GB2284739A - Processing of whelks - Google Patents

Abstract

A method for (1) for processing of whelks is described. The whelks are initially washed in a tumble wash (5) and are cooked (6) by direct steam injection at a high pressure. There is both primary crushing (7) and secondary crushing (9) which involves crushing of the shells between rotating crushing rollers. Each crushing operation is followed by a vibration operation (8, 10) for further separation of shell and meat. The meat is washed by separation (8) in which a conveyor belt runs in a moving water stream carrying the meat. There is air injection washing (13) which agitates the meat by injection of the diffused air. <IMAGE>

Description

"Processing of Whelks" The invention relates to the processing of shellfish which have spiral shells such as whelks (buccinum undatum) or periwinkles. However, the invention applies particularly to the processing of whelks. Whelks are sometimes referred to as marine snails.

The whelk has a robust, spirally coiled shell, which is usually coiled to the right. Older, larger whelks which are of use in processing for the food industry have very thick and opaque shells which are extremely strong. A part of the body of the whelk which extends from the shell is a large muscular foot on which there is hard cover used for covering the shell opening when the foot is retracted.

The muscular foot is used for movement of the whelk along the seabed and also to burrow underneath the seabed. The innermost part of the whelk comprises various organs referred to generally as entrails which are housed within the narrowest and innermost part of the shell.

The processing of whelks involves the extraction of the muscular part of the body, which is edible. As will be immediately apparent, such processing is extremely difficult because of the complexity of the whelk and strength of the shell. The body of the whelk must be removed from the shell, the entrails must be removed and the hard cover or nail on the muscular foot must also be removed if the product is to be acceptable in the marketplace. While development work has been carried out in the processing of other shellfish such as bivalve shellfish, because of the complexity and awkward nature of processing of whelks, it has only been heretofore done manually.

Examples of methods for processing bivalve shellfish are described, for example, in patent specification Nos. GB A-2144619 US-A-3988805, W089/10699 and W092/22212. In all of these methods, steps are involved for opening of the shells and extraction of the body of the shellfish. Such methods would not apply to processing of shellfish having spiral shells because of their nature. In US 3,988,805 a method of shucking bivalve shellfish is described in which the meat is eviscerated to separate entrails, however, the overall process is not suitable for processing whelks because of their very different nature.

The invention is directed towards providing an automatic method of processing whelks and the like which results in the complete extraction of all unwanted parts so that the product may be shipped directly to the consumers. Another object of the invention is that the method be capable of handling a large quantity of whelks for commercially viability.

According to the invention, there is provided a method for processing of whelks or the like the method comprising the steps of: washing a quantity of whelks by tumbling them in a washing drum with application of water; cooking the washed whelks by direct steam injection in a sealed cooker at a pressure in excess of atmospheric pressure; crushing the whelk shells by passing the whelks between two moving crushing members; removing excess shell by vibrating the crushed whelks on a vibratory screen to complete primary shell removal steps; eviscerating the whelk meat; washing the whelk meat output from the crushing stage by conveying the meat through a water stream in which there is a contra moving conveyor having ridges for removal of shell pieces away from the water stream; and carrying out final washing by conveying the meat in a water bath, the water being agitated.

In one embodiment, the method comprises the further step of carrying out step of carrying out secondary crushing of the whelk at a secondary crushing station at which the whelks are passed between crushing members having a smaller separation than those of the crushing members used for initial crushing.

Preferably, the primary and secondary crushing operations involve passing the whelks between two rotary crushing members having elongate ridges in registry with each other, the whelks passing in a gap between the cylinders.

In another embodiment, both the primary and secondary crushing stages involve use of two pairs of crushing cylinders, the separation between the second pair in each operation being smaller than that of the first pair of crushing cylinders.

Preferably, the final washing step involves direct injection of air for agitation of a water bath to cause agitation of the meat on a mesh-type conveyor immersed in the bath.

Ideally, the method comprises the further step of flow freezing the washed meat and subsequently packing the frozen meat.

The invention will be more clearly understood from the following description of some embodiments thereof given by way of example only with reference to the accompanying drawings in which: Fig. 1 is a flow chart illustrating a method of the invention.; Fig. 2 is a diagrammatic view showing a washing station of the process; Fig. 3 is a plan view showing the washing station and conveying of the washed whelks to a cooker hopper; Fig. 4 is a diagrammatic cross-sectional view showing the cooking operation; Fig. 5 is a diagrammatic cross-sectional view showing crushing stages of the method; and Fig. 6 is a diagrammatic view showing washing of the product before freezing.

As shown on Fig. 1, the initial steps of the method involve weighing and recording whelks which arrive at the production plant. In one situation, for example, there may be up to 70 boats fishing for whelks and returning them on a daily basis. The whelks are weighed and recorded as they arrive in the fish boxes. In step 3 the whelks are graded by separation of boxes of different types and in step 4 there is bulk chilling of the shellfish before processing.

Referring both to Figs. 1, 2 and 3, washing of the whelks is described. Washing is carried out at a tumble washing station 20 in which there is a housing 21 for a barrel washer 22. Fresh water is injected into the housing 21 onto the barrel washer 22 on delivery of whelks from the chilling plant on a conveyor 23. The barrel washer 22 operates at approximately 30 rpm and approximately 5,000 gallons per hour of fresh or sea water is typically used.

The throughput of the plant 20 is 10 tonnes per hour.

Waste water is delivered out of a chute 24. As shown in Fig. 2, there is a longitudinal conveyor 25 having a movable barrier 26 for switching direction of the washed whelks either along the conveyor 25 or down a side conveyor 27. As shown in Fig. 3, there is additionally a direct output conveyor 29 feeding the whelks onto the longitudinal conveyor 25 and there is additional longitudinal conveyor 30 which delivers the washed whelks onto an upwardly-directed conveyor 31 feeding a cooker hopper 32. The switching barriers 26 provide for a change in direction of the path of the whelks and in one example it allows the washing plant 20 to be used (with different operating parameters) for washing of other types of shellfish and direction of such washed shellfish to different items of plant.

As indicated by step 6, the washed whelks are then cooked and this step is shown in more detail in Fig. 4. The whelks are delivered into an input hopper 32 which allows controlled delivery of the washed whelks into a vibratory hopper 33. In effect, the hopper 32 acts as a buffer feeding the vibratory hopper 33. The capacity of the vibratory hopper 33 is matched with that of a cooker 34, above which it is mounted. A batch of whelks is delivered through a hatch 35 onto a conveyor 36 which is operated to move as the batch is being delivered for even distribution of the washed whelks within the cooker 34. The conveyor 36 is of stainless steel mesh construction.The cooker 34 operates at a pressure of 4 bar and at a temperature of in the region of 120"C - 140"C. The cooking time is in the region of 2 - 5 minutes and preferably approximately 3 5 minutes. Cooking is by live steam injection. The cooked whelks are delivered through a PLC operated door 37 to an outlet conveyor 38 which delivers the cooked whelks onto an upwardly-directed conveyor 39 leading to a crushing station.

As indicated by step 7 of Fig. 1, primary crushing then takes place at a plant 40 as shown in Fig. 5. The primary crushing plant 40 comprises two pairs of rollers namely upper rollers 41 and lower rollers 42 having separations of 25 mm and 20 mm respectively. The rollers have elongate ridges, ridges of opposing rollers being in registry. The rollers 41 and 42 crush the shell of the whelks and deliver the crushed whelks onto a vibratory mesh 43. The shell and other debris which passes through the mesh is delivered to a container 43(a). The whelks are then conveyed by an upwardly-directed conveyor 44 to a secondary crushing station 46 which has two pairs of rollers 47 and 48. These rollers operate in much the same manner as those of the primary crushing station 40.The product is dispensed onto a vibratory hopper 49 having a housing 50 mounted on springs 51. There is another outlet, not shown, for shell and other debris. The crushing and vibrations steps are indicated by the numerals 7 - 10 inclusive in Fig. 1. Although in this embodiment each crushing station has two pairs of rollers, it is envisaged that there may only be pair.

After crushing, the whelks are in step 11 cleaned by being passed through an eviscerator such as that described in US 3,988,805. This separates the remaining shells and entrails and the processed whelks are then delivered out to a washing station 69 shown in Fig. 6.

The washing station 69 is a combination station and initially involves conveying the product in a water stream 71 in which there is a conveyor 70. The conveyor 70 has transverse teeth or ridges and moves contra to the water flow. Accordingly, small pieces of shell drop onto it and are conveyed away from the meat. This is particularly effective at removing shell. The product moves in the water stream 71 towards an aerator washing portion of the washing station 69. In this portion, the meat is conveyed on a mesh conveyor 80 which is immersed for most of its length in a water bath into which fine bubbles are injected via a conduit 81. This agitates the meat and causes items of debris such as small pieces of shell or entrails to become separated. These steps are indicated by the numerals 12 and 13 of Fig. 1. This station ensures that the meat is sufficiently clean.

After the washing station 69, the meat is delivered in step 14 to a vibratory hopper which feeds a flow freezer station for freezing in step 15. Following flow freezing, the frozen product is graded in steps 16 and may be block frozen then in step 17, or alternatively packed in step 18, depending on the customer's requirements.

It will be appreciated that the invention provides for the processing of whelks to provide the clean meat which is acceptable in the market place in high volume.

The invention is not limited to the embodiments hereinbefore described, but may be varied in construction and detail.

Claims (8)

1. A method for processing of whelks or the like the method comprising the steps of: washing a quantity of whelks by tumbling them in a washing drum with application of water; cooking the washed whelks by direct steam injection in a sealed cooker at a pressure in excess of atmospheric pressure; crushing the whelk shells by passing the whelks between two moving crushing members; removing excess shell by vibrating the crushed whelks on a vibratory screen to complete primary shell removal steps; eviscerating the whelk meat; washing the whelk meat output from the crushing stage by conveying the meat through a water stream in which there is a contra moving conveyor having ridges for removal of shell pieces away from the water stream; and carrying out final washing by conveying the meat in a water bath, the water being agitated.

2. A method as claimed in claim 1 comprising the further step of carrying out secondary crushing of the whelk at a secondary crushing station at which the whelks are passed between crushing members having a smaller separation than those of the crushing members used for initial crushing.

3. A method as claimed in claim 2 wherein the primary and secondary crushing operations involve passing the whelks between two rotary crushing members having elongate ridges in registry with each other, the whelks passing in a gap between the cylinders.

4. A method as claimed in any preceding claim, wherein both the primary and secondary crushing stages involve use of two pairs of crushing cylinders, the separation between the second pair in each operation being smaller than that of the first pair of crushing cylinders.

5. A method as claimed in any preceding claim, wherein the final washing step involves direct injection of air for agitation of a water bath to cause agitation of the meat on a mesh-type conveyor immersed in the bath.

6. A method as claimed in any preceding claim comprising the further step of flow freezing the washed meat and subsequently packing the frozen meat.

7. A method substantially as hereinbefore described with reference to the accompanying drawings.

8. Whelks whenever processed by a method as claimed in any preceding claim.