IE85391B1 - Process for packing mussels - Google Patents

Abstract

ABSTRACT The present invention is concerned with a process for packing bivalve seafood such as mussels, and comprises depositing a portion of the mussels into a two part container having a lower layer in tray form, and an upper layer applied to the tray, the container being evacuated and heat shrunk in order to prevent the opening of the mussels during a subsequent heating step.

Description

Process for packing mussels The present invention is concerned with a process for packing bivalve seafood, for example mussels.

Seafood, and notably bivalve seafood for example mussels, has become an increasingly popular source of food. Although bivalve seafood, in particular mussels, are naturally occurring in coastal waters, they are now in many instances harvested in coastal waters on a commercial scale to meet market demands. However, one problem is that the major markets for the mussels are often distant from the source of the mussels and it is necessary to trans— ship the food over long distances.

One basic problem is that mussels cannot be frozen live or raw, nor can they be kept live by chilling, for long periods of time in a ready to cook state, i.e. graded, cleaned and dcbyssed.

The meat in a mussel generally forms a coating on the inside surface of the mussel shell. In order to facilitate the removal of the meat from the shell it is necessary that the mussel be cooked while it is still live or raw. The cooking process induces the meat to contract or curl up so that it is easily eaten. However, if the mussel is frozen while live or raw in its shell, when cooked the mussel meat will not curl up or contract to give the vendable appearance of normal cooked mussel meat. Once the mussel dies after being out of its natural environment for about a week or so, the meat will not curl up when it is being cooked. Thus, two methods of shipping mussels have been used to date.

First, live or raw mussels, after being harvested from the sea, are purified and trained to retain their juices in depuration tanks for about fo1ty—eight hours, and in conventional manner are then graded and packed in ventilated bags and shipped to customers at ambient temperatures. This method has a number of disadvantages. First changes in temperatures during shipping can induce premature spawning which may render an entire consignment useless. l-‘urther, the mussels are in some instances at least one full week out of the sea when received by the customer. Most mussels are only seasonally available and the product does not enjoy a high level of acceptability with top rank chefs and caterers due to lack of freshness, long preparation time and wastage.

Second, mussels can be trans—shipped in a prc—cooked frozen state. In this method the mussels are harvested, purified in conventional manner, graded, debyssed and washed, pressure cooked or boiled, and then frozen, packed and shipped to the customer. This method also has some disadvantages, namely in the cooking process the shell opens and the natural juices and hence much of the flavour is lost. Also, the handling creates a danger of bacterial contamination. This product does not find great favour with top rank chefs and caterers, as the mussel meat without the protection of the juices around it, acting as a protective glaze, is deteriorated in both taste and texture by the action of the freezing PYOCCSS.

Furthermore, mussels which have been cooked and are subsequently chilled, although not frozen, are also less highly regarded since, because of the loss of juices, the meat tends to deteriorate by becoming dry with subsequent loss of taste.

EP0242 l 83 discloses a process for packing and cooking mussels or similar bivalve seafood in which the mussels are located in a plastic envelope through an open end of the envelope, and are subsequently manipulated into a single layer within the envelope. The envelope is then evacuated and heat shrunk, in order to conform tightly around the shell of each of the mussels to prevent same from opening during cooking. Once the envelope has been scaled, the envelope and the contents are subjected to a heat process to cook the mussels, and the cooked mussels are then preferably frozen for transport/storage.

Thus, it is an obj eet of the present invention to provide a process for packing and treating bivalve seafood, in particular mussels, which improves the known process disclosed above. l\) U1 According to a first aspect of the invention there is provided a process for packing and treating mussels or other bivalve seafood, the process comprising arranging the bivalves in at least one layer in a flexible container; at least partially evacuating the container such that the container is drawn tightly around the bivalves; heating the bivalves and container for sufficient time and at sufficient temperature to at least partially cook the bivalves; characterized in that the container is formed from a lower layer and an upper layer of plastics material, and the upper layer is positioned over and secured to the lower layer after the bivalves have been arranged in the at least one layer on the lower layer, the lower layer is in the form of a tray, which is formed by the heated deformation of the lower layer of plastics material, the process further comprising the step of vibrating the lower layer when the bivalves are located thereon.

Preferably, the process comprises the step of applying pressure, from above, to the bivalves located on the lower layer, in order to substantially level the lower layer.

Preferably, the process comprises the step of vibrating the bivalves, from above, when located on the lower layer and before positioning of the upper layer.

Preferably, the process comprises the step of providing the container as a heat—shrinkable plastics material, the heat shrinking the container simultaneously or sequentially with the evacuation of the container.

Preferably, the process comprises arranging the bivalves in a single layer with a substantially common orientation.

Preferably, the process comprises the step of freezing the container and bivalves following heating.

Preferably, the process comprises, prior to arranging the bivalves in the container, storing the bivalves in a reservoir of water at a temperature of between 0° and 10°.

Preferably, the reservoir of water is salt water.

The invention further provides a pack of bivalves whenever prepared in accordance with the process according to the first aspect of the invention.

The present invention will now be described with reference to the accompanying drawings, in which: Fig, 1 illustrates a perspective view of a double line of trays formed in a plastic sheet, which trays form the lower portion of a container for ; Fig. 2 illustrates the trays of Fig. 1, one having been filled with a single layer of mussels; Fig. 3 illustrates a sectioned side elevation of the filled tray of Fig. 2, with a second sheet of plastic material having been applied over the first sheet of material, in order to close or seal the trays; and Fig. 4 illustrates the sectioned side elevation of Fig. 3, after the partial evacuation of the trays such that the upper and lower sheets of material have confirmed tightly around the mussels.

Refeirin g now to the accompanying drawings, the process for packing mussels according to the present invention will now be described. Mussels 10 are harvested and purified in conventional manner, for example, in purification tanks (not shown). Next, the mussels 10 are graded by size in a conventional grading machine (not shown). Once the mussels 10 are graded they are “debyssed” which is the know term used to describe the removal of the long threads or cords by which the mussels 10 attach themselves to rocks or the like in the sea.

The mussels 10 are then ready to be packed according to the process of the present invention. Prior to packing, it is preferable that the mussels 10 are stored in a reservoir of cooled water, preferably salt water. This ensures that while the mussels 10 are waiting to be packed, the low temperature of the water, which is preferably between 0° and 10°C, the mussels 10 remain tightly shut, and so do not lose any of the water or juices contained therein. The mussels 10 comprise a top shell portion 12 and a bottom shell portion 14 which are hinged together and which remain tightly shut when the surrounding temperature is sufficiently low.

When the mussels 10 are to be packed according to the process of the present invention, a quantity or portion of the mussels 10, in the example illustrated twenty four, are deposited into the lower half of a respective container 16 (not shown in Figs. 1 and 2). Each container 16 comprises a lower layer or half in the form of a tray 18, and an upper layer or half in the form of a cover 20 which closes and ultimately seals the respective tray 18, as will be described in detail hereinafter. In the preferred embodiment illustrated, in order to facilitate the assembly line packing of the mussels 10, an array of the trays 18 are formed in a first sheet 22 ofplastics material, as illustrated in Figs. 1 and 2. It is preferable that the first sheet 22 is provided in roll form (not shown), and is drawn off the roll along the assembly line through a number of stations (not shown) or the like, at which various activities are carried out as set out in detail hereinafter. Thus at a first station, the array of trays 18 is formed in the first sheet 22. In particular, the sheet 22 is momentarily halted while a pair of heated dies or the like (not shown) are pressed into the sheet 22 and a suction pressure applied in order to form each row of the trays 18. Although in the embodiment illustrated the trays 18 are formed in rows of two on the first sheet 22, it will be appreciated that any other arrangement of the trays 18 may be provided.

Once the trays 18 have been formed in the first sheet 22, the sheet 22 is advanced along the assembly line and at the next station (not shown) a quantity of mussels 10 are deposited into each tray 18, as illustrated in Fig. 2. Although only one of the trays 18 is shown with a portion of mussels 10 therein in Fig.2, it will be appreciated that each of the trays 18 will be similarly filled. The process of the invention also preferably includes the step of vibrating the trays 18, preferably from an underside thereof by way of a vibrating bed (not shown) or the like, once the mussels 10 have been deposited into the trays 18. This vibration serves to substantially level the mussels 10 into a single layer, as illustrated in Fig. 2.

One ofthe major benefits of utilising the two part form of container 16, namely the tray 18 and cover 20, as opposed to a sleeve, is in allowing an operator, prior to the application of the cover 20, to directly contact the mussels 10 in order to manually manipulate same within each ofthe trays 18, to achieve the single layer as illustrated in Fig. 2. Although this manual manipulation could be achieved if the musselsl0 were located in a plastic sleeve or envelope, the mussels 10 could not be directly contacted and would have to be manipulated through one layer of the envelope. It will be appreciated that it is quicker and easier to manipulate the mussels 10 when an operator is able to directly contact the mussels 10.

The use of the tray 18, which is in the form of a depression providing a well-defined boundary at the edges thereof, ensures that during both the Vibrational levelling and the manual levelling, the mussels 10 are constrained within the tray 18. It is not therefore possible for any ofthe mussels 10 to spill out ofthe tray 18, or in other words the tray 18 provides a positive barrier to the mussels 10 when they are being spread into a single layer.

This feature speeds up the process of spreading the mussels 10 into the single layer illustrated in Fig 2, by reducing the care required by an operator in arranging the mussels 10 into a single layer. The trays 18 are preferably dimensioned to hold a pre—defined number ofmussels 10.

Once the mussels 10 have been deposited into the trays 18 and, optionally manually or vibration levelled, the first sheet 22 is then advanced on to a further station (not shown), in order to continue the packing process according to the present invention. As an optional step before the cover 20 is applied to each of the trays 18, downward pressure may be applied to the mussels 10 in each tray 18, in order to further effect the substantial levelling of same. This downward pressure may be applied, for example, by manually pressing a flat plate or the like (not shown) downwardly onto the exposed mussels 10. Such a plate would preferably be slightly smaller in dimension than that of the individual trays 18. The pressure applied is preferably achieved using hydraulic or pneumatic means. It is also preferable that while said pressure is being applied, the plate (not shown) is vibrated, which will fuither serve to level the mussels 10 within each tray 18. The vibration applied to the plate (not shown) may be achieved through any conventional means.

Following the above optional step in the packing process, the first sheet 22 is advanced onto the next station, where the cover 20 is applied to each of the trays 18, in order to close the trays 18 and thus fomi the completed containers 16. The cover 20 of each of the trays 18 is preferably initially provided as a continuous second sheet 24 of plastics material in roll form, which is advanced into position overlying the first sheet 22. The second sheet 24 is preferably of a similar or identical width to the first sheet 22. Once the second sheet 24 has been positioned over and in contact with the first sheet 22, the second sheet 24 is sealed onto the tirst sheet 22 as hereinafter described. In the present embodiment, each of the trays 18 are separated from one another by a border 26, which border 26 provides an area around each of the trays 18 at which the second sheet 24 can be heat-sealed onto the first sheet 22 in conventional fashion.

As the second sheet 24 is being heat—sealed onto the first sheet 22, each of the trays 18 are evacuated. In a preferred embodiment, in order to facilitate this evacuation, one side of each of the containers 16 is left unsealed, and a conventional vacuum system (not shown) is suitably applied to that open side of the container 16. Simultaneously or sequentially, the container 16 is subjected to a suitable temperature to cause it to shrink. Thus as the container 16 shrinks and is sucked onto the top and bottom shell portions 12, 14 respectively of the mussels 10, substantially all of the air within the container 16 is also removed. The one remaining open side of the container 16 is then heat-sealed in conventional fashion, under the vacuum conditions. Thus, as illustrated in Fig.4, the tray 18 and cover 20 of each container 16, as defined by the first sheet 22 and second sheet 24 respectively, are drawn tightly around the layer of mussels 10, so that the top and bottom shell portions 12, 14 are securely held together in a closed position.

Next, the sealed containers 16 are subjected to a heat process, for example by immersion in heated water, steam, or air, or a combination of same, to cause the meat within the mussels to contract and curl up to form the nomial vendable appearance. This heating step may be achieved using any suitable equipment, but is preferably implemented using a steam oven or a spiral oven in order to minimise the footprint of the oven.

Following this heating process, the vacuum sealed containers 16 are preferably cooled to ambient temperature and may then be frozen for transport/ storage, or remain at ambient temperature. As with the heating step, it is preferably that the freeze step is implemented using a spiral freezer.

The individual containers 16 are preferably separated from one another at this stage by cutting along the borders 26, although it will be appreciated that this separation could be undertaken at any other suitable point in the packing process.

Claims (9)

Claims

1. l. A process for packing and treating mussels or other bivalve seafood, the process comprising arranging the bivalves in at least one layer in a flexible container; at least partially evacuating the container such that the container is drawn tightly around the bivalves; heating the bivalves and container for sufficient time and at sufficient temperature to at least partially cook the bivalves; characterized in that the container is formed from a lower layer and an upper layer of plastics material, and the upper layer is positioned over and secured to the lower layer after the bivalves have been arranged in the at least one layer on the lower layer, the lower layer is in the fonn of a tray, which is formed by the heated deformation ofthe lower layer ofplastics material, the process further comprising the step of vibrating the lower layer when the bivalves are located thereon.

2. A process according to claim 1 comprising the step of applying pressure, from above, to the bivalves located on the lower layer, in order to substantially level the bivalves in the lower layer.

3. A process according to any preceding claim comprising the step of vibrating the bivalves, from above, when located on the lower layer and before positioning of the upper layer.

4. A process according to any preceding claim comprising providing the container as a heat-shrinkable plastics material, and heat shrinking the container simultaneously or sequentially with the evacuation of the container.

5. A process according to any preceeding claim comprising arranging the bivalves in a single layer with a substantially common orientation.

6. A process according to any preceding claim comprising the step of freezing the container and bivalves following heating.

7. A process according to any preceding claim comprising, prior to arranging the bivalves in the container, storing the bivalves in a reservoir of water at a temperature of between 0° and 10°. 5

8. A process according to claim 7 in which the reservoir of water is salt water.

9. A pack of bivalves whenever prepared in accordance with the process according to any of claims 1 to 8.