FIELD OF THE INVENTION

The present invention relates to an apparatus and method for processing shell fish such as, for example, shrimps, prawns, chitons, snails and bivalves.

BACKGROUND OF THE INVENTION

Shell fish can be broadly described as creatures having a body covered by and attached to a shell. Their body may be wholly or partially enclosed by the shell. While the following description is made with reference to bivalve molluscs and in particular scallops, it is to be understood that the present invention is equally applicable to other types of shell fish.

The processing of scallops is usually performed by hand and includes the step of shucking. Shucking involves opening of the shell of the scallop and removing the internal body of the scallop. This is performed by using a knife to chop or hack away a portion of the scallop where its constituent shells meet and then inserting a blade of the knife through an opening so formed to wedge the shells apart. The knife can then be used to detach the body from the interior of the shell. The body of a scallop comprises an adductor muscle which is an edible white disc shaped muscle, and surrounding viscera (i.e. "guts"). Shucking can be followed by evisceration which involves removing the viscera from the body leaving the edible adduction muscle of the scallop. This is generally achieved by physically pulling the viscera away from the adductor muscle. The hand processing of shell fish as described above suffers from several disadvantages. By its very nature, this process is labour intensive and therefore expensive. It is also very common for operators in the process to cut their hands either on the shells of the scallops or accidentally on the knives. It will be appreciated that the presence of blood mixed with the scallops can produce health risks for the end

consumer. In addition, processing by hand is limited to certain types of shell fish due to the hardness of the associated shells and, for molluscs, the strength of associated closure muscles. Furthermore, shucking shell fish by hand can lead to a wastage of meat due to the difficulty in detaching the body and in particular the adductor muscle from the shell. Apredecessor of the present applicant has previously sought to overcome the above problems by developing an apparatus and method for processing shell fish in which the shell fish are passed through a bath of heated water. The heated water causes the body to release itself from its corresponding shell and, in the case of molluscs, weaken the closure muscle. This then allows simple mechanical shucking and evisceration. While this process is a great advancement over hand shucking and eviscerating the applicant has found that this process is not entirely satisfactory. The reason for this is that passing molluscs through a hot water bath tends to colour and/or partially cook the adductor muscle of the mollusc which greatly reduces its commercial value. This is due to the relatively slow heat transfer rate from the water to the shell which lengthens the time required in the bath for the body to release itself from the shell, and because hot water can freely flow into the shell. A further problem with this apparatus is that large volumes of water are required as the heated water is regularly changed and the process is also energy intensive due to the need to maintain the temperature of the water and to heat the changed water. This also reduces the output of the process as there is an inherent delay while the changed water is heated to the required temperature. •

SUMMARY OF THE INVENTION

The present invention was developed in an attempt to overcome the deficiencies in the above described prior art.

According to one aspect of the present invention there is provided an apparatus for processing shell fish- comprising an electromagnetic radiation generating means adapted for radiating said shell fish with electromagnetic radiation of a power and frequency adapted to cause the body

of each shell fish to substantially release itself from its shell. Preferably said electromagnetic radiation is

(j. microwave radiation.

5 According to another aspect of the invention there is provided an apparatus for processing shell fish comprising: feeding means for feeding said shell fish from a supply of shell fish onto a conveyor, said conveyor arranged to transport said shell fish along a processing path; 10 an electromagnetic radiation generating means disposed adjacent said processing path and adapted for radiating said shell fish with electromagnetic radiation of a power and frequency adapted to cause the body of each shell fish to substantially release itself from its shell. 15 Preferably said electromagnetic radiation is microwave radiation.

Advantageously said electromagnetic radiation generating means is adapted to vary the power of the electromagnetic radiation in response to the number of shell

20 fish radiated per unit time such that the energy absorbed by each shell fish is substantially the same.

Preferably said electromagnetic radiation generating means comprises an electromagnetic radiation cavity resonator configured to surround a length of the processing path; an 25 electromagnetic radiation source for producing electromagnetic radiation located remotely from said electromagnetic radiation cavity resonator; and a channel for transmitting said electromagnetic radiation from the electromagnetic radiation source to the electromagnetic cavity resonator. 30 Preferably said electromagnetic radiation cavity resonator is a microwave cavity, said electromagnetic radiation source is a microwave source and said channel is a waveguide. Preferably said microwave source is a magnetron. Preferably said apparatus further comprises first 35 separating means located upstream of said electromagnetic radiation generating means along said processing path for separating the body from its shell.

Preferably said first separating means is adapted to direct the body to an eviscerating means and to direct the shells to a second separating means.

Preferably said first separating means includes a grid shaped and dimensioned to allow the body to pass there through to said eviscerating means and to direct the shells to said second separating means.

Preferably said first separating means includes at least one pair of counter-rotating rollers for directing and impacting said shell fish against said grid.

Preferably said second separatingmeans separates the bodies from shells not separated by the first separating means and directs said bodies into said eviscerating means.

Preferably said second separating means comprises a trommel.

According to another aspect of the present invention there is provided a method for processing shell fish comprising the step of: radiating said shell fish with electromagnetic radiation of a power and frequency adapted to cause the body of each shell fish to substantially release itself from its shell.

Preferably said radiating step comprises radiating said shell fish with microwave radiation. According to another aspect of the present invention there is provided a method for processing shell fish comprising the steps of: feeding shell fish from a supply of said shell fish onto a conveyor means; conveying said shell fish on said conveyor means along a processing path; radiating said shell fish with electromagnetic radiation as said shell fish are conveyed along at least a portion of saidprocessing path, said electromagnetic radiation being of a power and frequency adapted to cause the body of each shell fish to substantially release itself from its corresponding shell; and, separating the body from its corresponding shell.

Preferably said radiating step comprises radiating said shell fish with microwave radiation.

Preferably said radiating step further comprises the step of varying the power of said electromagnetic radiation in

^• 9* 5 response to the number of shell fish radiated per unit time such that the energy absorbed by each shell fish is substantially the same.

According to another aspect of the present invention there is provided an apparatus for processing shell fish 10 comprising: feeding means for feeding said shell fish from a supply of shell fish onto a conveyor, said conveyor arranged to transport said shell fish along a processing path; and, liquid spray means disposed adjacent said processing 15 path for spraying said shell fish with a liquid of a temperature so as to cause the body of each shell fish to substantially release itself from its shell.

Preferably said liquid spray means comprises a plurality of spray jets configured to spray opposite sides of 20 each shell fish with said liquid.

Preferably said liquid spray means further comprises an enclosure through which a length of said processing path passes, said enclosure adapted to direct substantially all of said liquid sprayed from said spray jets to a pumping means for

25 recirculation to the spray jets.

Preferably said conveyor comprises an endless belt formed with a plurality of separate compartments, each compartment configured to hold a shell fish and to allow the opposite sides of each shell fish to be sprayed by said liquid

30 from the spray jets.

Preferably said conveyor further comprises a substantially planar surface above which said endless belt travels, said planar surface including a length disposed in said enclosure adapted to allow said liquid to pass

35 therethrough.

Preferably said apparatus further comprises first separating means located upstream of said liquid spray means

along said processing path for separating the body from its shell.

BRIEF DESCRIPTION OF THE DRAWINGS

Several embodiments of the present inventionwill now be described in detail, by way of example only, with reference to the accompanying drawings in which:

Figure 1 is a side view of one embodiment of the apparatus for processing shell fish from the side;

Figure 2 is a elevation view from the side of an eviscerator used in the apparatus illustrated in Figure 1;

Figure 3 is an elevation view of the eviscerator from the top;

Figure 4 is an elevation view of the eviscerator from one end; Figure 5 is a side view of a second embodiment of the apparatus for processing shell fish;

Figure 6 is a side view of a third embodiment of the apparatus for processing shell fish; and,

Figure 7 is a plan view of a conveyor used in the third embodiment illustrated in Figure 6.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As shown in Figure 1, a first embodiment of the apparatus 2 for processing shell fish, comprises a storage means in the form of a hopper 4 for storing a supply of shell fish for example, scallops, and a feeding means in the form of a reciprocating tray 6 for feeding scallops from the hopper 4 onto an underlying conveyor belt 8. The conveyor belt 8 transports the scallops along a processing path coterminous with an upper surface 10 of the conveyor belt 8. An electromagnetic radia^on generating means in the form of a microwave gen -or 1 is disposed along the processing path and radiates t.- scallops with microwave radiation of a power and frequency adapted to cause the body of each scallop to substantially release itself from its corresponding shell. A first separating means 14 for separating the body from its shell is located upstream from the microwave generator

12. The first separator 14 includes a pair of counter-rotating rollers 16, 18. The rollers 16, 18 are disposed so that scallops falling off an end 20 of the conveyor belt 8 are directed therebetween. The counter-rotating rollers 16, 18, grip the scallops and impact them against a grid 22. The grid 22 is dimensioned and shaped so that the body can pass therethrough into an underlying slide 2 . The slide 24 terminates in a chute 26 and directs the body onto an eviscerator 28. The grid 22 also directs the shells of the scallop into a second slide 30 which directs the shells into a second separating means taking the form of a trommel 32. The trommel 32 is slightly inclined so that an end 34 near the rollers 16, 18 is elevated with respect to its opposite end 36. A plurality of holes 38 are formed in the trommel 32. The holes 38 are dimensioned so as to prevent the shells from passing therethrough. The trommel 32 rotates above a hopper 40 which has a first opening 42 located above the eviscerator 28 and a second opening 44 located above a waste tray 46.

Referring to Figures 2 and 3 it can be seen that the eviscerator 28 comprises a plurality of rollers 48a to 481 (referred to in general as "rollers 48" or "each roller 48") disposed side by side in a single plane. The rollers 48 are journelled in a frame 50. The eviscerator 28 is divided into first and second sections 52, 54 respectively, by a plate 56. Each roller 48 is formed of a first length 60 which extends for a major portion of the length of the roller and an integral second length 62 making up the remainder of the length of the roller 48. The first length 60 is substantially longer than the second length 62. Each roller 48 is further provided with helical teeth 64 of a first sense along the first length 60 and helical teeth 66 of an opposite sense on the second length 62. The second lengths 62 of the rollers 48a to 48f in the first section 52 are adjacent each other and located near one end 68 of the frame 50. The second length 62 of the rollers 48g to 481 in the second section 54 are similarly adjacent each other but located near an opposite end 70 of the frame 50. The teeth along immediately adjacent rollers 48 are also formed in an opposite sense. For example, the teeth along first length 60

of roller 48a are orientated in an opposite sense to those teeth formed in first length 60 of roller 48b. The same is also true for the teeth along the respective second lengths 62 of rollers 48a and 48b. The helical teeth 64, 66 of any one roller 48 mesh with helical teeth 64, 66 of an immediately adjacent roller 48. As can be seen most clearly from Figure 5, the direction of the tangent of rotational movement along a line where adjacent rollers mesh alternates from downwardly to upwardly along the rollers 48a to 481. For example, the tangent of motion along a line where rollers 48a and 48b mesh is directed downwardly whereas the tangent of motion where rollers 48b and 48c mesh is directly upwardly.

The plate 56 extends from a point near the junction of the first and second lengths 60, 62 of the roller 48f to the end 70 of the frame 50.

The operation of the apparatus 2 will now be described in detail.

Scallops, once caught, are placed into the hopper 4 and directed by gravity to the reciprocating tray. The tray 6 is constantly reciprocated backwards and forwards, so that scallops on the tray 6 are progressively shuffled toward conveyor belt 8. The feed rate can be controlled by varying the speed of the reciprocating portion of the tray 6.

The conveyor belt 8 rot-ater i a clockwise direction and therefore carries the sc. lop. through the microwave radiat generator 12. The speed of rotation of the conveyor belt 8 -d thus the period of time the scallops are under the influence of the microwave radiation generator 12 can be varied in accordance with the feed rate and the size of the scallops to be processed. The power of the microwave radiation generated by the microwave oven 12 can also be adjusted to the required level to ensure that the body substantially releases itself from its corresponding shell. It has been found that at least within predetermined limits, radiating the scallops with microwave radiation causes the body to substantially release itself from the inside of the shell without either colouring or cooking the viscera itself. Typically, the

microwave radiation output power is up to 7 kw. Advantageously the microwave radiation is produced by a magnetron.

The scallops then fall off the conveyor belt 8 at end 20 and between the rollers 16, 18. The rollers 16, 18, grip the scallops and impact them against the grid 22. This causes the shells to open and a substantial portion of the body for the majority of the scallops to leave the shell. The separated body is directed by slide 24 and chute 26 and onto the eviscerator 28. The shells are directed by slide 30 into the trommel 32. Typically the shells may contain approximately 5% to 10% of the original body.

The trommel 32 is constantly rotating and this rotating action operates to separate any remaining body portions or whole bodies from its corresponding shell. The separated bodies/body portions fall through holes 38 into the hopper 40 and through opening 42 onto the eviscerator 28. The shells exit the trommel 32 at end 36, fall into hopper 40 and are discharged through opening 44 into the waste chute 46.

Due to the sense of the helical teeth formed on the rollers 48 and the direction in which the rollers 48 are rotated, bodies deposited on the first section 52 of the eviscerator 28 near end 70 are propagated toward end 68. As this occurs the viscera is gripped between pairs of rollers 48 which have a downwardly directed tangent of motion, e.g. between rollers 48a and 48b; 48c and 48d; and, 48e and 48f, and is ripped away leaving the adductor muscle. The viscera then falls into the underlying waste tray 46. The movement of the bodies toward end 68 is retarded by the helical teeth 66 on the second length 62 of the rollers in the first section 52.* A water jet (not shown) is arranged to force the bodies in this region past plate 56 onto the second section 54. The bodies are then caused to travel along the rollers 48g to 481 in the direction of end 70. Again any remaining viscera is gripped by roller pairs which have a downwardly directed tangent of motion, e.g. between pairs 48g, 48h; ^' 48i, 48j ; and 48k, 481 and fall into the waste tray 46. The travel of bodies toward end 70 is retarded by the second length 62 of rollers 48g to 481 and directed by another water jet (not shown) into a collection

tray. At this point, substantially all of the viscera has been removed leaving only the adductor muscles.

In a second embodiment illustrated in Figure 5, in which like features are denoted by identical reference numbers, the microwave generator 12 of the first embodiment is split into its main constituent components, being an electromagnetic radiation cavity resonator in the form of a microwave cavity 72, an electromagnetic radiation source in the form of a magnetron 74, and control electronics 76. The microwave cavity 72 encloses a portion of the length of the conveyor belt 10. The magnetron 74 which is used as the source of the microwaves is located remote from the microwave cavity 72 beneath the conveyor 8. The microwaves generated by the magnetron 74 are transmitted to the microwave cavity 72 through a channel in the form of waveguides 78. Chokes 80 are provided on each side of the microwave cavity 12 to assist in reducing radiation leakage.

Other minor variations between this embodiment and that shown in Figure 1 are: the inclusion of a chute 82 located beneath the lower end of the tray 6 for directing scallops falling from the tray 6 onto the underlying conveyor belt 8; and, the general elongation of the apparatus 2 to accommodate the separate components of the microwave generator, and in particular the microwave cavity 72 and chokes 80. In all other respects, the salient features and method of operation of the second embodiment shown in Figure 5 is the same as that described with reference to the first embodiment of Figure 1. In a third embodiment illustrated in Figure 6, in which like features are denoted by identical reference numbers, the microwave generator 12 of the first embodiment, and the microwave generator 72, 74, 76 of the second embodiment are replaced ^τ - a liquid spray means in the form of spray jets 84 for spraying the scallops with a heated liquid, typically water, of a temperature adapted to cause the body of each scallop to substantially release itself from its shell.

Hot water is supplied to the spray jets 84 through pipes (not shown) from a boiler 86 located under the conveyor belt 8. The spray jets 84 are located on opposite sides of the

upper surface 10 of the conveyor belt in order to spray the opposite sides of each scallop with hot water. An enclosure 88 surrounds the spray jets 84 and a length of the conveyor belt 8. The enclosure 88 substantially prevents the loss of water beyond its confines and directs the sprayed water through a pipe 90 to a filter 92. After passing through the filter 92, the returned ater is pumped by pump 94 for recirculation through the boiler 86 and spray jets 84. Gaseous waste products from the boiler 86 are vented through a flue 96. Any waste products removed from the shells of the scallops while passing between spray jets 84 is carried by the water to a primary trash trap and sump 98. A pipe 100 leads from the sump 98 to the waste tray 46.

The conveyor belt 8 is in the form of an endless belt having a plurality of separate compartments 102 (refer Figure 7) . The compartments 102 are arranged in a staggered manner transversely across the belt 8. Each of the compartments 102 is in the form of a square-shaped wire loop and is configured to hold one scallop. Underlying the belt 8 is a planar surface in the form of an elongate metal sheet 104. A scallop held within any one of the compartments 102 is supported on the sheet 104. When the conveyor belt 8 is rotating, scallops within the compartments 102 are dragged up the sheet 104 toward the spray jets 84. The sheet 104 includes a length 106 located within the enclosure 88 which is adapted to allow liquid from the spray jets 84 to pass therethrough. Most conveniently, this is achieved by forming holes through the sheet 104 for the length 106 or alternatively, inserting a planar mesh in the sheet 104 for the length 106. The holes or mesh are sized to ensure that a scallop will not fall through. This allows hot water from the spray jets 84 to strike opposite sides of the scallops passing therebetween.

The direct spaying of hot water on opposite sides of the scallop ensures a high rate of heat transfer and thus quick temperature rise of the shell itself. This is particular advantageous as it allows the shell to be heated very quickly without any significant rise in the temperature of the body within the shell. Furthermore, as the water is sprayed at an

angle substantially normal to the opposite sides of a flat lying shell, the water deflects away from the periphery of the shell thus minimising water penetration into the shell itself which has the undesirable effect of increasing the temperature of the body.

A water temperature of approximately 105° and a spray jet pressure of approximately 140 kilopascals has been found to provide rapid heat transfer to the scallops. Vapour released from the sprayed water is trapped within the enclosure 88 which provides pre-heat to the shell andminimises oxidation of the flesh.

In order to fill each compartment 102 with a single scallop, the tray 6 of the first and second embodiments is replaced with a rotating brush 108 and outlet of the hopper 4 is shaped to arrange the scallops into three separate lines. The brush 108 picks up the leading scallops in each of the three lines, the outlet of hopper 4 and places them flat into corresponding compartments 102. In all other respects, the features and method of operation of the third embodiment, once the scallops have fallen off end 20 of the conveyor belt 8 is substantially the same as that described with reference to the first and second embodiments.

Now that several embodiments of the present invention have been described in detail, it will be apparent to those skilled in the relevant arts that numerous modifications and variations may be made without departing from the basic inventive concepts. For example, the eviscerator 28 is illustrated as comprising a number of counter-rotating rollers 48. However, any other type of eviscerator can be used. Furthermore, the juxtaposition of the conveyor belt 8, and the trommel 32 and eviscerator 28 can be varied to suit the location of the apparatus 2. For example, in certain applications it may be preferable for the trommel 32 and eviscerator 28 to be arranged adjacent end 20 of the conveyor belt 8 rather than being located underneath the conveyor belt 8 as illustrated in Figure 1. In addition, any type of microwave radiation generator can be used to cause each body to release from its corresponding shell. While the above

embodiments are described in relation to scallops they can with suitable modifications be applied to other shellfish. All such modifications and variations are to be considered within the scope of the present invention, the nature of which is to be determined from the foregoing description and the appended claims.