WO1999055166A1

WO1999055166A1 - Humane crustacean processor

Info

Publication number: WO1999055166A1
Application number: PCT/GB1999/001309
Authority: WO
Inventors: Simon Buckhaven
Original assignee: Simon Buckhaven
Priority date: 1998-04-27
Filing date: 1999-04-27
Publication date: 1999-11-04
Also published as: EP1075189A1; CA2418248A1; AU3719299A

Abstract

An apparatus for applying an electric current to a crustacean comprising: (i) a tank adapted to contain the crustacean; (ii) a plurality of electrodes arranged such that the crustacean can be placed between the electrodes; and (iii) means for creating an electrical potential across the electrodes such that in use current flows between the electrodes and through the crustacean such that the crustacean is anaesthetised or killed.

Description

Humane Crustacean Processor Field of Invention

The present invention relates to an apparatus and a method for applying an electric current to a crustacean such that the crustacean is, anaesthetised or killed. The invention extends to apparatus and methods for the bulk treatment of Crustacea.

Background to the invention

The cooking of fresh shellfish or crustaceans has always presented some people with an ethical dilemma. The flesh of a crustacean decays very quickly after death which significantly affects the flavour of the meat. Lobsters and other crustaceans do spoil rapidly after death, which is why many buyers insist on receiving them alive.

If the lobster is "headed" before or soon after death, the body meat will keep fresh longer. This is because the head area contains the thorax which is the site of most of the viscera and gills which spoil much more rapidly than the claw or tail meat.

Freezing slows deterioration and harmful chemical reactions that follow death.

Neither of these solutions are totally effective as they either involve removing parts of the animal or the possibility of damaging the delicate flesh through freezing. The most desirable method of cooking crustaceans is when they are at their optimum freshness i.e. alive. However many people have an ethical objection to the concept of cooking a live animal.

It is accordingly an object of the present invention to provide an apparatus for applying an electric current to a crustacean such that the crustacean is anaesthetised or killed and which overcomes or at least mitigates one or more of the problems noted above.

Summary of the Invention According to the present invention there is provided an apparatus for applying an electric current to a crustacean comprising:

(i) a plurality of electrodes arranged such that the crustacean can be placed between the electrodes; and

(ii) means for creating an electrical potential across the electrodes such that in use current flows between the electrodes and through the crustacean such that the crustacean is anaesthetised or killed.

A corresponding method of applying an electric current to a crustacean comprises the steps of:-

(i) placing the crustacean between at least two electrodes; and (ii) creating an electrical potential across the electrodes such that in use current flows between the electrodes and through the crustacean such that the crustacean is anaesthetised or killed.

This provides the advantage that a crustacean such as a lobster can be quickly and simply killed or anaesthetised prior to cooking. The crustacean does not have to be cut or decapitated or cooked whilst still alive.

Preferably the apparatus further comprises a tank adapted to contain the crustacean. This provides the advantage that the crustacean can be held in the tank prior to processing and is prevented from moving away. Also, the user is protected from the crustacean whilst it is held within the tank and is also protected from any other contents of the tank. Preferably the tank is adapted to hold an electrically conductive fluid. For example a saline solution can be used. Using a fluid in this way gives the advantage that the crustacean itself does not need to come into contact with the electrodes and the risk of burning or other damage from the electrodes themselves is reduced. Preferably the tank further comprises a heat source such that it is possible to retain the crustacean in the fluid filled tank for cooking, after the crustacean has been anaesthetised or killed.

According to one embodiment of the invention the electrodes are substantially rigid. These electrodes are simple to manufacture and install. According to another embodiment of the invention the electrodes are deformable and are adapted to be placed against the crustacean such that in use the electrodes conform to fit the shape of the crustacean. This has the advantage that a good electrical contact between the electrodes and the crustacean can be readily achieved. The area of contact between the electrodes and the crustacean is increased by allowing the electrodes to conform to the shape of a crustacean which can be irregular and varied in shape.

In a further embodiment of the invention each electrode comprises a plurality of curved fingers. This has the advantage that a crustacean can be held in place between the electrodes and also a good electrical contact between the electrodes and the crustacean is achieved. in another embodiment each electrode comprises a resilient mesh. In this way one or more Crustacea can be held between the electrodes and a good electrical contact achieved. The resilient mesh is deformable and conforms to fit against the crustacean. In another embodiment each electrode comprises a plurality of resiliently biased probes arranged to protrude from the periphery of the tank towards the centre. A

3 crustacean can be placed between the probes, which then conform to fit the shape of the crustacean and maintain a good electrical contact with it. By increasing the number of points of contact of the electrodes with the crustacean the delivery of an effective dose of electricity is more readily achieved. Preferably, at least one electrode comprises a grille within the tank such that in use a crustacean's body can be supported on the grille but the crustacean is substantially unable to stand on the grille. This enables electrical contact to be made with the lower part of the main body shell of the crustacean and helps to prevent the crustacean from rising onto the ends of its legs during the application of the electrical stun. If the crustacean rises onto its legs, the electrical resistance is increased and the risk of damage to the crustacean and of the crustacean shedding its legs is increased.

In one embodiment at least one electrode comprises a flexible mesh mounted over a resiliently deformable body. The resiliently deformable body acts to bias the mesh against the body of a crustacean and enables a good electrical contact to be achieved between the mesh and the crustacean.

In another embodiment at least two electrodes are arranged to form at least part of the sides of a funnel such that in use a crustacean may be dropped into the funnel and lodge between the sides of the funnel, forming contact with the electrodes. An apparatus that is inexpensive and simple to manufacture is thus provided. Also, a batch of crustaceans can quickly and easily be processed using this apparatus by simply dropping the crustaceans, one at a time, into the funnel.

Preferably, an upper part of said funnel is electrically isolated. This improves the safety of the apparatus and reduces the risk of human operators contacting electrically charged areas of the apparatus. Advantageously, the funnel is openable, such that in use when a crustacean is lodged in the funnel the funnel may be opened to remove the crustacean. This provides a simple and effective method of removing the crustacean from the funnel.

Preferably, at least one of said electrodes forms at least part of a moving platform adapted to support the crustacean; and at least one other electrode forms at least part of a rotating brush, positioned above the moving platform. This has the advantage that the motion of the platform and the rotating brush can be used to draw a crustacean through the apparatus in order that several Crustacea can be processed consecutively. Advantageously the apparatus comprises a pair of moving carrier surfaces adapted to move in the same direction, said carrier surfaces being positioned so that they are facing each other such that in use a crustacean can be supported between the surfaces. This has the advantage that the motion of the platforms can be used to draw a crustacean through the apparatus in order that several Crustacea can be processed consecutively. The Crustacea can be held between the two carrier surfaces and prevented from moving about or falling off the apparatus. Also, at least two of said electrodes may each comprise a rotating brush, said brushes being positioned substantially opposite each other on either side of the moving carrier surfaces and wherein for each brush at least some bristles of the brush are arranged to extend through one of the moving surfaces such that in use, when a crustacean is supported between the carrier surfaces, the crustacean contacts at least some of the bristles of each brush at the same time. This enables electrical contact to be made with the Crustacea held between the moving carrier surfaces.

In a further example, said electrodes comprise a bed of rotating rollers adapted to support at least one crustacean. This provides the advantage that motion of the rollers can be used to draw Crustacea through the apparatus thus allowing several

5 Crustacea to be processed quickly. The apparatus may further comprises a frame for supporting the bed of rotating rollers wherein the frame is inclined towards its base. By inclining the bed of rollers using the frame the Crustacea slide down the bed of rollers and are drawn through the apparatus. In another embodiment the apparatus comprises a chute adapted such that in use a crustacean may be slid down the chute and wherein at least two electrodes are located in side walls of the chute such that in use, when a crustacean is slid down the chute it contacts the electrodes. This provides a simple and effective apparatus for processing several Crustacea which is inexpensive to produce and operate. In another example, one of said electrodes comprises the screw of an auger and at least one other electrode comprises a casing of the auger. This allows several Crustacea to be drawn through the auger because of the motion of the screw.

Advantageously, the apparatus comprises an apparatus for determining the electrical resistance between the electrodes and for adjusting the voltage applied across the electrodes on the basis of the determined resistance. This enables the correct current to be applied to the crustacean and prevents undue suffering of the crustacean.

In another example at least two of the electrodes comprise fine piercing elements adapted to pierce the shell of a crustacean. This allows direct electrical contact with the soft body tissues of the crustacean and allows the crustacean to be anaesthetised or killed using lower voltages and currents. By using fine piercing elements the risk of excessive damage to the shall is reduced.

In another example, at least two of the electrodes form part of a pair of tongs, said pair of tongs being adapted to grip a crustacean in use. This enables the crustacean to be restrained, held and moved during application of a stun. Also, the tongs can be used to apply a stun either across the body of the crustacean or across the head or other specified body part of the crustacean.

6 In another example the apparatus comprises a nozzle arranged such that in use, an electrically conducting liquid may be passed through the nozzle to form a jet of liquid and wherein at least one of said electrodes is arranged in use to apply an electrical potential to said jet of liquid. The liquid forms a good contact with the crustacean and is simple to apply.

Preferably, said means for creating an electrical potential across the electrodes comprises means for creating a pulsed or alternating potential across the electrodes. This enables a pulsed or alternating current to be applied to the crustacean which has been found to be effective for killing or anaesthetising Crustacea. Preferably the tank further comprises a sealable lid and the apparatus further comprises a safety device adapted to prevent opening of the lid whilst electric current flows between the electrodes. This prevents the cook from electrocuting him or herself accidentally.

It is also preferred that the apparatus further comprises at least one detector, adapted to detect the presence of the crustacean between the electrodes. This enables the flow of electric current to be prevented except when a crustacean is present in the apparatus.

Preferably, said method of applying an electric current to a crustacean further comprises at least one of said electrodes being arranged to extend along substantially the full body length of the crustacean. This provides the advantage that good electrical contact is obtained between the electrode and the crustacean in order that the crustacean may be effectively anaesthetised or killed.

Preferably, said method of applying an electric current to a crustacean further comprises the step of applying an electrically conductive gel or liquid to at least one of the electrodes. This enables the electrical contact between the electrode and the crustacean to be improved. Description of the drawings

The invention will be further described, by way of example, with reference to the accompanying drawings in which: Figure 1 shows an alternating voltage.

Figure 2 shows a pulsed voltage.

Figure 3 is a schematic diagram of the electronic components of an apparatus for applying an electric current to a crustacean.

Figure 4 is a perspective view of the apparatus. Figure 5 is a perspective view of a fixed electrode version of the apparatus.

Figure 6 is a perspective view of a wire mesh version of the apparatus.

Figure 7 is a perspective view of a spring contact electrode version of the apparatus.

Figure 8 is a side view of two finger electrodes in an open configuration.

Figure 9 is a side view of two finger electrodes in a closed configuration. Figure 10 is a perspective view of two finger electrodes.

Figure 11 is a side view of a vertical feed system version of the apparatus.

Figure 12 is a side view of a horizontal feed system version of the apparatus.

Figure 13a illustrates a crustacean in a shallow bath electrode.

Figure 13b illustrates a crustacean on an array of rods or wires. Figure 13c illustrates a crustacean on an array of rollers.

Figure 13d illustrates a crustacean in contact with a conductive net with additional pressure and conductive fluid being provided by a sponge.

Figure 14 shows the electrodes of a stunning funnel without the necessary protective insulated housing. Figure 15 shows crustaceans on a conveyer belt passing under rotating drums which have conductive bristles or fingers.

8 Figure 16 shows a crustacean passing between two vertical brush or finger drums. Figure 17 shows a crustacean trapped between slotted belts and passing between rotating brush drums. Bristles pass through the belt to make electrical contact with the crustacean. Figure 18 shows two crustaceans on a series of rotating, electrified rollers.

Figure 19 shows a crustacean sliding down a chute, each wall of the chute being at a different electrical potential.

Figure 20 shows an inclined bed of contra-rotating rollers at different electrical potentials. Figure 21 shows a side view of a humane crustacean processing apparatus which has a tray for carrying Crustacea.

Description of preferred embodiments

Embodiments of the present invention are described below by way of example only. These examples represent the best ways of putting the invention into practice that are currently known to the Applicant although they are not the only ways in which this could be achieved.

Theory of Operation This section will describe the method of humanely anaesthetising or killing of the crustacean used by the apparatus. The practical implementation of these methods will be discussed later in this document.

The basis of operation is that an animals' neurology can be disturbed by the application of external electric currents. The application of an electric current may render an animal unconscious or even kill it if the disturbance to the neurological structure is sufficiently great. The response that an externally applied current has on an animal depends on the level of current applied, the type of current and its duration.

The crustacean is placed in a dry or liquid-filled vessel containing two or more electrodes which may be in contact with the crustacean. A voltage potential is created across the electrodes using either direct, pulsed or alternating current. The term electrode is used to refer to any conductor by which a current enters or leaves the region around the crustacean. For example, an electrode could be a metal plate as shown in figure 5 or a wire mesh as shown in figure 6. An electrode can also be a plurality of spring loaded contact probes as shown in figure 7 or a bar with a plurality of curved fingers extending from it as shown in figure 10. Another possibility is for the electrode to be a conductive mesh conveyor belt as shown in figures 11 and 12, a tank of saline solution, a series of rollers or brushes that may be inclined or the side walls of a chute. Examples of these are shown in the figures. Another example is for one electrode to comprise a stream or jet of electrically charged saline solution. In this case a nozzle is provided and saline or other electrically conducting liquid is passed through the nozzle to form a jet of liquid. The nozzle is arranged so that the jet of liquid is projected towards the Crustacea. One electrode is arranged to apply an electric charge to the jet of liquid.

Direct current flows from the negative electrode (cathode) to the positive electrode (anode). In the case of alternating current the electrodes alternate between being cathode and anode continuously as the alternating voltage reverses its polarity and the direction of flow of the current. Alternating current is generally based on a sinusoidal signal producing a wave form similar to that shown in the graph in figure 1. In figure 1 the y axis 1 represents volts and the x axis 2 represents time.

10 Direct current produces a unidirectional current. However, this current can be switched on and off to produce a pulsed wave-form as shown in figure 2. As for figure 1 , the y axis 1 represents volts and the x axis 2 represents time.

The frequency and duty cycle of direct current pulses or the frequency of the alternating current can have a variety of effects on animals varying from involuntary muscle contraction to paralysis, unconsciousness and death. The effect that frequency has varies from species to species, but the most effective frequency of operation tends to be in the region of 10 to 120 hertz.

The level of voltage and current required depends on the conductivity of the water or saline solution, if present. The reason for immersing the crustacean in a liquid is to reduce the possibility of localised burning at the electrode contact point and to allow the possibility of current flow into parts of the crustacean which are not in direct contact with the electrodes.

The conductivity of these fluids will normally lie in the range of 50 to 2,000 microsiemens. A fluid with a low conductivity will require a greater potential voltage to sustain the required current than a fluid with a high conductivity. This implies that the voltage source required may range from 100 to 1 ,000 volts depending on the conductivity of the fluid.

The magnitude of current necessary will depend on the size and nature of the crustacean and the conductivity of any liquid present. The person skilled in the art can determine the preferred current flow by experiment. The means for creating an electrical potential may also include a means for varying the current.

11 The electrical voltage to be used for stunning can be constant (DC) voltage or may vary periodically in time with a range of wave forms and frequencies. The voltage may also be varied in response to the impedance of the crustacean being stunned.

In one example, the electrical resistance between the electrodes is measured and if it is within a range that indicates that a good electrical stun can be achieved, a voltage is applied for a short, measured period of time to put the crustacean into a state of insensibility to pain. The period during which the crustacean remains insensible after the electrical current is ceased is dependant on both the current which passed through the crustacean and the time period for which it was passed. If enough current is passed for sufficient time and the crustacean is cooked shortly after the end of the stunning current then the crustacean remains insensible until it is killed by the cooking process.

The electrical stun may be achieved either with a single application of electrical current or with an initial application of current under the controlled conditions described above to render the crustacean insensible, followed by a reinforcing stun of longer duration under less controlled conditions to ensure the period of insensibility lasts until the death of the crustacean. Several stuns of increasing duration or strength may be used in this way to render the crustacean insensible, anaesthetise the crustacean and eventually kill it.

The electrical current flowing through the crustacean may be determined by the resistance of the crustacean and the voltage applied across the electrodes. Any conventional method or apparatus may be used to determine the resistance in this way. It is also possible to use an automatic system to rapidly identify the resistance of each crustacean and monitor this resistance during the period of a stun. The applied voltage

12 can then advantageously be adapted, taking into account the resistance, so as to achieve the required current levels during a stun.

Apparatus and Systems In this section we will look at the methods of implementing the above concept. The design of apparatus can be split into single use and continuous use systems. A single use system is primarily for the consumer market and allows for one crustacean or a batch of crustaceans to be killed in a single cycle. The continuous use system is for large domestic, commercial or industrial applications where crustaceans can be placed on a conveyor or other continuous flow processing lines. Both of these systems will use similar electronics which will be explained later.

Single Use/Consumer Version

This version of the crustacean processor is designed for use in catering establishments or the home. An example is shown in figure 4. The crustacean processor apparatus 41 has the outward appearance of a box 44 with a sealed lid on it 42. On one side of the box there is a control panel/display 43 and a lid or door release mechanism. The lid 42 is provided with a hinge 45 that has a safety interlock switch. The crustacean processor box 44 comprises a processing tank which contains electrodes and may also be filled with liquid of suitable salinity. The user opens the apparatus, places the crustacean or crustaceans inside the tank or box 44 and shuts the lid 42. The user then selects the type/quantity of crustacean on the control panel 43 which then starts the humane electrocution process. The user may also have the ability to cook the crustacean by use of an electrical heating element within the crustacean processor which can rapidly boil the water. Alternatively the user can remove the now anaesthetised/dead crustacean from the processor and cook in a conventional manner with the knowledge

13 that any suffering of the animal has been kept to a minimum. Internally the crustacean processing apparatus may be one of several designs.

Figure 5 shows a simple design of apparatus which consists of fixed electrodes 51 positioned at diametrically opposite sides or ends of a tank 52. This design necessitates that the crustaceans must be immersed in a fluid 53 of suitable salinity for electrical current to flow. The electrodes in this version can be of any conventional design. An electronics module 54 is provided to control and power the electrodes 51.

Figure 6 shows a direct contact version where the bottom and top of the tank 61 have a conductive woven wire mesh 62, 64 supported by springs 63 or a large soft elastomer. The crustacean is placed on the lower electrode 62 and as the lid is closed the upper and lower mesh elastomeric surfaces 62, 64 will conform to the contours of the crustacean providing a reliable electrical contact. This method does not rely on fluid for electrical conductivity although fluid could still be used to improve contact resistance. This embodiment is intended to encompass any form of resiliently deformable or resiliently mounted electrode. The object is to increase the electrode/crustacean contact.

Another method of implementing the flexible electrode method is shown in figure 7. In this design the elastomer mesh support is replaced by a matrix or array of spring loaded contact probes 71 which conform to the shape of the crustacean on closing the lid 72. The spring loaded contact probes extend from the base of the tank 73 as well as from

the lid 72 of the tank.

14 The fourth version is shown in figures 8, 9 and 10. It consists of two sets of curved electrodes 81 mounted in inter-digitated format on two independent shafts 82 which also form electrical bus bars. The two shafts can rotate and the electrodes are mounted offset on the two opposing shafts producing an effect similar to interlocking fingers of two human hands. When the lid of the processor is opened as shown in figures 8 and 10 the two sets of "fingers" move apart to allow the crustacean to be placed between them. On closing the lid the two sets of fingers move back together to hold the crustacean as shown in figure 9 and provide good electrical contact. This method may be used with or without fluid 83.

All four designs have common attributes such as safety interlocks on the lid to make it physically impossible for the lid to open whilst there is electric current flowing between the electrodes. The designs also share the same electronics and are all "double insulated" i.e. there are no external metal parts connected to earth.

Another example of a single use/consumer version is shown in figure 13. Figure 13a shows a crustacean 130 placed in an electrically insulated container 131 on a lower electrode that is integrated into the container 131 . An electrically conductive liquid such as salt water is placed into the bottom of the container 131 to form a shallow bath 132. The liquid in the bath 132 is deep enough to contact the lower part of the main body shell of the crustacean 130 as shown in figure 13a. This allows good electrical contact with the main body of the crustacean 130 over a wide area. The second electrode may be mounted on the lid of the container as shown in figure 13d. However, any type of

second electrode can be used.

15 Instead or in addition to the shallow bath 132, an array of rods, wires or freely rotating cylinders 133 can be used as the lower electrode. These rods, wires or cylinders form a grille within the container 131. This provides the advantage that the crustacean 130 is unable to stand on the rods, wires or cylinders 133 and rests its body on them so that electrical contact is made with the lower part of the crustacean's main body shell (as shown in figures 13b, 13c and 13d). In instances where the crustacean is able to stand on the electrode (such as when it is a flat sheet of metal) the crustacean tends to rise onto the ends of its legs during the application of the electrical stun and this increases its electrical resistance and increases the risk of damaging or shedding the legs of the crustacean during the stun. This is a significant disadvantage because it makes the stun more difficult to apply effectively and also impairs the appearance of the crustacean.

Figure 13d shows one example of the upper electrode. The upper electrode is mounted on the lid of the container 134 and, comprises a fine, flexible, conductive net 135 such as chain mail. This is used to provide a conformable and robust method of making electrical contact over a wide area of the upper part of the body shell of the crustacean

130. The net 135 is suspended from a few points above the crustacean with enough slack to enable it to conform to the shape of the top part of the crustacean's shell as shown in figure 13d. However, the net 135 is not so slack as to enable it to contact the other electrode 133 in the absence of a crustacean 130. Additional pressure to ensure good electrical contact can be applied with an elastic body such as a sponge 136, mounted behind and protected by, the net 135 as shown in figure 13d. The net 135 can be coated with an electrically conductive gel or liquid to improve electrical contact with the shell of the crustacean 130. This coating can be achieved by immersing the net 135 in saline solution immediately prior to use, by spraying the net 135 while it is in contact

16 with the crustacean shell, or by mounting a sponge 136 behind the net 135 so that by pressing down on the sponge 136, as for example, when closing the lid 134, the liquid or gel in the sponge is forced out and wets the net 135 and the shell.

Once the lid 134 is closed, the electronic stunning circuit (not shown in figure 13) checks the electrical resistance presented by the crustacean, and if it is within a suitable range applies the electrical stun for a pre-determined time period.

An alternative method of making electrical contact with the crustacean is to pierce the shell with one or two fine electrodes. This allows direct electrical contact with the soft body tissues of the crustacean. It is necessary to drive these electrodes with sufficient force to rapidly pierce the shell and to apply the electrical current immediately to avoid increased suffering. Small diameter electrodes are used to avoid excessive damage to the shell. It may be necessary to leave the shell penetrating part of the electrodes in place during cooking to avoid excessive loss of body fluids. In this case the electrodes must be disconnected from the electrical supply after stunning. Crustaceans can also be stunned by application of electrical stunning tongs.

These can be used to apply a stun either across the body of the crustacean or across the head or other body part. These tongs may be designed with multiple contact points enabling the crustacean to be restrained, held, or moved during application of the stun.

Such tongs can be used to apply an initial controlled stun. Crustaceans can, for example, be unloaded from a crate picking them up with a pair of tongs which applies the initial stun. They may then be placed on a chute or auger, as described below which passes further electrical current through the crustacean to extend the period of insensibility while moving them to the point of cooking. This is described further below in the section headed "continuous use/ commercial application". Figure 14 shows an example in which crustaceans are stunned by dropping them into a stunning device 140 that comprises a pair of converging electrodes 141 in

17 the form of a funnel. The crustacean dropped down this will lodge and make electrical contact where the funnel is too narrow for the crustacean to fall further. The upper part of the funnel may be electrically isolated for operator safety (not shown). The funnel electrodes 141 can be continuously wetted by a fine spray of film of a conducting liquid. This improves the electrical contact made with the crustacean. To remove the crustacean the funnel is opened or some other in-built retrieval device is used.

Figure 10 illustrates a humane crustacean processing apparatus that is particularly suited for stunning single crustaceans such as lobsters and crabs. This apparatus can be arranged to provide a stun to the crustacean in order to render the crustacean insensible for approximately 2 minutes. The stunned crustacean can then be immersed in boiling water in which it dies after approximately 1 minute from immersion. In this way the crustacean is killed before it regains consciousness. However, it is not essential for the crustacean to only be stunned using this apparatus. It is also possible to increase the strength and duration of the current applied in order that the crustacean is killed in the apparatus.

The apparatus comprises a tank or housing 1000 that is similar to the housing of a conventional microwave oven. That is, the housing 1000 is based on a modified microwave oven carcass, from which all the electronics have been removed. This gives a neat and pleasing exterior that blends well with the other equipment in a kitchen environment. The housing 1000 has a door as for a conventional microwave oven. The electronic apparatus required for the crustacean processor are not shown in figure 10. These may be housed separately or alternatively are incorporated into the housing 1000 in any suitable way.

The apparatus has two electrodes one of which (not shown) is positioned on the base 1002 of the shell or housing 1000 and the other 1001 which is placed on the top of the housing. The electrical shock is thus delivered from the top to the bottom of the

18 crustacean. Safety interlocks are provided in the housing 1000 which ensure that the electrodes can never be powered with the door of the housing open. An additional safety interlock may also be provided which ensures that the electrodes can only be powered when the upper electrode 1001 is in contact with a crustacean. The upper or top electrode 1001 comprises a foam pad that is covered with stainless steel chain mesh. Thus the electrode 1001 is deformable and when pressed against the top of a crustacean the electrode 1001 conforms to fit the upper surface of the crustacean. Any suitable type of foam or other deformable material can be used. Similarly, the stainless steel chain mesh can be replaced with any suitable conducting material that is deformable. One advantage of using foam material is that electrolyte solution can be absorbed into the foam so that when the foam is pressed against the crustacean electrolyte is released and runs over the crustacean to form a good electrical contact. A container of electrolyte can be positioned in the housing and arranged to feed the foam or other deformable electrode with electrolyte as required. The bottom or lower electrode comprises a stainless steel or other conducting plate which is arranged to contact the underside of the crustacean. In order to facilitate loading of a crustacean into the apparatus this stainless steel plate is mounted into the base of a drawer or tray 1005. The drawer or tray 1005 can be mounted on runners or slides within the housing 1000 that enable the drawer 1005 to be drawn out of the housing 1000 as shown in Figure 10. ^"When the drawer is pulled out a crustacean 1003 can be placed into or removed from the housing easily. The drawer 1005 may contain a shallow bath of electrolyte 1004 such as saline solution. This acts to improve electrical contact between the crustacean 1003 and the lower electrode.

A lever (not shown) or other suitable mechanism is provided for lowering the upper electrode 1001 down into contact with a crustacean 1003 that is placed in the drawer 1005 inside the housing 1000.

19 The housing 1000 and drawer 1005 are preferably made from a corrosion resistant material that is easy to clean such as stainless steel.

The housing is sized and shaped to deal with crustaceans up to about 275mm in length and between 50mm and 75mm thick. The apparatus is also designed to cope with Crustacea of a live weight of about 500 grams. Also, the lever or other mechanism for lowering the upper electrode is able to clamp the crustacean using a force of up to about 20 N.

Details of the electronic apparatus for the crustacean processor in this example are given below as an example only: - An isolated electrical supply of up to 110V, 50Hz AC is provided that is capable of supplying up to 3.5 Amps.

^• A timer is provided to allow the length of the stun to be controlled for a period of between 0 to 5 seconds in 1 second intervals. The control has a manual override so that longer stuns can be applied if required or the stun can be stopped if required. The timer can be integral with the mechanical unit.

^• Safety interlocks are provided as described above to ensure that the unit is operated safely. These are integral with the mechanical unit.

^• An electronic power unit is also provided. This may be housed separately from the mechanical unit or may be integrated with the housing 1000 as required. The operation of the crustacean processor illustrated in Figure 10 is now described.

The door of the housing (not shown) is first opened and the drawer 1005 pulled out as illustrated in Figure 10. A crustacean 1003 is then placed into the drawer 1005 which may contain a shallow bath of electrolyte. In this way the crustacean 1003 is placed so that its underside is in contact with the steel plate that forms part of the lower electrode. The drawer 1005 is then pushed back into the housing 1000 and the door of the housing closed. The lever or other mechanism is then operated to bring the upper

20 electrode 1001 into contact with the crustacean 1003. As the upper electrode 1001 is pressed against the crustacean it conforms to fit the upper surface or shell of the crustacean in order that a good electrical contact is formed. Also, the crustacean 1003 is gently pressed down against the steel plate in the bottom of the drawer 1005 which forms part of the lower electrode.

The timer is then set to the required stunning time and the stun initiated by pressing a "start" button or other activation mechanism. Once the stun has been completed the lever is released and the upper electrode 1001 drawn up to its rest position away from the crustacean as shown in Figure 10. The drawer 1005 is then pulled out in order that the stunned crustacean can be removed.

By using a drawer 1005 to hold the crustacean 1003 the process of placing the crustacean into and removing the crustacean from the apparatus is made easier. The user does not have to remove a lid from the tank and reach over the sides of the tank of housing 1000 in order to insert the crustacean. By using a drawer 1005 in this way the upper electrode 1001 is effectively shielded from the user and this improves the safety of the apparatus. Use of the drawer 1005 permits side entry of the crustacean 1003 to the apparatus which avoids the user needing to reach past one of the electrodes.

The mechanism for lowering and raising the upper deformable electrode is particularly advantageous. This allows the crustacean to be clamped in place during application of the stun which helps to -prevent damage to the crustacean and prevents the crustacean from moving about within the drawer. Also the clamping action acts to improve the electrical contact with the crustacean which enables the stun to be efficiently and effectively applied. A further advantage of the mechanism for lowering and raising the upper deformable electrode is that this electrode is raised to a shielded position during insertion and removal of the crustacean and this improves the safety of the apparatus.

21 Continuous Use/Commercial Application

This version of the processor is for use in large domestic, commercial or industrial operations where a large number of crustaceans need to be processed quickly and humanely. Two versions are described:- a hopper style version shown in figure 11 and a conveyor style processor shown in figure 12.

The hopper processor shown in figure 11 consists of two vertically running belts 110. The belts comprise conductive woven wire mesh or are of non-conducting material coated with a conductive layer or have a conductive wire mesh sewn into them. Each belt is connected to one of the electrodes via a slip ring. The belts are gently sprung loaded 111 so that they approach close together but do not actually contact each other. The belts are driven by an electric motor so that they are continuously moving down and towards themselves in the middle section as shown by the arrows in figure 11. The method of operation is that the crustaceans are fed into the hopper at the top 112 of the processors. As the crustaceans reach the middle part of the processor the spring mounted belts 1 10 move apart and adjust themselves to the width of the crustacean. After the crustacean contacts both belts it is exposed to the electric current which anaesthetises/kills it. The presence of a crustacean at the anaesthetising position is sensed by a detector 113 which signals the electronics to activate the electrodes. The crustacean then drops out of the bottom of the processor for further processing such as cooking in boiling water 114.

The horizontal processor shown in figure 12 works on the same principle as the hopper processors. Two conveyor belts which approach but do not touch each other are used. The important point to notice is that the conveyor part of the processing unit is either electrically isolated from the rest of the conveyor system for safety reasons, or has the exposed conveyor electrode at ground potential 120. The crustacean is contained between the two belts 121 and then lowered into a saline solution 122. When

22 the presence of a crustacean is sensed 123 at the central point the electrodes are activated.

Once again both methods use the same electrical discharge techniques described in this document to anaesthetise and or kill the crustacean. Further examples suitable for continuous use and commercial application are now described. For example, the crustaceans can be electrically stunned as they slide down a chute, are driven along on or between belts, or driven on a bed of rollers directly to the place they are to be killed by cooking.

Figure 15 shows how crustaceans 150 may be placed, spaced apart on an electrically conducting conveyor belt 151 which moves them under a series of rotating brushes 152. The conveyor belt 151 forms one electrode and the brushes 152 another electrode. As the crustaceans 150 pass under the rotating brushes 152 electrical contact is made between the brushes and the crustaceans and, once continuous electrical contact has been established, electrical power is applied to stun the crustacean 150. The stun can be reinforced, to ensure the period of insensibility lasts long enough by applying an electrical current as the crustacean passes under a second or third rotating brush (as shown in figure 15). The crustaceans are spaced on the conveyor belt 151 so that the rotating brush or drum 152 can contact no more than one crustacean at a time. An alternative configuration of this is shown in figure 16. The crustacean 160 is placed on a non-conducting belt 161 or slide between pairs of vertical brush 162 or finger drums. The pairs of drums or brushes 162 make contact on each side of the crustacean 160 as it passes through and deliver the electrical stun. Another example is shown in figure 17. If the crustaceans 170 need to be restrained or moved more positively then they can be held between non-conducting slotted belts 171. In this case the bristles of the drums 172 are able to penetrate slots in the belt 171 in order to make contact with the crustacean 170. For example, the belt may be made from mesh

23 type material or may be perforated. Any suitable material can be used to form the belt. The bristles of the drums 172 are resiliently deformable. As the crustacean is drawn into the nip between the drums 172 the bristles penetrate the belt 171 and touch the crustacean. This causes the bristles to deform resiliently and this improves the electrical contact with the crustacean.

Figure 18 shows a situation in which movement and stunning of a crustacean 180 can be achieved using a series of rotating rollers 181. The rollers 181 are held at different electrical potentials as shown in figure 18 so that electrical current is passed through the crustaceans as they are moved. This is because the crustaceans are large enough to occupy an area over the bed of rollers 181 which include area of different electrical potential. Current then flows through the body of the crustacean 180. The rollers are spaced apart so that current does not flow between then in the absence of a crustacean 180. Electrical contact between the crustacean 180 and the rollers 181 is enhanced where the rollers 181 have a slightly compliant surface. Lack of positive contact between the electrodes 181 and the crustacean 180 makes this method suitable for the application of a reinforcing stun rather than an initial stun.

Figure 19 shows an example where movement and stunning of a crustacean 190 is achieved by sliding the crustacean down a chute 191 . The walls 192, 193 of the chute 191 form the two electrodes and deliver the electric current to the crustacean 190. Lack of positive contact between the electrodes 181 and the crustacean 180 makes this method suitable for the application of a reinforcing stun rather than an initial stun.

Figure 20 shows an example where movement and stunning of the crustaceans 200 is achieved by placing the crustaceans on an inclined bed of counter-rotating rollers 201 , 202. The rollers are held at different electrical potentials as shown in figure 20. As the crustaceans 200 slowly slide down the bed they make contact with an adjacent pair of rollers and so receive an electrical stun.

24 In another example, the movement of crustaceans is achieved by use of an auger. A screw of the auger is held at a different electrical potential to a casing of the auger and so crustaceans contacting both as they are moved along the auger receive an electric stun. Examples of stunning multiple crustaceans in a batch are now described.

Crustaceans can be batch stunned in large plastic crates such as those in which they might be delivered to the processing facility. This can be achieved by applying an electrical potential across the whole crate. The electrodes can include a shallow pool of conducting liquid in which the crate stands, conducting brushes or fingers which can be applied through the perforations at the top and bottom of the crate, or conducting grids built into or inserted in the ends of the crate. Where this is not possible, the crustaceans can be transferred from the delivery crates into a purpose built stunning crate. When using the batch stunning method measurements are made to determine the electrical potential which must be applied to achieve a suitable electrical current through each crustacean. This can either be done for each batch or an predetermined value used. The target electrical current is slightly higher then that used when stunning single crustaceans to allow for differences in the current received by different crustaceans.

Generic Electronics

The key parts of the electronics are shown in Figure 3. The purpose of the electronics is to provide a controlled current to the electrodes which are in contact with the crustacean. As already discussed the frequency, duty cycle and duration of the current pulse need to be controlled. The purpose of each principle part of the electrical circuit will now be defined. Figure 3 shows the electronics in the context of the single use

25 system and any differences between the electronics for the single use and continuous use system is described where necessary.

Mains isolator 31

The use of mains electricity in the proposed environment can be potentially hazardous. The proposed design must have a mains isolation transformer 31 between the mains electricity supply and the device. This is essential in a consumer product but may not be necessary in a commercial environment. EC wide EMC and LVD requirements are met by suitable protection components.

Power Supply Unit 32

The apparatus requires a stabilised low voltage DC supply for a voltage generator 33 and to power auxiliary components such as a microcontroller 34 and amplifier circuits 35. The voltage levels required for a commercial system may vary from those required for a consumer system.

Voltage Generator 33

This module produces the high voltages required to effectively kill a crustacean. The voltage generated will need to be in the range of 100 to 1 ,000 volts depending on the crustacean and the existing conductivity within the vessel. The discharge power level and duration are controlled by the microcontroller 34. The high voltages that are required may be generated by a step-up transformer circuit or by capacitive discharge. A capacitive discharge power supply would not be suitable for a continuous use system unless the throughput was adjusted to match the capacitor re-charge time, but would be ideal for a single use consumer system. This module also contains circuitry for limiting the maximum voltage discharge and controlling the duration of the discharge.

26 Pulse Shaper 36

This is one of the most important modules of the electronics system. As previously described the type of current wave form applied to the crustacean is very important. The pulse shaper 36 contains circuitry that can produce alternating, pulsed or direct current output from the voltage generator 33. It will also be able to produce different frequencies and alter the duty cycle of the output wave form. These variables can be adjusted via the micro-controller 34 to pre-determined values or by manual adjustment.

Micro-controller 34

The micro-controller 34 controls the overall operation of the apparatus. The microcontroller is responsible for determining the correct voltage level, current type, frequency, duty cycle and duration which has to be applied to the crustacean. The values that it selects for these attributes are dependant on the type of crustacean and the existing electrical conductivity across the electrodes 37. The controller is also responsible for informing the user of what is happening and enabling the user to select the type and quantity of crustacean. In the continuous use system it also has to monitor and control the throughput rate. In both single use consumer product or industrial applications the micro-controller also has to monitor various safety aspects.

Safety Interlock

This is an essential part of the single use consumer product, where the electrodes 37 might be accessible to the user during loading/unloading of crustaceans. The safety interlock provides the dual purpose of making it electrically impossible for any current to flow to the electrodes when the user could touch them. It is also used to inform the

27 micro-controller 34 whether the lid of the device is open or closed. Continuous use systems will have a safety interlock on their protective guards so that current cannot flow to electrodes when the guards are removed for maintenance.

Electrodes/Conductivity Detectors 37, 38

The electrode 37 is the part of the circuit which delivers the electrical charge and detects the conductivity. The electrodes 37 and the detectors 38 may be separate devices or may be integrated into the same device for the single use system, but would have to be separate contacts in the continuous use system.

Conductivity Amplifier 35

This module simply monitors the conductivity across the conductivity detectors 38 and converts this into a suitable analogue voltage for use by the microcontroller 34. It ensures that there is sufficient high conductivity to ensure full electrical discharge to humanely kill or anaesthetise the crustacean and avoids malfunction of the apparatus.

Keypad/Display 39

The user will need to be able to input parameters into the device such as type and quantity of crustacean, cooking time, etc. This is effected using the keypad / display 39. The keypad / display 39 can also be used to give visual feedback to the user as to the current status of the device. Indicators will signal the status of the safety circuits. A control panel which is part of the key pad/display may include the door release and its safety interlock.

A number of general points are now described.

28 It is advantageous in many cases to rinse the crustaceans in fresh water prior to stunning. Salt water is a good conductor of electricity and if the crustaceans are wet with saline solution then any electrical current applied to the crustacean is likely to flow through the film of salt water across the surface of the crustacean rather than through the body of the crustacean. This reduces the effectiveness of the electric stun on the crustacean. Removal of the salt water by, for example replacing it with fresh water which has a higher electrical resistance, will reduce the conductivity of this path and so increase the proportion of the electric current which passes through the body of the crustacean.

It is also possible to place the crustacean in a container prior to stunning in order to facilitate its transfer to a cooking device and subsequent removal from that cooking device. The container may take the form of a basket such as a conventional potato chip basket and may include one or both electrodes. The container may then be driven through a long vat of boiling water, or a steam bath in order to cook the crustacean. In this way an accurate cooking time can be ensured without the need to accumulate a batch of stunned crustaceans for batch cooking.

29

Claims

1. An apparatus for applying an electric current to a crustacean comprising:

(i) a plurality of electrodes arranged such that the crustacean can be placed between the electrodes; and (ii) means for creating an electrical potential across the electrodes such that in use current flows between the electrodes and through the crustacean such that the crustacean is anaesthetised or killed.

2. An apparatus as claimed in claim 1 which further comprises a tank adapted to contain the crustacean.

3. The apparatus as claimed in claim 2 wherein the tank is adapted to hold an electrically conductive fluid.

4. An apparatus as claimed in claim 2 or claim 3 wherein the tank further comprises a heat source such that it is possible to retain the crustacean in the fluid filled tank for cooking, after the crustacean has been anaesthetised or killed.

5. An apparatus as claimed in any preceding claim wherein the electrodes are substantially rigid.

6. An apparatus as claimed in any of claims 1 to 4 wherein the electrodes are deformable and are adapted to be placed against the crustacean such that in use the electrodes conform to fit the shape of the crustacean.

30

7. An apparatus as claimed in any of Claims 1 to 4 wherein each electrode comprises a plurality of curved fingers.

8. An apparatus as claimed in any of Claims 1 to 4 wherein each electrode comprises a resilient mesh.

9. An apparatus as claimed in any of Claims 2 to 4 wherein each electrode comprises a plurality of resiliently biased probes arranged to protrude from the periphery of the tank towards the centre.

10. An apparatus as claimed in any of Claims 2 to 4 wherein the tank further comprises a sealable lid and the apparatus further comprises a safety device adapted to prevent opening of the lid whilst electric current flows between the electrodes.

11. An apparatus as claimed in any of Claims 2 to 4 wherein at least one electrode comprises a grille within the tank such that in use a crustacean's body can be supported on the grille but the crustacean is substantially unable to stand on the grille.

12. An apparatus as claimed in any of Claims 1 to 4 wherein at least one electrode comprises a flexible mesh mounted over a resiliently deformable body.

13. An apparatus as claimed in any of Claims 1 to 5 wherein at least two electrodes are arranged to form at least part of the sides of a funnel such that in use a crustacean may be dropped into the funnel and lodge between the sides of the funnel, forming contact with the electrodes.

31

14. An apparatus as claimed in claim 13 wherein an upper part of said funnel is electrically isolated.

15. An apparatus as claimed in claim 13 or claim 14 wherein the funnel is openable, such that in use when a crustacean is lodged in the funnel the funnel may be opened to remove the crustacean.

16. An apparatus as claimed in any of Claims 1 to 4 wherein at least one of said electrodes forms at least part of a moving platform adapted to support the crustacean; and at least one other electrode forms at least part of a rotating brush, positioned above the moving platform.

17. An apparatus as claimed in any of Claims 1 to 4 which further comprises a pair of moving carrier surfaces adapted to move in the same direction, said carrier surfaces being positioned so that they are facing each other such that in use a crustacean can be supported between the surfaces.

18. An apparatus as claimed in claim 17 wherein at least two of said electrodes each comprise a rotating brush, said brushes being positioned substantially opposite each other on either side of the moving carrier surfaces.

19. An apparatus as claimed in claim 18 wherein for each brush at least some bristles of the brush are arranged to extend through one of the moving carrier surfaces such that in use, when a crustacean is supported between the carrier surfaces, the crustacean contacts at least some of the bristles of each brush at the same time.

32

20. An apparatus as claimed in any of Claims 1 to 4 wherein said electrodes comprise a bed of rotating rollers adapted to support at least one crustacean.

21. An apparatus as claimed in claim 20 which further comprises a frame for supporting the bed of rotating rollers and wherein the frame is inclined towards its base.

22. An apparatus as claimed in any of Claims 1 to 4 which further comprises a chute adapted such that in use a crustacean may be slid down the chute and wherein at least two electrodes are located in side walls of the chute such that in use, when a crustacean is slid down the chute it contacts the electrodes.

23. An apparatus as claimed in any of Claims 1 to 4 wherein one of said electrodes comprises the screw of an auger and at least one other electrode comprises a casing of the auger.

24. An apparatus as claimed in any preceding claim which further comprises an apparatus for determining the electrical resistance between the electrodes and for adjusting the voltage applied across the electrodes on the basis of the determined resistance.

25. An apparatus as claimed in any preceding claim wherein said means for creating an electrical potential across the electrodes comprises means for creating a pulsed or

alternating potential across the electrodes.

26. An apparatus as claimed in any preceding claim further comprising at least one detector, adapted to detect the presence of the crustacean between the electrodes.

33

27. An apparatus as claimed in any of Claims 1 to 4 wherein at least two electrodes comprise fine piercing elements adapted to pierce the shell of a crustacean.

28. An apparatus as claimed in any of Claims 1 to 4 wherein at least two electrodes form part of a pair of tongs, said pair of tongs being adapted to grip a crustacean in use.

29. An apparatus as claimed in any of Claims 1 to 4 which further comprises a nozzle arranged such that in use, an electrically conducting liquid may be passed through the nozzle to form a jet of liquid and wherein at least one of said electrodes is arranged in use to apply an electrical potential to said jet of liquid.

30. A method of applying an electric current to a crustacean comprising the steps of:- (i) placing the crustacean between at least two electrodes; and

(ii) creating an electrical potential across the electrodes such that in use current flows between the electrodes and through the crustacean such that the crustacean is anaesthetised or killed.

31. A method as claimed in claim 30 wherein at least one of said electrodes is arranged to extend along substantially the full body length of the crustacean.

32. A method as claimed in claim 30 or claim 31 which further comprises the step of applying an electrically conductive gel or liquid to at least one of the electrodes.

34

33. A method as claimed in any of claims 30 to 32 which further comprises the step of placing the crustacean in a tank of electrically conducting liquid.

34. An apparatus as claimed in any of claims 1 to 4 wherein at least one of the electrodes is deformable and adapted to be placed against a crustacean in use.

35. An apparatus as claimed in claim 34 wherein said at least one deformable electrode comprises foam material.

36. An apparatus as claimed in claim 35 wherein said at least one deformable electrode further comprises chain metal positioned over the foam material.

37. An apparatus as claimed in any of claims 2 to 4 wherein the tank comprises a drawer adapted to contain a crustacean.

38. An apparatus as claimed in claim 37 wherein at least one of the electrodes comprises an electrically conductive plate positioned in the base of said drawer.

35