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Title:
PROCESS AND APPARATUS FOR MANUFACTURE OF A DRIED FISH OR SHELLFISH PRODUCT
Document Type and Number:
WIPO Patent Application WO/1998/007326
Kind Code:
A1
Abstract:
This invention relates to a process and apparatus for the manufacture of a dried fish or shellfish product. The apparatus comprises reduction means (6) to reduce the fish or shellfish meat to a liquid paste or slurry; and drying means (9) to dry the liquid paste or slurry to a powder, the drying means operating at relatively low drying temperature and for relatively short drying time.

Inventors:
Dorst, Richard Warrington (197 Greenoaks Drive, Atherton, CA, US)
Boyd, Neil Stuart (26 Hardie Street, Palmerston North, NZ)
Application Number:
PCT/NZ1997/000101
Publication Date:
February 26, 1998
Filing Date:
August 21, 1997
Export Citation:
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Assignee:
EN'ZAQ AQUACULTURE LIMITED (1st floor, 300 Trafalgar Street, Nelson, NZ)
Dorst, Richard Warrington (197 Greenoaks Drive, Atherton, CA, US)
Boyd, Neil Stuart (26 Hardie Street, Palmerston North, NZ)
International Classes:
A23B4/03; A23L3/46; A23L17/10; A23L17/40; (IPC1-7): A22C29/00; A23L3/00
Foreign References:
US1027128A1912-05-21
US4405653A1983-09-20
JPS4722268B1
Other References:
SOVIET PATENT ABSTRACTS, Derwent Publications Ltd., Class D12, AN 85-030506; & SU,A,1 101 215 (KLYUCHNIK), 07-07-84.
Attorney, Agent or Firm:
Hawkins, Michael Howard (Baldwin Son and Carey, NCR Building 342 Lambton Quay, Wellington, NZ)
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Claims:
CLAIMS:
1. A process of manufacturing a dried fish or shellfish product compπsing: providing shucked shellfish or fish for processing; reducing the shucked shellfish or fish to a paste or slurry; and drying the paste or slurry using relatively low drying temperature and relatively short drying time, to obtain a dried powder shellfish or fish product .
2. A process of claim 1 , in which the drying comprises the use of a hotair fluidised bed.
3. A process of claim 1 , in which the drying comprises the use of a spouted bed drier.
4. A process of any one claims 1 3, in which the drying temperature is less than 100°C.
5. A process of any one of claims 1 4, in which the drying time is less than two minutes.
6. A process of any one of claims 1 3, in which the drying temperature is less than 90° C and/or the drying time is less than one minute.
7. A process of any one claims 1 3, in which the drying temperature is approximately 70°C and the drying time is less than 30 seconds.
8. Apparatus for use in the manufacture of a dried fish or shellfish product, the apparatus compπsing: reduction means to reduce the fish or shellfish meat to a liquid paste or slurry; drying means to dry the liquid paste or slurry to a powder, the drying means operating at relatively low drying temperature and for relatively short drying time.
9. Apparatus of claim 8, which optionally includes first separation means to separate shellfish meat from the shell.
10. Apparatus of claim 9, which optionally includes first transfer means, to transfer the separated shellfish meat from the first separation means to the reduction means.
11. 1 1 . Apparatus of any one of claims 810, which includes second transfer means intermediate the reduction means and the drying means.
12. 1 2. Apparatus of any one of claims 81 1 , in which the reduction means is a colloid mill.
13. 1 3 Apparatus of any one of claims 81 2, which optionally includes storage means intermediate the reduction means and the drying means.
14. 14 Apparatus of any one of claim 81 3, in which the drying means is a spray drier.
15. 1 5 Apparatus of any one of claims 81 3, in which the drying means is a spouted bed drier.
16. 1 6. Apparatus of any one of claims 81 5, which includes an atomiser located after the drying means.
17. 1 7. Apparatus of claim 1 6, in which the atomiser is an atomising nozzle.
18. 1 8. Apparatus of any one of claims 81 7, which includes second separation means to allow for separation of the dried product from undesirable fines.
19. 19 Apparatus of claim 1 8, in which the second separation means is a cyclone.
20. 20 Apparatus of any one of claims 819 which includes collection means to collect the dried product.
21. 21 A process of claim 1 , substantially as herein described with reference to either of the Examples 22 A process of any one of claim 1 7, substantially as herein described.
22. 23 Apparatus of claim 8, substantially as herein described with reference to Figure 2.
23. 24 Apparatus of any one of claims 820, substantially as herein described.
24. 25 A dried fish or shellfish product, when prepared by a process of any one of claims 1 7, 21 or 22, or when prepared by apparatus of any one of claims 8 20, 23 or 24.
Description:
PROCESS AND APPARATUS FOR MANUFACTURE OF A DRIED FISH OR SHELLFISH PRODUCT

Technical Field

This invention relates to a process and apparatus for the manufacture of a dried fish or shellfish product.

In particular, although not exclusively, the invention relates to a process and apparatus for the manufacture of a dried powder from mussels.

Background Of The Invention

Previous technologies have provided dried shellfish products such as a dried powder from mussels or similar shellfish.

Conventional techniques for providing such a manufacture have involved the use of freeze driers or spray driers. However, conventional drying processes may result in degradation of the material being dried. This may affect the quality and flavour of the finished product.

Therefore, it is an object of the present invention to provide a process of manufacturing a dried fish or shellfish product which goes some way towards overcoming some of the disadvantages of the prior art or which at least provides the public with a useful choice.

Disclosure Of The Invention

According to one aspect of the invention there is provided a process of manufacturing a dried fish or shellfish product comprising:-

- providing shucked shellfish or fish for processing; reducing the shucked shellfish or fish to a paste or slurry; and, drying the paste or slurry using relatively low drying temperature and relatively short drying time, to obtain a dried powder shellfish or fish product.

Preferably the drying comprises the use of a hot-air fluidised bed. Alternatively, a spouted bed drier may be used.

Preferably the drying temperature is less than 100°C.

Preferably the drying time is less than two minutes

More preferably the drying temperature is less than 90°C and/or the drying time is less than one minutes.

More preferably the drying temperature is approximately 70°C and the drying time is less than 30 seconds.

According to a further aspect of the invention, there is provided apparatus for use in the manufacture of a dried fish or shellfish product, the apparatus compπsing:-

reduction means to reduce the fish or shellfish meat to a liquid paste or slurry; drying means to dry the liquid paste or slurry to a powder, the drying means operating at relatively low drying temperature and for relatively short drying time.

Preferably, the apparatus optionally includes separation means to separate shellfish meat from the shell.

Preferably, the apparatus optionally includes means to transfer the separated shellfish meat from the separation means to the reduction means

Preferably, the reduction means is a colloid mill

Preferably, the apparatus includes means intermediate the reduction means and the drying means.

Preferably, the apparatus optionally includes storage means intermediate the reduction means and the drying means.

Preferably, the drying means is a spray drier utilising a hot-air fluidised bed Alternatively, the spray drier is a spouted bed drier.

Preferably, the apparatus includes an atomiser located after the drying means, to allow for further processing of the dried product. More preferably, the atomiser is an atomising nozzle.

Preferably, the apparatus includes separation apparatus to allow for separation of the dried product from undesirable fines. More preferably, the separation apparatus comprises a cyclone.

Preferably, the apparatus includes collection means to collection the final product.

Brief Description Of The Drawings

The invention will now be described by way of example only and with reference to the accompanying drawings in which:-

Figure 1 : shows a flow diagram of the process according to the invention, from harvesting to packaging of the final product; and, Figure 2: shows a schematic diagram of apparatus suitable for use in the process of the invention.

Best Mode For Carrying Out The Invention

Although the following description is given with reference to the processing of mussel meat, the process and apparatus of the invention may also be used in the processing of fish. Whole, cleaned fish may be processed, as may fish frames, which are fish excluding fillets and steaks but including head, backbone, guts (cleaned gut volume, including roe) and the like. Ocean or fresh water fish, such as hoki, hake and ling may be successfully processed using the process and apparatus of this invention. Shellfish other than mussels may also be successfully processed. Furthermore, while the following description is give with reference to the processing of fresh fish or shellfish, the process and apparatus may be used to process frozen fish or shellfish, properly thawed.

Thus, references in the specification and claims to the processing of fish or shellfish "meat" are intended to include where appropriate, material such as fish frames and the like.

Figure 1 shows the steps for a process of producing mussel powder.

Many of the initial steps of the process are included in this preferred embodiment to outline some of the quality controls placed on the produce throughout the entire process. However, it should be realised that the invention may be performed with a variety of quality controls as required.

As a preliminary step, mussels are harvested, generally from a commercial source. For example, the mussels may be harvested from a long ne farming environment.

The harvested mussels are preferably subjected to an initial inspection, during which a check is made for dirt and other contaminants. This may be a visual check. Unless seriously and obviously substandard, the mussels will be accepted.

In an optional step also conducted at this stage, the temperature of the fresh mussels may be checked. If the temperature is greater than approximately 1 6 °C, the mussels may be rejected for further processing.

It may also be necessary to check the quality of water from which the mussels have been harvested, for bacteria and the like.

The harvested mussels are then transported to a factory, for processing. During transportation, it is desirable that the mussels are chilled. For example, the mussels may be placed in bins of ice to ensure they do not exceed a predetermined temperature during transportation. In one preferred form of the invention, the temperature during transportation should not exceed approximately 1 6 °C.

The chilling process may merely comprise placing ice in the bins and running an air compressor until the ice has melted at which time the residual water from the melted ice can be drained from the tanks.

It is also desirable that a time limit be set for the delay in placing the mussels in transport. In one preferred form of the invention, a six hour time limit from the time of harvest is suitable.

Once the mussels have been transported to the factory, further inspection may be performed to ensure that the mussels and harvesting documents are correct.

The weight, temperature and history of the transportation may be checked.

Once at the factory, the chilled fresh mussels should be transferred to a chiller if they are to be stored for any length of time. An optimum temperature range for such a chilling operation is between approximately 2°C and 7°C, or more preferably 2°C and 5 °C.

A typical upper limit for temperature is 1 6°C and it is desirable that the time from harvest is less than 1 2 hours.

Within the preferred time limit, the mussels should be subjected to the next processing step. As shown in Figure 1 , this next step involves transferring the mussels to a process room (this may be either directly from the transporter or via the chiller).

In the next step, the meats may be separated from the shell. Again, a desirable time limit before processing occurs is approximately two hours

As the shells are removed, a further inspection of the meats may be performed to remove all broken and dead mussels or other foreign material. The mussel meats are then passed to further machinery for reduction into a liquid paste or slurry. In this preferred form, it is desirable that the output from the reduction equipment allows the liquid paste or slurry to pass through a 0 5mm screen

The resultant liquid paste or slurry is then transferred or pumped to drying apparatus. If necessary, intermediate storage may be provided in a suitable storage facility, such as a storage vat. However, to maximise product quality, such intermediate storage should be for no longer than two hours or, if a longer time is necessary, the storage should be provided at a refrigerated temperature of approximately less than 7°C.

The liquid paste or slurry, whether direct from the mill or through the intermediate storage, is then introduced into a drying unit.

The drying unit is preferably a spouted bed drier or vacuum spray drier using a hot-air fluidised bed to perform the drying function and maintain a partial vacuum.

Preferably, the drying unit comprises a drying chamber. The liquid paste or slurry is sprayed into a counter current flow of warm air which creates a significant vacuum in the drying chamber. Temperatures of exposure are about the same as used in conventional freeze-drying processes, but for a time of a minute or less, instead of a day or more. Thus, organoleptic and nutritional qualities are generally better than is achieved using conventional techniques.

In one particularly preferred form, the paste or slurry is pumped into the drier such that the drying occurs at an outlet temperature of approximately 70°C. The drying process takes place over a short span of time. For example, in one preferred embodiment, drying takes less than 30 seconds and the dried powder is then collected and checked for moisture, colour and taste. Generally, the moisture content post-drying should be less than 5% .

The colour and flavour of the powdered mussel product may be visually checked to ensure a light colour and a fresh flavour.

It is also normal to provide a sample of the product to a suitable laboratory for bacteria and listeπa testing.

The dried product may then be packaged, preferably in a vacuum pack with the vacuum being less than negative 20 inches of mercury.

The final packaged product may be stored in a cool and dry place for short term storage and, if long term storage is required, should be stored in a cool room at, for example, 5 °C to 7°C.

Figure 2 shows apparatus suitable for use in the process of this invention, in schematic form. The shellfish such as mussels are transported to the factory, typically in iced container bins or bags 2 of perhaps 1 tonne capacity These

are optionally placed in a chiller operating within the preferred temperature range of 2 °C to 7 °C.

When required, the shellfish are transferred to a meat processing machine 4 to separate meats from shell. It has been found that a processing machine as described in New Zealand Patent Specification No. 272771 is suitable for this purpose.

The meats emerging from the apparatus 4 are then transferred by a transfer means 5 such as a pump to suitable reduction equipment 6 for reduction into the liquid paste or slurry. A colloid mill is one form of apparatus found to be suitable for the reduction, however a range of reduction equipment will perform the task.

Once in the form of a liquid paste or slurry, intermediate storage may be provided in a suitable storage vat 7 if required.

A further transfer means such as a feed pump 8 is then employed to transfer the paste or slurry to a drier 9. Preferably, a spray drier utilising a hot-air fluidised bed or a spouted bed drier is used. Such driers typically have a burner 1 0 supplied by suitable fuel 1 1 such as LPG. The drier supplies heated air up through the drier at an inlet air temperature of less than 1 80°C and with the outlet temperature preferably being maintained at an optimum 70°C.

The products applied to the drier may be atomised through an atomising nozzle with the introduction of compressed air 1 2. During the spray process, suitable operating parameters are an air pressure of 50psι and an air volume of 50% .

The drying member chamber 9 operates under vacuum such that the dried product and heated air coming from the drier 9 are transported along a conduit 1 3 to a suitable separation apparatus 14 such as a cyclone. This vacuum is provided by suitable means such as a fan 1 5 in communication with the cyclone 14 and thereby the drier 9. The separation apparatus 14 allows the dried product to be separated and removed through outlet 1 6 while the air and any undesirable fines are removed through the primary fan 1 5 to the exhaust 1 7.

The following Examples exemplify the process of this invention.

Example 1 - Mussel Powder

Dehydrated mussel powder is made from freshly harvested live New Zealand greenshell mussels. The product is produced using a vacuum spray drying process as described above. An emphasis is placed on ensuring low drying temperatures and short residence times during the process to optimise organoleptic quality.

The resulting powder has the following characteristics.

Appearance: Light brown to tan coloured fine grain powder. Some seasonal colour variations do occur depending on the carotenoid content of the fresh mussels.

Flavour: Fresh seafood flavour characteristic of freshly harvested mussels.

Odour: Fresh seafood odour without any oxidised notes or off- odours.

Packaging: 1 0 kg cardboard cartons with barrier vacuum sealed liners.

Moisture: 3 - 4% pH 6.5

Microbiology: Total count: < 10 4 /g Colιforms: < 1 00/g

Listeπa: negative Salmonella: negative

Typical analysis: Carbohydrate 33% Protein 45 %

Minerals 1 3 % Lipid 6%

Ammo acids 1 9, including all essential

The resulting mussel powder is a significant source of marine mucopolysaccharides.

Example 2 - Fish Powder

Dehydrated fish powder is made from freshly harvested New Zealand hoki. The product is produced using a vacuum spray drying process as described above. An emphasis placed on ensuring low drying temperatures and short residence times during the process to optimise organoleptic quality

The resulting powder has the following characteristics.

Appearance: Light brown coloured fine grain powder.

Flavour: Fresh seafood flavour characteristic of fresh fish.

Odour: Fresh seafood odour without any oxidised notes or off- odours.

Packaging: 1 0 kg cardboard cartons with barrier vacuum sealed liners.

Moisture: 3-4%

Microbiology: Total count < 10 4 /g Coliforms < 1 00/g Listeπa: negative Salmonella negative

Thus it can be seen that the preferred embodiment of the invention provides a process and apparatus which provides a dried shellfish or fish product such as dried mussel meats in which the contact times and temperatures of the product through the drying process are kept to a minimum. This helps minimise the degradation caused through temperatures damage so that the product may enjoy an improved flavour and colour over similar products placed through alternative drying procedures.

The final product is a nutritious powder which may be used in the preparation of soups and also in stocks and flavourings.

The application of the process and apparatus of this invention to whole fish also has the advantage that the fish may be processed into a product which can be transported to distant markets where there are no refrigeration facilities.

Where in the foregoing description references has been made to specific components or integers of the invention having known equivalents then such equivalents are herein incorporated as if individually set forth.

Although this invention has been described by way of example and with reference to preferred embodiments thereof it is to be understood that modifications or improvements may be made thereto without departing from the scope of the invention as defined in the appended claims.