GB2462622A

GB2462622A - Method of processing whole crab

Info

Publication number: GB2462622A
Application number: GB0814783A
Authority: GB
Inventors: Gerard Andrew Mulloy; Ann-Marie Mulloy; Patrick Joseph Mulloy
Original assignee: Individual
Current assignee: Individual
Priority date: 2008-08-13
Filing date: 2008-08-13
Publication date: 2010-02-17
Anticipated expiration: 2028-08-13
Also published as: GB2462622B; GB0814783D0

Abstract

A method of processing whole crab comprising a primary grading stage 7, where female crabs are graded into a plurality of grades depending on their estimated weight, stunning 13, then cooking 17 the graded crabs for a period of time suitable for their estimated weight. The crabs are then cooled 19 and washed 23 before the crabs are put through a secondary grading stage 25, in which the crabs pass along a moving conveyor through salinated water. The conveyor moves at a rate and the water is salinated such that crabs below their estimated weight float up away from the conveyor means and are regraded or discarded. Finally the retained crabs are chilled 29, vacuum packed 31 and frozen 37. Crab having an undesirable amount of meat for that grade are discarded from the process prior to final grading and packaging and therefore the customer receives a crab with an amount of meat that meets their expectations. Furthermore, the process is simple quick and effective and may be carried out in an efficient manner.

Description

"A Method of Processing Whole Crab"

Introduction

The present invention relates to a method for processing whole crab. More specifically, the invention relates to a method for processing whole brown crab.

Processed crab is sold in a number of different forms. One popular form of processing crab is so-called whole shell crab in which the crab is sold complete with outer shell intact. It is thought that customers find the product particularly aesthetically pleasing and therefore demand for the product is relatively strong.

However, there are problems with selling whole shell crab. First of all, it is not uncommon for a crab to have a relatively small amount of meat in the purse, shell & claw of the crab, disproportionate to the size of the shell. In particular, juvenile crab can have very little meat contained therein. Often, the quantity of crabmeat fails to meet the expectations of the customer resulting in a disappointed customer.

Therefore, it is vital to identify accurately and efficiently crabs containing relatively low meat content so that these may be removed and not sold on to the customer.

Heretofore, it is extremely difficult to identify crabs having low meat content in a simple and efficient as well as accurate manner.

Various crab processing methods have been disclosed. One such crab processing method is that disclosed in WOO3/053147 in which live crabs are cooked, chilled or frozen and thereafter packaged for sale. Another such crab processing method is that disclosed in 1E980651 in which live crabs are also cooked, chilled or frozen and thereafter packaged for sale. Neither of these applications attempts to overcome the problem of identifying crabs with low meat content. US2929502 discloses a machine for use in crab processing in which the cooked crab is crushed prior to being placed in a tank of salinated water. Once in the tank of salinated water, the crushed, cooked crab meat is separated from its shell by allowing the meat to rise to the surface for harvesting and allowing the shell to fall to the bottom of the tank. However, US2929502 is not concerned with the problem of identifying and removing crabs with low meat content in a whole crab processing method.

It is an object of the present invention to provide a method for processing whole crab that allows those crabs with a low meat content to be identified and removed in a simple, efficient and effective manner.

Statements of Invention

According to the invention there is provided a method of processing whole crab comprising the sequential steps of: (a) receiving a consignment of live crab; (b) inspecting the consignment of live crab and removing any dead crab from the process, identifying and separating any male crab for separate further processing steps; (c) primary grading the remaining live female crab into a plurality of grades depending on the estimated weight of the live female crab; (d) transferring in turn each grade of live female crabs to a stunning unit and stunning the graded crab with an electrical current in the stunning unit; (e) once stunned, transferring the stunned crab to a cooking pot and cooking the crab at a temperature of the order of between 95 and 100°C for a cooking time dependent on the graded estimated weight of the crab, the cooking time being no less than 15 minutes and no longer than 30 minutes; (f) once cooked, cooling the crab to a temperature of less than 15°C; (g) once cooled, transferring the cooled crab to a high pressure water washing unit, washing both sides of the crab to remove any protein and extraneous matter exuded during the cooking process onto the external surfaces of the crab from the crab; (h) transferring the cleaned crab to a secondary grading unit comprising an elongate tank having salinated water therein and a submerged conveyor passing there-through, the salinity of the water and the speed of the conveyor being specified based on the primary graded estimated weight of the crab, the salinity of the water and the speed of the conveyor being chosen so that the crab below a minimum desired estimated weight for that primary graded crab float to the surface of the water in the tank before reaching the end of the conveyor; (i) removing any floating crab from the tank and separating those crab from the remaining crab; (j) removing any crab that have passed through the secondary grading unit submerged along the conveyor from the end of the conveyor and draining those crab for a predetermined period of time; (k) blast chilling the drained crab to a temperature of less than 5°C in 150 minutes; and (I) vacuum packing the blast chilled crabs individually in vacuum bags.

In one embodiment of the invention there is provided a method for processing whole crab in which the method comprises the additional step of: (m) blast freezing the vacuum packed crab to a minimum temperature of the order of -18°C in 14 hours.

In another embodiment of the invention there is provided a method for processing whole crab in which after the crabs have been vacuum packed in step (I), the steps are carried out of: (n) pasteurising the vacuum packed crab by cooking the crab for a sufficient time and at a sufficient temperature so that the crab reaches a core temperature of 74°C for a minimum of two minutes; and (o) cooling the crab after pasteurisation to a temperature of less than 5°C.

In one embodiment of the invention there is provided a method of processing whole crab in which in step (b) the separate further processing steps comprise: (p) harvesting the claws of the male crabs; (q) cooking the harvested claws; and (r) trimming, grading and packaging the cooked harvested claws.

In a further embodiment of the invention there is provided a method of processing whole crab in which the step (c) of primary grading the live female crab into a plurality of grades depending on the estimated weight of the crab further comprises grading the remaining female crab into three grades: (i) Grade 1 crabs having an estimated weight of equal to or more than 400 gram mes and less than 600 gram mes; (ii) Grade 2 crabs having an estimated weight of equal to or more than 600 grammes and less than 800 grammes; and (iii) Grade 3 crabs having an estimated weight of equal to or in excess of 800 grammes.

In another embodiment of the invention there is provided a method of processing whole crab in which Grade 1 crabs are cooked at a temperature of between 95 and 100°C for between 15 and 20 minutes, Grade 2 crabs are cooked at a temperature of between 95 and 100°C for between 17 and 22 minutes and Grade 3 crabs are cooked at a temperature of between 95 and 100°C for between 20 and 30 minutes.

In one embodiment of the invention there is provided a method of processing whole crab in which the step (g) of washing both sides of the crab comprises washing a first side of the crab with a high pressure water washing unit, inverting the crab and thereafter washing the second side of the crab.

In a further embodiment of the invention there is provided a method of processing whole crab in which the submerged conveyor in the tank of the secondary grading unit is V-shaped to fully submerge the crab on the conveyor as the crab progresses along the conveyor through the tank.

In another embodiment of the invention there is provided a method of processing whole crab in which the step (o) of cooling the crab comprises cooling the crab to a temperature of the order of 10°C in 90 minutes and thereafter cooling the crab to a temperature of less than 5°C in 150 minutes.

In one embodiment of the invention the step (f) of cooling the crab to a temperature of between 10 and 15°C additionally comprises further cooling the crab to a temperature of less then 5°C in 150 minutes.

In a further embodiment of the invention the step (q) of cooking the harvested claws further comprises cooking the claws at a temperature of the order of between 95 and 100°C for a period of between 8 and 15 minutes.

Detailed Description of the Invention

The invention will be more clearly understood from the following description of an embodiment thereof, given by way of example only with reference to the accompanying drawing, in which there is shown a flow diagram of the method of processing whole crab according to the present invention.

Referring to the drawing, there is shown a flow diagram of the method of processing whole crab according to the present invention, indicated generally by the reference numeral 100. In step 1, a consignment of whole crab, typically brown crab (Cancer Pagurus) are taken in for processing. The whole crab are given a cursory inspection to ensure that they are of suitable quality and if not, they are returned to the supplier in step 3. If however the whole crab are of suitable quality, they are placed in chill storage in step 5 at a temperature of between 0 to 5°C until they are to be processed.

Once ready for processing, the whole crab are removed from the chill storage and a primary grading and inspection is carried out in step 7. The inspection consists of a quality control inspection, whereby any dead crab are removed from the process and discarded and any male crab are removed from the live female crab for further separate processing of the male crab in step 9. The dead crab are rejected in step 11. The primary grading consists of a course primary grading of the live female crab into three sizes, Grade 1 crab with a weight equal to or above 400 grammes and less than 600 grammes, Grade 2 crab with a weight equal to or in excess of 600 grammes and less than 800 grammes and Grade 3 crab with a weight equal to or in excess of 800 grammes. The crabs are not weighed, but rather their weight is estimated by visual inspection.

In step 13, the graded crabs are transferred to a stunning unit comprising a tank filled with water (not shown) in which an electrical current is discharged via the water to the crab. The crab remain in a stunned condition for a period of up to 30 minutes and the duration of the period for which the crab remain in a stunned condition is determined by the voltage input and the current used to stun the crab. The crab are transferred to the stunning unit in turn and by that what is meant is that each grade of crab are transferred to the stunning unit with other crabs of the same grade. In step 15, the crab are transferred to cooking baskets once they have been stunned. In step 17, the crab are passed in the cooking baskets to cooking pots and the crab are cooked for a minimum of 15 minutes and a maximum of 30 minutes at between 95 &100°C.

Preferably, the Grade 1 crab having an estimated weight of between 400 and 600 grammes are cooked for between 15 and 20 minutes. The Grade 2 crab having an estimated weight of between 600 and 800 grammes are cooked for between 17 and 22 minutes and Grade 3 crab having a weight in excess of 800 grammes are cooked for between 20 and 30 minutes.

In step 19, the crab are cooled to between 10 and 15°C. The crabs are cooled in situ in the cooking pots in their stainless steel cooking baskets. This is achieved by draining the cooking pots of hot water and then gradually filling the cooking pots with cold water until the crab are cooled sufficiently. Once cooled, the crabs are removed from the cooking pots and transferred to a tipping unit in step 21 where the contents of the baskets are tipped from the stainless steel containers into a washing unit.

The crabs are washed in step 23 in the washing unit which comprises a high pressure water washing unit. High pressure water is delivered by a series of jets (not shown) onto the crab to remove the proteins and other extraneous matter exuded during the cooking process onto the external surfaces of the crab. The crab are then inverted and conveyed into a second stage washer that repeats the high pressure jet washing to ensure that all the external surfaces are thoroughly washed and rendered clean. Once washed in step 23, the washed crabs proceed to step 25 to a secondary grading step.

The secondary grading step 25 comprises passing the cooked, cooJed crab along a conveyor into a flotation tank filled with salinated water. The conveyor is submerged as it passes through the flotation tank. Any undesirable light crab having a weight below the estimated desired graded weight of the crab will float to the top of the tank where they may be removed from the process, whereas other heavier desirable crab will remain on the submerged conveyor and will be carried to the end of the conveyor at the discharge end of the flotation tank. The effectiveness of the grading process is largely dependent on the travel through time of the belt combined with a salinity level of the water in the tank. Careful selection of these two parameters governs the overall effectiveness of the flotation grading. Both the salinity and the speed of the belt can be manipulated and adjusted to suit the size of the crab being graded through the system and also the incoming condition of the crab and the tolerances allowable in the market, based on the market expectations for the time of the season in which the grading is conducted. A scoop, or other device may be used to remove any light crab that have floated to the surface.

It is envisaged that a salinity level of between 15 and 25, preferably 20 for Grade 1 crab would suffice. Furthermore, a salinity level of between 20 and 30, preferably 25 for Grade 2 crab would suffice and a salinity level of between 25 to 35, preferably 30 for Grade 3 crab would suffice when combined with a suitable conveyor speed. It is envisaged that the Grade 3 crab may require the slowest conveyor speed and the highest salinity level, whereas smaller crabs may require a slightly faster conveyor speed and little or no salinity level.

Once the secondary grading step 25 is complete, the crab that reach the discharge end of the flotation tank are placed into perforated shallow crates and are drained for a predetermined period of time in step 27. Once drained, the crabs are chilled to less than 5°C in 150 minutes in a blast chilling unit in the crates in step 29. Once chilled, the crabs are individually bagged into vacuum bags and vacuum sealed with an absorbent layer pad (optional) inside the bag along with the crab in step 31. If it is desirable to pasteurise the product for the market, the optional steps 33 and 35 are carried out. Step 33 comprises the step of further cooking the vacuum packaged crab so that the crab reaches the minimum core temperature of 74°C for at least two minutes, Step 35 further comprises the step of cooling the vacuum packaging crab to a temperature of less then 5°C. Preferably the crabs are cooled to of the order of 10°C in 90 minutes and then to under 5°C in 150 minutes in step 35. The vacuum packaged crab, whether they have undergone the pasteurisation step in step 33 and the cooling step in step 35, or have come directly from the vacuum packing station in step 31 are then placed in a blast freezer in step 37 in perforated baskets for freezing to a minimum temperature of -18°C in 14 hours. They then undergo final grading, packaging and despatch step 39. The pasteurised chilled crab may bypass blast freezing in step 37 and go directly to final grading, packing & despatch step 39. In certain instances, the pasteurisation step 33 and the subsequent cooling step 35 that follows the pasteurisation step 33 may be skipped and the process may proceed directly from the vacuum packing step 31 to blast freezing step 37.

By having such a process, the crab may undergo three separat grading processes.

The first grading process allows for a rough estimation of th crab weight to be ascertained and the crab to be treated and processed accordingly. The second grading process carefully removes any sub-standard crab for that grade so that the crab can be either discarded or placed into a different grade. For example, crab that fail the Grade 3 test may then be passed into the Grade 2 crab and similarly crab that failed the Grade 2 flotation test may be placed into Grade 1 crab and sold as Grade 1 crab instead. The third and final grading process precisely weighs the crab and automatically diverts into the pre-determined bin for that grade. The crab may then be accurately and legally labelled. In this way, higher customer satisfaction is achieved as the customer understands precisely the approximate weight of crab that they are getting and receives a crab having meat content commensurate with the purchase price and their expectations. Furthermore, the process is relatively simple and may be automated in a relatively straight-forward manner without significant human intervention.

In the specification the terms "comprise, comprises, comprised and comprising" or any variation thereof and the terms "include, includes, included and including" or any variation thereof are deemed to be totally interchangeable and they should all be afforded the widest possible interpretation and vice versa.

The invention is not limited to the embodiments hereinbefore described but may be varied in both construction and detail within the scope of the appended claims.

Claims

CLAIMS1. A method of processing whole crab comprising the sequential steps of: (a) receiving a consignment of live crab; (b) inspecting the consignment of live crab and removing any dead crab from the process, identifying and separating any male crab for separate further processing steps; (c) primary grading the remaining live female crab into a plurality of grades depending on the estimated weight of the live female crab; (d) transferring in turn each grade of live female crabs to a stunning unit and stunning the graded crab with an electrical current in the stunning unit; (e) once stunned, transferring the stunned crab to a cooking pot and cooking the crab at a temperature of the order of between 95 and 100°C for a cooking time dependent on the graded estimated weight of the crab, the cooking time being no less than 15 minutes and no longer than 30 minutes; (f) once cooked, cooling the crab to a temperature of less than 15°C; (g) once cooled, transferring the cooled crab to a high pressure water washing unit, washing both sides of the crab to remove any protein and extraneous matter exuded during the cooking process onto the external surfaces of the crab from the crab; (h) transferring the cleaned crab to a secondary grading unit comprising an elongate tank having salinated water therein and a submerged conveyor passing there-through, the salinity of the water and the speed of the conveyor being specified based on the primary graded estimated weight of the crab, the salinity of the water and the speed of the conveyor being chosen so that the crab below a minimum desired estimated weight for that primary graded crab float to the surface of the water in the tank before reaching the end of the conveyor; (i) removing any floating crab from the tank and separating those crab from the remaining crab; (j) removing any crab that have passed through the secondary grading unit submerged along the conveyor from the end of the conveyor and draining those crab for a predetermined period of time; (k) blast chilling the drained crab to a temperature of less than 5°C in 150 minutes; and (I) vacuum packing the blast chilled crabs individually in vacuum bags.
2. A method for processing whole crab as claimed in claim 1 in which the method comprises the additional step of: (m) blast freezing the vacuum packed crab to a minimum temperature of the order of -18°C in 14 hours.
3. A method for processing whole crab as claimed in claim I or 2 in which after the crabs have been vacuum packed in step (I), the steps are carried out of: (n) pasteurising the vacuum packed crab by cooking the crab for a sufficient time and at a sufficient temperature so that the crab reaches a core temperature of 74°C for a minimum of two minutes; and (0) cooling the crab after pasteurisation to a temperature of less than 5°C.
4. A method of processing whole crab as claimed in any preceding claim in which in step (b) the separate further processing steps comprise: -11 - (p) harvesting the claws of the male crabs; (q) cooking the harvested claws; and (r) trimming, grading & packaging the cooked harvested claws.
5. A method of processing whole crab as claimed in any preceding claim in which the step (c) of primary grading the live female crab into a plurality of grades depending on the estimated weight of the crab further comprises grading the remaining female crab into three grades: (i) Grade 1 crabs having an estimated weight of equal to or more than 400 gram mes and less than 600 grammes; (ii) Grade 2 crabs having an estimated weight of equal to or more than 600 grammes and less than 800 grammes; and (iii) Grade 3 crabs having an estimated weight of equal to or in excess of 800 g rammes.
6. A method of processing whole crab as claimed in claim 5 in which Grade 1 crabs are cooked at a temperature of between 95 and 100°C for between 15 and 20 minutes, Grade 2 crabs are cooked at a temperature of between 95 and 100°C for between 17 and 22 minutes and Grade 3 crabs are cooked at a temperature of between 95 and 100°C for between 20 and 30 minutes.
7. A method of processing whole crab as claimed in any preceding claim in which the step (g) of washing both sides of the crab comprises washing a first side of the crab with a high pressure water washing unit, inverting the crab and thereafter washing the second side of the crab.
8. A method of processing whole crab as claimed in any preceding claim in which the submerged conveyor in the tank of the secondary grading unit is V-shaped to fully submerge the crab on the conveyor as the crab progresses along the -12-conveyor through the tank.
9. A method of processing whole crab as claimed in claim 3 in which the step (o) of cooling the crab comprises cooling the crab to a temperature of the order of 10°C in 90 minutes and thereafter cooling the crab to a temperature of less than 5°C in 150 minutes.
10. A method of processing whole crab as claimed in any preceding claim in which the step (f) of cooling the crab to a temperature of between 10 and 15°C additionally comprises further cooling the crab to a temperature of less then 5°C in 150 minutes.
11. A method of processing whole crab as claimed in claim 4 in which the step (q) of cooking the harvested claws further comprises cooking the claws at a temperature of the order of between 95 and 100°C for a period of between 8 and 15 minutes.
12. A method of processing whole crab substantially as hereinbefore described with reference to and as illustrated in the accompanying drawing.