GB2355911A - Production of uncooked prawn food products - Google Patents

Abstract

A process for producing frozen prawn food products involves freezing at -18 to -22{C for about 3 days after de-heading the prawns. The tails are thawed out slowly at ambient temperature for 3 to 10 hours. The shells may then be very easily removed by simply cracking and sliding off the meat. The pieces are then individually frozen and are individually glazed by dipping momentarily in chilled water. The pieces are then vacuum packed. The raw prawn meat thus obtained has a fresher taste than prawn meat subjected to greater temperature variations and/or chemical treatment.

Description

2355911 "Production of Prawn Food Products" The invention relates to

production of prawn food products. 5 Various processes have been devised for production of prawn food products. Some of these processes involve cooking prawns, such as the process described in British Patent Specification No. GB222293 1. In this process, the prawns are quick-frozen, heated to 90-100'C, and then cooled.)While such processes generally provide a stable product, there is a strong demand for uncooked prawn food products.

Japanese Patent Specification No. JP60210944 describes a process for producing uncooked prawns in which the prawns are frozen for more than six hours, melted with a room-temperature water shower, and the freezingmelting cycle is repeated three times. Another process is described in European Patent Specification No. 743013. In this process whole prawns are produced by dipping in preservative liquid, blast freezing, and glazing by spraying in two stages in which the glazing liquid comprises a solution of a polyphosphate-based compound.

In general, the prior processes for production of uncooked prawn products involve a large extent of manipulation of the prawns by way of large temperature variations, impingement with water jets, and/or treatment with preservative or glazing chemical solutions. Many consumers believe that such approaches tend to impair the food taste, and yield is not as high as desirable due to losses at various treatment stages.

Another aspect of the prior processes for producing uncooked prawn products is that they do not remove the prawn shell because of the difficulty of separating the meat from the shell when uncooked.

There is therefore a need for a process which produces uncooked prawn food products with less manipulation, without use of additives of any type, and which involves removal of the shell.

According to the invention, there is provided a process for producing prawn food products comprising the steps of.

receiving whole fresh prawns at ambient temperature and washing away any foreign debris by spraying, removing the tails from the prawns and placing the tails in containers, freezing the tails at a temperature in the range of -18'C to -22'C for a time period between two and five days, allowing the prawn tails to thaw at ambient temperature for a time period of 3 to hours, for each prawn tail in turn, cracking the shell and removing it by sliding over the meat, and freezing and packing the prawn meat.

In one embodiment, the temperature for freezing before shelling is approximately - 200C.

In one embodiment, the time duration for freezing before shelling is approximately 3 days.

In one embodiment, the ambient temperature thaw period is in the range of 4 to 5 hours.

In one embodiment, the prawn meat is individually frozen on trays. 5 In another embodiment, the prawn meat is frozen at a temperature of between 36'C and - 44'C.

In one embodiment, the prawn meat is frozen at a temperature of approximately - 400C.

In a further embodiment, the prawn meat is glazed after freezing by dipping in chilled water.

In one embodiment, the individually frozen prawns are vacuum packed.

Detailed Description of the Inventio

The invention will be more clearly understood from the following description of 20 some embodiments thereof given by way of example only.

The invention provides a process for producing frozen prawn meat pieces which are uncooked. There is no need for the consumer to remove the shell and the meat has not been exposed to any additives for preservation or otherwise. 25 In more detail, the process involves receiving fresh prawns at ambient temperature and ensuring that they are clean. This is achieved by spraying with a low pressure fresh water spray which removes any foreign debris such as seaweed and sand. The prawns are then de-headed, which is a simple manual operation. 30 The tails (which contain the prawn meat) are placed in containers in which the tails are stacked ten to twenty high and the containers are placed in a freezer. This freezing stage is a very important part of the process because it effectively separates the membrane which secures the prawn meat to the shell. The parameters for freezing the tails are a time duration of 2 to 5 days and preferably 3 days, and a temperature of between - 18'C and - 22'C and preferably - 20'C.

The prawn tails are then removed from the freezer and are allowed to thaw out at ambient temperature for a time period of 3 to 10 hours, and preferable 4 to 5 hours where the ambient temperature is between 15'C and 20'C.

After the tails have thawed to ambient temperature, the shell is cracked by applying hand pressure at the sides and then simple sliding the cracked shell over the meat and discarding it. This is a very simple operation because it has been found that the nature of the freezing operation causes the membrane to separate and so no mechanical pressure is required to remove the shell.

The individual pieces of prawn meat are then placed separately on trays and are placed in a freezer to individually freeze. The temperature is in the range of - 36'C and - 44'C, and is preferably - 40'C.

The frozen pieces are then glazed by dipping in chilled water for a I to 10 seconds. Because of the low temperature of the pieces, the chilled water in contact with the meat freezes to provide a glaze without use of additives.

The prawn pieces are then graded and are vacuum packed for shipment.

It will be appreciated that the invention provides a process which involves little manipulation of the prawns. There is only one freezing and thawing cycle before freezing for packing and this achieves the objective of allowing removal of the shell.

I This is a major achievement as it has previously been thought that either cooking or mechanical pressure was required to achieve removal of the shell. Another major advantage of the invention is that the process does not involve use of any chemicals or additives of any type and so the products have a natural taste. Another benefit is that because the meat only is shipped and because of the final freezing operation, the products are stable and have a fresh taste and appearance when de-frosted by the consumer.

The invention is not limited to the embodiments described, but may be varied in 10 construction and detail within the scope of the claims.

Claims (11)

Claims

1. A process for producing prawn food products comprising the steps of receiving whole fresh prawns at ambient temperature and washing away any foreign debris by spraying, removing the tails from the prawns and placing the tails in containers, freezing the tails at a temperature in the range of -18'C to -22'C for a time period between two and five days, allowing the prawn tails to thaw at ambient temperature for a time period of 3 to 10 hours, for each prawn tail in turn, cracking the shell and removing it by sliding over the meat, and freezing and packing the prawn meat.

2. A process as claimed in claim 1, wherein the temperature for freezing before shelling is approximately -20'C.

3. A process as claimed in claims 1 or 2, wherein the time duration for freezing before shelling is approximately 3 days.

4. A process as claimed in any preceding claim, wherein the ambient temperature thaw period is in the range of 4 to 5 hours.

5. A process as claimed in any preceding claim, wherein the prawn meat is individually frozen on trays.

6. A process as claimed in claim 5, wherein the prawn meat is frozen at a 5 temperature of between -36'C and -44'C.

7. A process as claimed in claim 6, wherein the prawn meat is frozen at a temperature of approximately -40'C.

8. A process as claimed in any preceding claim, wherein the prawn meat is glazed after freezing by dipping in chilled water.

9. A process as claimed in any of claim 5 to 8, wherein the individually frozen prawns are vacuum packed. 15

10. A process substantially as described herein.

11. Prawn food products whenever produced by a process as claimed in any preceding claim.