A process for harvesting dry matter in fish meal production

Abstract

The application discloses a process for harvesting dry matter in fish meal production. The process is as follows: after cooking fish raw materials, squeezing the cooked fish raw materials to obtain squeezing liquid, centrifuging the squeezing liquid to obtain middle layer protein water; in the above process, 0.1-0.8 g of sodium dihydrogen pyrophosphate and 0.05-3.0 g of calcium chloride are added to each 100 mL of the squeezing liquid / protein water; more lower layer precipitate can be obtained by centrifugation, which is good in safety and breeding effect evaluation as fish meal raw material, solves the problems of environmental pollution (odorous gas pollutes the air environment) and organic wastewater caused by subsequent processing of traditional protein water; the investment cost of large equipment (cooling equipment) is greatly reduced; the energy consumption problems of a large amount of water vapor and volatile organic odorous gas generated by drying protein water and subsequent cooling water vapor are greatly reduced; and the high energy consumption problem of subsequent processing of protein water is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of fish meal production, and particularly relates to a process method for optimizing and improving the harvesting of dry matter from press liquor / protein water in the existing fish meal production process. BACKGROUND

[0002] Fish meal is a product obtained by cooking, pressing, drying, and crushing after taking the whole fish (including shrimp and other aquatic animals) or the remaining part of the processed fish product as raw material. Fish meal is a main animal protein raw material required by farmed animals. At present, about 1.5 million tons of fish meal are imported in China every year, and about 1 million tons are produced every year, which are concentrated in Liaoning, Shandong, Zhejiang, Fujian, Guangdong, Guangxi and other coastal areas.

[0003] At present, the fish meal production process is basically as shown in Figure 1 , which is also the basic process of fish meal production in China at present, that is, raw material-cooking-pressing-centrifugal separation-drying-crushing, etc. In the pressing link, juice (also known as press liquor) and press cake are produced, and then the press liquor is centrifugally separated to form the surface layer of crude fish oil, the middle layer of protein water, and the bottom layer of fish residue. Among them, the bottom layer of fish residue becomes fish meal (fish meal and fish oil) Figure 1 and Figure 2 after drying, processing, etc., which is also the part that the production enterprises hope to harvest more. However, the dry matter content in the press liquor is only about 10%, and the separation and harvesting of the dry matter therein have always been a difficulty for enterprises to improve the efficiency of fish meal production, which is also a problem that technicians in the field care about but cannot effectively solve, that is, how to improve the harvesting of the lower layer dry matter in the press liquor under the premise of as low cost as possible.

[0004] Furthermore, from the fish meal production material balance chart (material balance chart) Figure 2 , it can be seen that the mass of the protein water produced accounts for more than 50% of the mass of the raw fish, and the protein water contains nutrients such as protein, polypeptide, and amino acid as main components. Therefore, enterprises have not found a better processing scheme for the subsequent processing of the protein water (protein water processing scheme) Figure 2First, direct discharge could lead to both wasted resources (proteins, peptides, amino acids, etc.) and environmental pollution. If direct drying or preliminary concentration followed by drying is used to harvest the protein, the process typically involves heating the protein water to evaporate most of the water and volatile organic compounds (VOCs). The dried material is then used to produce fishmeal. The water vapor and VOCs are then cooled to become liquid, during which some water vapor and VOCs are released outdoors, polluting the air, especially since VOCs have an unpleasant odor. Environmental engineering techniques are then used to treat the cooled wastewater containing organic matter. This process is energy-intensive and pollutes the environment. Third, deep concentration of the protein water to produce fish slurry is another option. This method is very costly in terms of equipment and energy consumption, and even after concentration, the water content remains around 50%, making it highly uneconomical. How to efficiently and efficiently separate and harvest the dry matter (nutrients) from the protein water is also a pressing need for fishmeal producers and a problem that researchers in this field urgently need to solve. Summary of the Invention

[0005] The purpose of this invention is to provide a process for harvesting dry matter in fishmeal production; including a process for harvesting dry matter from the pressing liquor in fishmeal production, and an energy-saving and environmentally friendly process for harvesting dry matter from protein water. This process is achieved through the following technical solution: fish raw materials are steamed and then pressed to obtain pressing liquor; the pressing liquor is centrifuged to separate a surface layer of fish oil, a middle layer of protein water, and a bottom layer of fish residue; the protein water is concentrated / dried to form dry matter, which is then dried together with the bottom layer of fish residue to produce fishmeal. Figure 1 and Figure 2 In the above process, disodium dihydrogen pyrophosphate and calcium chloride are added to the pressing liquor and / or protein water respectively, mixed well, and the precipitate (dry matter) is collected by centrifugation for the preparation of fishmeal. The addition of disodium dihydrogen pyrophosphate and calcium chloride has the technical effect of improving the quality of the dry matter separated by centrifugation from the pressing liquor / protein water, reducing energy consumption, and reducing waste gas emissions. The addition ratio is: 0.1–0.8 g of disodium dihydrogen pyrophosphate and 0.05–3.0 g of calcium chloride per 100 mL of pressing liquor / protein water.

[0006] For the technical solution described above, the dry matter content of the pressed liquor / protein water generally varies in the range of 0.5 to 15.0 g / 40.0 mL; a further preferred range is 1.0 to 12.0 g / 40.0 mL; more preferably 2.0 to 8.0 g / 40.0 mL; even more preferably 2.5 to 7.5 g / 40.0 mL; and most preferably 3.0 to 7.0 g / 40.0 mL.

[0007] The amount of dry matter in the pressed liquid / protein water is usually mainly related to the type of fish raw material, its freshness, and the conditions of steaming, pressing and other processes in the production process. The fish raw material mentioned in this application can be selected from whole fish or part of the fish body (for example, the remaining part after processing the whole fish into fish products, including but not limited to fish viscera, fish head, fish tail, etc.).

[0008] In a further preferred embodiment of the above-described technical solution, the amount of disodium dihydrogen pyrophosphate added to the pressed liquid / protein water is 0.1–0.7 g / 100 mL; more preferably, it is 0.2–0.6 g / 100 mL.

[0009] In a further preferred embodiment of the above-described technical solution, the amount of calcium chloride added to the pressed liquid / protein water is 0.1–2.3 g / 100 mL; more preferably, it is 0.15–2.0 g / 100 mL; even more preferably, it is 0.4–1.8 g / 100 mL; and even more preferably, it is 0.8–1.7 g / 100 mL.

[0010] In a further preferred embodiment of the above-described technical solution, the centrifugation conditions are as follows: centrifugal force (also known as separation factor, RCF) 55–13820 g (corresponding to centrifuge speed RPM, 500–12000 rpm), centrifugation time 1.0–25.0 min (extending the time can increase the mass of the lower layer of dry matter); after centrifugation, the pressed liquor is separated into an upper layer (a thin layer of oil), a middle layer (aqueous solution), and a lower layer (precipitate), wherein the mass of dry matter obtained after drying the lower layer precipitate in the experimental group is 43.13–387.23% higher than that in the control group (pressed liquor only); after centrifugation, the protein water is separated into an upper layer (aqueous solution) and a lower layer (precipitate), wherein the mass of dry matter obtained after drying the lower layer precipitate in the experimental group is 28.79–9954.54% higher than that in the control group (protein water only).

[0011] For the technical solution described above, in a further preferred embodiment, the centrifugal force is 115 g (RPM, 750 rpm) to 7770 g (9000 rpm) and the centrifugation time is 1.0 to 15.0 min; more preferably, the centrifugal force is 115 g (750 rpm) to 3520 g (4200 rpm) and the centrifugation time is 1.0 to 15.0 min; even more preferably, the centrifugal force is 225 g (1000 rpm) to 3520 g (4200 rpm) and the centrifugation time is 1.0 to 10.0 min;

[0012] This invention utilizes existing centrifugal separation equipment to add calcium chloride and disodium dihydrogen pyrophosphate to the press liquor / protein water. Without changing the investment cost, it allows for the harvesting of more lower sediment (i.e., dry matter) from the press liquor / protein water for subsequent processing (typically drying into fishmeal). Furthermore, using the above-mentioned method of this invention, the separation and acquisition of the upper oil (fish oil) is almost unaffected. Simultaneously, it significantly reduces the amount of moisture and volatile organic compounds (VOCs) in the drying (protein water), as well as the equipment required for cooling water vapor and VOCs. Moreover, the dry matter content in the press liquor and / or protein water is lower, and the harvested lower sediment (i.e., dry matter) is a mixture of fish meat, fish bones, fish scales, fish viscera, etc., which is dried to produce fishmeal. Therefore, in the experiment, the volume of the press liquor and / or protein water was the primary consideration, and the amount of calcium chloride and disodium dihydrogen pyrophosphate added was determined accordingly.

[0013] Compared with the prior art, the present invention has the following beneficial effects:

[0014] 1. The best results of this invention are as follows: under the optimal reagent / pressed liquor or protein water ratio ("0.8M disodium dihydrogen pyrophosphate 1.00mL + 6.0M calcium chloride 0.75mL" / 40.0mL pressed liquor or protein water), the mass of the lower sediment (dry weight) in the pressed liquor experimental group is about 3.4 times higher than that in the control group (existing production process); the mass of the lower sediment (dry weight) in the protein water experimental group is about 61.6 times higher than that in the control group.

[0015] 2. The centrifugal force and centrifugation time of the method of the present invention have a wide range of applicability and a wide range of stable effects.

[0016] Within a wide range of centrifugal forces (55–13820 g) and centrifugation times (1.0–25.0 min), the mass of the lower precipitate dry matter obtained was significantly higher than that of the control group (43.13–387.23% higher in the experimental group of pressed liquor than the control group; 28.79–9954.54% higher in the experimental group of protein water than the control group) and remained stable; moreover, the amount of lower precipitate obtained increased with the extension of centrifugation time.

[0017] 3. The safety and aquaculture effect of the lower sediment harvested by the method of the present invention as a raw material for fishmeal have been evaluated as good.

[0018] (1) The lower sediment is harvested during the processing of fishmeal from whole fish and used as a raw material for fishmeal feed. In the example, a safety evaluation was conducted using 150 flounder as experimental subjects, which proved that there was no significant difference between the experimental group and the control group in terms of aquaculture safety (P>0.05), the health of aquaculture organisms (P>0.05), and the growth and feeding effects of flounder (P>0.05).

[0019] (2) The lower sediment collected during the processing of whole fish products (including but not limited to fish viscera, fish head, fish tail, etc.) and fish meal as raw materials is used as fish meal raw material. In the example, 60 juvenile sea cucumbers were raised for 28 days. From the perspective of the growth performance indicators of juvenile sea cucumbers, there was no significant difference in safety and breeding effect between the experimental group and the control group (the juvenile sea cucumber feed was prepared by purchasing commercial fish meal as raw material) (P>0.05).

[0020] 4. It solves the problems of environmental pollution (unpleasant gases polluting the air) and organic wastewater caused by the subsequent processing of protein water in traditional methods; it significantly reduces the investment cost of large-scale equipment (cooling equipment); it significantly reduces the energy consumption problems of large amounts of water vapor and volatile organic unpleasant gases generated during the drying of protein water, as well as the energy consumption problems of subsequent cooling water vapor; and it solves the high energy consumption problem of subsequent protein water treatment. Attached Figure Description

[0021] Figure 1 This is a material balance diagram for fishmeal production in existing technology;

[0022] Figure 2 This is a flow chart of the fishmeal production process in existing technology;

[0023] Figure 3. Comparison photos of the pressed liquid before and after centrifugation; among them, blank group (40.0 mL of sterile deionized water with "sodium dihydrogen pyrophosphate + calcium chloride"), control group (40.0 mL of pressed liquid), and experimental group 3 (40.0 mL of pressed liquid with "sodium dihydrogen pyrophosphate + calcium chloride").

[0024] Figure 4 Comparison photos of protein water before and after centrifugation; including blank group (40.0 mL sterile deionized water with added "sodium dihydrogen pyrophosphate + calcium chloride"), control group (40.0 mL protein water), and experimental group (40.0 mL protein water with added "sodium dihydrogen pyrophosphate + calcium chloride"). Detailed Implementation

[0025] The present invention will be further described below with reference to the embodiments, but it should be understood that the scope of protection of the present invention is not limited to the embodiments.

[0026] In this embodiment of the invention, unless otherwise explicitly stated, percentages and contents are all expressed by mass. Unless otherwise specified, the experimental methods used are conventional methods, and the materials and reagents used are commercially available.

[0027] All reagents used in the embodiments of this invention are feed-grade or / and food-grade, and the water used is sterile deionized water;

[0028] In the embodiments of this invention, "disodium dihydrogen pyrophosphate" refers to a 0.8M aqueous solution of disodium dihydrogen pyrophosphate.

[0029] "Calcium chloride" refers to a 6.0M aqueous solution of calcium chloride;

[0030] The raw materials for the pressed liquid and protein water used in the embodiments of the present invention are as follows: (1) Pressed liquid and protein water made from whole fish, which are fresh pressed liquid and protein water produced during the production of fishmeal at a fishmeal factory in Dalian. They are sent back to the laboratory within 4 hours, packaged, and frozen. (2) Pressed liquid and protein water made from fish heads, tails, viscera, etc., are fresh pressed liquid and protein water produced in the laboratory according to the fishmeal production and processing process, packaged, and frozen. Before use, the frozen pressed liquid / protein water is taken out, left at room temperature overnight (with small ice cubes), heated, and shaken well before use. The pressed liquid was tested and found to have a dry matter content between 2.70 and 7.48 g / 40.0 mL. The protein water was tested and found to have a dry matter content between 3.12 and 5.09 g / 40.0 mL.

[0031] The method for determining the dry matter content described in the following embodiments of the present invention is as follows: During the experiment, 40.0 mL of the pressed liquid / protein water was taken separately and poured into glass petri dishes, and dried at 90°C to constant weight. The dry matter content of the pressed liquid / protein water was then weighed and calculated.

[0032] The dry matter content of the pressed liquor used in the following embodiments of the present invention was 6.50 g / 40 mL, and the dry matter content of the protein water used was 3.50 g / 40 mL. Each group had 3 parallel samples, expressed as mean ± standard deviation, and one-way ANOVA was used.

[0033] The press liquor and protein water used in this invention embodiment were obtained from the aforementioned fishmeal factory in multiple batches. Each batch of press liquor and protein water was tested separately and not mixed. The whole fish used in each batch included, but was not limited to, the following species: anchovies, sardines, mackerel, cod, flounder, etc., with similar experimental results. Fish viscera, heads, tails, etc., were extracted from the whole fish of anchovies, sardines, mackerel, cod, flounder, etc., with similar experimental results.

[0034] The main differences in the main substances contained in the pressing liquid (juice) and protein water used in the embodiments of the present invention are shown in Table 1 below:

[0035] Table 1. Main components of press liquor and protein water

[0036]

[0037] Following a similar method to Examples 1 or 2 described below, tests were conducted on press liquor and protein water with dry matter content of 2.7 g / 40 mL or 7.48 g / 40 mL. The optimal reagent / press liquor or protein water ratio (0.8 M disodium dihydrogen pyrophosphate 1.00 mL + 6.0 M calcium chloride 0.75 mL / 40.0 mL press liquor or protein water) was added. The results were consistent with those of Example 1, demonstrating that the lower precipitate dry matter mass obtained was approximately 25–10000% higher than the control group, even with a wide range of centrifugal forces (55–13820 g) and centrifugation times (1.0–25.0 min).

[0038] Example 1

[0039] Reagents and amounts added before centrifugation to separate the pressed liquor

[0040] (1) Design of experimental groups (Table 2)

[0041] ① Preparation of blank groups 1, 2 and 3: Add 40.0 mL of sterile deionized water to 9 50.0 mL plastic centrifuge tubes. Add sodium dihydrogen pyrophosphate to 3 of them as blank group 1, add calcium chloride to 3 of them as blank group 2, and add "sodium dihydrogen pyrophosphate + calcium chloride" to the remaining 3 as blank groups 1, 2 and 3 respectively.

[0042] ② Preparation of control group, experimental groups 1, 2, and 3: 40.0 mL of the pressed liquid was added to several 50.0 mL plastic centrifuge tubes. The group without any reagents other than the pressed liquid served as the control group; the group with the addition of disodium dihydrogen pyrophosphate (DHP) served as experimental group 1; the group with the addition of calcium chloride served as experimental group 2; and the group with the addition of both disodium dihydrogen pyrophosphate and calcium chloride served as experimental group 3.

[0043] (2) Centrifuge tubes of the blank group, control group and experimental group were centrifuged at 1375 g (2500 rpm) for 5 min. After taking out the centrifuge tubes for observation, the lower precipitate was dried to constant weight and then weighed.

[0044] (3) Take 40.0 mL of the pressed liquid and put it into a glass petri dish. Weigh it (after subtracting the mass of the petri dish, it is called "wet weight of pressed liquid"). Dry it to constant weight and weigh it (after subtracting the mass of the petri dish, it is called "dry weight of pressed liquid").

[0045] (4) Experimental results:

[0046] No precipitate formed in blank groups 1, 2, and 3; that is, the liquids before and after centrifugation were clear and transparent, as can be seen from the results in Table 2.

[0047] After centrifugation, the control group (pressed liquid) separated into an upper layer (a thin layer of oil), a middle layer (aqueous solution), and a lower layer (precipitate). The middle layer of liquid remained turbid, and the average mass of the lower layer of precipitate after drying was 0.634g ± 0.038g.

[0048] Experimental group 1 (pressed liquor with added disodium dihydrogen pyrophosphate) was also separated into upper, middle and lower layers after centrifugation. As shown in Table 2, there was no significant difference in the mass of the sediment in experimental groups 1-1, 1-2, 1-3, 1-4 and 1-5 compared with the control group (P>0.05).

[0049] Experimental group 2 (calcium chloride added to the pressing liquid) was also separated into upper, middle and lower layers after centrifugation. As the amount of calcium chloride added increased, the mass of the lower layer precipitate also increased (Table 2). The mass of experimental groups 2-1, 2-2, 2-3, 2-4 and 2-5 increased by 28.55%, 28.86%, 61.99%, 87.70% and 115.77% respectively compared with the control group.

[0050] Experimental group 3 (with disodium dihydrogen pyrophosphate and calcium chloride added to the pressing liquid) investigated the synergistic effect of calcium chloride and disodium dihydrogen pyrophosphate in separating the pressing liquid. After centrifugation, the same upper layer (a thin layer of oil), middle layer (aqueous solution) and lower layer (precipitate) were formed. In some groups, the middle layer liquid became clear (with slight flocculent matter). Moreover, the mass of the lower layer precipitate was not only increased compared with the control group, but also increased compared with the corresponding groups in experimental group 2 that added the same amount of calcium chloride. Even in the experimental groups with the lowest addition of disodium dihydrogen pyrophosphate (3-1-1, 3-2-1, 3-3-1, 3-4-1, and 3-5-1), the mass of the lower precipitate in experimental group 3-1-1 was 9.57% higher than that in experimental group 2-1 (all with 0.10 mL of calcium chloride), showing a significant difference (P<0.05). The lower precipitate volumes in experimental groups 3-2-1, 3-3-1, 3-4-1, and 3-5-1 were 27.29%, 18.99%, 19.08%, and 14.62% higher than those in experimental groups 2-2, 2-3, 2-4, and 2-5 with the corresponding amounts of calcium chloride, respectively, all showing highly significant differences (P<0.01). Therefore, the synergistic effect of disodium dihydrogen pyrophosphate and calcium chloride significantly improves the quality of the lower precipitate in the centrifuged press liquor. Furthermore, under the same calcium chloride addition conditions, the mass of the lower precipitate obtained by centrifugation increased significantly with the increase of disodium dihydrogen pyrophosphate addition. Under the optimal reagent addition ratio (1.00 mL disodium dihydrogen pyrophosphate + 0.75 mL calcium chloride), experimental group 3-4-4 obtained 3.37 times more lower precipitate than the control group and 1.33 times more than experimental group 2-4, which only added 0.75 mL calcium chloride. This further demonstrates that the synergistic effect of disodium dihydrogen pyrophosphate and calcium chloride significantly improves the mass of the lower precipitate in the centrifuged press liquor.

[0051] Table 2. Experimental design and results of centrifugation (2500 r / 1375 g, 5 min) of pressed liquor (reagents and their dosage range)

[0052]

[0053] Note: 1. For each experimental group in the blank group, the amount of sterile water added was 40.0 mL;

[0054] 2. For each experimental group, the amount of pressed liquid added was 40.0 mL.

[0055] In Table 2, disodium dihydrogen pyrophosphate refers to a 0.8M disodium dihydrogen pyrophosphate solution.

[0056] In Table 2, calcium chloride refers to a calcium chloride solution with a concentration of 6.0 M.

[0057] Example 2

[0058] Reagents and amounts added before centrifugation to separate protein water

[0059] (1) Design of experimental groups (Table 3)

[0060] ① Preparation of blank groups 1, 2 and 3: Add 40.0 mL of sterile deionized water to 9 50.0 mL plastic centrifuge tubes. Add sodium dihydrogen pyrophosphate to 3 of them as blank group 1, add calcium chloride to 3 of them as blank group 2, and add "sodium dihydrogen pyrophosphate + calcium chloride" to the remaining 3 as blank groups 1, 2 and 3 respectively.

[0061] ② Preparation of control group, experimental groups 1, 2, and 3: 40.0 mL of protein-rich water was added to several 50.0 mL plastic centrifuge tubes. The group without any reagents other than protein-rich water served as the control group; the group with disodium dihydrogen pyrophosphate added (in addition to protein-rich water) served as experimental group 1; the group with calcium chloride added served as experimental group 2; and the group with both disodium dihydrogen pyrophosphate and calcium chloride served as experimental group 3.

[0062] (2) Centrifuge tubes of the blank group, control group and experimental group were centrifuged at 1375 g (2500 rpm) for 3 min. After taking out the centrifuge tubes for observation, the lower precipitate was dried to constant weight and then weighed.

[0063] (3) Take 40.0 mL of protein water, put it into a glass culture dish, weigh it (after subtracting the mass of the culture dish, it is called "wet weight of protein water"), dry it to constant weight and weigh it (after subtracting the mass of the culture dish, it is called "dry weight of protein water").

[0064] (4) Experimental results:

[0065] No precipitate was formed in blank group 1, 2 and 3 samples, meaning that they were clear and transparent liquids before and after centrifugation, as can be seen from the results in Table 3.

[0066] After centrifugation, the control group (protein water) sample showed almost no layering and its color was almost identical to that of the original protein water. After centrifugation, the upper liquid was poured off, and the lower precipitate was dried. The average mass of the precipitate was 0.032g ± 0.003g.

[0067] After centrifugation, the sample in experimental group 1 (protein water with added disodium dihydrogen pyrophosphate) was slightly separated into upper and lower layers. The color of the upper liquid was almost indistinguishable from that of the original protein water, while the lower precipitate contained very little. After the upper liquid was poured off, the mass of the lower precipitate after drying is shown in Table 3. The mass of the lower precipitate in 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 to the control group.

[0068] After centrifugation, the sample in experimental group 2 (protein water with added calcium chloride) separated into upper and lower layers. The upper liquid was significantly lighter in color than the original protein water but still turbid. The mass of the lower precipitate increased with increasing calcium chloride addition (Table 3). The mass of the lower precipitate in experimental groups 2-1, 2-2, 2-3, 2-4, and 2-5 after drying increased by 546.87%, 1187.50%, 1693.75%, 2453.12%, and 2843.75% respectively compared to the control group. Moreover, the dry weight of the lower precipitate in experimental group 2 was significantly higher than that in experimental group 1.

[0069] Experimental group 3 (protein water with added disodium dihydrogen pyrophosphate and calcium chloride) investigated the synergistic effect of calcium chloride and disodium dihydrogen pyrophosphate in separating dry matter in protein water. After centrifugation, two layers were formed, with the upper liquid being basically clear and some samples containing slight flocculent matter. The mass of the lower precipitate was significantly increased compared to the control group. More importantly, the dry weight of the lower layer precipitate in experimental group 3 was significantly higher than that in experimental group 2 when the same amount of calcium chloride was added. Furthermore, even in experimental group 3, the groups with the lowest amounts of disodium dihydrogen pyrophosphate (3-1-1, 3-2-1, 3-3-1, 3-4-1, and 3-5-1) showed significantly higher lower layer precipitate masses than experimental groups 2-1 (0.10 mL calcium chloride), 2-2 (0.25 mL calcium chloride), 2-3 (0.50 mL calcium chloride), 2-4 (0.75 mL calcium chloride), and 2-5 (1.00 mL calcium chloride), respectively (P < 0.01). This demonstrates that the synergistic effect of disodium dihydrogen pyrophosphate and calcium chloride significantly improved the quality of the lower layer precipitate in centrifuged protein water. Furthermore, under the same calcium chloride addition conditions, the mass of the lower precipitate obtained by centrifugation increased significantly with the increase of disodium dihydrogen pyrophosphate addition. Under the optimal reagent addition ratio (1.00 mL disodium dihydrogen pyrophosphate + 0.75 mL calcium chloride), the lower precipitate obtained by centrifugation in experimental group 3-4-4 increased by 61.6 times compared to the control group, by 8.36 times compared to experimental group 1-4 which only added 1.00 mL disodium dihydrogen pyrophosphate, and by 1.45 times compared to experimental group 2-4 which only added 0.75 mL calcium chloride. This further demonstrates that the synergistic effect of disodium dihydrogen pyrophosphate and calcium chloride significantly improves the mass of the lower precipitate in centrifuged protein water.

[0070] Table 3. Experimental design and results of protein separation by centrifugation (2500 r / 1375 g, 3 min) (reagents and their dosage ranges)

[0071]

[0072] Note: 1. For each experimental group in the blank group, the amount of sterile water added was 40.0 mL;

[0073] 2. For each experimental group, the amount of protein water added was 40.0 mL.

[0074] In Table 3, disodium dihydrogen pyrophosphate refers to a 0.8M disodium dihydrogen pyrophosphate solution.

[0075] In Table 3, calcium chloride refers to a calcium chloride solution with a concentration of 6.0 M.

[0076] Example 3

[0077] Under optimal reagent ratios, the centrifugal force and centrifugation time required for centrifugal separation of the pressed liquid.

[0078] (1) For experiments with centrifugal speeds of 500 rpm (centrifugal force 55 g) to 4200 rpm (centrifugal force 3520 g), a floor-standing centrifuge was used, and 40.0 mL of the pressed liquid was added to each 50.0 mL plastic centrifuge tube. For experiments with centrifugal speeds of 7000 rpm (centrifugal force 4700 g) to 12000 rpm (centrifugal force 13820 g), a benchtop centrifuge was used, and 8.0 mL of the pressed liquid was added to each 10.0 mL plastic centrifuge tube. The control group was the group that did not add any reagents other than the pressed liquid. The experimental group was the group that added reagents ("0.8M disodium dihydrogen pyrophosphate 2.50 mL + 6.0M calcium chloride 1.88 mL" / 100.0 mL pressed liquid). The control group and experimental group 1 to 12 were divided into different groups according to the centrifugal force and centrifugation time. The specific experimental design and results are shown in Table 4. After centrifugation, remove the centrifuge tube for observation, then dry the lower precipitate until constant weight and weigh it.

[0079] (2) Take 40.0 mL of the pressed liquid and put it into a glass petri dish. Weigh it (after subtracting the mass of the petri dish, it is called "wet weight of pressed liquid"). Dry it to constant weight and weigh it (after subtracting the mass of the petri dish, it is called "dry weight of pressed liquid").

[0080] (3) Experimental results

[0081] In both the control and experimental groups under all experimental conditions, centrifugation resulted in the formation of an upper layer (a thin layer of oil), a middle layer (aqueous solution), and a lower layer (precipitate). The middle layer of the control group was turbid, while the middle layer of the experimental group (centrifugation speed 500 rpm) was slightly turbid, while the middle layers of the other experimental groups were relatively clear. Table 4 shows that the lower precipitate content of the experimental groups under different centrifugation forces and times was 43.13–387.23% higher than that of the control group. This indicates that adding the reagent (disodium dihydrogen pyrophosphate + calcium chloride) to the pressing liquor, with centrifugation forces of 55–13820 g and centrifugation times of 1.0–25.0 min, can efficiently separate the pressing liquor and increase the mass of the lower precipitate.

[0082] Table 4. Experimental design and results of centrifugal force and centrifugation time range for centrifugation of press liquor under optimal reagent addition conditions.

[0083]

[0084] Note 1: The optimal ratio is "2.50 mL of 0.8M disodium dihydrogen pyrophosphate + 1.88 mL of 6.0M calcium chloride" / 100.0 mL of pressed liquor.

[0085] Note 2: **, The experiment was conducted using a benchtop high-speed centrifuge, and the amount of pressed liquid added to both the control group and the experimental group was 8.0 mL.

[0086] *In the experiment conducted using a floor-standing centrifuge, the amount of pressed liquid added to both the control and experimental groups was 40.0 mL.

[0087] Note 3: ▲▲, This benchtop high-speed centrifuge is set to a centrifugation time of 1.0 min. Its speed increases from 0 rpm to the set speed, and then it is centrifuged at this speed for 1.0 min. After that, the speed gradually decreases back to 0 rpm.

[0088] ▲This floor-standing centrifuge is set to a 1.0-minute centrifugation time. It takes 45 seconds for the speed to increase from 0 rpm to 2500 rpm, then it centrifuges at this speed for 15 seconds, after which the speed gradually decreases to 0 rpm. This is the actual operating condition of the centrifuge at a speed of 2500 rpm for 1 minute.

[0089] Note 4: In actual operation, the centrifugal force (speed) may fluctuate by about 1%.

[0090] Example 4

[0091] Under optimal reagent ratio conditions, the centrifugal force and centrifugation time required for separating protein water by centrifugation;

[0092] (1) For experiments with centrifugal speeds of 500 rpm (centrifugal force 55 g) to 4200 rpm (centrifugal force 3520 g), a floor-standing centrifuge was used, and 40.0 mL of protein water was added to each 50.0 mL plastic centrifuge tube; for experiments with centrifugal speeds of 7000 rpm (centrifugal force 4700 g) to 12000 rpm (centrifugal force 13820 g), a benchtop centrifuge was used, and 8.0 mL of protein water was added to each 10.0 mL plastic centrifuge tube. The control group consisted of no reagents added except for protein water; the experimental group consisted of reagents added (using "0.8M disodium dihydrogen pyrophosphate 2.50 mL + 6.0M calcium chloride 1.88 mL" / 100.0 mL protein water). Based on the centrifugal force and centrifugation time, the groups were divided into control and experimental groups 1–14. Specific experimental designs and results are shown in Table 5. After centrifugation, the centrifuge tubes were removed for observation, and the lower precipitate was dried to constant weight and then weighed.

[0093] (2) Take 40.0 mL of protein water and put it into a glass culture dish. Weigh it (after subtracting the mass of the culture dish, it is called "wet weight of protein water"). Dry it until constant weight and weigh it (after subtracting the mass of the culture dish, it is called "dry weight of protein water").

[0094] (3) Experimental results

[0095] In both the control and experimental groups under all experimental conditions, a supernatant (liquid) and a sub-sediment (precipitate) were formed after centrifugation. The supernatant of the control group was turbid, with a color similar to or slightly lighter than the original protein water. In the experimental groups, except for the 500 rpm group where the supernatant was slightly turbid and the surface of the sub-sediment had flocculent matter, the supernatant of the other experimental groups was relatively clear and the sub-sediment was relatively compact. Furthermore, the sub-sediment mass (dry weight) of the control group at 12000 rpm was 0.257 ± 0.037 g (Table 5), only 22.36% less than that of the experimental groups. This may be because the centrifugal force under this condition was sufficiently high, causing most of the dry matter in the protein water to precipitate. In this case, adding reagents would help separate the dry matter, but the effect would be relatively small. Apart from this group, the sub-sediment mass of the experimental groups under different centrifugal forces and times was 211.14–9954.54% higher than that of the control group. It is evident that adding reagents (sodium dihydrogen pyrophosphate + calcium chloride) to protein water and centrifuging at a force of 55 g (500 rpm) to 10580 g (10500 rpm) and a centrifugation time of 1.0 to 25.0 min can effectively separate protein water and increase the mass of the lower precipitate.

[0096] Table 5. Experimental design and results of centrifugal force and centrifugation time range for protein-water separation under optimal reagent addition conditions.

[0097]

[0098] Note 1: The optimal ratio is "2.50 mL of 0.8M disodium dihydrogen pyrophosphate + 1.88 mL of 6.0M calcium chloride" / 100.0 mL of protein water.

[0099] Note 2: **, The experiment was conducted in a benchtop high-speed centrifuge, and the amount of protein water added to both the control group and the experimental group was 8.0 mL.

[0100] * In an experiment conducted in a floor-standing centrifuge, the amount of protein water added to both the control and experimental groups was 40.0 mL.

[0101] Note 3: ▲▲, This benchtop high-speed centrifuge is set to a centrifugation time of 1.0 min. Its speed increases from 0 rpm to the set speed, and then it is centrifuged at this speed for 1.0 min. After that, the speed gradually decreases back to 0 rpm.

[0102] ▲ This floor-standing centrifuge is set to a 1.0-minute centrifugation time. It takes 45 seconds for the speed to increase from 0 rpm to 2500 rpm, then it centrifuges at that speed for 15 seconds before gradually decreasing to 0 rpm. This is the actual operating condition of the centrifuge at a speed of 2500 rpm for 1 minute.

[0103] Note 4: In actual operation, the centrifugal force (speed) may fluctuate by about 1%.

[0104] Example 5

[0105] The fishmeal obtained using the method of this invention was used in aquaculture experiments. The lower sediment harvested during the pressing liquid / protein water stage in the fishmeal processing of whole fish was used as the raw material for fishmeal feed. The experiment compared and investigated its role in the aquaculture of the fish species, specifically the brown flounder.

[0106] (1) Brown flounder farming:

[0107] The lower sedimentary layer harvested during the pressing stage: turkey ( Paralichthys olivaceus After being temporarily held for 7 days, 150 fish (weighing 41.5±1.1 g) were randomly selected and divided into 6 250 L tanks. Three tanks served as control groups 1, 2, and 3, and the remaining 3 tanks served as experimental groups 1, 2, and 3. During the 56-day experiment, the water temperature was maintained at 19±2℃, aeration was provided 24 hours a day, the water was changed 3 times a day, and the fish were fed twice a day (2% of the brown flounder's body weight in feed). Before feeding, the fish were siphoned to remove impurities.

[0108] The lower sediment group harvested during the protein water stage: same as above.

[0109] (2) The feed ingredients are prepared as follows:

[0110] The lower sediment harvested during the pressing stage consisted of: 62.0% fishmeal, 5.0% fish oil, 21.0% shrimp meal, 5.0% soybean meal, 5.5% seaweed meal, 1.0% wheat flour, and 0.5% mixed vitamins. The control group used purchased fishmeal, while the experimental group used 50% (dried) lower sediment obtained from experimental group 3-4-4 in Example 1 plus 50% purchased fishmeal. All ingredients were mixed, crushed, and extruded to form feed for both the control and experimental groups.

[0111] The lower sediment group harvested during the protein water stage consisted of: 62.0% fishmeal, 5.0% fish oil, 21.0% shrimp meal, 5.0% soybean meal, 5.5% seaweed powder, 1.0% wheat flour, and 0.5% mixed vitamins. The control group used purchased fishmeal, while the experimental group used 50% (dried) lower sediment obtained from experimental group 3-4-4 in Example 2 plus 50% purchased fishmeal. All ingredients were mixed, crushed, and extruded to form the control and experimental group feeds, respectively.

[0112] (3) Before and after the pressing liquid / protein water stage experiments, each fish in each tank was weighed, and the growth indicators of the brown flounder, including weight gain rate, specific growth rate, and feed conversion ratio, were calculated. In addition, after weighing at the end of the experiment, nine fish were randomly selected from each group, dissected on ice, and the liver and intestines were removed. After rinsing with physiological saline to remove surface blood, the fish were dried with filter paper, weighed, and the liver-to-body ratio and viscera-to-body ratio were calculated. The required methods are as follows:

[0113] ① Weight gain rate (WGR, %) = 100 × (average final body mass of brown flounder - average initial body mass of brown flounder) / average initial body mass of brown flounder;

[0114] ②Specific growth rate (SGR, % / d) = 100 × (Ln final body weight of brown flounder - Ln initial body weight of brown flounder) / number of days of rearing;

[0115] ③ Feed coefficient (FCR) = Feed intake / (average final body mass of brown flounder - average initial body mass of brown flounder);

[0116] ④ Liver-to-body weight ratio (HIS, %) = 100 × liver weight / final body weight of flounder;

[0117] ⑤ Visceral weight ratio (VSI, %) = 100 × visceral weight / final body weight of brown flounder.

[0118] (4) Results of the fishmeal feeding group obtained from the lower sediment obtained by using the pressed liquid as raw material

[0119] During the 56-day experiment, the number of dead brown flounder in the control group 1, 2, 3 and the experimental group 1, 2, 3 were 3, 2, 3 and 3, 1 and 2, respectively. The average number of dead brown flounder in the control group and the experimental group were 2.7±0.6 and 2.0±1.0, respectively. It can be seen that there is no significant difference in aquaculture safety between the experimental group and the control group (P>0.05).

[0120] The liver, as one of the most important metabolic organs in turbot, plays a vital role in the metabolism of various nutrients such as proteins, lipids, carbohydrates, and minerals, and serves as an important indicator for assessing the growth, health, and nutritional status of the fish. At the end of the experiment, the results of the liver-to-body ratio and viscera-to-body ratio of the turbot are shown in Table 6. The average liver-to-body ratios of the control group and the experimental group were 2.10±0.10% and 1.96±0.07%, respectively (P>0.05), and the average viscera-to-body ratios were 5.05±0.14% and 4.95±0.18%, respectively (P>0.05). This indicates that there was no significant difference in the health of the cultured organisms between the experimental and control groups (P>0.05).

[0121] Table 6. Liver-to-body ratio (HIS) and visceral-to-body ratio (VSI) of brown flounder at the end of the fishmeal pressing trial.

[0122]

[0123] Note: In the process of producing fishmeal from whole fish, the method of this invention was used to harvest the lower sediment during the pressing liquor stage as fishmeal raw material for a flounder farming experiment.

[0124] The growth and feeding effects of brown flounder are shown in Table 7. The average initial body weight of brown flounder in the control group and the experimental group were 41.4±1.2 g and 41.6±1.3 g, respectively (P>0.05), and the average final body weight was 177.3±3.0 g and 183.1±6.8 g, respectively (P>0.05). The average weight gain rate, average specific growth coefficient, and average feed conversion ratio of brown flounder in the control group and the experimental group were 328.64±7.09% and 340.13±9.34%, respectively (P>0.05), 2.73±0.05% / d and 2.75±0.09% / d (P>0.05), and 1.72±0.03 and 1.72±0.05, respectively (P>0.05). It can be seen that there was no significant difference between the experimental group and the control group in terms of growth and feeding effects of brown flounder (P>0.05).

[0125] Table 7. Fishmeal from Pressed Liquid for the Farming of Brown Turbot ( Paralichthys olivaceus Growth and feeding effects

[0126]

[0127] Note: In the process of producing fishmeal from whole fish, the method of this invention was used to harvest the lower sediment during the pressing liquor stage as fishmeal raw material for a flounder farming experiment.

[0128] (5) Results of the experiment on the group fed with fishmeal prepared from protein water

[0129] During the 56-day experiment, the number of dead brown flounder in the control group 1, 2, 3 and the experimental group 1, 2, 3 were 3, 2, 3 and 1, 1 and 3, respectively. The average number of dead brown flounder in the control group and the experimental group were 2.7±0.6 and 1.7±1.2, respectively. It can be seen that there is no significant difference in aquaculture safety between the experimental group and the control group (P>0.05).

[0130] The liver, as one of the most important metabolic organs in the brown turbot, plays a vital role in the metabolism of various nutrients such as proteins, lipids, carbohydrates, and minerals, and serves as an important indicator for assessing the fish's growth, health, and nutritional status. At the end of the experiment, the results of the liver-to-body ratio and viscera-to-body ratio of the brown turbot are shown in Table 8. The average liver-to-body ratios of the control group and the experimental group were 2.10±0.10% and 1.98±0.08%, respectively (P>0.05), while the average viscera-to-body ratios were 5.05±0.14% and 4.98±0.18%, respectively (P>0.05). This indicates that there was no significant difference in the health of the cultured organisms between the experimental and control groups (P>0.05).

[0131]

[0132] The growth and feeding effects of brown flounder are shown in Table 9. The average initial body weight of brown flounder in the control group and the experimental group were 41.4±1.2 g and 41.6±1.1 g, respectively (P>0.05), and the average final body weight was 177.3±3.0 g and 182.6±4.3 g, respectively (P>0.05). The average weight gain rate, average specific growth coefficient, and average feed conversion ratio of brown flounder in the control group and the experimental group were 328.64±7.09% and 339.11±9.85%, respectively (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, respectively (P>0.05). It can be seen that there was no significant difference between the experimental group and the control group in terms of growth and feeding effects of brown flounder (P>0.05).

[0133] Table 9. Protein-rich fishmeal-cultured brown flounder ( Paralichthys olivaceus Growth and feeding effects

[0134]

[0135] Note: In the process of producing fishmeal from whole fish, the method of this invention is used to harvest the lower sediment during the protein water stage as fishmeal raw material for flounder (Brassica juncea). Paralichthys olivaceus Aquaculture experiment.

[0136] Example 6

[0137] Fishmeal obtained from the lower sediment harvested during the pressing liquid / protein water stage using the method of this invention was used in aquaculture experiment 2. The lower sediment harvested during the pressing liquid / protein water stage of the remaining parts after whole fish processing (including but not limited to fish viscera, fish head, fish tail, etc.) and fish fillet meal processing raw materials were used as fishmeal raw materials. The experiment compared and investigated their role in sea cucumber-spiny sea cucumber aquaculture.

[0138] (1) For the fishmeal feeding group prepared from the pressed liquid / protein water, the experimental sea cucumbers were divided into groups:

[0139] First, select sea cucumbers that are vigorous, relatively uniform in size, and weigh approximately 2.0 g. Apostichopus japonicus Approximately 100 juvenile sea cucumbers were temporarily raised in tanks for 5 days. Feeding was stopped 24 hours before the experiment began. Sixty juvenile sea cucumbers were removed and divided into six 40L tanks, with 10 sea cucumbers in each tank. The weight of each juvenile sea cucumber was measured as the initial body mass for the experiment. Three tanks served as control groups 1, 2, and 3, while the remaining three tanks served as experimental groups 1, 2, and 3. During the 28-day experiment, the water temperature was maintained at 14–17℃, with aeration provided 24 hours a day (aeration was suspended during feeding and tank cleaning). Feeding was provided once a day at a rate of 15.0 mg / L (per 40L of water). Bottom cleaning was performed every two days, and water was changed every four days (approximately one-third of the total water volume was replaced). At the end of the experiment, feeding was stopped for 24 hours, and the weight of each sea cucumber was measured again as the final body mass for the experiment.

[0140] (2) The feed ingredients for the fishmeal feeding group prepared from the pressed liquid were as follows: Sargassum powder 58.0%, sea mud 20.0%, fishmeal 9.0%, soybean meal 5.0%, wheat flour 4.0%, seaweed powder 2.0%, mixed vitamins 1.0%, and mineral mixture 1.0%. The fishmeal raw material for the control group was purchased fishmeal, while the fishmeal raw material for the experimental group was fish viscera, fish head, and fish tail. During the production of fishmeal, the lower sediment (dried) obtained from experimental group 3-4-4 in Example 1 was used. All raw materials were mixed and crushed into powder, and feed for the control group and the experimental group were prepared respectively.

[0141] The feed ingredients for the fishmeal feeding group prepared from protein water were as follows: 58.0% Sargassum powder, 20.0% sea mud, 9.0% fishmeal, 5.0% soybean meal, 4.0% wheat flour, 2.0% seaweed powder, 1.0% mixed vitamins, and 1.0% mixed minerals. The control group used purchased fishmeal, while the experimental group used fish viscera, heads, and tails as raw materials. During the fishmeal production process, the lower sediment (dried) obtained from experimental group 3-4-4 in Example 2 was used. All raw materials were mixed, pulverized into powder, and used to prepare the control group feed and the experimental group feed, respectively.

[0142] (3) The growth indicators of juvenile ginseng are calculated as follows:

[0143] ① Weight gain rate (WGR, %) = 100 × (average final body weight of juvenile sea cucumbers - average initial body weight of juvenile sea cucumbers) / average initial body weight of juvenile sea cucumbers;

[0144] ②Specific growth rate (SGR, % / d) = 100 × (average final body weight of Ln juvenile sea cucumbers - average initial body weight of Ln juvenile sea cucumbers) / number of days of feeding.

[0145] (4) Results of the experiment on the fishmeal fed with the pressed liquid

[0146] The growth performance of juvenile sea cucumbers in control groups 1, 2, and 3 and experimental groups 1, 2, and 3 is shown in Table 10. There was no significant difference (P>0.05) between the control group (using commercially available fishmeal as feed) and the experimental group (using the remaining parts of the whole fish after processing (including but not limited to fish viscera, heads, and tails) and fish meal as feed, and using the lower sediment harvested from the experimental group in Example 1 as fishmeal feed) in the 28-day sea cucumber juvenile rearing experiment. Therefore, it is safe and effective for sea cucumber juvenile rearing experiments using fishmeal produced using the method of this invention, even with the worst fish feed.

[0147] Table 10. Effects of pressed fishmeal as feed ingredient on the growth performance of juvenile sea cucumbers.

[0148]

[0149] Note: In the process of producing fishmeal from fish viscera, fish heads, fish tails, etc., the lower sediment obtained by the method of this invention in the pressing liquor stage is used as the raw material for fishmeal.

[0150] (5) Results of the experiment on the group fed with fishmeal prepared from protein water

[0151] The growth performance of juvenile sea cucumbers in control groups 1, 2, and 3 and experimental groups 1, 2, and 3 is shown in Table 11. There was no significant difference (P>0.05) between the control group (using commercially available fishmeal as feed) and the experimental group (using the remaining parts of the whole fish after processing (including but not limited to fish viscera, heads, and tails) and fish meal as feed, and using the lower sediment harvested from the experimental group in Example 2 as fishmeal feed) in the 28-day sea cucumber juvenile rearing experiment. Therefore, it is safe and effective for sea cucumber juvenile rearing experiments using fishmeal produced using the method of this invention, even with the worst fish feed.

[0152] Table 11. Effects of protein-rich fishmeal as feed ingredient on the growth performance of juvenile sea cucumbers (Apostichopus japonicus).

[0153] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A process for harvesting dry matter in fish meal production, c h a r a c t e r i s e d in that, The fish raw material is cooked, and then pressed to obtain a pressed liquid. The pressed liquid is centrifuged to obtain a middle layer protein water. In the above process, dihydrogen sodium pyrophosphate and calcium chloride are added to the pressed liquid and / or the protein water, mixed, and then centrifuged. The addition ratio is: 0.1-0.8 g of dihydrogen sodium pyrophosphate and 0.05-3.0 g of calcium chloride per 100 mL of the pressed liquid / protein water. The amount of dry matter in the pressed liquid / protein water is 0.5-15.0 g / 40.0 mL. Dihydrogen sodium pyrophosphate and calcium chloride are added to the pressed liquid / protein water, mixed, and then centrifuged: centrifugal force 55-13820 g, centrifugal time 1.0-25.0 min.

2. The method of claim 1, wherein, The amount of dry matter in the pressed liquid / protein water is 1.0-12.0 g / 40.0 mL.

3. The method of claim 1, wherein, The amount of dihydrogen sodium pyrophosphate added to the pressed liquid / protein water is 0.1-0.7 g / 100 mL.

4. The method of claim 3, wherein, The amount of dihydrogen sodium pyrophosphate added to the pressed liquid / protein water is 0.2-0.6 g / 100 mL.

5. The method of claim 1, wherein, The amount of calcium chloride added to the pressed liquid / protein water is 0.1-2.3 g / 100 mL.

6. The method of claim 5, wherein, The amount of calcium chloride added to the pressed liquid / protein water is 0.4-1.8 g / 100 mL.

7. The method of claim 5, wherein, The amount of calcium chloride added to the pressed liquid / protein water is 0.8-1.7 g / 100 mL.

8. The method of claim 1, wherein, The centrifugal force is 105-7770 g for 1.0-15.0 min.

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