Method and apparatus for detaching meat from bone

Bones (10) with meat attached thereto are suspended in a substantially fluid medium (14). The fluid medium or matrix (14) includes meat, fat and other soft material (16) which behaves similarly to a fluid when a pressure is applied thereto. The substantially fluid medium (14) also includes a substantially compressible material (18) such as a gas included in voids within the matrix. Once the bones (10) are properly suspended, the entire matrix of material (14) is compressed from an initial pressure to a detachment pressure which may be in a range of 5 pounds per square inch over atmospheric to 1000 pounds per square inch over atmospheric. The meat attached to the bones (10) within the matrix (14) tends to migrate away from the bone and eventually detach from the bone. However, since of all of the bones (10) remain suspended in a substantially fluid medium, pressure is applied evenly across the entire surface of the bones without breaking the bones and contaminating the meat with bone fragments.

BACKGROUND OF THE INVENTION 
This invention relates to meat processing, and, more particularly, to a 
method for detaching meat from bone either before or after hand deboning. 
The invention also includes an apparatus for performing the meat detaching 
method according to the invention. 
Particularly in beef and pork production, the majority of meat is manually 
removed from the prepared carcass. Beyond this manual separation process, 
numerous automated processes have been devised for recovering meat from a 
carcass or bone pieces. For example, heat may be applied to the whole 
carcass or bones left after the initial processing to cook the meat off 
the bones. To remove meat without applying heat, the bone and meat left 
after initial processing may be passed through a separator device having a 
separator screen and a blade which periodically passes over the screen 
openings. Pressure applied to the bone and meat within the separator 
device causes the meat to push out through the screen openings where it is 
periodically cut off by the passing blades. 
There are several problems associated with prior methods for removing meat 
from bone. The process of removing cuts of meat manually in the 
traditional fashion is labor intensive and requires skilled workers. As 
for the automated processes, the heat required in heat processing changes 
the character of the meat and makes the recovered product unsuitable for 
incorporating into many other products. The screen-type processes are used 
mainly with bones and meat left after initial processing. Also, although 
prior screen-type separators are generally effective at separating a 
portion of the remaining meat from bone, these separators commonly leave 
some amounts of meat still attached to the bones. Another problem with 
conventional screen-type separators is that the blades in such separators 
can chip off portions of the bone and other hard undesirable material, and 
this undesirable material can pass through the screen openings to reduce 
the quality of the separated product. Furthermore, screen-type separators 
can only produce an emulsified or course ground product rather than a true 
solid muscle. 
SUMMARY OF THE INVENTION 
It is an object of the invention to provide a meat processing method that 
overcomes the above-described problems and others associated with prior 
meat processing systems. More particularly, it is an object of the 
invention to provide a method for detaching meat from bone while leaving 
the bone substantially intact. Another object of the invention is to 
provide an apparatus for detaching meat from bone. 
The method according to the invention includes containing bone and attached 
meat in a particular manner while applying a detachment pressure to the 
bone and meat. The detachment pressure causes the meat attached to the 
bone to move with respect to the bone, eventually overcoming the strength 
of the attachment and causing the meat to detach. The invention is not 
necessarily a meat separating method in that the meat may not be 
segregated from the bone. Rather, the meat is simply detached, leaving the 
detached meat still mixed with the bone. Also, the process may not provide 
complete detachment from the bone, but may only isolate strong attachment 
points. However, since the method according to the invention leaves the 
meat substantially detached from the bone, the meat can be more easily 
separated from the bone by hand or by some other suitable process. 
In order to produce the desired detachment, the bone and attached meat is 
suspended in a substantially fluid medium or matrix. The fluid medium 
includes a compressible medium, preferably a gas such as air, contained 
within voids within the remainder of material making up the fluid medium. 
With the bone and attached meat properly suspended, the method includes 
compressing the fluid medium from an initial pressure to the detachment 
pressure. As the pressure increases, the meat strands attached to the bone 
tend to flow or move with respect to the bone. When the pressure reaches 
the detachment pressure, the meat detaches at its attachment point to the 
bone. The detached meat is not separated, but remains with the bone to be 
separated by some suitable process. 
In the preferred form of the invention, the substantially fluid medium or 
matrix comprises the compressible medium, bones or bone pieces with 
attached meat, and other soft material such as fat. The make-up of the 
matrix is important to maintain the desired suspension of bones during the 
compression process. If the matrix includes too much bone in relation to 
soft material, the bones may become trapped by the mechanism used to apply 
the detachment pressure, causing some of the bones in the matrix to break. 
The volume of meat and other soft material in relation to the volume of 
bone and the compressible medium must be sufficient to keep mechanical 
forces from concentrating on the bones throughout the compression process. 
With the bones suspended in the substantially fluid material, the only 
pressure applied to the individual bones is pressure from the meat, the 
compressible medium, and any other soft material such as fat contained 
within the matrix. The meat, compressible medium, and other soft material 
in the matrix behave somewhat similarly to a fluid in the manner in which 
pressure is applied to the bones. This pressure presses evenly around the 
bones without any mechanical concentrations which would occur by direct 
contact between the bones and a compressing mechanism. Applying only fluid 
pressure to the bones leaves the individual bones substantially intact and 
in a condition in which the bones may be easily separated from the 
detached meat and other soft components. 
As used herein, "bone" may include whole bones or cartilage, bone pieces 
cut from whole bones, or multiple whole bones remaining connected 
together, such as in a whole carcass or a substantial portion of a whole 
carcass. Thus, the method of the invention may be applied to whole 
carcasses or substantial portions of whole carcasses to produce an initial 
detachment. This initial detachment step makes manual and other separation 
processes easier and more effective in separating meat from bone. 
The compressible medium may comprise any material or combination of 
materials which may reduce in volume as the pressure on the matrix of 
material increases to the detachment pressure. For example, the 
compressible medium may be a gas exposed directly to other materials in 
the matrix. Alternatively, the compressible medium may comprise a suitable 
fluid contained within a flexible or elastic containment device or 
bladder. The fluid in the containment device may be compressible or 
substantially incompressible. In this latter case, the containment device 
must have a passage through which the incompressible material may be 
withdrawn to reduce the volume of the containment device as the pressure 
increases on the matrix of material. 
In the preferred form of the invention, the matrix of material is contained 
within a cylinder and the pressure is applied by a piston which may be 
extended into the cylinder. An input opening is associated with the 
cylinder and allows the material making up the matrix to be introduced 
into the cylinder. The input opening then may be closed to produce a 
pressure vessel for applying the desired detachment pressure. The 
detachment pressure which must be applied and which the vessel must be 
capable of withstanding, varies depending upon the type of meat being 
processed and the nature of the bones from which the meat is to be 
detached. The detachment pressure within the scope of the invention may 
range from 5 pounds per square inch or less to 1000 pounds per square inch 
or more as long as mechanical forces cannot concentrate on any of the bone 
pieces within the matrix. Higher pressure could tend to liquefy meat or 
produce some other undesirable effect in the meat. 
These and other objects, advantages, and features of the invention will be 
apparent from the following description of the preferred embodiments, 
considered along with the accompanying drawings.

DESCRIPTION OF PREFERRED EMBODIMENTS 
FIGS. 1 through 3 illustrate the manner in which meat is detached from bone 
according to the invention. In FIG. 1, bones 10 having meat to be detached 
are suspended in a matrix 14 comprising a substantially fluid medium. The 
matrix 14 is contained within a cylinder 11 having a piston 12 which may 
be moved within the cylinder 11 to compress the matrix. The substantially 
fluid medium or matrix of material 14 includes bones 10, soft material 16 
such as meat and soft material associated with meat, and a substantially 
compressible material 18. Examples of soft material in addition to the 
meat include fat and sinew. The substantially compressible material 18 is 
preferably a gas such as air contained in voids between individual pieces 
of the soft material 16. 
It will be apparent to those skilled in the art that certain components of 
the matrix of material 14, particularly the bones 10, are not themselves a 
fluid material. However, the matrix 14 as a whole represents a flowable 
mixture at temperatures above freezing, and behaves similarly to a fluid, 
particularly in the way forces are transferred within the mixture. This 
mixture or matrix of material 14 is defined as "substantially fluid" for 
purposes of this disclosure. 
The compressible material 18 within the matrix 14 may be any substantially 
compressible material, such as any suitable gas. However, liquids which 
reduce substantially in volume under pressure may also be used according 
to the invention. Also, the bones 10 in the matrix 14 are not limited to 
separated bones or bone pieces, but may comprise bones of a substantial 
portion of a whole carcass left intact with all of the meat still 
attached. 
Referring still to FIG. 1, bones 10 in the matrix of material 14 each have 
meat attached thereto. This meat comprises a portion of the soft material 
16 and may be detached and separated from the bone, and then incorporated 
into products such as ground meat, for example. This meat included in soft 
material 16 is commonly connected by tissue along the length of the bone 
10 and may include one or more major attachment points. The major 
attachment points are points at which the meat is strongly connected to 
the bone, while the majority of the connections other than at these strong 
attachment points are relatively weak in comparison. In certain bone 
pieces within the matrix 14, the part of the bone having the relatively 
stronger major attachment points may have been removed in earlier 
processing, leaving only the relatively weak attachment along the length 
of the bone piece. In FIG. 1A, the intersections of lines A--A, B--B, 
C--C, and D--D with the bone 10 each represents an attachment point 
between meat and bone. Attachment points for lines A--A and B--B comprise 
weak attachment points while the points for lines C--C and D--D comprise 
relatively strong attachment points. 
According to the invention, each bone 10 in the matrix of material 14 is 
suspended within the soft material 16 and the compressible medium 18 so 
that the bones are each substantially surrounded by the soft material 16. 
In order to provide this arrangement, the matrix 14 requires a substantial 
amount of soft material 16 relative to the bone 10 and compressible medium 
18 within the matrix. For example, the matrix 14 according to the 
invention may contain 50% bone and compressible medium or less by volume 
relative to the generally non-compressible, soft material 16. Other volume 
percentages of bone pieces 10 and compressible medium 18 to soft material 
16 may be used according to the invention as long as the bones, whether in 
contact with other bones or otherwise, each remain substantially suspended 
in the soft material throughout the process. 
The method of the invention includes first formulating the matrix of 
material 14 as described above. With the matrix 14 formulated and the bone 
10 suspended within the soft material 16 and substantially compressible 
material 18 at an initial pressure, the method includes compressing the 
matrix of material. Referring to FIGS. 2 and 2A, as the matrix of material 
14 is compressed from the initial pressure, which may be atmospheric 
pressure, the soft material 16 within the mixture tends to migrate within 
the mixture. That is, the soft material 16 tends to flow to areas formerly 
taken up by the voids of compressible medium 18, which are now smaller in 
volume due to the compressibility of the medium. 
Additionally, meat attached to each bone 10 tends to migrate or move 
relative to the bone to which it is attached. Initially, this tendency to 
migrate within the matrix of material 14 can overcome the relatively weak 
attachments to the bone with very little pressure applied to the matrix. 
As shown in FIG. 2A, the meat at the weak attachment points has detached 
from the bone 10 as represented by the offset at A--A and B--B. 
Regardless of the point in compression at which meat detaches from the bone 
10, each bone remains substantially suspended in the substantially fluid 
material or matrix 14 throughout the compression step. The bones 10 may 
contact each other, however, they must not become trapped between rigid 
members of the compressing arrangement, such as piston 12 and opposite end 
(not shown) of the cylinder 11. Thus, the pressure in the matrix 14 is 
applied evenly to the bones 10 and normal to each surface on the 
respective bone piece. This is in contrast to the pressure applied by 
mechanical contact with other solid material at opposing points on an 
object, which concentrates force at the contact points. The former contact 
with the soft material leaves the bones intact even after applying very 
high pressure, while the latter contact between rigid materials causes the 
bone to break apart at relatively low pressure. This breaking of bone, 
which would occur if the bones were not suspended according to the 
invention, would leave bone fragments in the matrix which would be 
difficult to separate, and would thus ultimately lower the quality of the 
recovered meat. 
The method continues by compressing the matrix 14 further until reaching a 
meat detachment pressure as illustrated in FIGS. 3 and 3A. At this 
pressure, the tendency for the previously attached meat to migrate 
overcomes even most of the strong attachment points as illustrated by the 
offsets at C--C and D--D. Thus at this point, much of the meat formerly 
attached to the bones 10 is now detached from the bone. While some of the 
very strong attachment points may still be present, the meat will have 
detached at the relatively weak attachment points leaving only isolated 
strong attachment points which can easily be severed by another process to 
recover the meat. 
In FIGS. 3 and 3A, which illustrate the point at which the detachment 
pressure is applied, meat in the soft material 16 and bones 10 still 
remain together in the matrix of material 14. In order to recover the meat 
for use in other products, the meat must still be separated from the bones 
10. This separation step may be accomplished in any suitable manner either 
by hand after the detachment pressure is released, or by any other 
suitable method. 
The pressure at which meat detaches from bone according to the invention 
varies with the type of meat and the manner in which the meat is left on 
the bone. For example, pork has relatively weak attachments and requires 
relatively lower pressure in order to cause the meat to detach from the 
bones. On the other hand, beef has relatively stronger attachments and 
requires a higher detachment pressure. In any event, detachment pressures 
within the scope of the invention range from 5 pounds per square inch or 
less over atmospheric pressure, to 1000 pounds per square inch or more 
over atmospheric pressure. Higher pressures, however, may adversely effect 
the meat and limit the manner in which it may be used. Some attachments 
may be even too strong to completely separate with pressure alone as 
discussed above. However, even where one or two attachment points remain, 
the isolated attachment points may be located easily and the meat may be 
severed from the bone by hand or otherwise to recover the meat. 
FIG. 4 shows an apparatus 30 for performing the method according to the 
invention. This apparatus is adapted particularly for test purposes and 
operates in a batch process. The apparatus 30 includes a cylindrical 
vessel 11 having a first end 32 and a second end 33 connected together 
with a flange arrangement 34. The apparatus 30 also includes piston 12 
which may be advanced into the second end 33 of the cylinder 11 to apply 
the detachment pressure, and then retracted using the puller fittings 43. 
The piston 12 includes suitable seals such as "O" rings 44 for sealing 
against the cylinder wall as the piston is advanced into the cylinder 11. 
In the illustrated test apparatus 30, the piston 12 is advanced into the 
second end 33 of the cylinder 11 by applying fluid pressure above the 
piston through fitting 45 in the first end 32 of the cylinder. Any other 
suitable drive arrangement may be used to drive the piston 12 to apply the 
desired pressure. 
In operation, the cylinder 11 is first filled with the matrix of material 
14 discussed above with reference to FIGS. 1, 1A, 2, 2A, 3 and 3A. The 
matrix of material 14 is preferably formulated outside the cylinder 11 in 
the proper volume ratios to ensure that the bone pieces within the matrix 
remain surrounded by meat, the other soft material, and the compressible 
material throughout the compression step. The cylinder 11 is filled by 
removing the cylinder first end 32 and then pulling the piston 12 from the 
second end 33 using the puller fittings 43 in the piston. With the piston 
12 removed, the material making up the matrix 14 may simply be loaded into 
the cylinder second end 33 through the opening therein. 
Once filled with the matrix of material 14 including bone 10, meat and 
other soft material 16, and the compressible material 18 (FIG. 1), the 
piston 12 is placed in the cylinder second end 33, and then the first end 
32 is reconnected by flange 34. Fluid pressure is then applied through 
fitting 45 to advance the piston 12 into the cylinder second end 33. As 
the piston 12 advances into the cylinder second end 33, it applies 
pressure to the matrix of material 14, increasing the pressure from the 
initial pressure to the final detachment pressure at which point the 
piston is stopped. After applying the detachment pressure, drive fluid 
pressure is released through fitting 45 and then the first cylinder end 32 
may be removed to allow access to the piston 12. The piston 12 may then be 
retracted and the matrix of material 14 removed for further processing, 
including separating out the now detached meat from the bones. 
As shown in FIG. 5, at least a portion of the compressible material may 
comprise a gas 50 contained in a flexible or elastic container or bladder 
52 within the matrix of material 54. These gas filled bladders 52 may be 
used to help ensure that sufficient compressible medium is left in the 
matrix to prevent mechanical forces from concentrating at any points on 
the bones 10 as the matrix 54 is compressed. The bladder 52 may be made 
from any suitable flexible or elastic material which allows the volume of 
the bladder to change as pressure is applied to the bladder. The material 
may be generally any impermeable material such as a plastic or rubber 
which is suitable for contact with food products. Also, the bladders 52 
are precharged with the gas 50 at a pressure below the detachment pressure 
to be applied to the matrix 54. This gas pressure allows the bladders 52 
to collapse as the pressure rises to the detachment pressure in the matrix 
54. The collapse in the bladders 52 allows the meat 16 in the matrix to 
move with respect to the bones 10 and detach as discussed above with 
reference to FIGS. 2, 2A, 3 and 3A. 
FIG. 6 shows another alternate matrix of material 64. In this matrix 64, at 
least a portion of the compressible material or medium comprises one or 
more fluid filled bladders 62. The fluid 60 in the bladders 62 may be a 
compressible gas, or a substantially incompressible liquid. Each bladder 
62 is connected by a passage 66 to the exterior of the cylinder 11 and a 
valve 68 controls the flow of fluid to or from the bladder. The bladders 
62 function similarly to the bladders 52 and collapse or reduce in volume 
as pressure increases on the matrix 64, allowing meat 16 to move with 
respect to the bones 10 as the pressure increases. Unlike the form of the 
invention shown in FIG. 5, however, the passage 66 and valve 68 allow the 
pressure to be regulated in the bladders 62 and allow the bladder volume 
to change even when the material contained in the bladder is 
incompressible. When the fluid 60 is incompressible, the fluid may be 
removed from the bladder 62 as the pressure increases in the matrix 64. 
This fluid removal reduces the volume of the bladder 62 and facilitates 
the required movement between the meat 16 and bone pieces 10. As with 
bladder 52 in FIG. 5, bladder 62 may be made from any suitable impermeable 
food handling grade flexible or elastic material. 
Passage 66 and valve 68 arrangement shown in FIG. 6 also allows one or more 
of the flexible bladders 62 to be used to increase the pressure in the 
matrix 64. In this case, the fluid is pumped by a suitable pump (not 
shown) or otherwise forced through passage 66, increasing the volume of 
the bladder 62 and raising the pressure on the matrix 64. When one or more 
of the bladders 62 are used to apply pressure to the matrix 64, other 
bladders 62, or bladders such as 52 in FIG. 5 or some other compressible 
material must be included in the matrix. 
The shapes of the bladders 52 in FIG. 5 and bladders 62 in FIG. 6 are not 
limited to the illustrated shapes. The bladders 52 need not be spherical 
and the bladders 62 need not be elongated. Other forms of the invention 
may comprise simply an area of flexible material incorporated into the 
wall of a cylinder 11 or other suitable device for containing the matrix 
of material. Such a flexible wall would allow sufficient movement within 
the matrix to facilitate the relative movement between the meat 16 and the 
bone pieces 10 to produce the desired detachment. 
The above described preferred embodiments are intended to illustrate the 
principles of the invention, but not to limit the scope of the invention. 
Various other embodiments and modifications to these preferred embodiments 
may be made by those skilled in the art without departing from the scope 
of the following claims. For example, the method according to the 
invention need not be performed in a batch process such as the process 
performed by the test apparatus shown in FIG. 4. In other forms of the 
invention, the detachment pressure may be applied in a continuous process 
rather than in discrete batches of the matrix.