WO1996001058A1

WO1996001058A1 - Improved process for producing fish-based food and feed products

Info

Publication number: WO1996001058A1
Application number: PCT/NO1995/000078
Authority: WO
Inventors: Anne Bahus Garvik; Einar NYGÅRD
Original assignee: Sildolje- Og Sildemelindustriens Forskningsinstitutt
Priority date: 1994-07-01
Filing date: 1995-05-12
Publication date: 1996-01-18
Also published as: NO942486L; NO179731B; NO942486D0; AU2938195A; IS4403A; ZA954059B; GB9627125D0; GB2303776B; PE34695A1; GB2303776A; NO179731C; DK151196A

Abstract

A process for the production of a food or feed product on the basis of fish raw material and other ingredients as vitamins, minerals etc., where fish material with a water content of 20-80 % by weight is mixed with stick water concentrate having a water content of 50-83 % by weight to form a mixture which if desired after concentrating to a water content of 20-50 % by weight, is converted to a product of desired form, size, consistency and density, and that the converted product is dried to a water content of below 12 % by weight.

Description

IMPROVED PROCESS FOR PRODUCING FISH-BASED FOOD AND FEED PRODUCTS

BACKGROUND OF THE INVENTION

1. Field of the invention

This invention relates to a process for producing fish- based food and feed products, and more particularly to a process for producing dry feed for breeding fish, although the resulting products may also find application as general animal feed and for human consumption.

2. Background Information Feed for breeding fish, both salmon/trout and species of marine fish, is usually in the form of pellets which are made of fish meal.

In the production of fish meal the raw material (fish, testaceous animals, and parts thereof) is heated, after which it is pressed or centrifuged. There is formed thereby a solid phase, press cake and sludge, and a liquid phase, press liquer. The press liquer is separated into oil and stick water, and the latter is added after concentrating to the press cake and sludge which is dried to a meal having a water content of less than 12%, preferably between 5 and 10%.

The fish meal is admixed with vitamins, minerals, carbohydrates and if desired other ingredients. The mixture is processed in an extruder/pellet press or similar appa¬ ratus. During this processing water, steam and mechanical energy in the form of a shearing load and pressure are supplied. The temperature of the mixture is raised during the processing. After this processing the pellet is dried. The fat content of the dried pellets can be increased by the spraying on of oil.

In the production which is described above the fish raw material is repeatedly exposed to the influence of heat and drying which involves changes in the characteristics of the protein, such as water-binding and gel-forming properties. This entails having to supply foreign glue materials and binding agents so that it will remain possible to achieve sufficient solidity of the pellet. As glue material/ binding agent carbohydrates and/ or pure binding agents are used. (By pure binding agents are meant consistency-yielding additive materials which have little or no nutritional value) . With these the desired solidity can be obtained. The desired solidity can be determined by defining the demands on the ultimate strength, the water stability of the pellet together with the ability to endure mechanical and pneumatic tran¬ sportation. However the ability of the salmon to digest carbohydrates is limited and the tolerance to carbohydrates of types of marine fish appears to be still lower than for salmon. This also poses the question of the influence of carbohydrate on the surroundings around the cages.

The production of dry feed by known processes has a relatively high energy consumption due to the fact that the fish material must be heated several times and significant quantities of water must be evaporated, and thereafter supplied during the subsequent feed production.

The production of dry feed by known processes is therefore energy unfavourable and the components of the feed mixture are repeatedly exposed to relative high temperatures and large mechanical loads. The object of the present invention is therefore to produce a process which makes possible the production of dry feed in an energy favourable manner and having good nutritio¬ nal and physical properties.

SUMMARY OF THE INVENTION

Accordingly, the present invention resides in a process for producing a fish-based product comprising the steps of:

(a) mixing fish material having a water content of at least 20 % by weight, optionally predried to a lower water content, with a stick water concentrate having a water content of at least 50 % by weight, under conditions whereby the binding properties of the components are substantially maintained (b) converting the resulting mixture at a temperature of 20-120°C into a product of predetermined shape, size, consistency and density, and

(c) drying the converted product to form an end product having a water content of less than 12 % by weight. Desirably, the resulting mixture is concentrated to a water content of from 20-50 % by weight before step (b) . Up towards the upper temperature limit the advantage of killing bacteria is obtained.

It has proved most convenient for the fish material to have a water content of 20-80 % by weight and the stick water concentrate to have a water content of 50-83 % by weight.

The main raw material in the process according to the invention is preferably an intermediate product formed during the production of fish meal, such as press cake, sludge, and stick water, while in the known processes ready dried fish meal is used.

In the process according to the invention raw materials are used while these have a relatively high water content. Thereby the removal of added water is avoided, and the process becomes particularly favourable nutritionally since in this way the mixture is not exposed to repeated temperature and mechanical loads. BRIEF DESCRIPTION OF THE DRAWINGS

In order that the invention can be more clearly under¬ stood, a preferred embodiment thereof will now be described, by way of example, with reference to the accompanying drawing which is a flow diagram illustrating the steps of the process of that embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The fish material is subjected to grinding up in a step 1. The most usual is to use press cake/sludge while it is still warm after coagulation or predrying. The ground up product is mixed in a step 2 with stick water concentrate, and the mixture is dried to a solid content of 5.0-80 % by weight. Thereafter additive materials, such as vitamins and minerals, are added to the mixture. After the mixing/ drying the mixture is transferred to an extruder/pellet press in a step 3. There more stick water concentrate is added if desired, and oil is added in an amount which is dependent on the fat content of the final product and the consistency of the product. The additive materials can, if this is found to be appropriate, be added at this stage. After the extruding the pellets produced are subjected to drying in a step 4. After the drying the pellets are sifted for the removal of dust and other small particles if this is desirable. In order to regulate the fat content of the end product additional oil is sprayed on to the product, after drying, in a step 5, after which the product is cooled in a step 6. After possible renewed sifting the product is now ready for packing in a step 7. The invention will be further illustrated by means of the following Examples:

Example 1

Fish feed pellet Al was produced from intermediate products from sand eel. content of 56-61% was mixed with 20 kg. of stick water concentrate having a solid content of 27.8%. 9.95 kg. of fish oil was added by the spraying on. There was produced feed pellets having a diameter of 3.5 mm. The feed included 2% "Suprex" (heat-treated maize starch) , and no form of pure binding agents. By the commercially used process of to-day it is not technically possible to produce feed with such a composition. Feed Bl is a commercially produced feed of the feeds which are on the market to-day having the lowest possible carbohydrate content (10-12%) , together with the lowest possible content of binding agents.

Feed Bl is thus not directly comparable on the basis of composition, but is nevertheless that feed which is most naturally to be compared with the "new" feed, Al.

The Table below shows a comparison of physical quality between the "new" feed, Al, and that feed which is on the market to-day, Bl.

Table 1

Feed No. Mechanical *) Water Stability Water Content Fat Content

Durability Weight % Weiσht %

Al 98.8 80.5 2.5 26.9

Bl 99-100 86.5 6.1 26.9

Commentary on Table 1: The figures for mechanical durability show that the two feeds tolerate mechanical handling equally well, in spite of there being a very large difference in composition as to carbohydrates and pure binding agents.

The content of fat is the same for the two feeds, while feed Al is much drier than feed Bl. Low moisture of the feed often produces a weakening of the strength of the feed. In spite of this feed Al thus shows good mechanical durability. It is important to be able to control the final moisture in the feed pellet and is not regarded as any problem in the process according to the invention. That it is somewhat low here is due to the technical test run at the pilot plant which was employed.

Example 2

There was produced a feed A2 with a starting point in intermediate products from Norway pout. The moisture in the intermediate products which were included in the process were as follows:

Fish material having a 59% water content.

Stick water concentrate having a solid content of 27- 30%.

The feed was produced totally free of carbohydrates and pure binding agents.

To produce a feed with this composition by a commercial process of to-day is certainly not technically possible.

Therefore for the sake of comparison feed Bl was, as submitted in Example 1, also employed here, even if feed Bl with respect to strength will derive benefit from 10-12% carbohydrates as included.

Table 2

The Table shows a carbohydrate-free feed, A2, compared with the feed which is on the market to-day which is naturally to be compared with, feed Bl .

Feed No . Mechanical Water Water Content Fat Content

Durability Stability Weight % Weight %

A2 95.2 88. 4 3.7 26.7

Bl 99-100 86.7 6.1 26. 9 Comments for Table 2:

As is evident from the numbers above the feed is pro¬ duced from intermediate products of somewhat weaker technical quality with reference to mechanical durability than the feed produced by a commercial process, but when the water stabili¬ ty of the feed is concerned feed from intermediate products is best. The figures in the Table must be read in connection with what is compared here a carbohydrate- and binding agent- free feed with a feed where the carbohydrate content is up to 10-12%. These results are very interesting and gives an impression of which possibilities the process according to the invention produces.

Commentary for the water and fat content are here as under Example 1.

Example 3

Feed produced under conditions as in the production referred to in Example 1, but with a carbohydrate content comparable with feed Bl, was investigated in biological studies with fish.

The background for the test was to be able to answer the central question as inter alia

- Which composition produces the most optimal feed?

- The quality of the feed relative to the best types of feed which are on the market to-day. There were employed in this test 6 different types of feed, 5 test mixtures/diets and one control feed.

Diet 1 : Control feed. Feed Bl, (from Example 1 and 2)

Diet 2 : Feed produced from fish material from sand eel with a water content of 56-61%, with the addition of a quantity of stick water concentrate corresponding to conventional whole meal. The stick water concentrate had a solid content of 27.8% Carbohydrate content 4-6%. Vitamins and minerals added in normal amounts. Diet 3 : Feed produced from fish material from sand eel (the same fish material as diet 2) , with the addition of an amount of stick water corresponding to double of that which is normally used in a whole meal composition, that is to say double the quantity of stick water concentrate related to test diet 2. Carbohydrates, vitamins and minerals as diet 2.

Diet 4 : Feed produced from fish material from sand eel (same fish material as diet 2), with the addition of stick water concentrate corresponding to diet 2. This diet included in addition about 15% minced raw fish. Carbohydrates, vitamins and minerals as diet no. 2.

Diet 5 : Feed produced by a traditional feed process from fish meal taken out in the same production in the fish meal factory as the intermediate products in the diets 2-4, were taken out from. Carbohydrates, vitamins and minerals, as diet

2.

The fish meals which were used in (diet 5 and 6) were thus from the same type of raw material (sand eel) and production as the intermediate products.

The diets 2-6 were produced at SSF (Norwegian herring oil and meal industry research institute) , while the control feed, diet 1, is that feed on the market to-day which lies closest up to the low quantity of carbohydrate it is desirable to compare with, feed Bl, from Example 1 and 2.

The results from the test show generally good growth and low feed consumption of the fish which became the feed. Diet no. 2 is distinguished positively with about 8% greater growth compared with the remaining tests diets 3-6, and also with Bl.

Example .

Parts of Example 3 were repeated as diets 1 (control) and 2 were produced from another raw material source. The tests were extended to testing in cages in the sea. The tests were also this time carried out fully according to plans, both what production of feed and biological experiments concern.

The results indicated general good growth and low feed consumption by the fish which was given the feed.

Compared to the control, feed Bl, diet 2 gave an increase in growth of about 15% by weight when the experi¬ ments were carried out in a vessel and an increase of up to 40% by weight when the experiments were carried out in cages in the sea. It is to note, however, that the experiments in the cages lasted for a longer period of time.

Example 5.

37 kg press cake/sludge which was predried to a water content of between 5 and 7% by weight was mixed with 19 kg stick water concentrate having a solid content 23%, and other ingredients, such as vitamins and minerals. The water content of the mixture was about 27% by weight.

Thereafter step 3 and the following steps were carried out to obtain a final feed.

While specific embodiments of the invention have been described in detail, it will be appreciated by those skilled in the art that various modifications and alternatives to those details could be developed in light of the overall teachings of the disclosure. Accordingly, the particular process disclosed is meant to be illustrative only and not limiting as to the scope of the invention which is to be given the full breadth of the appended claims and any and all eσuivalents thereof.

Claims

We claim :

1. A process for producing a fish-based food and/or feed product comprising the steps of:

(a) mixing fish material having a water content of at least 20 % by weight, optionally predried to a lower water content, with a stick water concentrate having a water content of at least 50 % by weight, under conditions whereby the binding properties of the components are substantially maintained

(b) converting the resulting mixture at a temperature of 20-120°C into a product of predetermined shape, size, consistency and density, and (c) drying the converted product to form an end product having a water content of less than 12 % by weight.

2. A process according to claim 1, comprising the step of concentrating the resulting mixture, before step (b) , to a water content of 20 - 50 % by weight.

3. A process according to claim 1 or 2, wherein the fish material has a water content of 20 - 80 % by weight and the stick water concentrate has a water content of 50 - 83 % by weight.

4. A process according to claim 1 or 2, comprising converting the resulting mixture in step (b) into pellets.

5. A process according to claim 1 or 2, wherein the fish material and the stick water concentrate are intermediate products in the production of fish meal at elevated temperatures and are mixed while still warm.

6. A process according to claim 1 or 2, comprising adding predetermined amounts of vitamins and minerals in step (a) .

7. A process according to claim 1 or 2, comprising spraying the end product of step (c) with fish oil in order to regulate the fat content thereof.

8. A process according to claim 1 or 2, comprizing use of press cake or sludge as fish material.

9. A fish-based food and/or feed product prepared by the process of any of claims 1-8.