NZ501597A - Shellfish processing method comprising blow drying, applying oil, draining, sealing in a vacuum bag, cooking and cooling - Google Patents

Abstract

This method of treating shellfish comprises: a) blow drying the shellfish by means of heated, unheated or dehydrated air; b) applying an edible oil such as a vegetable, animal, synthetic or mineral oil, to the shellfish; c) draining the oiled product for up to 24 hours; d) vacuum sealing the oiled product in a vacuum bag; e) cooking the vacuum bagged product in an immersion type cooker or the like for up to 5 minutes at an immersion medium temperature of up to 99°C; f) allowing the vacuum bagged product to cool to about 60 or 70°C; g) cooking the vacuum bagged product at about 60 to 70°C for up to 15 minutes; h) cooling the cooked product in an ice slurry or similar for up to 30 minutes and blast freezing the bagged product to substantially -18°C. Addition to 501597

Description

2 SHELLFISH PROCESSING METHOD The present invention relates to a method of processing shellfish and the product thereof which is an improvement on the method described and claimed in New Zealand Patent Specification No. 286133.

More particularly, but not exclusively, the invention relates to a method of processing, freezing and cold storage of shellfish intended to mitigate the effects of ice formation during the freezing of the shellfish product and to reduce enzyme damage to shell stock.

The present invention relates to an improved processing method which reduces the susceptibility of shellfish or mollusc shells to fracturing and cracking during freezing and subsequent frozen storage and transport.

It is well known in the art to freeze various food substances prior to packaging, shipping and/or storage. There have been numerous techniques developed in the frozen food industry related to freezing and preservation of products such as vegetables and meats. An example is the processing method described in New Zealand Patent Specification No. 286133. This method overcame known problems to a significant degree.

Commercialisation of this method has led to the discovery of relatively minor problems. For one the vacuum bag in which the final stages of the process are undertaken has been found to be susceptible to the high temperature cooking so that the bag's final appearance is affected if the cooking is undertaken for a prolonged period. Secondly uneven cooking can occur as the heat is not distributed evenly through the shell stock making the cook uneven.

Accordingly, it is an object of the present inve obviates the disadvantages which are inherent provide the public with a useful choice. 3 The present invention provides for a method of treating shellfish comprising: blow drying shellfish by means of heated, unheated or dehydrated air; applying an edible oil to the shellfish; draining the oiled product; vacuum sealing the oiled product in a vacuum bag; cooking the vacuum bagged product in an immersion type cooker or the like for up to 5 minutes at an immersion medium temperature of up to 99°C; allowing the vacuum bagged product to cool to about 60°C; cooking the vacuum bagged product at about 60 to 70°C for up to 15 10 minutes; cooling the cooked product in an ice slurry or similar for up to 30 minutes; and blast freezing the bagged product to substantially -18°C.

Preferably the initial drying step (dehydrating step) where the shellfish are placed 15 in a dehydrating cabinet for drying is for between one and four hours at between 20° and 30°C.

Preferably the oil is pre-warmed to up to about 30°C.

Optionally the shellfish are chilled during the draining step wherein the draining step occurs for up to 24 hours.

Preferably the shellfish are blow dried at a temperature of 30°C or less. 25 Preferably the edible oil is a vegetable, animal synthetic or mineral oil.

The above mentioned process can be applied to univalve and bivalve shellfish and similar molluscs.

A particular embodiment of the invention will now be described, by way of example only. 4 The shellfish are usually harvested from the sea, washed/graded in fresh water, held in wet storage for about 1 2 to 24 hours then removed, washed and graded again.

The shellfish are then dried by blowing large volumes of air at approximately 30°C or less across or through the product. Alternatively, the air may be unheated or dehydrated.

It is to be understood that the washing and drying process is not limited to a single 10 cycle.

The shellfish are dried by means of dehydrating cabinets in order to remove substantially all of the moisture from the shell exterior. The drying step is performed for 1 to 4 hours at a temperature of about 20° - 30°C.

The shellfish are then removed from the dehydrating cabinets and immediately immersed in vegetable oil. The vegetable oil can be pre-warmed to up to 30°C. It is envisaged that the oil used to coat the shellfish can be derived from a vegetable or animal. However some synthetic or mineral oils may be appropriate and the 20 inclusion of these is contemplated to be within the scope of the present invention. The present example is discussed with reference to vegetable oil as this has been shown to be particularly suitable for use in the present process.

The oiled product (shellfish) can be held in a chiller for draining or further 25 processing. The chiller is cooled to a temperature specified by food processing regulations relevant to the art. Draining may be performed for up to 24 hours.

The desired quantity of the oiled shellfish product is placed in a vacuum bag which is then vacuum sealed. Such sealing processes are considered to be within the 30 purview of one skilled in the art and will not be discussed any further.

The vacuum bagged product is then processed in an immersion or similar cooking means. The cooking step may be in stages and may initially take from two to five minutes and, in the case of a water immersion cooker, the temperature in the cooker may be up to 99°C. After the initial cooking at a high temperature the vacuum bagged product can then be further cooked at about 60 to 70°C for up to 15 minutes.

Following cooking, the hot bags of shellfish product are placed in an ice slurry or similar to accelerate cooling. This cooling step may be performed for up to 30 minutes.

The shellfish product is then blast frozen to -18°C following which the bag product 10 is packaged further into units suitable for transport or holding in a freezer awaiting t downstream packaging. The cooking step may constitute pasteurisation.

Without being bound by any theory, it is understood that the oil coating described above acts as an agent which, upon freezing, reduces its volume as well as 15 displaces the water from the interstitial cavities and cracks in the shellfish shell. This reduces the susceptibility of the shellfish to cracking upon freezing and cold storage.

The above mentioned process and coating technique has been applied to cockles 20 (otherwise known as clams). However, it is envisaged that similar techniques may be applied to other shellfish.

It is understood that the scope of the invention is not limited to the described embodiment and therefore that numerous variations and modifications may be 25 made to the invention without departing from the scope of the attached claims.

Claims (9)

1. CLAIMS 6 5 10 15
2. 2. 20
3. 3.
4. 4. 25
5. 5. 30
6. 6. A method of treating shellfish comprising: blow drying the shellfish by means of heated, unheated or dehydrated air; applying an edible oil to the shellfish; draining the oiled product; vacuum sealing the oiled product in a vacuum bag; cooking the vacuum bagged product in an immersion type cooker or the like for up to 5 minutes at an immersion medium temperature of up to 99°C; allowing the vacuum bagged product to cool to about 60 to 70°C; cooking the vacuum bagged product at about 60 to 70°C for up to 15 minutes; cooling the cooked product in an ice slurry or similar for up to 30 minutes; and blast freezing the bagged product to substantially -18°C. A method as claimed in claim 1 wherein for the initial blow drying step (dehydrating) the shellfish are placed in a dehydrating cabinet for drying, preferably for between one and four hours at between 20° and 30°C. A method as claimed in any preceding claim wherein the oil is pre-warmed to up to 30°C. A method as claimed in any preceding claim wherein the shellfish are chilled during the draining step wherein the draining step occurs for up to 24 hours. A method as claimed in any preceding claim wherein the shellfish are blow dried at a temperature of 30°C or less. A method as claimed in any preceding claim wherein the edible oil is a vegetable, animal, synthetic or mineral oil. A method as claimed in any preceding claim applied to univalve and bivalve shellfish and similar molluscs. INTELLECTUAL PROPERTY OFFICE OF N.Z. 1 2 APR 2001
7. 7
8. 8. Shellfish treated according to any preceding claim.
9. 9. A method of treating shellfish as claimed in claim 1 substantially as 5 described herein. 10 WESTHAVEN SHELLFISH LIMITED By their Attorneys BALDWIN. '6 DEC !999 j -=S££e/ved I END