GB2378887A

GB2378887A - Preserving fish

Info

Publication number: GB2378887A
Application number: GB0215508A
Authority: GB
Inventors: Didrik Thronsen Thron
Original assignee: Norsk Hydro ASA
Current assignee: Norsk Hydro ASA
Priority date: 2001-07-13
Filing date: 2002-07-04
Publication date: 2003-02-26
Also published as: GB0215508D0; DK200201039A; IE20020582A1; NO20013473D0; NO20013473L; IS6461A; NO315922B1

Abstract

A method for preserving fish raw material comprises feeding the raw material to a hopper from which it is transferred to a conveyor belt by a screw feeder regulated by signals from a band weight, and where said material is subjected to an aqueous treatment agent in controlled amounts sprayed onto said material during its transport on a conveyor belt and/or in a treatment drum. Superfluous treatment agent is drained off before the finished product is conveyed to a storage bin for finished product. Preferably an aqueous solution of 20-40 weight% potassium formate and/or potassium diformate is applied as treatment agent in amounts giving 0.5-5 weight% solution in the fish raw material. An apparatus comprises a tank (9) for treatment agent which can be transported through line (10) by means of a dosage pump (11) to nozzles above a conveyor belt (4) and/or in a drum (14). Fish raw material is supplied through line (1) to a hopper (2) equipped with a screw feeder (3) above a conveyor belt (4) connected to a band weight (5). The unit further comprises a storage bin (16) and monitoring and regulatory means for controlling the dosage of treatment agent and for monitoring the amounts of fish material.

Description

Method and unit for treatment of fish and/or fish by-product The present invention relates to a method and unit for treatment of fish raw material and/or fish by-products with a preservative. The invention also comprises a preserved fish product according to said method.

Utilization of fish by-products and fish raw material usually requires that said material can be stored for a prolonged period of time. A major problem in this connection has been to obtain an efficient and cost effective preservation of said material and to obtain a consistant preserved fish material of required quality for subsequent use for production of fish feed. It has also been a problem to secure a uniform distribution of the treatment agent in said raw material.

It is known in the field to preserve fish and fish by-products with various preservative agents, but the quality of the finished preserved product has varied with regard to content of preservative because the methods of preservation have been inefficient or inaccurate. Too much preservative in the finished product might be just as bad as too little preservative. In the first case the fish meal from said product will contain more preservative than accepted by regulatory laws, and in the latter case said product might deteriorate before the production of fish meal starts.

The main object of the invention was to arrive at a simple. robust and cost effective method

and unit for treatment of fish raw material and/or fish by-products gjving a preserved I-I product with consistant quality and rest content of preservative.

In their efforts to solve the object of the invention, the inventors tned to utilize as much of proven and reliable components as possible and arrange said components into a method and treatment unit which could be operated with simple regulatory means and reliable monitoring of parameters for regulation of the process in question. It was then found that the problem could be solved by spraying a controlled amount of an aqueous solution of the treatment agent of defined concentration on to the fish raw material during its transportation to the storage bin for finished product. The treatment agent can be any useful preservative agent for the raw material in question. The most preferred treatment agent was found to be an aqueous solution of potassium formate or potassium diformate. The concentration of the potassium salt is not critical, but should be in the range of 20-40 weight% potassium formate/diformate, preferably about 30 weight%. It was further found that the fish raw material should be treated with solution in amounts giving 0.5-5 weight% solution in said raw material.

The method according to the invention comprises feeding the raw material to a hopper from which it is transferred to a conveyor belt by a screw feeder regulated by signals from a band weight. Said raw material is subjected to an aqueous treatment agent in controlled amounts sprayed onto said material during its transportation on a conveyor belt and/or a treatment drum, and where superfluous treatment agent is drained off before the finished product is conveyed to a storage bin for finished product.

The treatment agent can be mixed with pressurized air prior to being sprayed on the fish material.

The fish raw material can be transported on a conveyor belt having an inclined section c where treatment agent is sprayed on said material before it is transferred to the drum where further treatment agent is sprayed on said material. z The treatment agent can also be sprayed on the raw material during its transportation to the hopper.

The unit according to the invention comprises a tank 9 for treatment agent which can be transported through a line 10 by means of a dosage pump 11 to nozzles above conveyor belt 4 for the raw material and/or a drum. Fish matenal is supplied through line I to a hopper 2 equipped with a screw feeder 3 above a conveyor belt 4 connected to a band weight 5. The unit further comprises a storage bin 16 and monitoring and regulatory means for controlling dosage of treatment agent to monitored amounts of fish material.

The special feature of the product according to the invention is that the fish raw material contains 0.5-5 weight% of an aqueous solution of 20-40 weight% potassium formate and/or potassium diformate evenly distributed in said fish material.

The scope of the invention and its special features are as defined in the attached claims.

The invention is further explained in connection with the description of the figure.

Figure 1 shows a unit for treatment of fish material, with a preservative agent, according to the invention- In Figure 1 there is shown a treatment unit where an aqueous solution of a preservative is supplied through line 8 to a tank 9. Fish raw material and/or fish by-products are fed through line 1 to a funnel formed hopper 2 from which it is transported by means of a screw feeder 3 to a conveyor belt 4 and conveyed further on the inclined section 6 of the conveyor belt to a mixing drum 14. The advantage of having an inclined section 6 of the conveyor belt 4 is first of all that water can be drained from the raw material. It is also possible to spray treatment agent on the raw material in this section 6 (not shown) and dram off superfluous treatment agent. Optionally the raw material can be treated with said agent dunng its transportation on a conveyor belt ahead of hopper 2. In that case a

monitoring device, such as a band weight, must be arranged in line 1. Treated, finished "I ZD I' drained product from drum 14 is then collected in the storage bin 16-Controlled amounts

of raw material can be fed to the conveyor belt 4 as said belt 4 is connected to a band weight 5. The amount of treatment agent in predefined concentration is supplied through line 10, dosage pump 11, pressure equalizing tank 12 and line 10 to the mixing drum 14. The treatment agent can be mixed with pressurized air supplied through line 13 prior to spraying into drum 14. In drum 14 the aqueous solution of treatment agent. which might be mixed with pressurized air, is sprayed on to the raw material whereby an even distribution of the treatment agent in the raw material is obtained. Application of the drum 14 is preferred, but not compulsory as the treatment solution can be applied on the fish raw material while it is on the conveyor belt 4. Superfluous treatment solution is drained from the treated material before it is transferred trough line 15 to the storage bin 16. The drained off treatment solution can be returned to the storage tank 9.

The process can be performed in a simple way by utilizing proven regulatory and

monitoring means. Thus the speed of the screw feeder 3 can be regulated using signals g t, from the band weight 5. Dosage of treatment agent of predefined concentration is easily controlled by utilizing signals from the dosage pump 11 and the band weight 5. A uniform distribution of the treatment agent in the raw material can then be obtained by spraying pressurized treatment agent through at least one nozzle on the raw material in the drum 14 and/or through nozzles above the conveyor belt.

By the present invention the inventors have succeeded in arriving at a simple unit for treatment of fish raw material and fish by-products. The unit is robust and comprises well proven elements that can be connected together into an economic unit that can be fit into existing locations even on ships-The method is simple to operate giving a reliable process producing a product in which the preservative IS evenly distributed in the raw material.

Thus the finished product will have a cons ! Stant quahty of desired concentration of the treatment agent.

Claims

Claims I. A method for treatment of fish raw material and/or fish by-products with a treatment agent for preserving said material to be subsequently further processed,

compnsing feeding the raw material to a hopper from which it is transferred to a Z-1 1- conveyor belt by a screw feeder regulated by signals from a band weight. and where said material is subjected to an aqueous treatment agent in controlled amounts sprayed onto said material during its transport on a conveyor belt and/or in a treatment drum, and where superfluous treatment agent is drained off before the fmished product is conveyed to a storage bin for finished product
2. A method according to claim 1, characterized in that the treatment agent is mixed with pressurized air prior to being sprayed on the fish material.
3. A method according to claim 1 or claim 2, characterized in that the fish material is transported on a conveyor having an inclined section and where treatment agent is sprayed on said material before it is transferred to the drum where further treatment agent is sprayed on said material.
4. A method according to claim I or claim 2, character ! xed in that the treatment agent js sprayed on the raw material during its transportation to the flopped

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5 A method according to any one of claims I to 4 characterized in that

an aqueous solution of 20-40 \\eight potassium tormate and/or potassium c li i I-i c t c r I z c cl I ii lli ; tt dtformate) s apptied as treatment agent m amounts givmg 0. 5-5 \\eight9 (so ! ut) on Cilt'OJ-1-0, IIC IS Ippl) C (I IS trCLItIDCIII I ! Cllt III ! IDIOLIIITS 2jviii ! 0. 5-5 soltit'] OD in the Hsh iaw matenal.
6. A unit for treatment of fish raw material and/or fish by-products with a treatment

agent, comprising a tank (9) for aqueous treatment agent which can be transported z : 9 through line (10) by means of a dosage pump (11) to nozzles above the conveyor belt (4) and/or a drum (14) where it is sprayed on the fish material, and where the fish material is supplied through line (1) to a hopper (2) equipped with a screw feeder (3) for feeding the fish material to a conveyer (4) connected to a band weight (5) and where the conveyer (4) might have an inclined section (6), and where the unit further comprises a storage bin (16) for finished product and monitonng and regulatory means for controlling dosage of treatment agent to monitored amounts of fish material.
7. A treatment unit according to claim 6, 1 characterized in that the unit comprises a supply of pressurized air through line (13) to be mixed with the treatment agent in line (10) prior to spraying into drum (14).
8. A treatment unit according to claim 6 or claim 7, characterized in that said unit comprises a pressure equalizing tank (12) in line (10) after the dosage pump (11).
9. Preserved fIsh raw material and/or fish by-products made according to the method of any one of claims to 5, character zed) n that said fish material contains 0.5-5 weight%, of an aqueous solution of 20-40 weight% potassium formate and/or potassium diformate evenly distributed in said fishmaterial.