge 162 is generally transverse 
to the natural fault line 38 of the nut shell. At this point, the piston 
and cylinder assembly 164 is actuated to compress the nut between plates 
158, and 168. Here again, the maximum displacement of the plate 168 should 
be on the order of up to 4 mm, and more preferably from about 2-3 mm; the 
rate of displacement of the plate 168 should be from about 1-60 mm/min. 
This compression serves to break the nut into four separate quadrants 210, 
212, 214, and 216 (see FIG. 19), with each quadrant including a shell 
segment and a nut meat portion. 
The nut quadrants fall by gravity into and through hopper 170, and are then 
delivered to conveyor 172. Each individual quadrant is in turn engaged by 
an upstanding pin 182 carried by underlying belt 180, and is so moved 
upwardly toward the discharge end of the conveyor. The initial 
sandpaper-like surfaces 184 provided at the lower end of the conveyor 
serve to properly orient each quadrant as illustrated in FIG. 20, i.e., 
with the broken faces of the quadrant facing downwardly and engaging the 
side plates 174, 176. 
The aligned and oriented quadrants are then delivered to nut quadrant 
receiver 186 where they are successively fed into the V-shaped section 
192. The arm 190 is then pivoted downwardly and, during such pivoting the 
piston and cylinder assembly 196 is actuated to close finger 194 onto the 
upper shell segment of the quadrant. Movement of the arm 190 is this 
fashion serves to dislodge any improperly formed quadrants and allow these 
to be collected for separate processing; by the same token, properly 
formed quadrants are retained in the V-shaped section 192, with finger 194 
assuring proper delivery thereof to the secondary station 144. 
When the receiver 186 presents a quadrant to the station 144, the transport 
conveyor 208 grasps the quadrant and successively moves it through the 
devices 202-206. These latter operate exactly as described previously with 
reference to station 62, i.e., the respective quadrants are first gauged, 
then end-sanded, and then subjected to compression to separate the nut 
meat portions from the shell segments. Final separation, recovery and 
grading of the nut meat kernels is carried out by conventional means. 
Actual laboratory testing of the preferred method in accordance with the 
invention has demonstrated that nut meat yields are materially enhanced, 
as compared with conventional processing techniques. For example, using an 
average of 20 walnut samples where the walnuts were manually sanded to 
flatten the upper and lower ends thereof, and then subjected to 
compression in an Instron compression tester (10 mm/min. displacement 
rate, total displacement 3 mm), yields of from about 14.3-18.2% by weight 
wet basis were obtained. This corresponded to a nut meat recovery rate of 
from about 67-84% of the theoretical yield, amounts far in excess of 
yields conventionally obtained. 
Another advantage of the method and apparatus of the invention is that a 
comparatively large fraction of the nut meat kernels recovered are of 
relatively large size, which can be sold for a premium price. Finally, 
inasmuch as greater yields of nut meat are obtained, the resultant 
collected shells therefore contain less of the nut meat. This is important 
in that the shells have various industrial uses, such as abrasives, and 
shells having reduced nut meat fractions are less likely to be 
objectionable on the basis of excess oil or rancidity.