GB1561185A

GB1561185A - Method and apparatus for the treatment of fish material

Info

Publication number: GB1561185A
Application number: GB45830/77A
Authority: GB
Original assignee: Rationalisierung Halle Veb
Current assignee: Rationalisierung Halle Veb
Priority date: 1976-11-15
Filing date: 1977-11-03
Publication date: 1980-02-13
Also published as: DD128550A1; FR2370437A1; DE2746584A1; FR2370437B3; JPS5394059A

Description

(54) IMPROVED METHOD AND APPARATUS FOR THE TREATMENT OF FISH MATERIAL (71) We, VEB RATIONALI SIERUNG HALLE, a corporation organised and existing under the laws of the German Democratic Republic, of Strasse der DSF 86a, 4014 Halle, German Democratic Republic do hereby declare the invention, for which we pray that a patent may be granted to us, to be particularly described in and by the following statement: This invention relates to an improved method and apparatus for the treatment of fish material.

In the refining of fish the material (fish meat in the form of whole or divided carcasses) is placed in a refining brine in order to season it and improve its consistency by making it more tender. This process necessitates considerable time and space, as the refining extends over a period of several days (and in the case of salting, even over several weeks). It is true that it can be slighly speeded up by increasing the temperature during the refining, but the temperature increase is accompanied by an increased risk that the fish will go bad. The main drawback of the long refining period involved resides in the excessive loss of the fish material into the refining liquid, which loss varies according to the particular fish material concerned and may amount to up to 27% of the weight of the initial material.

Furthermore, the long time required for the refining or the salting and pickling operations to take effect set severe limits to the possibility of automating or mechanising the processing. It is only in very few cases, moreover, that present fish processing methods enable tests to be carried out in order to determine without loss of time the most suitable processing method for the material on hand, e.g. by varying the refining times, the refining bath composition or the temperature. Thus the quality of the finished product is influenced almost exclusively by the experience of the personnel concerned, so that on the whole it cannot be controlled in a planned manner.

Systems are known in which the tenderness of meat is improved by subjecting it to the action of ultrasonic energy. The parts of meat to be treated are subjected to the sound either direct or via a contact medium.

When this acoustic irradiation is effected through a contact medium the pieces of meat are processed in a frozen state, so that the meat is not rendered too dry by the loss of drops of moisture. A further purpose is to avoid reciprocal action between the meat and the contact medium.

An object of the invention is to provide an improved method of treating fish.

In accordance with the invention there is provided a method for the treatment of fish material in which the fish material is continuously mixed in predetermined proportions with a preserving and/or seasoning liquid while being subjected to ultrasonic energy, the arrangement being such that the liquid serves the secondary purpose of transmitting the ultrasonic energy to the fish material. The action of the ultrasonic energy loosens firmer parts of the tissue, thus greatly increasing the tenderness. Furthermore, as a result of the pheretic effect of the ultrasonic waves, the seasoning enters the fish tissue uniformly. In the salting or pickling of fish a seasoning liquid will be replaced by a salt brine as a transmitting medium.

The fish material can be first placed in a salt solution of defined concentration, which again serves simultaneously as the transfer medium for the ultrasonic waves, and after a certain degree of refining has been reached, it is subsequently treated in a seasoning liquid for the purpose of acidification and further refining, and subjected here as well to the aforementioned effect of the ultrasonic energy.

The fish material may be placed in a closable, liquid-permeable container which is immersed in the said preserving and/or seasoning liquid in a tank, converters for said ultrasonic energy being in contact with the outside of the tank, and the liquidpermeable container may be rotated to mix the fish material with the preserving and/or seasoning liquid while the latter transmits ultrasonic energy to the fish material from the wall of the tank.

Alternatively, the fish material may be placed together with said preserving and/or seasoning liquid in a liquid-tight container which is rotated while immersed in cooling liquid in a tank to the outside of which converters for said ultrasonic energy are applied, the arrangement being such that ultrasonic energy is transmitted via the cooling liquid to the container and via preserving and/or seasoning liquid to the fish material.

According to the state of the particular fish material concerned the different parameters of the process may be varied in such a way that the degree of refining can be controlled within certain limits. The different state of the fish material is not only determined by the variety of fish used, as follows naturally, but it also has to be considered whether the material, for instance, is frozen, sliced. etc.

It has been found that when the process of the invention is used for the refining of fish a great deal of time can be saved and a final product of high quality obtained if the following parameters are adopted: Ultrasonic frequency: 20-50 kHz, preferably 40 kHz.

Acoustic intensity: up to 2 Watts/cm2 maximum.

Duration: 0.5 - 5 h. according to fish material.

Temperature: 10-20"C.

Ratio of refining brine to fish material: from 0.5:1 by weight up to a maximum of 2:1 by weight.

When the fish material is subjected to a single treatment the preserving and/or seasoning liquid should contain 3.5 - 12.0% by weight salt and 1.5 - 7.0% by weight vinegar, each of these proportions depending on the quantitative ratio between the brine and the fish material, while the flavour can be further influenced by the addition of sugar. pepper essence, onion essence, laurel essence and mustard seeds. When the fish material is subjected to successive treatments in different liquids the concentrations (again depending on the quantitative ratio between the liquid and the fish material) amount to between 3.5 and 20% by weight salt in a first treatment and to between 4 and 8% by weight vinegar in a subsequent treatment.

The fish material can be subjected exclusively to the treatment of the invention, or it may be subjected to a brief after-refining treatment in the conventional manner (i.e.

not using acoustic irradiation).

For effective use of the process to which the invention relates it has proved particularly suitable for the main parameters, i.e.

the intensity and duration of the acoustic irradiation, to be varied in the course of the processing, in accordance with the state of the fish material, in order to ensure optimum quality, being varied in such a way that the material is subjected to acoustic irradiation at maximum intensity for a certain initial interval of time to be suitably determined. This is followed by at least one further interval during which a reduced intensity is applied. As the state of the material can be verified comparatively rapidly, between the intervals, for its degree of refining, it is also possible for the duration and intensity for the subsequent interval in each case to be determined in accordance with the state now reached.

In accordance with another aspect of the present invention there is provided apparatus for carrying out the method of the invention which comprises a tank, a liquidpermeable container having a removable closure rotatably mounted in the tank, means for rotating the container, mans for controlling the temperature of liquid in the tank and in which the container is immersed, a generator of ultrasonic energy and a plurality of converters connected to the generator and in contact with the outside of the tank.

Alternatively, apparatus for carrying out the method of the invention may comprise a tank, a plurality of liquid-tight containers arranged in the tank so that each will be immersed in a cooling liquid contained in the tank and so that each is rotatable in the tank, means for rotating each container, a generator of ultrasonic energy, a plurality of converters connected to the generator and in contact with the outside of the tank and means for regulating a flow of the cooling liquid through the tank so as to control the temperature of cooling liquid in the tank.

In this latter apparatus the ultrasonic waves permeate the walls of the containers without any appreciable energy losses, so that no additional measures for increasing the intensity are required. The preserving and/or seasoning liquid, as in the previous embodiment, performs a dual function of refining and transfer of the acoustic energy within each container. To transmit the ultrasonic energy from the ultrasonic converters to the inserted containers use is made of a liquid which is filled into the tank up to the required level and which at the same time is used for cooling purposes in the system as a whole. As a transmitting and cooling medium water is particularly suitable owing to its favourable sonic impedance values and its high thermal capacity.

By regulating the filling to a suitable level and removing the heated cooling liquid the temperature of the fish material to be treated can likewise be kept at the required level.

Preferred embodiments of the invention will now be described with reference to the accompanying drawings, in which: Figure 1 illustrates a first apparatus for the performance of the process according to the invention, and Figure 2 illustrates a second apparatus for the performance of the process according to the invention.

The apparatus illustrated in Figure 1 comprises a tank 2 fitted with ultrasonic converters 4 which contact the exterior of the tank. The ultrasonic energy required for the treatment is generated and provided by ultrasonic generators 3. The tank 2 is fitted with a drum 13 which is driven by means of a drive 9 and which is provided, for the purpose of introducing fish material, with a closure 15. The wall of the drum 13 is permeable by a preserving and/or seasoning liquid 1 filled into the tank 2. The fish material to be processed is placed in the drum and is subjected, while at the same time thoroughly mixing with the liquid 1 (by slow rotation of the drum 13), to the action of the ultrasonic energy. In this process the liquid 1 not only functions as a preserving and/or seasoning liquid but also constitutes a transfer medium for the ultrasonic energy.

A feed inlet 5 and a discharge outlet 6 serve respectively to fill the liquid 1 into the tank and to remove it therefrom. A cooling system 14 required for the purpose of maintaining the processing temperature is provided with an inlet pipe 11 and an outlet pipe 12 for a cooling medium. In the treatment of fish fillets (herrings) by the process of the invention. successful results have been obtained by the adoption of the following parameters, taking into account the degree of processing reached: Ultrasonic frequency: 38kHz Ultrasonic intensity: 0.5 W cm2 Duration of ultrasonic irradiation: 2 hrs.

Preserving and/or seasoning liquid temperature: 150C Compositions: 2.5% acid 4% NaCl Quantitative ratio of fish to liquid: 1:1 In the application of the process covered by the invention it has been found particularly advantageous to subdivide the process into a number of separate steps (at least two). the irradiation intensity and also the irradiation time being altered from one step to the next. In the treatment of fillets with an ultrasonic intensity of 0.5 W cm2 and an ultrasonic irradiation time of 90 minutes and with the further parameters already given in the first phase, for example, a final product of excellent quality has been obtained and losses have been reduced by 5% by the adoption of the following values in the second phase: Ultrasonic intensity: 0.2 Wcm2 Duration of ultrasonic irradiation: 210 minutes.

An alternative apparatus for carrying out the invention is shown in Figure 2. The fish material to be acoustically irradiated is placed in liquid-impermeable barrels 7, which are then placed in a tank 2. Each of the barrels 7 contains the fish material and refining brine 1 mixed together in a preselected ratio. For the thorough mixing of the material to be processed the barrels 7 are placed on rollers 10, which are driven by a suitable drive 9, and set in slow rotation by means of the said rollers 10. For the transmission of ultrasonic waves from ultrasonic converters 4, fed via ultrasonic generators 3, to the said barrels 7, the tank 2 is filled with a liquid medium 8, which in addition to its function as a transmitting medium also serves as a cooling medium. By regulating the filling to a suitable level, removing the heated cooling liquid via an outlet pipe 12 and correspondingly feeding in fresh cooling liquid via an inlet pipe 11, the temperature of the fish material to be treated can be kept at a pre-selected constant level.

WHAT WE CLAIM IS: 1. A method for the treatment of fish material in which the fish material is continuously mixed in predetermined propom tions with a preserving and/or seasoning liquid while being subjected to ultrasonic energy, the arrangement being such that the liquid serves the secondary purpose of transmitting the ultrasonic energy to the fish material.

2. A method as claimed in claim 1, wherein the treatment is carried on for a period of between 0.5 and 5 hours, wherein the preserving and/or seasoning liquid is maintained during the treatment at a temperature in the range 10 - 20"C, wherein the said predetermined proportion by weight of liquid to fish material is in the range 0.5:1 to 2:1 and wherein the ultrasonic energy is applied at an intensity of not more than 2 watts/cm2 with a frequency of 20 to 50 kHz.

3. A method as claimed in claim 2, wherein the frequency of the ultrasonic energy is 40 kHz.

4. A method as claimed in any preceding claim, wherein the fish material is placed in a closeable, liquid-permeable container which is immersed in the said preserving and/or seasoning liquid in a tank, converters for said ultrasonic energy being in contact with the outside of the tank, and wherein

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. cooling medium water is particularly suitable owing to its favourable sonic impedance values and its high thermal capacity. By regulating the filling to a suitable level and removing the heated cooling liquid the temperature of the fish material to be treated can likewise be kept at the required level. Preferred embodiments of the invention will now be described with reference to the accompanying drawings, in which: Figure 1 illustrates a first apparatus for the performance of the process according to the invention, and Figure 2 illustrates a second apparatus for the performance of the process according to the invention. The apparatus illustrated in Figure 1 comprises a tank 2 fitted with ultrasonic converters 4 which contact the exterior of the tank. The ultrasonic energy required for the treatment is generated and provided by ultrasonic generators 3. The tank 2 is fitted with a drum 13 which is driven by means of a drive 9 and which is provided, for the purpose of introducing fish material, with a closure 15. The wall of the drum 13 is permeable by a preserving and/or seasoning liquid 1 filled into the tank 2. The fish material to be processed is placed in the drum and is subjected, while at the same time thoroughly mixing with the liquid 1 (by slow rotation of the drum 13), to the action of the ultrasonic energy. In this process the liquid 1 not only functions as a preserving and/or seasoning liquid but also constitutes a transfer medium for the ultrasonic energy. A feed inlet 5 and a discharge outlet 6 serve respectively to fill the liquid 1 into the tank and to remove it therefrom. A cooling system 14 required for the purpose of maintaining the processing temperature is provided with an inlet pipe 11 and an outlet pipe 12 for a cooling medium. In the treatment of fish fillets (herrings) by the process of the invention. successful results have been obtained by the adoption of the following parameters, taking into account the degree of processing reached: Ultrasonic frequency: 38kHz Ultrasonic intensity: 0.5 W cm2 Duration of ultrasonic irradiation: 2 hrs. Preserving and/or seasoning liquid temperature: 150C Compositions: 2.5% acid 4% NaCl Quantitative ratio of fish to liquid: 1:1 In the application of the process covered by the invention it has been found particularly advantageous to subdivide the process into a number of separate steps (at least two). the irradiation intensity and also the irradiation time being altered from one step to the next. In the treatment of fillets with an ultrasonic intensity of 0.5 W cm2 and an ultrasonic irradiation time of 90 minutes and with the further parameters already given in the first phase, for example, a final product of excellent quality has been obtained and losses have been reduced by 5% by the adoption of the following values in the second phase: Ultrasonic intensity: 0.2 Wcm2 Duration of ultrasonic irradiation: 210 minutes. An alternative apparatus for carrying out the invention is shown in Figure 2. The fish material to be acoustically irradiated is placed in liquid-impermeable barrels 7, which are then placed in a tank 2. Each of the barrels 7 contains the fish material and refining brine 1 mixed together in a preselected ratio. For the thorough mixing of the material to be processed the barrels 7 are placed on rollers 10, which are driven by a suitable drive 9, and set in slow rotation by means of the said rollers 10. For the transmission of ultrasonic waves from ultrasonic converters 4, fed via ultrasonic generators 3, to the said barrels 7, the tank 2 is filled with a liquid medium 8, which in addition to its function as a transmitting medium also serves as a cooling medium. By regulating the filling to a suitable level, removing the heated cooling liquid via an outlet pipe 12 and correspondingly feeding in fresh cooling liquid via an inlet pipe 11, the temperature of the fish material to be treated can be kept at a pre-selected constant level. WHAT WE CLAIM IS:

1. A method for the treatment of fish material in which the fish material is continuously mixed in predetermined propom tions with a preserving and/or seasoning liquid while being subjected to ultrasonic energy, the arrangement being such that the liquid serves the secondary purpose of transmitting the ultrasonic energy to the fish material.

the liquid-permeable container is rotated to mix the fish material with the preserving and/or seasoning liquid while the latter transmits ultrasonic energy to the fish material from the wall of the tank.

5. A method as claimed in any of claims 1 to 3, wherein the fish material is placed together with said preserving and/or seasoning liquid in a liquid-tight container which is rotated while immersed in cooling liquid in a tank to the outside of which converters for said ultrasonic energy are applied, the arrangement being such that ultrasonic energy is transmitted via the cooling liquid to the container and via preserving and/or seasoning liquid to the fish material.

6. A method as claimed in any preceding claim, wherein the intensity of acoustic irradiation is reduced during the treatment.

7. A method as claimed in any preceding claim, and comprising the preliminary step of continuously mixing the fish material with a salt solution of a strength between 3.5 and 20% by weight while subjecting it to ultrasonic energy, the salt solution serving to transmit the ultrasonic energy to the fish material.

8. A method as claimed in claim 7, wherein the preserving and/or seasoning liquid used in the subsequent treatment comprises 4 - 8% by weight vinegar.

9. A method as claimed in any of claims 1 to 6, wherein the preserving and/or sea soning liquid comprises 3.5 - 12% by weight salt and 1.5 - 7.0% by weight vinegar.

10. Apparatus for carrying out the method claimed in any of claims 1 to 4, or any of claims 6 to 9 as appendant to claims 1 to 4, comprising a tank, a liquid-permeable container containing the fish material having a removable closure rotatably mounted in the tank, means for rotating the container, means for controlling the temperature of liquid in the tank and in which the container is immersed, a generator of ultrasonic energy and a plurality of converters connected to the generator and in contact with the outside of the tank.

11. Apparatus for carrying out the method claimed in any of claims 1 to 3 or 5, ar any of claims 6 to 9 as appendant to claim 5, comprising a tank, a plurality of liquidtight containers containing the fish material and preserving and/or seasoning liquid and arranged in the tank so that each will be immersed in a cooling liquid contained in the tank and so that each is rotatable in the tank, means for rotating each container, a generator of ultrasonic energy, a plurality of converters connected to the generator and in contact with the outside of the tank and means for regulating a flow of the cooling liquid through the tank so as to control the temperature of cooling liquid in the tank.

12. A method as claimed in claim 1 for the treatment of fish material substantially as hereinbefore described.

13. Apparatus for carrying out the method claimed in any of claims 1 to 9 or 12 constructed and arranged to operate substantially as hereinbefore described and as shown in Figure 1 or Figure 2 of the accompanying drawings.