A fish meal production process and system

Abstract

The present invention discloses a low-energy-consumption and environmentally friendly fish meal production process and system. The process mainly includes the following steps: 1) adding disodium dihydrogen pyrophosphate and calcium chloride to the protein water, mixing evenly, and centrifuging to produce supernatant I and precipitate I at the lower layer; 2) heating the supernatant I obtained in step 1) to 60-85°C and standing still to produce flocculants; 3) adding disodium dihydrogen pyrophosphate and calcium chloride to the flocculants at the lower layer obtained in step 2), and centrifuging to produce supernatant III and precipitate III at the lower layer, collecting precipitate I and III at the lower layer for subsequent preparation of fish meal; at the same time, a system conforming to the above process is designed, thus effectively solving the problems of high energy consumption caused by heating and concentration in the protein water link of fish meal production, as well as the environmental protection problems of subsequent treatment of a large amount of water vapor and volatile organic compounds contained therein.

Description

Technical Field

[0001] The present invention relates to the technical field of fish meal processing, and particularly to a fish meal production process and system. Background Art

[0002] Fish meal is an important animal protein raw material and has extensive and indispensable applications in the field of aquaculture feed. In the past five years, the annual consumption of fish meal in China has been about 2.5 million tons, of which about 1 million tons are domestic.

[0003] At present, fish meal production in China basically adopts the wet process ( Figure 1 ). Figure 1 The high-energy-consuming equipment (such as the protein water concentration system, condenser and other equipment) and environmental protection equipment (deodorization tower, pickling tower, alkali washing tower, photocatalysis and other equipment) are marked by dotted lines on the right side. On the one hand, the equipment investment is high and the floor area is large. On the other hand, its operating cost is high and the energy consumption is high. The moisture content of 1 ton of raw fish is about 75%. In the existing fish meal production process, especially in the protein water stage (accounting for more than 60% of the total water volume of raw fish), almost all the water needs to be heated and dried, so the energy consumption is very high. At the same time, during the heating process, nutrients such as protein will be lost more and about organic waste gas will be generated, which not only loses nutrients but also pollutes the environment. Therefore, it is urgent to propose a new low-energy-consuming and environmental protection fish meal production process and system to solve the above problems. Summary of the Invention

[0004] The purpose of the present invention patent is to provide a new low-energy-consuming and environmental protection fish meal production process and system to solve the high-energy-consuming problem caused by heating and concentration in the protein water link of fish meal production and the environmental protection problem of subsequent treatment of a large amount of water vapor and volatile organic compounds contained therein as mentioned in the above background art.

[0005] The process method of the present invention mainly improves the optimization of the "protein water" treatment process in the traditional fish meal production process. The process of obtaining the protein water includes the following processes: after the fish raw materials are cooked, the pressing liquid is obtained by pressing, and the pressing liquid is centrifugally separated to form surface fish oil, middle-layer protein water and bottom-layer fish residue (this middle-layer protein water is the initial raw material to be processed in this application). The protein water is concentrated / dried to form dry matter, and after being dried together with the above bottom-layer fish residue, fish meal is made ( Figure 1 and Figure 2 ).

[0006] To achieve the above object, the present invention first analyzes the essence of the above problems. Since the protein water contains a certain amount of nutrients such as protein and amino acids, but the water content in the protein water is about 90%. The existing production process heats and concentrates the protein water to harvest the dry matter therein, and then dries it and uses it as part of the fish meal. In this process, almost all of the water needs to be heated into water vapor, resulting in too much energy consumption; at the same time, a large amount of volatile organic matter is generated, polluting the air, and a series of environmental protection equipment must be used for treatment. If the (partial) dry matter in the protein water can be harvested by a safe, efficient and low-energy method, and the remaining nutrients can be efficiently utilized (such as subsequent use as water-soluble fertilizer), then the existing high-energy-consuming equipment such as heating and concentration and cooling, and the environmental protection equipment for subsequent treatment of a large amount of waste gas and waste water will no longer be needed.

[0007] Based on the above analysis, the present invention first proposes a low-energy-consuming and environmentally friendly fish meal production process, as shown in Figure 2 , and the process mainly includes the following steps:

[0008] (1) Add disodium dihydrogen pyrophosphate and calcium chloride to the protein water, mix well, and then centrifuge to separate, generating supernatant I and precipitate I (also called dry matter) at the bottom layer. Collect precipitate I at the bottom layer for subsequent preparation of fish meal; add 0.1 - 0.8 g of disodium dihydrogen pyrophosphate and 0.05 - 3.0 g of calcium chloride to every 100 mL of protein water;

[0009] (2) Heat the supernatant I obtained in step (1) to 60 - 85 °C to generate a large amount of flocs; let it stand for more than 20 min, and separate to generate supernatant II and flocs at the bottom layer;

[0010] (3) Add disodium dihydrogen pyrophosphate and calcium chloride to the flocs at the bottom layer obtained in step (2), and then centrifuge to separate, generating supernatant III and precipitate III (also called dry matter) at the bottom layer. Collect precipitate III at the bottom layer for subsequent preparation of fish meal; add 0.1 - 0.8 g of disodium dihydrogen pyrophosphate and 0.05 - 3.0 g of calcium chloride to every 200 mL of the flocs at the bottom layer.

[0011] For the above technical solution, in a further preferred case, the raw material of the fish meal production process is fish raw material. After cooking, it is pressed to obtain a pressed liquid, and the pressed liquid is centrifuged to separate the surface fish oil, the middle layer protein water, and the bottom layer fish residue; in the above process, after adding disodium dihydrogen pyrophosphate and calcium chloride to the protein water, mix well, and centrifuge to collect the precipitate (dry matter) for the preparation of fish meal; adding disodium dihydrogen pyrophosphate and calcium chloride has the technical effect of increasing the amount of dry matter separated by centrifugation of the protein water, thereby reducing energy consumption and reducing waste gas emissions.

[0012] For the technical solutions described above, in a further preferred case, the upper clear liquid II obtained in step (2) and the upper clear liquid III obtained in step (3) (which is a light brownish-yellow, clear and transparent liquid, still containing a small amount of proteins, amino acids, and containing nutrient salts such as nitrogen and phosphorus) can be used for the production of water-soluble fertilizers.

[0013] For the technical solutions described above, the amount of dry matter in the protein water generally varies in the range of 0.5 - 15.0 g / 40.0 mL; the further preferred range is 1.0 - 12.0 g / 40.0 mL; more preferably 2.0 - 10.0 g / 40.0 mL; most preferably 3.0 - 9.0 g / 40.0 mL.

[0014] The amount of dry matter in the protein water described above is usually mainly related to the type and freshness of the fish raw materials, and conditions such as cooking and pressing in the production process. The fish raw materials described in this application can be selected from whole fish or parts of the fish body (for example, the remaining parts after processing whole fish into fish products, including but not limited to fish viscera, fish heads, fish tails, etc.).

[0015] For the technical solutions described above, in a further preferred case, the amount of disodium dihydrogen pyrophosphate added to the protein water is 0.1 - 0.7 g / 100 mL; more preferably 0.2 - 0.6 g / 100 mL.

[0016] For the technical solutions described above, in a further preferred case, the amount of calcium chloride added to the protein water is 0.1 - 2.3 g / 100 mL; the more preferred amount is 0.15 - 2.0 g / 100 mL; the more preferred amount is 0.4 - 1.8 g / 100 mL; the more preferred amount is 0.8 - 1.7 g / 100 mL.

[0017] For the technical solutions described above, in a further preferred case, the amount of disodium dihydrogen pyrophosphate added to the lower flocculates in step (3) is 0.1 - 0.7 g / 200 mL; more preferably 0.2 - 0.6 g / 200 mL.

[0018] For the technical solutions described above, in a further preferred case, the amount of calcium chloride added to the lower flocculates in step (3) is 0.1 - 2.3 g / 200 mL; the more preferred amount is 0.15 - 2.0 g / 200 mL; the more preferred amount is 0.4 - 1.8 g / 200 mL; the more preferred amount is 0.8 - 1.7 g / 200 mL.

[0019] For the technical solution described above, in a further preferred case, the conditions for centrifugation are as follows: centrifugal force (also known as separation factor, RCF) of 55 to 13,820 g (the corresponding centrifuge speed in RPM is 500 to 12,000 revolutions per minute), and centrifugation time of 1.0 to 25.0 minutes (lengthening the time can increase the mass of the harvested lower-layer dry matter); after centrifuging the protein water, it is separated into an upper layer (aqueous solution) and a lower layer (precipitate). The mass of the dry matter obtained after drying the lower-layer precipitate in the experimental group is 28.79 to 9954.54% higher than that of the control group.

[0020] For the technical solution described above, in a further preferred case, the centrifugal force is 115 g (RPM, 750 revolutions per minute) to 7770 g (9000 revolutions per minute), and the centrifugation time is 1.0 to 15.0 minutes; more preferably, the centrifugal force is 115 g (750 revolutions per minute) to 3520 g (4200 revolutions per minute), and the centrifugation time is 1.0 to 15.0 minutes; more preferably, the centrifugal force is 225 g (1000 revolutions per minute) to 3520 g (4200 revolutions per minute), and the centrifugation time is 1.0 to 10.0 minutes;

[0021] With the aid of existing centrifugal separation equipment in production, the present invention adds calcium chloride and disodium dihydrogen pyrophosphate to the protein water. Without changing the investment cost, more lower-layer precipitate (i.e., dry matter) can be harvested from the protein water for subsequent processing (usually drying and processing into fish meal). At the same time, the equipment for drying (the water in the protein water) and volatile organic compounds, as well as cooling water vapor and volatile organic compounds, is greatly reduced. Moreover, the content of dry matter in the protein water is lower, and the harvested lower-layer precipitate (i.e., dry matter) is a mixture composed of components such as fish meat, fish bones, fish scales, and fish viscera. After drying, it is made into fish meal. Therefore, in the experiment, the volume of the protein water or the like is taken as the main consideration factor, and the amounts of calcium chloride and disodium dihydrogen pyrophosphate added are determined accordingly.

[0022] For the technical solution described above, further preferably, the heating temperature in step (2) is 60 - 65 °C.

[0023] For the technical solution described above, further preferably, the standing time in step (2) is preferably 20 - 60 minutes. After standing, it is divided into upper and lower layers. The standing time can be extended, and with the extension of time, the layering effect is better. The standing time can be adjusted according to the production efficiency requirements in actual production.

[0024] In the second aspect of the present invention, a low-energy-consumption and environmentally friendly fish meal production system is proposed. The system includes: a liquid storage tank, mixing tank I and mixing tank II, automatic feeder I and automatic feeder II, and centrifuge I and centrifuge II;

[0025] The mixing tank I is connected to an automatic feeder I, and the mixing tank I is connected to a centrifuge I through a pipeline; the centrifuge I is provided with an upper clear liquid I output port and a lower precipitate I collection port, and the upper clear liquid I output port is connected to a downstream liquid storage tank through a pipeline;

[0026] The outer layer of the liquid storage tank is provided with a heating layer, and the bottom of the liquid storage tank is provided with a lower floc collection port and an upper clear liquid II collection port;

[0027] The floc collection port is connected to a downstream mixing tank II through a pipeline. The upstream of the mixing tank II is also connected to an automatic feeder II through a pipeline. The reagent in the automatic feeder II is quantitatively transported into the mixing tank II. A centrifuge II is arranged downstream of the mixing tank II. The centrifuge II is provided with an upper clear liquid III output port and a lower precipitate III collection port;

[0028] The specific technological process realized by the above connection structure is as follows:

[0029] The protein water raw material liquid is transported to the mixing tank I arranged downstream through a pipeline. The reagent in the automatic feeder I is quantitatively transported into the mixing tank I. After the protein water and the reagent are fully mixed in the mixing tank I, they are input into the centrifuge I arranged downstream through a pipeline and then the upper clear liquid I and the lower precipitate I are obtained respectively. The lower precipitate I is collected as fish meal raw material; the upper clear liquid I is transported to the liquid storage tank. The upper clear liquid II is collected through a pipeline for use as a subsequent water-soluble fertilizer material; after the upper clear liquid I is heated at 60 - 85 °C in the liquid storage tank, it naturally settles for 20 - 60 minutes and is stratified into the upper clear liquid II and the lower flocs; the lower flocs collected by the floc collection port are transported to the downstream mixing tank II through a pipeline. After the liquid fully mixed in the mixing tank II is separated by the centrifuge II, the upper clear liquid III and the lower precipitate III are obtained; the upper clear liquid III is collected through a pipeline for use as a subsequent water-soluble fertilizer material; the lower precipitate III is collected as fish meal raw material.

[0030] For the above technical solution, further preferably, the automatic feeder I and the automatic feeder II are each provided with a drug metering pump, which can measure and output the amount of drug (adding disodium dihydrogen pyrophosphate and calcium chloride) according to the liquid volume in the mixing tank I or II. The metering rule of the automatic feeder I is the same as the previous metering rule (adding disodium dihydrogen pyrophosphate and calcium chloride to the protein water), and the metering rule of the automatic feeder II is 50% of the metering rule amount of the automatic feeder I.

[0031] For the above technical solution, further preferably, the heating temperature of the liquid storage tank is 60 - 85 °C.

[0032] For the technical solution described above, it is further preferred that the standing time of the liquid storage tank is preferably 20-60 minutes, and it is divided into an upper and lower layer after standing. The standing time can be extended, and the stratification effect is better as time goes by. The standing time can be adjusted according to the demand for production efficiency in actual production.

[0033] For the technical solution described above, it is further preferred that stirring paddles are provided in the mixing tank I and the mixing tank II for mixing the feed liquid;

[0034] For the technical solution described above, it is further preferred that the tube wall of the liquid storage tank is also provided with a transparent observation window, and the stratification of the liquid in the liquid storage tank is observed through the observation window, and the lower and upper liquids are output from the bottom of the tank to the outside in order according to the stratification, that is, the flocculent collecting port collects the flocculent in the lower layer, and the upper clear liquid II collecting port is used to transport the upper clear liquid II.

[0035] For the technical scheme described above, it is further preferred that, in addition to the structural units described above, the system further comprises a steamer, a press and a three-phase horizontal centrifuge; a press is arranged downstream of the steamer, the press is provided with a cake collecting port, and a pressed liquid collecting port is arranged on the other side; the pressed liquid collecting port is connected to the three-phase horizontal centrifuge through a pipeline; a surface fish oil outlet, a middle-layer protein water outlet and a bottom-layer fish residue outlet are arranged downstream of the three-phase horizontal centrifuge; the three-phase horizontal centrifuge separates "surface fish oil (containing a small amount of water and impurities), middle-layer protein water and bottom-layer fish residue"; wherein a centrifuge is arranged downstream of the fish oil outlet to centrifugally separate fish oil and protein water; the protein water outlet and the protein water outlet of the three-phase horizontal centrifuge are mixed and collected through a pipeline as a protein water raw material liquid.

[0036] For the technical solution described above, it is further preferred that the downstream of the conveying pipeline of the supernatant II of the system is connected with the downstream of the pipeline of the supernatant III, and they are combined into a water-soluble fertilizer material conveying pipeline.

[0037] For the technical solution described above, it is necessary to further explain that the automatic feeder provided in the system is used to add the pre-configured reagent into the protein water ( Figure 2 ), because the fish meal production process is basically a continuous process, the amount of reagent added to the protein water needs to be based on the volume or flow rate of the protein water. The types of centrifuges I and II provided in this system are not limited, and can be used to achieve centrifugal effects in industry, for example: commonly used horizontal centrifuges or butterfly centrifuges, etc. In addition, the heating layer of the liquid storage tank provided in this system is used to heat the upper clear liquid I to 60-85°C; the heating equipment is also not limited to any type, and can be used to achieve heating effects in industry. After the heating, as the temperature decreases, the subsequent separation effect is better.

[0038] Advantages of the present invention compared with the prior art:

[0039] (1) Under the optimal reagent / protein water ratio condition (“1.00 mL of disodium dihydrogen pyrophosphate 0.8M + 0.75 mL of calcium chloride 6.0M” / 40.0 mL of protein water), the mass of the lower layer precipitate (dry weight) in the protein water experimental group was approximately 61.6 times higher than that in the control group. In a relatively wide range of centrifugal forces from 55 to 13820 g and centrifugation times (1.0 to 25.0 min), the mass of the dry matter in the lower layer precipitate obtained was much higher than that in the control group (the experimental group was 28.79 to 9954.54% higher than the control group) and was stable; moreover, as the centrifugation time was prolonged, the amount of the lower layer precipitate obtained increased.

[0040] (2) The lower layer precipitate harvested by the method of the present invention was used as a fish meal raw material, and the safety and breeding effect in the culture of Paralichthys olivaceus were evaluated favorably.

[0041] (3) Comparison of the effects of the process of the present invention and the existing production process

[0042] Due to the innovation of the process method of the present invention in the protein water stage and subsequent stages, the comparison starts from the protein water.

[0043] ① Material comparison

[0044] Calculated based on 400.0 mL of protein water, the material results harvested by the existing process and the new process of the present invention are shown in Table 1 below.

[0045] Table 1. Comparison of the material harvest amounts of the existing process and the new process of the present invention

[0046]

[0047] The dry matter mass harvested by the existing production process is 35.17 ± 0.46 g, which has no significant difference (P > 0.05) from the dry matter mass of 35.90 ± 0.76 g contained in the protein water; the masses of crude protein and amino acids harvested by the existing process are 88.62% and 97.93% of those in the protein water respectively. The masses of dry matter (lower layer precipitate), crude protein and amino acids harvested by the new process of the present invention are 52.28%, 33.12% and 42.43% of those in the protein water respectively, which are much smaller than the harvest amounts of the existing process. However, while the new process of the present invention harvested the lower layer precipitate for subsequent fish meal production using 400.0 mL of protein water, it also harvested 301.5 mL of amino acid water-soluble fertilizer material. Adding up the masses of dry matter, crude protein and amino acids in the amino acid water-soluble fertilizer and the lower layer precipitate, they account for 112.42%, 94.95% and 101.06% of those in the protein water respectively, which are higher than the material amounts harvested by the existing process. This means that the key nutrients in the protein water are hardly wasted. Moreover, the indexes of the amino acid water-soluble fertilizer material are 3.32 g / L of amino acid, 8.67 g / L of total nitrogen, 0.84 g / L of total phosphorus, 6.0 g / L of chloride ion and pH value of 5.7, indicating that it is a very good material for producing amino acid water-soluble fertilizer.

[0048] ② Energy consumption comparison

[0049] Calculated based on 1000 kg of protein water, the energy consumption of the new process of the present invention is 233.6×103 kJ, which is only 5.12% of the energy consumption (4560.9×103 kJ) of the existing production process (corresponding part).

[0050] Furthermore, the process method of the present invention does not need to dry and heat the protein water to gas. On the one hand, this greatly reduces (or almost does not) generate organic gases (with unpleasant odors and requiring subsequent environmental protection equipment for treatment), and on the other hand, it greatly reduces the energy consumption. The present invention can remove the high energy consumption (such as the protein water concentration system) and environmental protection equipment (deodorization tower, pickling tower, alkali washing tower and photocatalysis equipment, etc.) in the existing fish meal production process, greatly reducing the equipment investment, and can also greatly reduce the high energy consumption in the protein water heating and concentration stage. Moreover, it has found a suitable way out for the separated clear liquid of the protein water, that is, to produce water-soluble fertilizer. Therefore, a new low-energy consumption and environmentally friendly process and equipment system for fish meal production is innovatively formed ( Figure 2 ). Description of the drawings

[0051] Figure 1 . It is the process flow chart and total material balance chart of the existing fish meal production process, taking 1000 kg of raw fish feed as an example.

[0052] Figure 2 . It is the process flow chart and total material balance chart of the new fish meal production process of the present invention, taking 1000 kg of raw fish feed as an example.

[0053] Figure 3 .New process (after protein water) flow and total material balance diagram.

[0054] Figure 4 .New process (after protein water) system structure diagram.

[0055] Figure 5 .System structure diagram of new fish meal production process.

[0056] Figure 6 .Effect of water-soluble fertilizer materials on the growth of Isochrysis galbana.

[0057] Figure 7 .Effect of water-soluble fertilizer materials on the growth of Chaetoceros.

[0058] Wherein: 11. Mixing tank I; 12. Automatic feeder I; 13. Centrifuge I; 2. Liquid storage tank; 31. Mixing tank II; 32. Automatic feeder II; 33. Centrifuge II. Detailed implementation manners

[0059] The present invention will be further described below in conjunction with embodiments, but it should be understood that the protection scope of the present invention is not limited by the embodiments. In the present invention, unless otherwise clearly stated, percentages and percentage contents are by mass. Unless otherwise specified, the experimental methods used are conventional methods, and the materials, reagents, etc. used can be purchased from commercial channels.

[0060] .Combination Figure 4 and 5 The new process and its system involved in the present invention are described in detail as follows:

[0061] A press is provided downstream of the cooking machine. The press is provided with a cake collection port and a pressed liquid collection port on the other side; the pressed liquid collection port is connected to a three-phase horizontal centrifuge through a pipeline; a surface layer fish oil output port, a middle layer protein water output port and a bottom layer fish residue output port are provided downstream of the three-phase horizontal centrifuge; the three-phase horizontal centrifuge separates "surface layer fish oil (containing a small amount of water and impurities), middle layer protein water and bottom layer fish residue"; the fish oil is further centrifugally separated into fish oil and protein water by a disc centrifuge.

[0062] This protein water is mixed with the protein water collected from the three-phase horizontal centrifuge and collected into the mixing tank I 11 provided downstream. The mixing tank I 11 is connected to the automatic feeder I 12 through a pipeline;

[0063] After the protein solution and the reagent are fully mixed in the mixing tank I11, they are input through a pipeline into the centrifuge I arranged downstream for centrifugation to obtain supernatant I and precipitate I respectively. The precipitate I is collected as fish meal raw material.

[0064] The supernatant I enters the downstream liquid storage tank 2. A heating layer is arranged on the outer layer of the liquid storage tank 2. After the supernatant I is heated at 60 - 65 °C in the liquid storage tank 2 and naturally settled for 1 hour, it is stratified into supernatant II and floccules at the lower layer. The pipe wall of the liquid storage tank 2 is provided with a transparent observation window, and the bottom of the tank is provided with a collection port for the floccules at the lower layer and a collection port for supernatant II. The liquid stratification situation in the liquid storage tank 2 is observed through the observation window, and supernatant II is collected through a pipeline for use as subsequent water-soluble fertilizer material.

[0065] The floccules at the lower layer collected at the floccules collection port are transported through a pipeline to the downstream mixing tank II 31, and the mixing tank II 31 is connected to the automatic feeder II 32 through a pipeline. A centrifuge II 33 is arranged downstream of the mixing tank II 31. After the liquid fully mixed in the mixing tank II 31 is separated by the centrifuge II 33, supernatant III and precipitate III are obtained. The supernatant III is collected through a pipeline for use as subsequent water-soluble fertilizer material. The precipitate III is collected as fish meal raw material.

[0066] Stirring paddles are arranged in both the mixing tank I11 and the mixing tank II31 for mixing the liquid materials.

[0067] II. The raw material characteristics in the new process involved in the present invention are described in detail as follows:

[0068] All the reagents used in the embodiments of the present invention are feed grade or (and) food grade, and the water used is sterilized deionized water (sand-filtered seawater is used in the culture of Paralichthys olivaceus).

[0069] All the "sodium acid pyrophosphate" used in the embodiments of the present invention is an abbreviation, which refers to an aqueous solution of sodium acid pyrophosphate with a concentration of 0.8 M; all the "calcium chloride" is also an abbreviation, which refers to an aqueous solution of calcium chloride with a concentration of 6.0 M.

[0070] The raw materials of the protein solution used in the embodiments of the present invention are as follows: (1) Protein solution with whole fish as the raw material, taken from the fresh protein solution generated during the production of fish meal in a fish meal factory in Dalian, and sent back to the laboratory within 4 hours, then sub-packed and stored frozen. (2) Protein solution with fish heads, fish tails, fish viscera, etc. as the raw materials, which is the fresh protein solution generated by the laboratory according to the fish meal production and processing process, sub-packed and stored frozen. Before use, the frozen protein solution is taken out, left overnight at room temperature (there are still small ice cubes), heated, and shaken well before use; after detection, the dry matter content of the above protein solution is between 3.12 - 5.09 g / 40.0 mL.

[0071] The method for measuring the dry matter content described in the following embodiments of the present invention: During the experiment, take 40.0 mL of protein water, pour it into a glass petri dish, and dry it to a constant weight at 90 °C. Weigh and calculate the dry matter content in the protein water accordingly.

[0072] The dry matter content of the protein water used in the following embodiments of the present invention is 3.50 g / 40 mL. Each group has 3 parallel samples, expressed as: mean ± standard deviation, and the one-way analysis of variance method is used.

[0073] The protein water used in the embodiments of the present invention is taken from the above-mentioned fish meal factory in multiple batches. Each batch of protein water is tested separately without mixing. The whole fish raw materials for each batch include but are not limited to the following types: such as anchovies, sardines, mackerel, cod, flounder, etc., and the experimental effects are similar. Fish viscera, fish heads, fish tails, etc. are taken from whole fish such as anchovies, sardines, mackerel, cod, flounder, etc., and the experimental effects are similar.

[0074] The protein water used in the embodiments of the present invention contains the main substances as shown in Table 2 below:

[0075] Table 2. Main components of protein water

[0076]

[0077] After using a method similar to that in Example 1 or 2 below, for protein water with a dry matter content of 2.7 g / 40 mL or 7.48 g / 40 mL, adding the optimal reagent / protein water ratio condition (1.00 mL of 0.8 M disodium dihydrogen pyrophosphate + 0.75 mL of 6.0 M calcium chloride " / 40.0 mL of protein water) for detection, it is found that the experimental results are also in line with those in Example 1, and it can maintain a mass ratio of the lower-layer precipitate dry matter higher than that of the control group by about 25 - 10000% within a wide range of centrifugal forces from 55 to 13820 g and centrifugation times from 1.0 to 25.0 min.

[0078] Example 1-1

[0079] Reagents and amounts added before centrifugally separating the protein water

[0080] (1) Design experimental groups (Table 3)

[0081] ① Prepare blank groups 1, 2, and 3: In 9 50.0 mL plastic centrifuge tubes, add 40.0 mL of sterilized deionized water respectively. Among them, add disodium dihydrogen pyrophosphate to 3 of them as blank group 1, add calcium chloride to another 3 as blank group 2, and add "disodium dihydrogen pyrophosphate + calcium chloride" to the remaining 3 as blank groups 1, 2, and 3 respectively.

[0082] ② Preparation of the control group, experimental groups 1, 2, and 3: In several 50.0 mL plastic centrifuge tubes, 40.0 mL of protein solution was filled respectively. Without adding any reagents except the protein solution, it served as the control group; adding sodium acid pyrophosphate in addition to the protein solution served as experimental group 1; adding calcium chloride served as experimental group 2; adding "sodium acid pyrophosphate + calcium chloride" served as experimental group 3.

[0083] (2) The centrifuge tubes of the above-mentioned blank group, control group, and experimental groups were centrifuged at 1375 g (2500 revolutions / min) for 3 min. After taking out the centrifuge tubes and observing, the lower-layer precipitate was dried to a constant weight and then weighed.

[0084] (3) 40.0 mL of protein solution was taken and placed in a glass petri dish, weighed (after subtracting the mass of the petri dish, it was called "wet weight of the protein solution"), and dried to a constant weight and then weighed (after subtracting the mass of the petri dish, it was called "dry weight of the protein solution").

[0085] (4) Experimental results:

[0086] Samples of blank groups 1, 2, and 3 did not form precipitates, that is, they were clear and transparent liquids before and after centrifugation, which could also be seen from the results in Table 3.

[0087] After centrifugation of the control group (protein solution) samples, almost no layering was seen, and the color was almost the same as that of the original protein solution. After pouring out the upper-layer liquid after centrifugation, the average mass of the lower-layer precipitate left after drying was 0.032 g ± 0.003 g.

[0088] After centrifugation of the samples in experimental group 1 (sodium acid pyrophosphate added to the protein solution), it was slightly seen that they were divided into upper and lower layers. The color of the upper-layer liquid was almost the same as that of the original protein solution, and the amount of the lower-layer precipitate was very small. After pouring out the upper-layer liquid, the mass of the lower-layer precipitate after drying is shown in Table 3. The masses of the lower-layer precipitates of experimental groups 1-1, 1-2, 1-3, 1-4, and 1-5 increased by 103.12%, 234.37%, 509.37%, 568.75%, and 556.25% respectively compared with the control group.

[0089] After centrifugation of the samples in Experimental Group 2 (calcium chloride added to the protein solution), they were divided into upper and lower layers. The color of the upper-layer liquid was significantly lighter than that of the original protein solution but was still turbid. The mass of the lower-layer precipitate increased with the increase in the amount of calcium chloride added (Table 3). The masses of the lower-layer precipitates of Experimental Groups 2-1, 2-2, 2-3, 2-4, and 2-5 after drying were increased by 546.87%, 1187.50%, 1693.75%, 2453.12%, and 2843.75% respectively compared with the control group. Moreover, the dry weight of the lower-layer precipitate in Experimental Group 2 was significantly higher than that in Experimental Group 1. Experimental Group 3 (sodium acid pyrophosphate + calcium chloride added to the protein solution) investigated the effect of the synergistic action of calcium chloride and sodium acid pyrophosphate on separating the dry matter in the protein solution. After centrifugation, it also formed upper and lower layers. The upper-layer liquid was basically clear, and there were slightly flocculent substances in some samples. The mass of the lower-layer precipitate increased significantly compared with the control group. More importantly, the dry weights of the lower-layer precipitates in Experimental Group 3 were significantly increased compared with those of the corresponding groups in Experimental Group 2 with the same amount of calcium chloride added; moreover, even in the experimental groups 3-1-1, 3-2-1, 3-3-1, 3-4-1, and 3-5-1 in Experimental Group 3 with the least amount of sodium acid pyrophosphate added, the masses of the lower-layer precipitates were increased by 68.12%, 50.48%, 82.23%, 50.92%, and 39.28% respectively compared with those of Experimental Groups 2-1 (0.10 mL of calcium chloride added), 2-2 (0.25 mL of calcium chloride added), 2-3 (0.50 mL of calcium chloride added), 2-4 (0.75 mL of calcium chloride added), and 2-5 (1.00 mL of calcium chloride added), and all had extremely significant differences (P<0.01). It can be seen that the synergistic action of sodium acid pyrophosphate and calcium chloride significantly improved the effect of increasing the mass of the lower-layer precipitate in the centrifuged protein solution. Moreover, under the condition of the same amount of calcium chloride added, with the increase in the amount of sodium acid pyrophosphate added, the mass of the lower-layer precipitate obtained by centrifugation increased significantly. Under the condition of the optimal ratio of reagent addition (1.00 mL of sodium acid pyrophosphate + 0.75 mL of calcium chloride), the lower-layer precipitate obtained by centrifugation in Experimental Group 3-4-4 was increased by 61.6 times compared with the control group, 8.36 times compared with Experimental Group 1-4 with 1.00 mL of sodium acid pyrophosphate added alone, and 1.45 times compared with Experimental Group 2-4 with 0.75 mL of calcium chloride added alone. This further proved that the synergistic action of sodium acid pyrophosphate and calcium chloride significantly improved the effect of increasing the mass of the lower-layer precipitate in the centrifuged protein solution.

[0090] Table 3. Experimental design and results of centrifugation (2500r / 1375g, 3 min) separation (reagents and their addition amount ranges) of protein solution

[0091]

[0092]

[0093]

[0094]

[0095] Note: 1. For each experimental group in the blank group, the added amount of sterilized water is 40.0 mL;

[0096] 2. For each experimental group in the experimental group, the added amount of protein solution is 40.0 mL.

[0097] 3. Disodium dihydrogen pyrophosphate refers to a disodium dihydrogen pyrophosphate solution with a concentration of 0.8 M, and calcium chloride refers to a calcium chloride solution with a concentration of 6.0 M.

[0098] Examples 1-2

[0099] Under the condition of the most suitable reagent ratio, the centrifugal force and centrifugation time required for centrifuging the protein solution;

[0100] (1) For experiments with a rotation speed of 500 rpm (centrifugal force of 55 g) to 4200 rpm (centrifugal force of 3520 g), use a floor-standing centrifuge. In a 50.0 mL plastic centrifuge tube, add 40.0 mL of protein solution respectively; for experiments with a rotation speed of 7000 rpm (centrifugal force of 4700 g) to 12000 rpm (centrifugal force of 13820 g), use a tabletop centrifuge. In a 10.0 mL plastic centrifuge tube, add 8.0 mL of protein solution respectively. Except for adding the protein solution, those without adding reagents are used as the control group; those adding reagents (in the ratio of "2.50 mL of 0.8 M disodium dihydrogen pyrophosphate + 1.88 mL of 6.0 M calcium chloride" / 100.0 mL of protein solution) are used as the experimental group. According to different centrifugal forces and centrifugation times, it is divided into the control group and experimental groups 1-14. The specific experimental design and results are shown in Table 4. After centrifugation, take out the centrifuge tube for observation, and then dry the lower-layer precipitate to constant weight and weigh it.

[0101] (2) Take 40.0 mL of protein solution respectively and put it into a glass petri dish, weigh it (after subtracting the mass of the petri dish, it is called "wet weight of protein solution"), dry it to constant weight and then weigh it (after subtracting the mass of the petri dish, it is called "dry weight of protein solution").

[0102] (3) Experimental results

[0103] For both the control group and the experimental groups under all experimental conditions, an upper layer (liquid) and a lower layer (precipitate) were formed after centrifugation. The upper-layer liquid of the control group was turbid, and its color was similar to or slightly lighter than that of the original protein solution. Among the experimental groups, except that the upper-layer liquid of the experimental group with a rotation speed of 500 r / min was slightly turbid and there were flocculents on the surface of the lower-layer precipitate, the upper-layer liquids of the other experimental groups were relatively clear and the lower-layer precipitates were relatively compact. In addition, the mass (dry weight) of the lower-layer precipitate of the control group at a rotation speed of 12,000 r / min was 0.257 ± 0.037 g (Table 4), which was only 22.36% less than that of the lower-layer precipitate of its experimental group. This might be because the centrifugal force under this condition was large enough so that most of the dry matter in the protein solution formed a precipitate. At this time, adding reagents had an effect on the centrifugal separation of dry matter, but the effect was relatively small. Except for the group under this condition, the lower-layer precipitates of the experimental groups under different centrifugal forces and centrifugation times were 211.14 - 9954.54% higher than those of their control groups. It can be seen that after adding reagents (sodium acid pyrophosphate + calcium chloride) to the protein solution, a centrifugal force of 55 g (500 r / min) - 10,580 g (10,500 r / min) and a centrifugation time of 1.0 - 25.0 min can effectively separate the protein solution and increase the mass of the lower-layer precipitate.

[0104] Table 4. Experimental design and results of the centrifugal force and centrifugation time ranges for the centrifugal separation of protein solution under the condition of the optimal reagent addition amount

[0105]

[0106]

[0107] Note 1: "2.50 mL of 0.8 M sodium acid pyrophosphate + 1.88 mL of 6.0 M calcium chloride" / 100.0 mL of protein solution is the optimal ratio.

[0108] Note 2: **, The experiment was conducted on a bench-top high-speed centrifuge, and the protein solution addition amount in both the control group and the experimental groups was 8.0 mL. *, The experiment was conducted on a floor-standing centrifuge, and the protein solution addition amount in both the control group and the experimental groups was 40.0 mL.

[0109] Note 3: ▲▲, This bench-top high-speed centrifuge was set with a centrifugation time of 1.0 min. Its rotation speed increased from 0 r / min to the set rotation speed, then centrifuged at this rotation speed for 1.0 min, and then the rotation speed gradually decreased to 0 r / min.

[0110] ▲, This floor-standing centrifuge was set with a centrifugation time of 1.0 min. It took 45 s for its rotation speed to increase from 0 r / min to 2500 r / min, then centrifuged at this rotation speed for 15 s, and then the rotation speed gradually decreased to 0 r / min. This is the actual operation of the centrifuge at a set rotation speed of 2500 r / min for 1 min;

[0111] Note 4: During actual operation, the centrifugal force (rotational speed) sometimes fluctuates up and down by about 1%.

[0112] Example 2

[0113] The fish meal obtained by using the method of the present invention was used for a culture experiment. The lower-layer precipitate harvested at the protein water stage during the process of processing fish meal with whole fish as raw materials was used as the fish meal feed raw material, and its role in the culture of fish - Paralichthys olivaceus was experimentally compared and investigated.

[0114] (1) Rearing of Paralichthys olivaceus:

[0115] For the group of lower-layer precipitate harvested by using the method described in the present invention: After 7 days of temporary rearing of Paralichthys olivaceus, 150 fish (body weight 41.5 ± 1.1 g) were randomly taken out and separately cultured in 6 250 L water tanks. Among them, 3 water tanks were used as control groups 1, 2, and 3, and the remaining 3 water tanks were used as experimental groups 1, 2, and 3. During the 56-day experiment period, the water temperature was maintained at 19 ± 2 °C, aerated for 24 h, the water was changed 3 times a day, and the bait was fed 2 times a day (the feed amount was 2% of the body weight of Paralichthys olivaceus). Before feeding, the sewage was siphoned and cleaned.

[0116] (2) The preparation of the bait raw materials is as follows:

[0117] For the group of lower-layer precipitate harvested by using the method described in the present invention: 62.0% fish meal, 5.0% fish oil, 21.0% shrimp meal, 5.0% soybean meal, 5.5% seaweed powder, 1.0% wheat flour, 0.5% mixed vitamins, etc. Among them, the fish meal raw material of the control group used the purchased fish meal, and the fish meal raw material of the experimental group used 50% of the lower-layer precipitate obtained from experimental group 3 - 4 - 4 in Example 2 (dried) + 50% of the purchased fish meal. After mixing and pulverizing various raw materials, they were extruded into shapes to prepare the control group bait and the experimental group bait respectively.

[0118] (3) Before and after the experiment, each fish in each water tank was weighed, and the growth indexes of Paralichthys olivaceus including weight gain rate, specific growth rate, and feed coefficient were calculated. In addition, after weighing at the end of the experiment, 9 fish were randomly taken from each group, dissected on ice, the liver and intestine were taken out, rinsed with physiological saline to remove the blood on the surface, then dried with filter paper and weighed, and the hepatosomatic index and viscerosomatic index were calculated. The required methods are as follows:

[0119] ① Weight gain rate (WGR, %) = 100×(average final body weight of Paralichthys olivaceus - average initial body weight of Paralichthys olivaceus) / average initial body weight of Paralichthys olivaceus;

[0120] ② Specific growth rate (SGR, % / d) = 100×(Ln average final body weight of Paralichthys olivaceus - Ln average initial body weight of Paralichthys olivaceus) / number of feeding days;

[0121] ③ Feed conversion ratio (FCR) = Feed intake / (Average final body weight of Paralichthys olivaceus - Average initial body weight of Paralichthys olivaceus);

[0122] ④ Hepatosomatic index (HSI, %) = 100 × Liver weight / Final body weight of Paralichthys olivaceus;

[0123] ⑤ Viscerosomatic index (VSI, %) = 100 × Visceral weight / Final body weight of Paralichthys olivaceus.

[0124] (4) Test results of the group fed with fish meal prepared from protein hydrolysate

[0125] During the 56-day test, the number of dead Paralichthys olivaceus in control groups 1, 2, 3 and test groups 1, 2, 3 were 3, 2, 3 and 1, 1, and 3 respectively. The average number of dead Paralichthys olivaceus in the control group and the test group were 2.7 ± 0.6 and 1.7 ± 1.2 respectively. It can be seen that there was no significant difference in the breeding safety between the test group and the control group (P > 0.05).

[0126] As one of the most important metabolic organs of Paralichthys olivaceus, the liver plays a very important role in the metabolism of various nutrients such as proteins, lipids, carbohydrates, minerals, etc., and is an important indicator for evaluating the growth health and nutritional status of fish. At the end of the test, the results of the hepatosomatic index and viscerosomatic index of Paralichthys olivaceus are shown in Table 5. The average hepatosomatic index of the control group and the test group were 2.10 ± 0.10% and 1.98 ± 0.08% respectively (P > 0.05), and the average viscerosomatic index were 5.05 ± 0.14% and 4.98 ± 0.18% respectively (P > 0.05). It can be seen that there was also no significant difference in the breeding biological health between the test group and the control group (P > 0.05).

[0127] Table 5. Hepatosomatic index (HSI) and viscerosomatic index (VSI) of Paralichthys olivaceus at the end of the protein hydrolysate fish meal breeding test

[0128] Test group Mean hepatic somatic index (HSI) (%) Mean visceral somatic index (VSI) (%) Control group 1 2.15±0.12 5.01±0.13 Control group 2 1.98±0.10 5.20±0.12 Control group 3 2.16+0.09 4.93±0.10 Experimental group 1 2.05±0.10 5.19±0.16 Experimental group 2 2.01±0.07 4.87±0.13 Experimental group 3 1.89±0.11 4.87±0.10

[0129] The growth and feeding effects of Paralichthys olivaceus are shown in Table 6. The average initial body weights of Paralichthys olivaceus in the control group and the experimental group were 41.4±1.2 g and 41.6±1.1 g (P>0.05), respectively, and the average final body weights were 177.3±3.0 g and 182.6±4.3 g (P>0.05), respectively. The average weight gain rates, average specific growth coefficients, and average feed conversion coefficients of Paralichthys olivaceus in the control group and the experimental group were 328.64±7.09% and 339.11±9.85% (P>0.05), 2.73±0.05% / d and 2.71±0.07% / d (P>0.05), and 1.72±0.03 and 1.74±0.04 (P>0.05), respectively. It can be seen that there was no significant difference between the experimental group and the control group in the growth and feeding effects of Paralichthys olivaceus culture (P>0.05).

[0130] Table 6. Growth and feeding effects of Paralichthys olivaceus cultured with protein hydrolysate fish meal

[0131]

[0132] Example 3 New process for fish meal production (after protein hydrolysate)

[0133] (1) Experimental process, its process flow and total material balance diagram ( Figure 3 )

[0134] ① After adding reagents to the protein hydrolysate, it was centrifuged and separated into supernatant I and precipitate I

[0135] In 4 plastic centrifuge bottles, 400.0 mL of protein hydrolysate was added respectively, and reagents were added (reagents disodium dihydrogen pyrophosphate and calcium chloride were added in the proportion of "2.50 mL (0.445 g) of 0.8 M disodium dihydrogen pyrophosphate + 1.88 mL (1.252 g) of 6.0 M calcium chloride" per 100.0 mL of protein hydrolysate), and then it was centrifuged at 3000 rpm (1980 g) for 3 min and divided into upper and lower layers. The upper layer liquid (referred to as "supernatant I") was collected and its volume was measured, and at the same time, the lower layer precipitate (referred to as "precipitate I") was collected and its mass (wet weight) was weighed, and then it was dried to constant weight at 90 °C and its mass (dry weight) was weighed.

[0136] ② After heating supernatant I, it was naturally sedimented and separated into supernatant II and lower floc

[0137] Mix the upper-layer clear liquid I and heat it to 60 - 65°C, or it can also be 60 - 85°C (subject to the appearance of flocculants floating in the liquid). Aliquot 40.0 mL of the upper-layer clear liquid I into several pre-weighed plastic centrifuge tubes, then let it stand for 20 - 60 min until it separates into upper and lower layers (the time can be extended, and the separation effect gets better as the time prolongs). Collect the upper-layer liquid (referred to as "upper-layer clear liquid II") and the lower-layer flocculants, and measure their volumes. At the same time, weigh the mass of the lower-layer flocculants (liquid). ③ After adding reagents to the lower-layer flocculants (liquid), centrifuge to separate them into upper-layer clear liquid III and lower-layer precipitate III

[0138] Mix the lower-layer flocculants (liquid) in b above. Aliquot them to 40.0 mL in several pre-weighed plastic centrifuge tubes, and add reagents (add sodium dihydrogen pyrophosphate and calcium chloride in the proportion of "1.0 mL (0.178 g) of 0.8 M sodium dihydrogen pyrophosphate + 0.75 mL (0.500 g) of 6.0 M calcium chloride" for every 100.0 mL of flocculants). Then centrifuge at 3000 revolutions per minute (1980 g) for 3 min and it separates into upper and lower layers. Collect the upper-layer liquid (referred to as "upper-layer clear liquid III") and measure its volume. At the same time, collect the lower-layer precipitate (referred to as "lower-layer precipitate III") and weigh its mass (wet weight), and then dry it at 90°C to constant weight and weigh its mass (dry weight).

[0139] ④ Form materials for producing water-soluble fertilizers

[0140] Merge the above-mentioned upper-layer clear liquid II and III as materials for producing water-soluble fertilizers (referred to as "water-soluble fertilizer materials").

[0141] ⑤ Detect the indexes of the above-mentioned protein solution, lower-layer precipitate I, upper-layer clear liquid I, II, and III and other samples

[0142] Respectively take 40.0 mL of protein solution, upper-layer clear liquid I, II, and III and put them into pre-weighed glass petri dishes, weigh them (after subtracting the mass of the petri dish, it is called "wet weight"), dry them to constant weight and then weigh them (after subtracting the mass of the petri dish, it is called "dry weight"). There are 3 parallels for each sample.

[0143] For the above-mentioned protein solution, upper-layer clear liquid I, II, and III, lower-layer flocculants, lower-layer precipitate I, water-soluble fertilizer materials and other samples, detect their crude protein and amino acid contents respectively by GB / T 6432 - 2018 and GB / T 18246 - 2019 (and NY 1429 - 2010), detect the total phosphorus and sodium chloride contents of the samples respectively by GB / T 6437 - 2018 and GB / T 6439 - 2007, and detect the water-insoluble matter content and pH value by NY / T 1973 - 2021.

[0144] (2) Experimental results

[0145] ① Dry matter mass in protein solution

[0146] The wet weight, dry weight after drying (also known as dry matter), and mass of evaporated water of 40.0 mL protein solution are 41.248 ± 0.682 g, 3.590 ± 0.076 g, and 37.658 ± 0.606 g respectively (Table 7). We use this experimental data to represent this protein solution for calculating the energy consumption required for drying the protein solution in the existing process. Thus, the dry matter mass in 400.0 mL protein solution is 35.90 g.

[0147] Table 7. Drying data of 40.0 mL protein solution

[0148]

[0149] ② Material production results of 400.0 protein solution in the new process

[0150] In the above experimental process, 400.0 mL protein solution was centrifuged and separated 4 times. All the experimental results were converted into the amounts of subsequent materials, their dry matter, crude protein, and amino acids produced by 1 400.0 mL protein solution (Tables 8 and 9).

[0151] Table 8. Production flow table of dry matter and crude protein in protein solution of the new process

[0152]

[0153]

[0154] Table 9. Production flow table of amino acids in protein solution of the new process

[0155]

[0156] Note: In Tables 8 and 9:

[0157] A. Add 6.78 g of reagent: 10.0 mL of 0.8 M disodium dihydrogen pyrophosphate (1.78 g) + 7.5 mL of 6.0 M calcium chloride (5.00 g);

[0158] B. The sum of 35.90 g of dry matter in 400 mL protein solution and the amount of added reagent (a) 6.78 g, that is, (35.90 g + 6.78 g);

[0159] C. Add 0.34 g of reagent: 0.40 mL of 0.8 M disodium dihydrogen pyrophosphate (0.071 g) + 0.40 mL of 6.0 M calcium chloride (0.266 g, where the amount of calcium element is 0.266 g × 36.13% = 0.096 g);

[0160] D. Obtained by subtracting the value of the upper supernatant II from the value of the upper supernatant I according to the material balance, such as 22.82 - 16.68 = 6.14;

[0161] E. Obtained by subtracting the value of the upper supernatant III from the value of the lower floc according to the material balance, such as 3.61 - 2.62 = 0.99.

[0162] a. Subsequent materials and quantities for the production of 400.0 mL of protein water

[0163] The amounts of dry matter, crude protein, and amino acids in 400.0 mL of protein water are 35.90 g, 26.36 g, and 16.92 g, respectively (Tables 8 and 9).

[0164] After adding reagents to 400.0 mL of protein water and centrifuging, it is divided into upper and lower layers. The upper layer is 308.5 mL of upper supernatant I, which is semi-clear, semi-transparent, and brown, and the amounts of its crude protein and amino acids are 17.52 g and 10.95 g, respectively. The lower layer is the lower precipitate I, which is grayish-white, and its dry weight and the amount of amino acids are 17.33 g and 6.19 g, respectively, accounting for 40.60% and 36.58% of the amounts of dry matter and amino acids in 400 mL of protein water.

[0165] After heating the upper supernatant I to 60 - 65 °C, a large amount of flocs are produced and dispensed into several centrifuge tubes, with 40.0 mL dispensed into each centrifuge tube. After standing for natural sedimentation for 20 - 60 min, it is divided into upper and lower layers. The upper layer is 234.0 mL of upper supernatant II, which is clear, transparent, and light brownish-yellow, and the amounts of its dry matter, crude protein, and amino acids are 16.68 g, 12.45 g, and 7.30 g, respectively. The lower layer is white flocs (liquid) with a volume of 74.5 mL, and the amounts of its dry matter, crude protein, and amino acids are 6.14 g, 5.04 g, and 3.61 g, respectively.

[0166] After adding reagents to the flocs (liquid) and centrifuging, it is divided into upper and lower layers. The upper layer is 67.0 mL of upper supernatant III, which is clear, transparent, and light green, and the amounts of its dry matter, crude protein, and amino acids are 4.91 g, 3.85 g, and 2.62 g, respectively. The lower layer is the lower precipitate III, which is grayish-white, and its dry weight, crude protein, and amino acids are 1.44 g, 1.18 g, and 0.99 g, respectively.

[0167] b. Materials for directly producing fish meal

[0168] Combining the lower precipitate I and III, the amounts of their dry weight, crude protein, and amino acids are 18.77 g, 8.73 g, and 7.18 g, respectively, accounting for 43.96%, 33.13%, and 42.45% of the dry matter (dry matter in protein water 35.90 g + added reagent 6.78 g), crude protein, and amino acids in the protein water, and then drying to produce fish meal.

[0169] c. Forming water-soluble fertilizer material

[0170] After combining the upper-layer clear liquid II and III, the volume is 301.5 mL. The free amino acid content is measured to be 33.2 g / L, the total phosphorus content is 0.84 g / L, the chloride ion content is 6.0 g / L, the water-insoluble matter content is ≤10 g / L, and the pH value is 5.7. According to the volumes of the upper-layer clear liquid II and III and the amino acid amount, the total nitrogen content of the mixed solution of the upper-layer clear liquid II and III is calculated to be 8.67 g / L. Moreover, through processes such as centrifugal separation and heating-natural sedimentation separation, the mixed solution of the upper-layer clear liquid II and III is a clear and transparent liquid. The comparison results of the water-soluble fertilizer material of the present invention and the indicators of the agricultural industry standard "Water-soluble Fertilizer Containing Amino Acids" NY1429-2010 are shown in Table 10, and this should be very good for making water-soluble fertilizer material.

[0171] Table 10. Comparison of the indicators of the water-soluble fertilizer material of the present invention and the agricultural industry standard "Water-soluble Fertilizer Containing Amino Acids" NY1429-2010

[0172]

[0173] (3) Energy consumption required for the subsequent production of protein water in the new process (part without environmental protection treatment)

[0174] Calculated based on 1000.0 kg of protein water. As can be seen from the above experiments, 400.0 mL of protein water in the new process produced 308.5 mL of upper-layer clear liquid I and 74.5 mL of floccules. Calculated according to this ratio, 1000.0 kg (about 1000.0 mL) of protein water can produce 771.5 kg of upper-layer clear liquid I and 186.5 kg of floccules. Then, the energy consumption required for 1000 kg of protein water in the new process is as follows.

[0175] A. Energy consumption for heating 1000.0 kg of protein water from 60 °C to 80 °C:

[0176] 4.2 kJ / (kg·°C) × (60 °C - 80 °C) × 1000.0 kg = 84.0×10 3 kJ

[0177] B. Energy consumption for centrifugal separation of 1000 kg of protein water:

[0178] 18.5 KW × 0.1 h = 1.85 kWh = 1.85 kWh × 3.6×10 3 kJ / kWh = 6.7×10 3 kJ

[0179] C. Energy consumption for heating 771.5 kg of upper-layer clear liquid I from 25 °C to 65 °C:

[0180] The protein solution produces supernatant I after standing still. At this time, the temperature should be at room temperature, which we set at 25°C.

[0181] 4.2 kJ / (kg·°C) × (65°C - 25°C) × 771 kg = 129.5×10 3 kJ

[0182] D. Energy consumption for centrifugal separation of 771.5 kg of supernatant I:

[0183] 18.5 KW × 0.1 h = 1.85 kWh = 1.85 kWh × 3.6×10 3 kJ / kWh = 6.7×10 3 kJ

[0184] E. Energy consumption for centrifugal separation of 186.5 kg of the lower flocculent substance:

[0185] 18.5 KW × 0.1 h = 1.85 kWh = 1.85 kWh × 3.6×10 3 kJ / kWh = 6.7×10 3 kJ

[0186] F. In the new process, the total energy consumption for producing fish meal powder and water-soluble fertilizer from 1000.0 kg of protein solution:

[0187] 84.0×10 3 kJ + 6.7×10 3 kJ × 3 + 129.5×10 3 kJ = 233.6×10 3 kJ

[0188] (4) Conclusions of the new process

[0189] Using the new process,

[0190] ① From 400 mL of protein solution, the amounts of dry matter, crude protein, and amino acids harvested are 18.77 g, 8.73 g, and 7.18 g respectively, accounting for 43.96%, 33.13%, and 42.45% of the amounts of dry matter, crude protein, and amino acids in 400 mL of protein solution, and are directly used for subsequent production of fish meal;

[0191] ② From 400 mL of protein solution, 301.5 mL of water-soluble fertilizer material is harvested, with 3.32 g / L of amino acids, 8.67 g / L of total nitrogen, 0.84 g / L of total phosphorus, 6.0 g / L of chloride ions, and a pH value of 5.7, which is a very good material for producing amino acid water-soluble fertilizer;

[0192] ③ Calculated based on 1000 kg of protein solution, the energy consumption is 233.6×10 3 kJ, only 4560.9×10 of the energy consumption of the existing production process (corresponding part)3 5.12% of

[0193] Example 4

[0194] Comparison with the existing process - drying protein water to produce dry matter and generating waste gas (environmental problems, energy consumption problems, etc.).

[0195] (1) Experimental process

[0196] Using the same sampled batch of protein water as the new process, the existing production process of fish meal was simulated in the laboratory, that is, drying protein water to harvest fish meal products. Take out the frozen protein water overnight, heat it to 60 - 65 °C the next day, mix well, and pour 40.0 mL of protein water into 9 pre-weighed glass petri dishes respectively. After weighing (the mass of the petri dish + protein water), dry it to constant weight at 90 °C, and then weigh (the mass of the petri dish + dried protein water). The above data are recorded in Table 4-1.

[0197] Collect the dried protein water dry matter, and detect the crude protein and amino acid contents using GB / T 6432-2018 and GB / T 18246-2019 or (and) NY1429-2010.

[0198] From the above data, it can be obtained that:

[0199] (Mass of petri dish + 40.0 mL protein water) - Mass of petri dish = Mass (g) of 40.0 mL protein water (wet weight);

[0200] (Mass of petri dish + dried 40.0 mL protein water) - Mass of petri dish == Mass (g) of 40.0 mL protein water dried to constant weight or Mass (g) of dry matter in 40.0 mL protein water;

[0201] (Mass of petri dish + 40.0 mL protein water) - (Mass of petri dish + dried 40.0 mL protein water) = Mass (g) of water evaporated during drying of 40.0 mL protein water.

[0202] (2) Experimental results

[0203] The wet weight, dried (also known as dry matter), and mass of water evaporated during drying of 40.0 mL protein water (Table 11) are respectively: 40.592 ± 0.473 g, 3.517 ± 0.046 g, and 37.076 ± 0.455 g.

[0204] Table 11. Data of drying 40.0 mL protein water (existing process)

[0205]

[0206] The dry matter of the collected protein solution was dried, and the contents of crude protein and amino acids were measured to be 66.42 g / 100 g and 47.11 g / 100 g, respectively. Therefore, using the existing fish meal production process, 400.0 mL of protein solution can yield 35.17 g of dry matter, 23.36 g of crude protein, and 16.57 g of amino acids.

[0207] The amounts of dry matter, crude protein, and amino acids harvested from 400.0 mL of protein solution using the new process were 18.77 g, 8.73 g, and 7.18 g, respectively, accounting for 53.37%, 37.37%, and 43.33% of the dry matter, crude protein, and amino acids harvested by the existing process. (3) Energy consumption required for the subsequent production of 1000.0 kg of protein solution by the existing process (excluding the environmental protection treatment part)

[0208] Calculated based on 1000.0 kg of protein solution and assuming its temperature is 60 °C, drying can produce 75.816 kg of dry matter and 924.155 kg of water vapor (including the organic gases generated during drying, assuming the mass of organic gases is 20.0 kg). If the protein solution is heated from 60 °C to 100 °C gas and then cooled to 30 °C water, the energy consumption calculation is as follows: [Specific heat capacity of water: 4.2 kJ / (kg·°C), latent heat of vaporization of water: 2257.2 kJ / kg]

[0209] ① Energy consumption during the heating and drying process of the protein solution:

[0210] a. Energy consumption for heating 1000 kg of water from 60 °C to 100 °C:

[0211] 4.2 kJ / (kg·°C) × (100 °C - 60 °C) × 1000.0 kg = 168.0×10 3 kJ

[0212] b. Energy consumption for heating and vaporizing 924.2 kg of water:

[0213] 2257.2 kJ / kg × 924.2 kg = 2086.1×10 3 kJ

[0214] ② Energy consumption during the cooling process of the water vapor:

[0215] Approximately 20 kg of organic gases were released, so the remaining water vapor is 924.2 kg - 20.0 kg = 904.2 kg.

[0216] a. Energy consumption during the cooling and phase change process of the water vapor:

[0217] 2257.2 kJ / kg × 904.2 kg = 2041.0×10 3 kJ

[0218] b. Energy consumption for cooling water from 100 °C to 30 °C:

[0219] 4.2 kJ / (kg·°C) × (100 °C - 30 °C) × 904.2 kg = 265.8×10 3 kJ

[0220] ③ In the existing process, the total energy consumption in the heating and cooling processes of 1000 kg of protein water:

[0221] (168.0 + 2086.1)×10 3 kJ + (2041.0 + 265.8)×10 3 kJ = 4560.9×10 3 kJ.

[0222] Example 5

[0223] Application effect of the amino acid water-soluble fertilizer material produced by the new process

[0224] Microalgae are single-celled seaweeds and are most sensitive to fertilizer products. Two types of microalgae were selected. One is the microalgae without a cell wall - Isochrysis galbana, and the other is the diatom with a cell wall - Chaetoceros. The effects of the amino acid water-soluble fertilizer material of the present invention on the growth of the two types of microalgae were investigated. The amino acid water-soluble fertilizer material is the amino acid water-soluble fertilizer material obtained in Example 3.

[0225] (1) Experimental process

[0226] In 9 500 mL conical flasks, 250 mL of Isochrysis galbana was inoculated with an initial density of 45×10 4 cells / mL. For the 1 - 3rd conical flasks, 0.25 mL of Conway nutrient salt was added to each flask as the control group; for the 4 - 6th conical flasks, 0.25 mL of the amino acid water-soluble fertilizer material was added to each flask as experimental group 1; for the 7 - 9th conical flasks, 0.25 mL of Conway nutrient salt and 0.25 mL of the amino acid water-soluble fertilizer material were added to each flask as experimental group 2.

[0227] For the experiment on the effect on Chaetoceros, except for inoculating Chaetoceros and its initial density of 39×10 4 cells / mL, the others were the same as the Isochrysis galbana experiment.

[0228] The above experiments were cultured at 25 °C in a light incubator with a light / dark cycle of 12 / 12. For the control group and the experimental groups, the algal liquid was taken every day to count the microalgae density.

[0229] (2) Experimental results

[0230] The inoculation densities of the control group, experimental group 1, and experimental group 2 of Isochrysis galbana were 45×10 4cells / mL. From the 8th day to the late exponential growth phase, their densities were (510.7±23.5), (492.0±7.9), and (637.3±12.7)×10 4 cells / mL( Figure 6 ). At this time, there was no significant difference in the microalgae density between the control group and experimental group 1 of Isochrysis galbana (P>0.05), and the microalgae density of experimental group 2 was 24.80% higher than that of the control group.

[0231] The inoculation density of Chaetoceros was 39×10 4 cells / mL. From the 8th day to the late exponential growth phase, their densities were (404.3±7.8), (398.0±14.7), and (495.7±6.5)×10 4 cells / mL( Figure 7 ). At this time, there was no significant difference in the microalgae density between the control group and experimental group 1 of Chaetoceros (P>0.05), and the microalgae density of experimental group 2 was 22.59% higher than that of the control group.

[0232] Comparing the control groups of Isochrysis galbana and Chaetoceros with their experimental group 1, it can be seen that the amino acid water-soluble fertilizer material of the method of the present invention has the same effect on the growth of Isochrysis galbana and Chaetoceros as that of Kangweifang nutrient salts ( Figure 6 and 7 ). Moreover, when adding both Kangweifang nutrient salts and the water-soluble fertilizer material of the present invention, the growth rates of the two microalgae are higher than those when adding a single nutrient salt. It can be seen that the amino acid water-soluble fertilizer of the method of the present invention not only has good safety in the growth and reproduction of microalgae, but also promotes the growth of microalgae.

[0233] The above is only the preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should all be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A fish meal production process, characterized in that, The process mainly includes the following steps: (1) The raw material for the fish meal production process is fish raw material. After steaming, it is pressed to obtain a pressed liquid. The pressed liquid is centrifuged to form surface fish oil, middle-layer protein water, and bottom-layer fish residue. Sodium acid pyrophosphate and calcium chloride are added to the protein water and mixed evenly without heating, and then centrifuged to produce upper-layer clear liquid I and lower-layer precipitate I. The lower-layer precipitate I is collected for subsequent preparation of fish meal. 0.1 - 0.6 g of sodium acid pyrophosphate and 0.4 - 1.7 g of calcium chloride are added to every 100 mL of protein water; (2) The upper-layer clear liquid I obtained in step (1) is heated to 60 - 85 °C to produce flocculants. After standing for more than 20 min, it is separated to produce upper-layer clear liquid II and lower-layer flocculants; (3) After adding sodium acid pyrophosphate and calcium chloride to the lower-layer flocculants obtained in step (2), it is centrifuged to produce upper-layer clear liquid III and lower-layer precipitate III. The lower-layer precipitate III is collected for subsequent preparation of fish meal. 0.2 - 0.6 g of sodium acid pyrophosphate and 0.8 - 1.7 g of calcium chloride are added to every 200 mL of lower-layer flocculants; The conditions for the centrifugation are a centrifugal force of 55 - 13820 g and a centrifugation time of 1.0 - 25.0 min.

2. The production process according to claim 1, characterized in that, It also includes combining the upper-layer clear liquid II obtained in step (2) and the upper-layer clear liquid III obtained in step (3) for the production of water-soluble fertilizer.

3. The production process according to claim 1, characterized in that, The amount of dry matter in the protein water is 2.0 - 10.0 g / 40.0 mL.

4. The production process according to claim 1, wherein In step (3), the amounts of sodium acid pyrophosphate and calcium chloride added to 100 mL of the lower-layer flocculants are 0.178 g and 0.500 g respectively.

5. The process according to claim 1, characterized in that, The system used in the process includes: a liquid storage tank (2), a mixing tank I (11) and a mixing tank II (31), an automatic feeder I (12) and an automatic feeder II (32), and a centrifuge I (13) and a centrifuge II (33); The mixing tank I (11) is connected to the automatic feeder I (12), and the mixing tank I (11) is connected to the centrifuge I (13) through a pipeline; The centrifuge I (13) is provided with an upper-layer clear liquid I output port and a lower-layer precipitate I collection port, and the upper-layer clear liquid I output port is connected to the downstream liquid storage tank (2) through a pipeline; The outer layer of the liquid storage tank (2) is provided with a heating layer, and the bottom of the liquid storage tank (2) is respectively provided with a lower-layer flocculant collection port and an upper-layer clear liquid II collection port; The flocculant collection port is connected to the downstream mixing tank II (31) through a pipeline. The upstream of the mixing tank II (31) is also connected to the automatic feeder II (32) through a pipeline. The reagents in the automatic feeder II (32) are quantitatively transported into the mixing tank II (31). The downstream of the mixing tank II (31) is provided with a centrifuge II (33), and the centrifuge II (33) is provided with an upper-layer clear liquid III output port and a lower-layer precipitate III collection port.

6. The process according to claim 5, characterized in that: Both the automatic feeder I (12) and the automatic feeder II (32) are respectively provided with medicine metering pumps.

7. The process according to claim 5, characterized in that: The heating temperature of the liquid storage tank (2) is 60 - 85 °C; The standing time of the liquid storage tank (2) is 20 - 60 min.

8. The process according to claim 5, characterized in that: Stirring paddles are provided in both the mixing tank I (11) and the mixing tank II (31).

9. The process according to claim 5, characterized in that: A transparent observation window is also provided on the pipe wall of the liquid storage tank (2).

10. The process according to claim 5, characterized in that: The system further includes a cooking machine, a press, and a three-phase horizontal centrifuge; the press is arranged downstream of the cooking machine, the press is provided with a cake collection port, and a pressed liquid collection port is arranged on the other side; the pressed liquid collection port is connected to the three-phase horizontal centrifuge through a pipeline; a surface fish oil output port, a middle protein water output port, and a bottom fish residue output port are arranged downstream of the three-phase horizontal centrifuge; wherein, a centrifuge is arranged downstream of the fish oil output port; the protein water output port and the protein water output port of the three-phase horizontal centrifuge are gathered through a pipeline and then input downstream.

11. The process according to claim 5, characterized in that: The downstream of the pipeline for conveying the upper layer clear liquid II is connected to the downstream of the pipeline for the upper layer clear liquid III, and they are gathered into a water-soluble fertilizer material conveying pipeline.

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