WO2004002230A1

WO2004002230A1 - Process for the preparation of fish portions

Info

Publication number: WO2004002230A1
Application number: PCT/GB2003/002755
Authority: WO
Inventors: Simon Jonathan Rilatt
Original assignee: Young's Bluecrest Seafood Limited
Priority date: 2002-06-26
Filing date: 2003-06-26
Publication date: 2004-01-08
Also published as: GB0314952D0; GB2390526B; AR039767A1; GB0214781D0; AU2003246909A1; GB2390526A

Abstract

A method of making an individual fish portion, comprising placing in a mould cavity (7) at least one piece of unfrozen fish loin (2) and at least one piece of unfrozen fish selected from fish loin pieces (2), fish middle pieces (3,4), fish tail pieces (5) and fish nape pieces (6), and subjecting the filled mould (13) to a temperature of not more than -8°C to freeze the fish pieces therein, and removing the frozen fish portion from the mould cavity (7).

Description

Process for the preparation of fish portions

The present invention relates to the manufacture of individual fish portions for use in subsequent processing steps, for example, coating and cooking.

For the manufacture of individual fish portions, for example, crumb-coated fish or battered fish, it is known for single pieces to be cut directly from the filleted fish and frozen individually. Pieces obtained in that way retain the textural quality of the original fish but, because of the wide variation of size and shape of fillets, a wide variation of fish content is obtained in coated products, which is undesirable. It is known to manufacture large frozen blocks of fish, typically of weight about 7.5kg, of regular shape. The frozen blocks are then cut by suitable cutting means , for example, saws or guillotines, into individual portions having a regular geometric shape corresponding to the configuration of the large block. In that way, portions of uniform size and shape can be obtained. If processed without further shape modification, the resulting product has an unnaturally angular presentation, as in the case of, for example, fish fingers. The individual frozen portions can be further processed by shaping to a desired configuration in the frozen state by the application of relatively high forces. Whilst that may remove the angular appearance, the textural quality of the fish may be reduced. WO 98/56256 describes a process of the kind in which frozen portions are cut from a large block and shaped. In the method described a parallelepiped frozen fish portion is placed in a shaping means comprising upper and lower moulding surfaces. Pressure is then applied to the shaping means to force them together. The arrangement is such that lateral movement of the fish is permitted without restraint. It is asserted that the process described enables the frozen pieces of fish to be shaped without disruption of the myotomal structure of the fish.

There remains a need for a simple and effective process for the manufacture of individual fish portions of substantially uniform size whilst having good textural properties, and further whilst making use of substantially all of the boneless fish fillet.

The present invention provides a method of making an individual fish portion, comprising placing in a mould at least one unfrozen piece of fish selected from fish tail pieces, fish nape pieces and fish loin pieces, and at least one unfrozen fish piece selected from fish middle pieces and fish loin pieces so as to fill the mould with fish pieces to a depth of at least 15mm, subjecting the filled mould to a temperature of not more than -8°C to freeze the fish pieces therein, and removing the frozen fish portion from the mould. Preferably, the mould is filled to a depth of at least 18mm.

The present invention also provides a method of making an individual fish portion, comprising placing in a mould at least one piece of unfrozen fish loin and at least one piece of unfrozen fish selected from fish loin pieces, fish middle pieces, fish tail pieces and fish nape pieces, subjecting the filled mould to a temperature of not more than -8°C to freeze the fish pieces therein, and removing the frozen fish portion from the mould.

The invention offers a simple and effective way of manufacturing individual portions of fish. Surprisingly, it has been found that, by combination of pieces, which may in some cases be pieces from certain different parts of the fish fillet, a fish portion with good eating qualities may be obtained. The essential features of the process are that the fish pieces are placed in the mould and subsequently frozen and it is in particular highly preferred that the fish is not subjected to any externally applied force. In that way, it is possible to obtain individual portions which are of good textural quality, even where a proportion of the cuts generally regarding as being of less attractive texture, such as tail, is present. The invention also offers efficient usage of the fish fillet, enabling substantially 100% of the boneless fish fillets to be used in the manufacture of the fish portions. Maximisation of the use of existing fish supply is particularly important in the light of the reducing fish stocks of many species .

The invention also offers the possibility of making fish portions of high quality and of a size suitable for further processing as individual fish portions from fish of species in which loin pieces are of a size and/or configuration that makes each single piece unsuitable for use as individual fish portions, for example, hake or Pollock.

The terms "loin", "middle", tail" and "nape" are used herein with reference to fish fillets in the sense in which those terms are generally used by those skilled in the art. The proportion of loin, middle, tail and nape may vary, significantly as between fish of different species and as between fish of different size of the same species. Whilst there may also be some variation in the way in which two different skilled fish processor will subdivide two identical fish fillets into loin pieces, middle pieces, tail and nape pieces, that variation is by comparison small and in practice can be disregarded for the purposes of the invention.

Advantageously, the fish placed in the mould comprises at least 20% by weight loin, based on the total fish present. Preferably, at least 35% and more preferably 50% by weight loin is present. (Advantageously, the fish placed in the mould comprises not more than 75% and preferably not more than 50%, by weight loin, based on the total fish present) .

Advantageously, the fish placed in the mould comprises at least 5% preferably at least 10% and preferably at least 20% by weight tail, based on the total fish present. For example, there may be present at least 40%, or at least 50%, by weight tail, based on the total fish present.

In one preferred method, there are placed in the mould at least one unfrozen piece of fish tail or nape and at least one unfrozen fish piece selected from fish middle pieces and fish loin pieces. In another preferred method, there are placed in the mould two or more fish loin pieces. In that case, the frozen fish portion preferably comprises at least 80% by weight, especially at least 90% by weight, loin, based on the total fish present. It may be advantageous for the freezing step to be carried out substantially without application of external force, that being understood as the application of no force or of no more than a small force of the magnitude that would be applied by simply placing a lid across the mouth of the mould.

Advantageously, the mould is integrally formed with a multiplicity of further moulds as a mould tray, a plurality of fish pieces being placed in each mould in the mould tray and a multiplicity of frozen individual portions being removed from the mould tray. The individual moulds of such a tray may be of identical size and shape, or may differ from one another in size and/or shape if desired. In general, the moulds will have a configuration such that the frozen fish portion will have a shape resembling a single piece cut from the fish fillet.

The mould is of a polymer material, for example, of silicone rubber or latex.

The mould is substantially rigid. Where a substantially rigid mould is used, the mould will expediently have a volume which is about 5% in excess of the desired volume of the frozen product. Advantageously, the mould then contains a liner that is more flexible that the mould and, after freezing of the fish, the liner containing the frozen fish is removed from the mould. The liner may be a pre-formed flexible or semi-flexible membrane of the liner. The use of such a liner facilitates removal of the frozen portions in the case of a rigid mould. The mould may be of metal .

Advantageously, the Shore hardness of the mould is at least 30. Advantageously, the Shore hardness of the mould is not more than 70. Preferably, the Shore hardness of the mould is from 40 to 60, especially about 50..

Moulds of material have a Shore hardness of less than 30 can be difficult to handle as a result of their softness. Where the Shore hardness is high, it may be difficult to eject the frozen portions, and in those circumstances it may be desirable to use a flexible liner as described further below. Advantageously, a closure member having a planar lower face is provided over the top of the mould (s) during at least a first part of the freezing step. Preferably, the closure member is present at least until the upper surface of the fish contained in the mould is frozen. Advantageously, the freezing step is carried out in a plate freezer, such freezers having been found to offer an effective and rapid freezing process whilst allowing the top surface of the fish in the moulds to be frozen especially quickly.

The freezing step may be carried out in an air blast tunnel. The freezing step may be accomplished by immersion in a liquid freezing medium, for example, liquid nitrogen.

Advantageously, the fish pieces are at a temperature of from 0 to 10 °C when introduced into the mould.

Advantageously, the fish is frozen to a temperature of -8°C or below, preferably -18°C. Advantageously, there is included in the mould at least one loin piece the size of which is substantially coextensive with at least one horizontal dimension of the mould.

In one particularly preferred method, freezing is carried out in a plate freezer, until the surface of the fish is crust frozen to a temperature of -8°C or below. The freezing process may then be continued in the plate freezer or using any other freezing process. In that manner, a relatively flat, even surface can be achieved. Certain illustrative embodiments of the invention will now be described in detail with reference to the accompanying drawings, in which:

Fig. 1 is a plan view of a typical fish fillet; Fig. 2 is a flow diagram showing the sequence of steps of the process;

Fig. 3a is a perspective view from below of a single mould cavity; Fig. 3b is a side view of the mould cavity of Fig. 3a; Fig. 3c is a plan view from above of the mould cavity of Fig. 3a;

Fig. 4 is a perspective view from above of a mould tray having a multiplicity of moulds;

Fig. 5 is an exploded view of an arrangement for freezing fish in a flexible mould tray; and

Fig. 6 is an exploded view of an arrangement for freezing fish in a rigid mould tray. With reference to Fig. 1, for use in the process of the invention a fish fillet 1 will normally be so butchered as to produce a loin piece 2, two middle pieces 3,4, a tail piece 5 and a nape piece 6. The loin portion of the fish fillet may be thicker and in general is denser than the other portions of the fillet, and may therefore be perceived by the consumer to have a meatier , eating quality. The tail portion and the nape portion are often regarded as being of lesser textural quality and the nape portion, ^• in particular, has conventionally been minced for use in processed fish products or as a filler in other fish products. Where used in the method of the present invention, the proportion of nape will preferably not exceed 10% by weight based on the total weight of the fish. The middle portion, made up of pieces 3 and 4 in Fig. 1, is of intermediate textural quality.

Referring to Fig. 2, the steps comprising one form of method of the present invention are as follows:

101 fresh fish cut into pieces by hand/machine and weighed 102 fish pieces placed in moulds

103 moulds are lidded

104 moulds are placed in freezer 105 frozen

106 fish removed from moulds

107 fish further processed

In more detail, after the fish has been cut into pieces by any suitable means, for example, by hand by a skilled operator, or by machine, the pieces are grouped into groups of two or more pieces such that the total weight of each group falls within a target weight range, for example of 80 ± 4g. Each group contains pieces from two or more different fillet regions. For example, if the first piece is a loin piece, the second piece may be a middle or tail piece and, if the first piece is a tail piece, the second piece may be a loin or middle piece. A first piece of fish selected from a said group is then placed into the mould. In the case of a loin piece, the fish piece will normally be placed in the mould without folding and will preferably extend along at least most of the internal length of the mould. Other pieces, especially tail pieces, may if appropriate or desired be folded. The one or more further pieces of fish from the same group, are then placed on top of or alongside the first piece. When the mould is substantially full, a lid is then placed on the mould. If desired the fish in the mould may be frozen substantially without application of external force. The fish is thus advantageously not subjected to a compression step for removing any retained spaces between the fish pieces. Therefore, whilst the lid may contact the surface of the fish and may then to at least some extent cause flattening of the upper surface, it is desirable that the moulds are not filled to such an extent that material compression of the fish throughout the mould occurs. Indeed, as will be described further below, it may be desirable to arrange for the volume of the moulds to be 5% larger than the desired volume of the individual product so as to ensure that the fish expands to fill the mould during freezing, and internally generated pressure is minimized.

The lidded moulds are placed in a suitable freezer, for example, a plate freezer or Gyro freezer at a temperature of -40 ^CC and are frozen to a temperature of -8°C or below. The moulds are then removed from the freezer, and the frozen fish portions removed from the moulds. The frozen fish portions are then subjected to further processing. The further processing may comprise coating of the frozen portion in a crumb coating or batter by any suitable method and subsequent cooking of the coated portion. The cooking step, which may be, for example, a frying step or a baking step, may effect partial or complete cooking of the fish portion. The further processing may comprise placing the frozen portions in a tray, pouring a sauce over the frozen portion and freezing the same. Fig. 3 shows a schematic view of a single mould cavity 7. That mould cavity 7 may be in the form of a single mould, or may with a multiplicity of identically and/or differently shaped mould cavities form a mould tray. A mould cavity has a bottom walls, side walls 9, 10 and end walls 11, 12. The mould cavity may be, for example, 105 mm in length, 45 mm in width and 20 mm in depth.

In Fig. 4 there is shown a mould tray 13 having 18 mould cavities 7 arranged in two rows of nine cavities. The mould tray 13 is of silicone rubber, and is flexible at temperatures below -20 °C, thus permitting the frozen portions to be ejected from the mould tray relatively simply by means of flexing the mould tray. Referring to Fig. 5, in an arrangement for freezing the fish portions in a plate freezer, two filled mould trays 13 and 13' may be placed in register separated by a steel separator plate 14. The lower mould tray 13 rests on a steel base 15. A steel lid 16 is placed over the upper mould tray 13'. The plate freezer has lateral freezer plate supports 17, 18 which are reciprocable towards and away from one another. After assembly of the trays 13, 13', the base 15, lid 16 and separator plate 14, the supports 17, 18 are placed at each end of the assembly,, and the upper and lower freezer plates (not shown) are, respectively, positioned above and below the assembly, the upper freezer plate being supported on the supports 17, 18. As is conventional in plate freezer practice, the heights of the supports, 17 and 18 are arranged to correspond to the total heights of all components in the stack 15, 13, 14, 13', 16, thus preventing the freezer plates exerting excess pressure on the silicone rubber moulds . The freezer plates cool the assembly and the fish contained therein and the freezing step continues until the entire fish portions are frozen to a temperature of -8°C or less.

In Fig. 6 there is shown another form of mould tray 19, which is generally of similar construction to the mould tray 13 except that it is of steel or aluminium and is therefore rigid. The mould tray 19 is provided with a flexible liner 20 which has mould liner portions 21 which are of such number, size and location that when the liner 20 is superimposed on tray 19 each liner portion 21 fits snugly into a respective mould 7. In the case of a rigid mould it is unnecessary for there to be provided a metal base such as the base 15 described above with reference to Fig. 5. The freezing step is, however, otherwise carried out as described with reference to Fig. 5. Further, the volume of the moulds 7 of mould tray 19 is arranged to exceed, for example, by about 5%, the volume of the fish to be placed therein. That allows for expansion of the fish on freezing without the generation of significant pressure within the lidded mould.

As already mentioned, the method of the invention enables substantially all, for example at least 90% by weight, and preferably at least 95% by weight, of a boneless fish fillet to be utilized in the manufacture of the products. Indeed, it has been found that, using the method of the invention, the overall quality of the final fish product is, surprisingly, better than would have been expected from consideration of the relative amounts of different parts of a fillet used in the manufacturing process .

Whilst reference is made herein to pieces of loin, middle, or tail respectively, it will be appreciated that the essence of the invention is the manufacture of fish portions from two or more different parts of a fillet.

Accordingly, the invention also includes processes in which the fish fillets are so cut as to give pieces of fish which contain a part of each of two or more of the regions of the fish fillet. For example, a first piece comprising both middle and tail may be combined with one or more like or different pieces.

Furthermore, the invention also encompasses methods in which two or more loin pieces are used, optionally in combination with one or more small pieces of fish, which may be offcuts of any part of the fish including the loin. In that case, it has been found in consumer tests that the fish portion so obtained is deemed to have superior eating qualities to individual loin pieces which have not been processed in accordance with the invention.

In Figs. 5 and 6, a double layer of trays is used to maximize efficiency in the plate freezer. It will be appreciated, however, that a single layer of trays may be used if desired.

Whilst it is preferred for the fish portions made in accordance with the invention to consist essentially of fish, they may if desired include additional ingredients, for example those conventionally used in the processing of fish products. Where present, any such additional ingredients will generally constitute no more than 5%, and preferably no more than 3% by weight, of the fish portion.

Claims

CLAIMS :

1. A method of making an individual fish portion, comprising placing in a mould at least one unfrozen piece of fish selected from fish tail pieces, fish nape pieces and fish loin pieces, and at least one unfrozen fish piece selected from fish middle pieces and fish loin pieces, so as to fill the mould with fish pieces to a depth of at least 15mm, subjecting the filled mould to a temperature of not more than -8°C to freeze the fish pieces therein, and removing the frozen fish portion from the mould.

2. A method of making an individual fish portion, comprising placing in a mould at least one piece of unfrozen fish loin and at least one piece of unfrozen fish piece selected from fish loin pieces, fish middle pieces, fish tail pieces and fish nape pieces, and subjecting the filled mould to a temperature of not more than -8°C to freeze the fish pieces therein, and removing the frozen fish portion from the mould.

3. A method according to claim 1 or claim 2 , in which the fish placed in the mould comprises at least 20% by weight loin, based on the total fish present.

4. A method according to claim 3, in which the fish placed in the mould comprises not more than 75% by weight loin, based on the total fish present.

5. A method according to any one of claims 1 to 4, in which the fish placed in the mould comprises at least 5% by weight tail, based on the total fish present.

6. A method according to any one of the preceding claims, in which there are placed in the mould at least one unfrozen piece of fish tail or fish nape and at least one unfrozen fish piece selected from fish middle pieces and fish loin pieces .

7. A method according to claim 1 or claim 2 in which there are placed in the mould two or more fish loin pieces.

8. A method according to claim 1 or claim 2 , in which the frozen fish portion comprises at least 80% by weight loin, based on the total fish present.

9. A method according to any one of claims 1 to 8, in which the mould is integrally formed with a multiplicity of further moulds as a mould tray, a plurality of fish pieces being placed in each mould in the mould tray and a multiplicity of frozen individual portions being removed from the mould tray.

10. A method according to any one of claims 1 to 9, in which the mould is of a polymer material.

11. A method according to claim 10, in which the mould is of silicone rubber or latex.

12. A method according to any one of claims 1 to 9, in which the mould is substantially rigid.

13. A method according to claim 9, in which the mould contains a liner that is more flexible that the mould and, after freezing of the fish, the liner containing the frozen fish is removed from the mould.

14. A method according to claim 12 or claim 13, in which the mould is of metal.

15. A method according to any one of the preceding claims, in which the Shore hardness of the mould is at least 30.

16. A method according to any one of the preceding claims, in which the Shore hardness of the mould is not more than

70.

17. A method according to claim 15 or claim 16, in which Shore hardness of the mould is from 40 to 60.

18. A method according to any one of the preceding claims, in which a closure member having a planar lower face is provided over the top of the mould (s) during at least a first part of the freezing step.

19. A method according to claim 18, in which the closure member is present at least until the upper surface of the fish contained in the mould is frozen.

20. A method according to claim 18 or claim 19, in which the freezing step is carried out in a plate freezer.

21. A method according to any one of claims 1 to 19, in which the freezing step is carried out in an air blast tunnel .

22. A method according to any one of claims 1 to 19, in which the freezing step is accomplished by immersion in a liquid freezing medium.

23. A method according to any one of the preceding claims, in which the fish pieces are at a temperature of from 0 to 10 °C when introduced to the mould.

24. A method according to any one of the preceding claims, in which the fish is frozen to a temperature of -8°C or below.

25. A method according to any one of the preceding claims, in which there is included in the mould at least one loin piece the size of which is substantially coextensive with at least one horizontal dimension of the mould.

26. A method according to any one of claims 1 to 25, in which the frozen portions are coated and the coated portions are subjected to a cooking step in which at least the applied coating is partially cooked.

27. A method according to claim 26, in which the coated portions are subjected to a freezing step after cooking and the frozen coated portions are packaged.

28. A method according to any one of the preceding claims, in which the freezing step is carried out substantially without application of external force.

29. A frozen individual fish portion comprising at least 20% fish loin, and 80% fish selected from fish middle, fish tail and fish nape the proportions being by weight based on the total fish content.

30. A frozen individual fish portion according to claim 29, which is covered by a coating.