IE20020728U1 - Method and apparatus for separating bivalve shells into two halves - Google Patents

Abstract

Abstract An apparatus for separating empty bivalve shells (10) into their two halves comprise a conveyor system (16, 18) for conveying the shells continuously beneath a series of banks of UV lamps (20) for irradiating the shells to weaken the joints between their two halves. From the conveyor (18) the irradiated shells are fed continuously into a rotating drum (24) for mechanically agitating the treated shells to break the joints. The half—shells (10’) with severed joints finally exit the drum onto a conveyor (26). F!6.’u,€E 1,

Description

This invention relates to a method and apparatus for separating empty bivalve shells, such as mussel shells, into their two halves.

In the preparation of mussels for retail sale, the mussel meat is removed from the shells, the empty shells are separated into their two halves by breaking the hinge joint between them, the half shells are placed in trays, and finally the half shells in the trays are re—filled with mussel meat and seasoned, typically with bread crumbs and garlic butter mix.

A disadvantage with the known process is that the empty mussel shells have to be broken into their two halves by hand, which is time—consuming and labour intensive.

According to the present invention there is provided a method of separating empty bivalve shells into their two halves, comprising treating the shells to weaken the joint between their two halves and mechanically agitating the treated shells to break the joints.

Preferably the shells are treated by irradiating them with UV light, and the mechanical agitation may take place in a rotating drum.

The process may be continuous, whereby the shells are conveyed continuously past a source of UV light and into a mechanical agitator from which they emerge with their joints severed.

The invention further provides an apparatus for separating empty bivalve shells into their two halves, comprising means for treating the shells to weaken the joint between their two halves and means for mechanically agitating the treated shells to break the joints.

An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings, in which: Fig. l is a schematic side view of an embodiment of an apparatus according to the invention for separating empty mussel shells into their two halves; Fig. 2 is an underneath view of one of the banks of UV lamps used in the apparatus of Fig. l; and Fig. 3 is a cross—section taken on the line III—III of Fig. 1.

Although the invention is primarily concerned with separating the empty mussel shells into their two halves, a summary of the entire process for preparing the mussels for retail sale will first be described.

It occurs in a number of stages, as follows.

Stage l: The mussels are harvested and brought to the factory in one tonne bags. They are then put into a mechanical hopper from where they are conveyed on conveyor belt to a pre—conditioner. The pre- conditioner is in essence a tank with water at a constant 41 deg.C. The conveyor passes through the tank with the mussels on it and the mussels are in the pre—conditioner for 3 minutes. The purpose of the pre—conditioner is to prepare the mussel for easier detachment of the meats from the shell.

Stage 2: Next the mussels to go to a steam cooker which they pass through for a period of 4 minutes at a temperature of 100 deg C. This cooks the mussel to the stage where the meat fully detaches from the shell.

At this stage the shell has opened fully.

Stage 3: The shells with the loose meats inside fall into a vibrating mesh screen which separates the meats completely from the shells. This takes approximately seconds. The meats drop through the screen onto another conveyor where they then pass through chilled water to cool them and from there they go into a spiral freezer for freezing.

Stage 4: The empty shells pass over the top of the mesh screen and are taken away by conveyor to open holding bins where they are stored awaiting separation of the open shells into their two halves.

!E02“723 Stage 5: This next stage is that the hinged joints of the mussel shells are broken so that the mussel shells are separated into their two halves. This is where the invention primarily lies and will be described below.

Stage 6: The half shells then proceed to packaging where they are placed by hand into trays with pre- formed indents for half shell mussels. These trays are suitable for microwave cooking by the consumer.

They then proceed by conveyor to a machine which places the pre—frozen meats into the half shell and the next work station adds pre—prepared bread crumbs and garlic butter mix. They are then be sealed and proceed through the spiral freezer prior to final packaging and cold storage.

Stage 5 will now be described in detail with reference to the drawings. The empty mussel shells 10 are loaded into a hopper 12 from where they are discharged through an adjustable door (not shown) at a controlled rate onto the lower end of an upwardly inclined endless conveyor belt 16. From there the shells travel up the conveyor 16 and are discharged onto one end of a substantially horizontal main endless conveyor belt 18 which is approximately 600mm wide.

The main conveyor 18 conveys the shells slowly along directly below a series of banks 20 of ultraviolet (UV) emitting lamps. Each bank 20 of UV lamps contains ten individual UV—emitting tubes 22 each 1500mm long.

IEn207?8 These tubes 22 are disposed in parallel side—by—side so that each bank 20 has a length of 1500mm and a width of 600mm (Fig. 2). The tubes 22 are 115 Watts each. The banks 20 of UV lamps are disposed end—to—end above the main conveyor 18 and there are eight banks 20 in total; thus the total length of the series of UV banks 20 is 12 metres and its width is 600mm, the same as the width of the conveyor 18. The distance of the UV tubes 22 from the conveyor 18 is approximately 75mm—l0Omm which gives a clearance of approximately 50mm—75mm from the UV tubes to the mussels 10. The conveyor 18 is driven at such a rate that the mussels take approximately 40 minutes to travel the 12 meters to pass completely under the series of banks 20 of UV lamps from one end to the other. sidewalls (not shown) prevent the shells falling off the sides of the conveyors.

The particular layout of system described above, which is capable of processing 144 shells per minute, is chosen so that the mussel shells are exposed to the UV light for a sufficiently long period that the UV light breaks down the organic material in the mussel shell Of course, joint so that it becomes weak and brittle. the system design can be varied. For example, the UV arrangement may be altered to use 600mm long UV tubes arranged at 90 degrees to the direction of travel of the conveyor 18, rather than 1500mm tubes in line with the conveyor. Also, if the UV tubes were higher wattage, the length of time for which the shells need be exposed can be shortened.

\E020723 After passing under the series of banks of UV lamps the irradiated shells are discharged by the conveyer l8 into the upper end of a downwardly inclined revolving drum 24. The drum 24 has internal baffles so that as the shells pass down along the drum they are mechanically agitated sufficiently to break the now brittle joints between their two halves. This takes approximately 20 to 30 seconds. Finally the separated shell halves 10’ are discharged from the lower end of the drum 24 onto a further conveyor 26 for transfer to the packing station.

The invention is not limited to the embodiment described herein which may be modified or varied without departing from the scope of the invention.

Claims (5)

Claims

1. A method of separating empty bivalve shells into their two halves, comprising treating the shells to weaken the joint between their two halves and mechanically agitating the treated shells to break the joints.

2. The method claimed in claim 1, wherein the step of treating the shells to weaken their joints comprises irradiating the shells.

3. The method claimed in claim 2, wherein the shells are irradiated with UV light.

4. The method claimed in claim 1, 2 or 3, wherein the shells are mechanically agitated in a rotating drum.

5. An apparatus for separating empty bivalve shells into their two halves, comprising means for treating the shells to weaken the joint between their two halves and means for mechanically agitating the treated shells to break the joints.