GB2181035A - Injection of liquid into meat - Google Patents

Abstract

A machine for injecting brine or other liquid into meat comprises a set of hollow needles, means for inserting the needles into the meat progressively in steps and means for injecting the liquid in pulses at a pressure of between 7 and 55 bar.

Description

SPECIFICATION Injection of Liquid into Meat The invention relates to the injection of liquid into meat, usually for the purpose of preservation.

Typically, for example, brine is injected into pork in the production of bacon. However, the invention has application to other meats and other liquids.

Existing machines for injecting liquid into meat insert hollow needles into the meat and continuously eject liquid from the needles under a pressure of typically 3 bars or so. The needles are moved continuously inwardly as the liquid is injected to distribute the liquid through the flesh.

With such an arrangement it is often difficult to ensure a uniform distribution of liquid and adequate liquid retention. The present invention seeks to provide an improvement.

According to the invention there is provided a machine for injecting liquid into meat, the machine comprising a set of hollow needles; a needle head arrangement on which the needles are mounted; a bed for supporting the meat to be injected; means for moving the needle head arrangement with respect to the bed in steps; means for controlling the injection of liquid from the needles in response to the stepped movement so that liquid is injected while the needles are stationary in the meat; and a liquid supply system whereby liquid is injected in pulses at a pressure of between 7 and 55 bar. The pressure used will depend upon the type and cut of the meat. For bacon production a pressure of about 30 bar is found particularly satisfactory but other pressures for this meat of between 15 and 40 bar, and particularly 20 to 35 bar are often satisfactory.

The pulsed injections are preferably controlled by a timer which governs the on/off cycle of the pressure pulsing. Typically, three to twenty pulses may be applied during one needle insertion. The pulses are generally given at different depths as the needle penetrates the meat.

Stepping control means of a mechanical form comprising a stepped cam and cam-follower or rack and latch arrangement may be provided. Preferably, however, a stepping control means is provided which is hydraulic and which comprises a fluid-filled measuring cylinder arrangement to determine the pitch of the steps.

Preferably, as the needles are moved inwardly there is provision for any needles to be displaced in the head on meeting an obstruction such as a bone.

Such displacement operates an individual valve for the needle so that the needle is then shut off.

Pulsing control for the liquid may be by way of a single on/off valve in the common liquid supply to all the needles. However, in a preferred arrangementthere is one main valve to initiate each liquid pulse and this is situated in the common liquid supply line for all the needles. A series of second valves, one in each flow line leading to a particular row of the needles, is effective to cut off the pulse. This arrangement ailows for differing injection levels at each row of needles. Further, the needle row may be divided in half, at the centre of the conveyor, providing an even greater degree of control of the injected brine level. The timing of the main valve opening and the second valve closing will control the injected brine level from zero upwards.This system provides the possibility of varying the injected brine levels to suit the particular section of the cut or carcass of meat under the needle head.

The invention will further be described with reference to the accompanying drawings, of which: Figure lisa side elevation of a brine injection machine embodying the invention; Figure 2 is a plan view of the machine of Figure 1; Figure 3 is an end elevation of the machine; Figure 4 is a diagram of a needle of the machine; Figure 5 is a side elevation of part of another machine embodying the invention; Figure 6 is an end elevation of parts of the machine of Figure 5; Figure 7 is a circuit diagram of a hydraulic stepping control which may be used alternatively to the mechanical control; and Figure 8 is a diagram of the control system of the machine.

Referring to Figures 1 to 3 the machine is for injecting brine into sides of pork in the production of bacon. The machine has a frame 1 mounted on wheels 2. The meat is carried on a conveyor 3 running about rollers 4 and driven by a conveyor motor 5.

A sub-frame 6 carries a needle head 7 which has rows of brine injection needles 8. There is an upper needle bank 8a for inserting needles into the meat from above and a lower needle bank 8b for inserting needles from below. In use, the conveyor runs the side of pork to a predetermined position whereupon pressure is applied to the needles to insert them from above and below. As the meat is carried along on the conveyor the needle head moves with it. In doing so, feelers associated with the needle head run down steps 10 formed on a profile plate 11 which is fixed to the machine. The needles follow the feelers in depth, so that they are inserted deeper into the meat in steps.

At each insertion step valves are operated by a computer control to apply brine under pressure of about 30 bar to the needles in a timed pulse. The timing of the pulse may be controlled to vary from step to step so as to adjust the quantity of brine injected at different levels. The control system is programmed to give brine injections appropriate to the nature of the cut of meat. Also, the profile plate 11 is removable and interchangeable so that an appropriate plate is selectable according to circumstances.

At the end of the inward travel of the needle head, the head is retracted and returned back along the conveyor to the start position. It may then be reinserted into the same meat to inject it at a different place. The computer may be programmed to control the injection dosage according to the longitudinal position of the needle head with respect to the meat.

Figure 4 shows a needle. The lower pointed end 13 is inserted into the meat. This end is fixed to a hollow shaft 14 which slides in a holder 15. On insertion into the meat the needle lifts and opens a valve 16a. Normally, the needle is kept extended by the effect of the pressure of air in cavity 15a.

However, should the needle encounter an obstruction on being inserted, it will travel back against the air pressure and shaft 14 will slide. Such sliding cuts off the supply of brine to the needle by means of the valve 16. Further resistance to movement of the needle end causes the needle holder to move back in the needle head block against air pressure.

Referring now to Figures 5 and 6 there is shown an arrangement similar to that of Figures 1 to 3. The needle head assembly is shown mounted on a carriage 17 associated with locking blocks 18 whereby the assembly is locked to the conveyor.

Vertical movement of the needle assembly is by virtue of runners 19 on columns 20. Each bank of needles consists of forty needles arranged in four columns often rows.

With reference to Figure 7 there is shown the hydraulic circuit diagram of an alternative and preferred form of needle stepping control. The needle head arrangement is driven towards the meat by brine pressure acting through four hydraulic cylinders (not shown). Coupled to the needle banks are four oil-filled control cylinders, cylinders 51 and 52 for the top needle bank 8a and cylinders 53 and 54 for the bottom needle bank 8b. A stepping control system is provided for each needle bank. For convenience only the system for the top needle bank will be described, it being understood that the other system operates in the same way.

Two oil-filled hydraulic cylinders 55, 56 are hydraulically coupled respectively to cylinder 51 and cylinder 52. Valves 59,60 are interposed between cylinder 51 and cylinder 55; and valves 61, 62 are interposed between cylinder 52 and the cylinder 56.

Valves 59 to 62 are three-way solenoid operated valves which change over on activation by the controlling micro-processor. Limit switches 63, 64 are coupled to a shaft 65 which is moved by pistons 66,67 in cylinders 55, 56.

As the needle head moves down, oil is driven from the lower part of cylinders 51,52 through valves 59 and 61 to the left hand sides of cylinders 55,56. Pistons 66 and 67 are moved to the right until the end of the piston stroke is reached. The microprocessor control responds to the limit switch actuation to operate the brine injectors. After a pause determined by the control program in the microprocessor the valves 59 to 62 are changed over, so allowing the direction of movement of shaft 65 to reverse. Thus, the needle head moves down another step after a short pause while the brine is injected. The stepping control is effective to halt and permit movement generated by the activating brine cylinders, just as in the case of the mechanical cam arrangement.The pitch of the steps can be adjusted by effectively shortening the cylinders 55, 56 by means of spacers or screw adjustment, for example.

Referring to Figure 8 there is shown a schematic block diagram of the control system for the machine.

The system is controlled by a micro-processor 71 which may be set by a manual control 72 in accordance with the cut of pork being processed.

Similarly, the profile plate as the control program must be appropriately selected, as described above.

The microprocessor controls a set of solenoid valves for the rows of needles. When the valves are switched on, brine from the pressure pump is applied to all the needles. The needles may be cut off selectively by selective operation of valves 74 which are common to each row often needles.

Thus, the length of the pressure pulse applied to each row of needles may be controlled by the microprocessor independently.

The manual control is effective to determine the quantity of brine to be injected into selected parts of the meat. For example, it may be decided to inject a first percentage of brine into the foreleg; a second percentage into the middle; and a third percentage into the gammon of a side of pork. The manual control is set accordingly. The quantity of brine is determined by the number of pulses, and thus the number of steps on the profile plate, one pulse being delivered at each step, and the duration of each pulse. The dwell time at each step is determined by the conveyor speed, which may be adjusted accordingly. Typically this may be between 0.2 and 0.7 seconds. The pulse length may be between 0.1 and 0.5 seconds, for example.

Afurther refinement is to control the microprocessor in response to a set of sensors 75 which detect the shape of the cross-section of meat where the needles are to be applied. The position of the meat for the purpose of controlling the injection dosage is thus determined by the sensors. In the preferred embodiments of the invention (Figure 7) the shape detectors are used also to control the stepping of the needle movement by the microprocessor.

The invention is not restricted to the details of the embodiments described above with reference to the drawings. For example, a single on-off valve 73 shown in broken line in Figure 8 may be used for brine injection control instead of individual valves 74 if there is no requirement for differential brine injection. Furthermore, the number and orientation of the needles in the head may be different. For example, needles may be arranged obliquely or horizontally. The needles may be arranged in several banks with differing patterns and numbers of needles in the banks.

It is important in accordance with the invention that a pulsed injection method be adopted. In this way penetration and precise quantity control of liquid is enhanced. It is convenient to move the needles in steps. However, in accordance with the invention continuous movement of the needles is possible provided that injection is pulsed.

Claims (9)

1. A machine for injecting liquid into meat, the machine comprising a set of hollow needles; a needle head arrangement on which the needles are mounted; a bed for supporting the meat to be injected; means for moving the needle head arrangement with respect to the bed in steps; means for controlling the injection of liquid from the needles in response to the stepped movement so that liquid is injected while the needles are stationary in the meat; and a liquid supply system whereby liquid is injected in pulses at a pressure of between 7 and 55 bar.

2. A machine as claimed in claim 1 wherein the liquid pressure is between 15 and 40 bar.

3. A machine as claimed in claim 2 wherein the liquid pressure is between 20 and 35 bar.

4. A machine as claimed in any of the preceding claims wherein stepping control means is provided in the means for moving the needle head arrangement which is mechanical and which comprises a stepped cam and cam-follower arrangement.

5. A machine as claimed in any of claims 1 to 4 wherein stepping control means is provided which comprises a fluid-filled measuring cylinder arrangement having a piston system in the cylinder arrangement which determines the pitch of the steps in accordance with the piston stroke.

6. A machine as claimed in claim 5 wherein the stroke of the piston arrangement is adjustable to alter the pitch of the steps.

7. A machine as claimed in any of the preceding claims wherein the needles are resiliently mounted in the needle head arrangement whereby an individual needle can yield on meeting an obstruction despite further movement of the needle head arrangement, there being a cut-off valve in each needle to cut off the liquid supply from the needle when an obstruction is encountered.

8. A machine as claimed in any of the preceding claims which operates under computer control, the computer being programmed to respond to adjust the pulse length and/or frequency of the injections according to the particular part of the meat being injected.

9. A machine for injecting liquid into meat substantially as hereinbefore described with reference to Figures 1 to 6 and 8 or Figure 7 of the accompanying drawings.