EP0699031A1

EP0699031A1 - The processing of animal intestines

Info

Publication number: EP0699031A1
Application number: EP94914982A
Authority: EP
Inventors: Neville William Smith
Original assignee: ENVIROS AUSTRALIA PTY Ltd
Current assignee: ENVIROS AUSTRALIA PTY Ltd
Priority date: 1993-05-19
Filing date: 1994-05-12
Publication date: 1996-03-06
Also published as: PL311659A1; BR9406413A; WO1994026120A1; NZ265894A; EP0699031A4; HU9503215D0; HUT73920A; CN1124005A

Abstract

In the processing of animal intestines for use as sausage casings or other product, the mucosal lining is extracted from the intestines by drawing the intestines past one or more vibrating heads which periodically compress the intestines against a reaction surface whereby the mucosal lining is extruded towards the rear of the intestines. The process results in significantly reduced water consumption during processing and a higher quality of the end product.

Description

THE PROCESSING OF ANIMAL INTESTINES

The present invention relates to the processing of animal intestines, and more particularly to the cleaning and preparation of animal intestines for use, for example, as casings for sausages and other food products, medical sutures, and sports racquet strings.

Animal intestines, particularly sheep intestines and hog intestines, are traditionally used as natural casings for sausages and other food products known as "small goods"; they may also be put to other uses, although casings represent their primary use. The intestine must undergo substantial processing to bring it into a state suitable for use. The process stages involve the removal of digesting foodstuffs from within the intestine, washing, removal of mucosal lining from within the intestine, removal of external muscle tissue which is known as the "thread", grading and preservation. Usually, the first stage involves pulling the intestine from its supporting membrane, stripping manure from the intestine and washing. An intestine so treated is known as a "runner". The runners are then grouped into bundles for treatment to remove the mucosal lining ("the mucosa") from the inside. This may be done by a hand scraping action or mechanically by passing the bundle across rotating beaters, and which causes the hning to be extruded out of the end of the runner. This action is carried out in the presence of water which is sprayed continually over the runner. Substantial quantities of water are used, particularly in the mechanical process which is used for larger scale processing and the run-off water is highly polluted by the contents of the runner. The hand scraping action and the mechanical scraping action provided by the rotating beaters can also cause damage to the runner resulting in an inconsistent quality of end product. The external muscle tissue, known as the thread, may also be partly removed during the scraping and any remaining thread is removed manually. Generally, existing processes are unable to achieve continuous treatment of the runner into a graded and preserved casing and existing processes use substantial quantities of water and lead to substantial pollution problems of the waste water.

According to the present invention there is provided a method of removing mucosal lining from the interior of an animal intestine, comprising drawing the intestine through an extraction device comprising a vibrating member and a reaction surface whereby the intestine is periodically compressed between the vibrating member and the reaction surface to release the lining and to extrude the lining towards a rear end of the intestine.

Preferably, the intestine is drawn through a plurality of such extraction devices arranged along a path of movement of the intestine. The vibrating members of the respective devices may operate at different vibrational frequencies and/or at different contact pressures with the intestine.

According to a preferred embodiment of the invention there is provided a method of processing animal intestines, comprising attaching a group of intestines at their forward ends to a carrier, advancing the carrier to draw the group of intestines through a heated hquid bath, drawing the group of intestines through at least one extraction device comprising a vibrating member operative to periodically compress the intestines against a reaction surface whereby to loosen mucosal lining from the interior of the intestines and to extrude the lining towards the rear ends of the intestine, and moving the carrier to draw the intestines through a processing zone including means for scraping muscle tissue from the exterior of the intestines.

Preferably, the forward ends of the intestines are attached to the carrier in such a manner that the group of intestines forms a substantially horizontal parallel row.

Preferably the reaction surface of the or each extraction device is of a rubber-like or other resilient material.

According to another aspect of the present invention, there is provided a method of processing animal intestines, comprising attaching a group of intestines at their forward ends to a carrier, and drawing the group of intestines through at least one extraction device whereby to loosen mucosal lining from the interior of the intestines and to extrude the lining towards the rear ends of the intestines.

According to yet another aspect of the invention, there is provided apparatus for carrying out a method defined above, comprising a carrier to which the forward ends of a group of intestines can be attached, means for driving the carrier along a predetermined path, and at least one extraction device on said path for removing mucosal lining from the interior of the intestines, said device comprising a vibratory member operative to periodically compress the intestines against a reaction surface whereby to release the lining and to extrude the lining towards the rear ends of the intestines as the carrier advances.

An embodiment of the invention will now be described by way of example only with reference to the accompanying drawing in which:

Figure 1 is a schematic side view of an upstream part of a processing line for processing intestines;

Figure 2 is a schematic side view of a downstream part of the line. Figure 3 is a schematic front view of a mucosa extraction device used in the processing line;

Figure 4 is a schematic side view showing in greater detail part of the line incorporating the extraction device; and

Figure 5 is a side view showing schematically a modified form of extracting device.

There is shown in the accompanying drawings a schematic view of a line for the continuous processing of a runner to final product stage. The system comprises a conveyor 2, preferably a chain conveyor, to which runner carriers 4 can be removably attached. Each carrier 4 extends transversely of the conveyor 2 and has a series of hinged clamping bars along its length such that the front ends of a group of runners 6 can be clamped between each clamping bar and the carrier 4, with the ends of the individual runners being distributed in a row along the length of the carrier 4. In one practical form the carrier 4 has three clamping bars and can carry about 50 runners 6, divided into three groups. After mounting of the runners 6 on the carrier 4. The carrier 4 is placed onto the conveyor 2 and is thereby advanced on to the processing line in order to draw the runners 6 from the storage container 8.

The first treatment stage on the line is a conditioning stage 10 which washes the runners 6 and puts the runners into a favourable condition for subsequent stages, particularly the mucosal extraction. Conditioning of the runners is effected by drawing the runners 6 through a shallow trough 12 of hot water, typically at a temperature of around 35 °C. The runners 6 tend to float on the water and pass through a series of combs as they move through the trough 12. This action causes the runners 6 to be straightened and also passage through the trough 12 washes external contamination from the runners. To improve the washing action the water is fed through the trough 12 in counterflow to the movement of the runners.

After leaving the water trough 12 the runners pass through a mucosal extraction stage 14 downstream of the trough 12. It has been determined that effective mucosal extraction can be achieved without using substantial quantities of water by a vibration technique. This involves passage of the runners 6 through at least one extraction device 16. The extraction device 16 comprises an upper vibrating head 18 which extends across the path of the runners 6 and a lower support 20 of a rubber-like or other resilient material (see Figures 3 and 4). The head 18 vibrates in a vertical plane against the support 20 and as the runners 6 are drawn across the support 20 the vibrating action causes the musocal lining to be loosened and extruded towards the rear end of the runners 6. The head 18 is controlled by a pneumatic or other fluid- operated system to adjust the pressure between the head 18 and the support 20 and also to raise the head 18 to permit passage of the carrier 4 through the extraction device 16 prior to operation on the runners 6 by lowering the head 18 onto the runners 6 immediately after the carrier 4 has moved beyond the head 18. The extraction device 16 includes a sensor to detect the presence of the carrier 4 in order to raise and lower the head 18 automatically in order to permit passage of the carrier 4.

Preferably, there is a series of successive extraction devices of this type with vibrating heads (in the embodiment shown there are two such devices 16). The heads 18 of the respective devices may be set at different operating frequencies and/or at different operating pressures and an operator has the choice of using a selected one or a plurality of the extraction devices depending on the characteristics of the runners 6 being treated. As the runners 6 pass through the or each extraction device 16 the mucosa is loosened and pushed towards the rear of the runners 6 in the manner of an extrusion. As a result of this action the pressure of mucosa within the runners 6 builds up upstream of the extraction head 18. The extent of the pressure build-up is dependent on the speed of the runners through the head 18, and the conveyor speed can be varied in order to control internal pressure build-up. This speed control can be under the manual control of the operator or may be achieved automatically. The pressure build-up within the runners 6 will result in an increased loading on the driving motor of the conveyor 2 and hence increased current. The current increase can be monitored manually or automatically in order to permit appropriate control of the speed.

During the extraction stage, the operator is able to activate high pressure water jets to remove threads (the external muscle tissue) which may build up in the zone of the vibrating heads 18. The extraction devices 16 are mounted above a collection trough 22 which receives mucosa extruded from the ends of the runners 6.

A preferred construction of extraction device is shown in Figures 3 and 4 wherein the head 18 is supported at each side by a bellows-type pneumatic cylinder 30 which is capable of accommodating the vertical vibration to which the head 18 will be subjected in operation. Each cylinder 30 is connected into a pneumatic circuit which can be fed selectively with high pressure air to raise the head 18 to permit passage of the carrier 4 through the extraction device, or low pressure air which retains the head 18 in a lowered operative position and controls the operating pressure of the head 18. Preferably a pressure control is incorporated in the pneumatic circuit to vary the lower pressure and hence to vary the operating pressure. An operating pressure equivalent to a loading on the blade of between about 50 and 60 Kg per lineal metre of blade length has been found to provide good results. Preferably the head 18 is in the form of a blade which extends across the path of the runners 6, the lower edge 18a of the blade in contact with the runners 6 being rounded as shown diagrammatically in Figure 4.

Vibration of the head 18 is preferably effected by means of two electric motors 32 mounted on the upper structure of the head. Each motor 32 has an eccentric rotor 34 and is orientated so that the axis of rotation of the rotor 34 is horizontal and extends in the longitudinal direction of the processing line. The two motors 32 are driven in opposite directions of rotation and are synchronous a.c. motors. With this configuration of two oppositely rotating motors, the rotors 34 tend inherently to move into synchronism such that they attain top and bottom dead centre positions at the same time whereby the vertical components of the out of balance forces act in the same direction and thereby combine to produce the vibration in a vertical plane, whereas the horizontal components act in opposite directions and thereby cancel out.

The runners 6 will typically be many metres in length and the carrier 4 is unable alone to advance the runners through the processing line, as the tension needed to do this would exceed the breaking stress of the runners and, in any event, the tension could not be uιι--formly applied throughout the length of the runners. To achieve controlled drawing of the runners 6 through the line and particularly through the extraction stage, a set of driven drawing rollers 35 is provided immediately downstream of each extraction device 16, as illustrated in Figure 4. The runners 6 pass around the driven rollers 35 in the manner illustrated and are drawn through the adjacent extraction device by the action of the rollers 35. The rollers 35 are rubber covered to provide grip with the runners 6, although some slippage can occur between the runners 6 and rollers 35 in the event of excessive build-up of tension. The chain conveyor 2 for the carrier 4 follows a path equivalent to the path defined by the rollers 35 whereby the carrier 4 moves between the rollers 35 in order to feed the runners 6 along the required path.

Advantageously, as shown in Figure 5, the lower support 20 of at least one of the extraction devices 16 is preferably stepped upwardly in the direction of travel of the runners 6 across the support 20, with the lower part 20a of the step being shaped to conform to the shape of the lower edge 18a of the blade 18 whereby there is a greater area of contact between the lower edge 18a of the blade and the runners 6. The stepped support 20 may also be adjustable in position in the direction of travel of the runners 6, for example by means of a screw mechanism schematically indicated by 38 in Figure 5, so as to permit adjustment of the horizontal component of pressure exerted on the runners 6 by the blade 18 due to the stepped configuration of the support.

The vibrational frequency of the extraction heads 18 will, to an extent, be determined empirically according to the characteristics of the runners 6 being treated. However, by way of example a frequency of around 3000 to 3500 cycles per minute has been found to provide effective mucosa removal. Tests have determined that if the frequency is less than about 2500 cycles per minute the head 18 will not be in sufficient contact with the runners 6 to effect smooth and continuous displacement of the mucosa through the runners. After the extraction stage 14, the runners 6 pass through a stage 44 for removal of remaining thread on the external surface of the runners 6. Thread removal is achieved by a scraping action for example by drawing the runners 6 through a scraping device shown schematically at 46 and which may comprise a series of tensioned, stationary, scraping wires extending transversely to the path of travel of the runners. After de-threading, the runners 6 are delivered into a storage container 48. At this intermediate storage stage, the runners are still attached at their front ends to the carrier 4, but the carrier 4 is not coupled to the conveyor 2.

The runners 6, while still attached to the carrier 4 can then be fed beneath a salt distribution canopy 50 of a preservation stage 52 and from which salt is discharged at a controlled rate onto the runners 6 moving beneath the canopy 50. The salt distribution system is preferably actuated by sensors in response to detection of the presence of the runners 6 moving beneath the canopy 50. Although the runners 6 could pass directly to the preservation stage 52 after the dethreading stage 44 by continuous feed using the conveyor 2, it is preferred to feed the runners 6 into the container 48 which acts as a storage zone between the two stages and then to feed the runners through the preservation stage, as this facilitates greater control of salting independently of mucosa extraction and dethreading.

It may sometimes be difficult to remove substantially all of the remaining thread by means of a scraping action using the system just described, whereby further manual processing for removal of remaining thread may be necessary in some circumstances; in existing processing plants thread removal at final stage processing after mucosa removal is effected entirely manually. The thread removal stage 44 and subsequent stages as described above may be omitted from the line, with further processing being performed instead by conventional, mostly manual, processing. In a conventional processing plant, it is the mucosa extraction stage which results in the use of substantial quantities of water and which, when polluted as a result of use, represents a significant effluent disposal problem. Accordingly, very significant advantages arise just by use of the described mucosa extraction process which results in substantially reduced water consumption, and substantially improved product quality as the vibrating heads used for mucosa extraction cause far less damage to the runners than the rotating beaters conventionally used for extraction.

.Although the use of the vibrating heads for mucosa extraction is of importance as it results in greatly improved product quality, it is believed that some advantage could be attained by using a processing line generally as described, but with conventional rotating beaters rather than vibrating heads for mucosa extraction. In this regard in conventional processing plants, a primary reason for the use of large quantities of water in mucosa extraction is to prevent the runners from becoming wrapped around the beaters. By attaching the forward ends of the runners to the carrier 4 which draws the runners across the beaters, the tendency of the runners to wrap around the beaters would be reduced, and hence a reduced water flow across the beaters may be used. While this is a possibility which enables some existing equipment to be retained, nevertheless it is emphasised that it is clearly preferred to use the vibrating heads for mucosa extraction.

The embodiments have been described by way of example only and modifications are possible within the scope of the invention.

Claims

CL-AIMS:-

1. A method of removing mucosal lining from the interior of an animal intestine, comprising drawing the intestine through an extraction device comprising a vibrating member and a reaction surface whereby the intestine is periodically compressed between the vibrating member and the reaction surface to release the hning and to extrude the lining towards a rear end of the intestine.

2. A method according to claim 1, wherein the intestine is drawn through a plurality of said extraction devices arranged along a path of movement of the intestine.

3. A method according to claim 2, wherein the -vibrating members of the respective devices operate at different vibrational frequencies and/or at different contact pressures with the intestine.

4. A method according to any one of claims 1 to 3, wherein the vibrating member vibrates at a frequency of above 2500 cycles per minute.

5. A method according to claim 4, wherein the vibrating member vibrates at a frequency of at least 3000 cycles per minute.

6. A method according to any one of claims 1 to 5, wherein the -vibrating member vibrates in a substantially vertical plane above the reaction surface.

7. A method according to claim 6, wherein the vibrating member is of blade-like form with a rounded lower edge which contacts the intestine.

8. A method according to claim 7, wherein the reaction surface is upwardly stepped in the direction of travel of the intestine and conforms partially in shape to the lower edge of the vibrating member.

9. A method according to any one of claims 1 to 8, comprising adjusting the frequency of the vibrating member and/or adjusting the pressure applied by the vibrating member to the intestine.

10. A method according to any one of claims 1 to 9, comprising attaching a group of intestines at their forward ends to a carrier, and moving said carrier through the or each said extraction device whereby to draw the group of intestines through the or each extraction device.

11. A method according to claim 10, wherein the intestines are arranged in a substantially horizontal row along the carrier.

12. A method according to claim 10 or claim 11, wherein the carrier draws the group of intestines through a heated quid bath prior to removal of the mucosal nning.

13. A method according to any one of claims 10 to 12, comprising moving the carrier to draw the intestines through means for scraping muscle tissue from the exterior of the intestines after removal of the mucosal hning.

14. A method of processing animal intestines, comprising attaching a group of intestines at their forward ends to a carrier, and drawing the group of intestines through at least one extraction device whereby to loosen mucosal lining from the interior of the intestines and to extrude the lining towards the rear ends of the intestine.

15. A method according to claim 14, comprising advancing the carrier to draw the intestines through a heated liquid bath prior to passage through the cleaning device.

16. A method according to claim 14 or claim 15, wherein the extraction device comprises a vibrating member and a reaction surface whereby the intestines are periodically compressed between the vibrating member and the reaction surface.

17. Apparatus for carrying out a method according to claim 1, comprising a carrier to which the forward ends of a group of intestines can be attached, means for driving the carrier along a predetermined path, and at least one extraction device on said path for removing mucosal lining from the interior of the intestines, said device comprising a vibratory member operative to periodically compress the intestines against a reaction surface whereby to release the hning and to extrude the lining towards the rear ends of the intestines as the carrier advances.

18. Apparatus according to claim 17, further comprising a bath on said path upstream of the extraction device, wherein in use of the apparatus said bath contains heated liquid through which the intestines are drawn prior to removal of the lining.

19. Apparatus according to claim 17 or claim 18, further comprising means for scraping muscle tissue from the exterior of the intestines, said scraping means being on said path downstream of the or each extraction device.