MXPA99004133A - Method for continuous production of dry feed for fish and shell fish - Google Patents

Abstract

In a method for production of dry feed for fish or shell fish (Crustacea) based on fresh fish raw material, vegetable carbohydrate products together with other additives are added to give a carbohydrate content in the produced feed of at least 5%during feed production. During all process steps up to the formation of feed pellets the water content is higher than 10%. The produced dry feed contains 25-60%protein, 10-40%fat and 5-25%carbohydrate. The feed contains 25-60%fish protein while the fat in the form of fish oil is up to 40%.

Description

"METHOD FOR THE CONTINUOUS PRODUCTION OF DRY FOOD FOR FISH AND SEAFOOD" The present invention relates to a method for the direct production of dry food for fish and shellfish (crustaceans) based on the raw material of fresh fish. The breeding of fish or fish farming of different species of fish and shellfish is currently a very expensive business line that is also expected to grow in many countries. The different species demand different types of food but they are common for many species, the demands on a high content of fish protein and fish oil. Previously, fresh fish or fresh fish residue was used for the production of fish feed. The fish or the fish residue was divided into pieces, mixed with different dry additives such as cereal products, protein additives such as fishmeal or blood meal, before the mixture was formed into granules. The water content of the granules formed was -40 percent. A food with this high water content, however, had a limited storage time. Currently, most of the fish foods found in the market are produced from dried products, where the fish protein is in the form of fish meal. During the production of fishmeal, fresh fish or fish residue is heated to a temperature of about 90 ° C in order to release water and fish oil. During this heating, the proteins are denatured, which means that the functional qualities deteriorate. After heating, the fish material is separated mechanically in several steps, first the free water and the oil of the fish material are drained in a sieve, after which an additional defatted dehydration is carried out by means of a press. screw. The water in the sieve and the press is clarified in a decanter, and the solid phase that separates from the decanter is added to the pressed cake. The water strength of the decanter is divided into a separator in fish oil and sticky water. During these process steps, the temperature is maintained around 90 ° C in order to achieve the best possible fat separation. After separation, the sticky water is concentrated through evaporation in the film drop evaporator to a dry substance content of 35 percent to 40 percent. The concentrated sticky water is mixed in the pressed cake and the mixture is dried in directly or indirectly heated driers to a water content of 6 percent to 10 percent water. The total production time until obtaining a finished fish meal is around 3 to 4 hours, and both fishmeal and fish oil are subjected to a considerable thermal effect, during conventional production. The fat content in finished fish will be, according to the international standard, of the order of 12 percent, but frequently the content is still lower. In order to reduce the thermal effect, there is now for sale a so-called flour-LT (Low Temperature). This flour is dried under vacuum at a temperature of 75 ° C to 80 ° C. When fish feed for fish meal is produced, different methods are currently used, wherein the granulation is carried out in a granulating machine e.g. California type or through thermal extrusion, where the dough is cooked. The most modern method is extrusion forming. In both methods, you start with a dry mix with the desired composition of fish meal and fish oil, alternative sources and proteins, cereals and vitamins, pigments and other things. If the formation is carried out through extrusion, the water is added to this dry mixture of elements in order to provide a homogeneous composition. Steam is introduced into the mixture in order to force the starch and cereals to gelatinize. During the next extrusion, a high pressure is accumulated in the product mixture and the temperature increases at the same time up to approximately 120 ° C. When the product passed from the extrusion apparatus, the pressure is lowered and a part of the water evaporates at the same time as the formed granules expand, where they obtain a porous structure and can absorb oil. During a subsequent coating with the oil, the fat content of the food product can be increased from 20 percent to 30 percent fat. After extrusion, the water content is high, from 20 percent to 30 percent, and the oil addition is preceded by drying with hot air at temperatures of 50 ° C to 100 ° C. The water content of the finished product is less than 10 percent. When the granulation is carried out in the granulating machine, the mixture is rolled through a matrix, a disk with cone-shaped openings. The food mixture is pressed through the openings by the cylinder with high pressure, and the formed granule has been pressed together with a strong and solid product. The stability of the granule depends on how intensively it is pressed. The fat content of the food mixture may not be too high during the training, since - - that a very high oil content provides a less powerful compression. As a consequence of the compression, the granule will be compact, which means that the ability to suck the oil during the subsequent coating will be limited. The maximum fat content at a sufficient mechanical strength of the granule is approximately 18 percent. In accordance with current technology, fishmeal is first produced from fresh fish raw material. When fishmeal is produced, a low fat content is usually required in fishmeal. In order to achieve this goal, it is about reducing the amount of oil in the raw material of fish during the production of fishmeal. When fish feed is produced, on the other hand, it is desired to produce a product with a high fat content and during the production process large amounts of fat are added to compensate for the low fat content in the fish meal. During extrusion, the food mixture must have a certain water content so that this step of the process can be carried out in an optimum manner. The fishmeal has been dried previously to a water content of about 10 percent - which has produced approximately a deterioration of the colloidal bond and protein nutrition value. After extrusion, the fish product is dried with a temperature effect up to a water content of 10 percent maximum, which also influences the quality of the protein. One object of the invention is to produce a fish feed directly from fresh fish raw material and avoid the intermediate step that constitutes the production of fish meal. In accordance with the Patent Number WO 96/01058, it is proposed that a fish feed is produced directly from the fish material by mixing an intermediate product from the fish meal production, with a sticky water concentrate, forming the mixture in a product at a temperature of 20 ° C to 120 ° C, the product of which is then dried. The food that is produced in accordance with this publication consists of pure fish. In accordance with the invention, a method is now proposed for the production of dried fish for fish and shellfish, from a raw material of fresh fish, which involves a gentle treatment of the raw materials during all the steps of the process until the products of food produced, but at the same time, provides possibilities for adaptation to special demands for different species of fish and shellfish.

- - The method according to the invention is characterized mainly by adding cooked vegetable carbohydrates (already in paste form) to the raw material of the fresh fish together with other additives such as minerals, vitamins and binding agents during the production of the food to provide a carbohydrate content in the food produced of at least 5 percent. The water content in the fractions that contain the fish proteins are, during all the steps of the process, up to the formation of granules of food above 10 percent where the dry food produced contains from 25 percent to 60 percent of protein, from 10 percent to 40 percent fat and from 5 percent to 25 percent carbohydrates where the diet contains 25 percent to 60 percent fish protein and up to 40 percent fish oil . In accordance with the proposed method, the production of the dry food is carried out in such a way that the unnecessary drying steps provided by a food product with a high nutritional value are avoided. Due to the fact that the water content never decreases below this value, the protein remains in colloidal form. Vegetable carbohydrate products consist of different kinds and amounts of cereals that can be metabolized by the species of fish for which the food is intended. The proposed method is properly carried out in such a way that a fish material obtained in fish raw material is heated to a temperature such that pasteurization / sterilization is carried out and that the fish material is separated into minus two reactions, the liquid and solid phase. The fraction containing the solid phase is dehydrated during a low thermal effect to a low water content that is at least 10 percent, while the liquid fraction is concentrated to a water content of 20 percent to 80 percent of water. The concentrated liquid fraction is mixed with the dehydrated solid phase, fish oil and a predetermined amount of carbohydrate containing products, possibly alternative protein sources and other additives. The mixture obtained is mixed together with an emulsification step in order to provide a homogeneous mixture, the water content of which is 10 percent to 40 percent. The mixture obtained is formed into granules which, in a finishing drying step, are dried at a water content of 6 percent to 10 percent under a low thermal effect.

With this method, a high quality of the fish element is obtained both with respect to the bacterial and functional quality due to the open pasteurization alternatively the sterilization. In this step of the process, both the destruction of bacteria and the inhibition of enzymes are carried out. Due to the dehydration of the solid phase and the concentration of the liquid fraction that are carried out separately, optimal conditions for these measurements can be obtained. In accordance with the method of the invention, the production of the food is carried out for a short period of time and with a low temperature effect on the nutritional substances in the fish. The drying step is carried out in a few minutes in accordance with the invention, while the total drying time during the conventional production of fish feed may require several hours. In accordance with the invention, the effect of temperatures is reduced to a minimum. The method also produces savings both with respect to energy and equipment. The separation of the fish material is usually carried out in such a way that three fractions are obtained, namely fish oil, sticky water and the solid phase. The fact that the fish oil is separated as a separate phase of the separation means that this fraction does not pass any additional heat treatment, at risk of deterioration of the quality of the fish oil. If appropriate, this separation is carried out in two steps, namely, in that the fish material is first divided into a liquid phase and a solid phase fraction in a decanter, after which the liquid fraction is separated into sticky water and fish oil, in a high speed separator. In accordance with the invention, the oil is emulsified and the mixture which is subsequently to be formed into granules. In conventional food production, fat has been added mainly by coating the formed granules. This has resulted in the oil being released during feeding and collected on the surface of the water. If you want to produce a fish feed with low ash content, the fish raw material is passed to a so-called "boning unit", where the spine, skull and gills are separated. It is appropriate that the fish raw material is finely divided before heating. Smaller particles provide better and faster heat transfer. If this fine grinding has been carried out and antioxidants can preferably be added before heating in order to prevent the fat from becoming rancid.

In order to be able to control the final composition of the dry feed, the finely diluted fish raw material can be analyzed with respect to the protein, oil and ash content. This analysis can be carried out through the use of GSM (Guided Microwave Spectrometry) or MIR (Medium Infrared) systems. Both of these methods are fast enough to be used in a continuous system. The result of the analyzes can be used to determine the amounts of additional alternative protein and oil to be added to the fish material. The fish material is advantageously heated to a temperature of 95 ° C for 120 seconds. At this temperature a considerable extermination of bacteria with a minimum thermal effect on fish proteins and fatty acids in fish oil is obtained. Preferably the concentrated sticky water and the fish oil and the additives are mixed until a homogeneous emulsion is formed in a first mixing operation. This emulsion is. mixing with carbohydrate products and homogenizing until a paste similar to a mixture in a second mixing step. In the third mixer step, the dehydrated solid phase is added, possibly together with additional protein and flavoring substances to the pasta as a mixture. The obtained mixture comprising all the components is formed into granules by extrusion at low pressure i-wet. The granules produced according to the invention can be coated with a flavor enhancing substance such as octopus extracts or other. The method according to the invention is further described with reference to the accompanying drawing which shows a flow chart through a process according to the invention which is selected as an example. The whole fish, fish waste and fish finely divided as a water content of 65 percent to 75 percent with an added antioxidant, finely divided and added to a heat exchanger scraper that works indirectly and is heated to a predetermined degree. After the desired heat treatment, which may be pasteurization or sterilization, the fish material is directed to a separator, suitably a decanter with a horizontal axis, wherein the fish material, in the embodiment shown in the drawing is divided into two phases, a liquid fraction and a solid phase fraction. The liquid fraction is directed to a high speed centrifugal separator and divided into sticky and oil water. If desired, a three phase decanter can be used instead.

The sticky water phase of the second separation step is appropriately evaporated to a water content of 55 percent to 65 percent in a falling film evaporator or a plate heat exchanger. If desired, this concentration can instead be carried out through ultrafiltration. The solid phase of the first separation dries quickly and gently to a water content of 10 percent to 20 percent that ensures that the functional qualities of the proteins are conserved in the best way. The concentrated sticky water phase is mixed with the fish oil and with the micro-ingredients such as vitamins, pigments and emulsifiers at a temperature of 60 ° C to 90 ° C. This mixture is emulsified to form a homogeneous liquid phase which is mixed with the cooked starch with a high degree of gelatinization, which provides a paste-like mixture. The semi-dry solid phase which has been obtained after drying is mixed with the liquid phase already formed in paste and mixed to a mixture similar to a dough. The mixture obtained has a water content of 20 percent to 3 percent and contains from 25 percent to 32 percent of oil counted in the dry substance, whose oil is bound in the mixture.

With this mixture, the formation of granules can be simplified if it can be carried out in a wall similar to that used to form the soft granules, the so-called wet or semi-wet granules. With this, the mixture is passed through a disk which is provided with openings with blades forming the granules. The formation provides granules of a desired length diameter. Food products in the form of granules for smaller fish are traditionally produced by crushing the granules with a subsequent sieving to the desired particle sizes. The granules formed are then dried to a water content of 6 percent to 10 percent, where a storage stable food product is obtained. The formed granules have sufficient mechanical strength to maintain their shape during transportation and handling. They also have the correct sinking speed and the oil is not released during feeding, since it is emulsified in the product for the most part. If desired, a higher oil content can be obtained by coating after granule formation. In a process according to this example, the process time from the delivery of the fish raw material, the plant to the drying of the formed granules, can be kept as short as possible up to 30 minutes. The method according to the invention is further described in the following example of the mass balance in the process for producing the food. The term "dry substance" refers to a dry substance free of fat. 1,000 kilograms of raw fish matter (herring) with a fat content of 11.9 percent fat, 70.2 percent water and 17.9 percent dry matter, are heated in a heat exchanger scraper, Contherm ™, for 120 seconds, 95 ° C, after which the fish material is directed to a decanter. In this, the fish material is divided into two fractions, where the fraction of the solid phase, 364 kilograms, contains 3.8 percent fat, 62.1 percent water and 34.1 percent dry matter. The solid phase fraction is sent to a dryer where 198 kilograms of water are evaporated. The dried solid phase fraction, 166 kilograms, contains 8.3 percent fat, 17.0 percent water and the content of the dry substance is 74.7 percent. The liquid fraction of the decanter, which is 636 kilograms, contains 16.5 percent fat, 74.9 percent water and 8.6 percent dry matter. This fraction is directed to a high speed centrifuge and is divided into three fractions, fish oil, sticky water and silt. Fish oil amounts to 97 kilograms with a fat content of 99 percent. The sticky water, 423 kilograms contained 0.8 percent fat, 7.6 percent dry matter and had a water content of 91.6 percent. The silt fraction had a weight of 118 kilograms, contained 4.5 percent fat and 76.3 percent water and 19.2 percent dry matter. The sludge fraction and the sticky water fraction are mixed again and directed to an evaporator where 359 kilograms of water are expelled. The sticky water fraction, 180 kilograms contained 4.8 percent fat, 65.0 percent water and 30.2 percent dry matter. The fish oil, 97 kilograms was mixed in an emulsifying step with concentrated sticky water, 180 kilograms and 6 kilograms of micro-ingredients. The emulsified liquid amounting to 444 kilograms contained 26.8 percent fat, 32.9 percent water and 40.3 percent dry matter. In the next step of mixing, the gelatinization step, 74 kilograms of cereals with a water content of 10 percent were added. From this second step of mixing, 518 kilograms were obtained in the feed mix, which contains 17.4 percent fat, 22.4 percent air and 60.2 percent dry matter. After further homogenization of the mixture, it is formed into granules in the forming equipment. The formed granules are dried in a vertical dryer in which 113 kilograms of water are expelled. As a final result, 405 kilograms of granules containing 29.5 percent of fat, 10 percent of water and 60.5 percent of the dry substance are obtained. In the dry substance, there are 7.4 percent ash, 37.4 percent protein and 15.7 percent carbohydrate.

Claims (13)

1. R E I V I N D I C A C I O N S 1. The method for the continuous production of dry food for fish and shellfish (crustaceans) based on a raw material of fresh fish, characterized in that the vegetable carbohydrate products together with other additives such as minerals, vitamins, binding agents are added to the raw material of fresh fish during the production of the food until the carbohydrate content of the food produced is at least 5 percent and that the water content of the fractions containing the fish proteins during all the steps of the process until the formation of the granules of food are greater than 10 percent, where the dry food produced contains 25 percent to 60 percent to 60 percent protein, 10 percent to 40 percent fat, and 5 percent to 25 percent. percent of carbohydrates and in that the feed contains from 25 percent to 60 percent of fish protein while the fat in the form of fish oil is h up to 40 percent. The method according to claim 1, characterized in that - a fish material, obtained from a fish raw material is heated to a temperature for pasteurization / sterilization to be carried out, the fish material is separated into at least two fractions, liquid and solid phase, - the fraction containing the solid phase is dehydrated under a low thermal effect up to a water content that is at least 10 percent, the liquid fraction is concentrated to a water content from 20 percent to 80 percent water, the concentrated liquid fraction is mixed with the dehydrated solid phase, the fish oil, a predetermined amount of carbohydrate containing products (containing starch), alternative protein sources and other additives, The obtained mixture is mixed in an emulsification step in order to provide a homogeneous mixture, the water content of which is from 10 percent to 40 per cent. While the mixture obtained is formed into granules, the granules formed are dried in a final drying step to a water content of 6 percent to 10 percent during the low thermal effect. 3. The method according to claims 1-2, characterized in that the fish material is separated into three fractions, fish oil, sticky water and solid phase. 4. The method according to claims 1 to 3, characterized in that the separation is carried out in two steps. 5. The method according to the preceding claims, characterized in that the raw material of fresh fish is finely divided before heating. 6. The method according to claim 5, characterized in that antioxidants are added to the finely diluted fish mixture. The method according to claim 5, characterized in that the composition of the finely diluted fish mixture is measured with respect to protein, oil and ash, using fast methods such as NIR, MIR and GSM, whose information is used to control the addition of alternative protein sources, oil and carbohydrates. 8. The method according to claims 1-2, characterized in that the fish mixture is heated to a temperature of 95 ° C for 120 seconds. The method according to any of claims 1 to 3, characterized in that the concentrated sticky water and the fish oil and the additives are mixed to form a homogeneous emulsion in the first mixing operation. The method according to claim 9, characterized in that the emulsion is mixed with carbohydrate products and homogenized in a mixture similar to a paste in a second mixing step. The method according to claim 10, characterized in that the mixture is mixed with the dehydrated solid phase possibly together with additional proteins and flavoring substances, in a third mixing step. The method according to claim 11, characterized in that the obtained mixture containing the total components is formed into granules through a semi-wet extrusion at low temperature. 13. The method for producing a dry food for fish and shellfish, characterized in that the granules of the food produced are coated with substances that lend flavor such as octopus extract, etc.