Slow-release floating type calcium formate additive for aquaculture and preparation method of slow-release floating type calcium formate additive

Abstract

The invention particularly relates to a slow-release floating type calcium formate additive for aquaculture and a preparation method thereof.The slow-release floating type calcium formate additive for aquaculture is particulate matter with a core-shell three-layer structure, calcium formate is wrapped inside, and a middle layer is porous elastic pressure-resistant sodium alginate chitosan gel; by means of the structural design, the calcium formate additive is endowed with floating and slow-release performance, the waterproof layer on the surface layer prevents dissolution in water, the light material on the middle layer is environmentally friendly, the problem of micro-plastic residues is avoided, and controllable buoyancy and slow-release performance are achieved. Due to the floating performance of the additive, the feeding amount can be conveniently observed in aquaculture, waste is avoided, and the raw material utilization rate of calcium formate is increased; meanwhile, the structural material is little released in the stomach and is accurately released in the intestinal tract, the overall density of the slow-release floating type calcium formate additive for aquaculture is 0.6-0.8 g / cm < 3 >, and the slow sinking time is 30-50 min; the dissolution loss rate is less than 5% after soaking in a water body for 1-3 h, and the integrity rate is greater than 90% after stirring simulation at 200-500 rpm for 5-10 min.

Description

Technical Field

[0001] The present invention relates to the technical field of animal feed additives, and particularly relates to a sustained-release floating calcium formate additive for aquaculture and a preparation method thereof. Background Art

[0002] As an acidifying agent and calcium source, calcium formate has a wide range of applications in the treatment of animal gastrointestinal diseases (such as diarrhea, indigestion, etc.); it can regulate the pH of the digestive tract, inhibit pathogenic bacteria and promote mineral absorption. The mechanism of action mainly involves the regulation of the gastrointestinal environment, the promotion of digestive enzyme activity and the balance of intestinal flora. Its action sites cover multiple digestive tract regions such as the oral cavity, stomach and intestine. Reducing the pH value of the gastrointestinal tract and inhibiting the reproduction of pathogenic bacteria; calcium formate decomposes into formic acid and calcium ions in the stomach, and formic acid releases hydrogen ions (H + ), reducing the pH value in the stomach and making it close to the optimal activity range of pepsin (pH 2.0 - 3.5), thereby activating pepsinogen and promoting the decomposition of proteins. In the intestine, calcium formate maintains a lower pH value through a buffering effect, inhibits the growth of harmful bacteria such as Escherichia coli and Streptococcus (suitable pH 6.0 - 8.0), and at the same time promotes the proliferation of beneficial bacteria such as Lactobacillus, forming a balance of intestinal flora, improving digestive enzyme activity and enhancing nutrient absorption.

[0003] After fish develop enteritis, the relevant immune cells on the inner wall of the intestine have weakened killing and clearance effects on invading pathogenic bacteria, and cannot prevent the invasion and infection of the body by pathogenic bacteria. Harmful bacteria will enter the fish body's blood and then enter other internal organs through the blood. For example, harmful substances enter the fish's liver, causing liver damage and even death in severe cases.

[0004] To regularly carry out intestinal health care, calcium formate can be used. On the one hand, it can relieve the damage of anti-nutritional factors in the feed to the intestinal mucosa, and on the other hand, it can improve the intestinal digestive function, prevent the reproduction of pathogenic microorganisms and harmful bacteria such as Vibrio, and promote mineral absorption.

[0005] However, there are the following limitations in directly adding traditional calcium formate to aquaculture feed. There is dissolution loss in water. Calcium formate is easily soluble in water, resulting in the loss of active ingredients after the feed is soaked, reducing the utilization rate. There is a contradiction between buoyancy and sedimentation. Aquaculture feed needs to have appropriate floating or slow-sinking characteristics to adapt to different aquaculture objects (such as upper-layer fish and benthic species). Expanded feed has a porous structure and is light in weight, and can float on the water. However, the expansion processing temperature is too high (120 - 180 °C), which destroys the stability of the additive calcium formate; the expanded feed prepared by simple mixing floats in water, and the calcium formate in it dissolves and is lost in water, resulting in insufficient release accuracy. Summary of the Invention

[0006] To address the above problems, this technology realizes controllable buoyancy and precise slow release through innovative coating technology, and is applicable to aquaculture scenarios.

[0007] This invention is realized through the following technical solutions:

[0008] A slow-release floating calcium formate additive for aquaculture, the slow-release floating calcium formate additive is a particulate matter, and the particulate matter sequentially includes an internal active ingredient, a porous slow-release coating layer, and an outer hydrophobic layer from the inside to the outside. The porous slow-release coating layer is used to wrap the internal active ingredient; the internal active ingredient includes calcium formate.

[0009] Preferably, the material of the porous slow-release coating layer is a sodium alginate-chitosan composite porous material; the material of the outer hydrophobic layer includes lipids and polylactic acid. The internal active ingredient also contains a disintegrant, and the disintegrant is starch or talcum powder; the middle layer is a porous elastic pressure-resistant sodium alginate-chitosan gel; it has light weight and floating performance; and the outer layer is a hydrophobic layer to prevent the particulate matter from dissolving in water.

[0010] Preferably, the mass percentages of the internal active ingredient, the porous slow-release coating layer, and the outer hydrophobic layer of the slow-release floating calcium formate additive are 88-93 wt%, 5-9 wt%, and 2-5 wt% respectively, and the particle size of the slow-release floating calcium formate additive is 0.5-4 mm.

[0011] Preferably, the lipid includes fat and / or beeswax; the mass ratio of sodium alginate to chitosan in the porous slow-release coating layer is 2-5:1, and the mass ratio of polylactic acid to lipid in the outer layer is 7-8:2-3.

[0012] Preferably, the overall density of the slow-release floating calcium formate additive is 0.6-0.8 g / cm 3 , and the slow-sinking time is 30-50 min.

[0013] Preferably, the dissolution loss rate of the slow-release floating calcium formate additive in water for 1-3 h is less than 5%, and after stirring simulation at 200-500 rpm for 5-10 min, the integrity rate > 90%.

[0014] Preferably, the preparation method of the slow-release floating calcium formate additive for aquaculture includes the following steps:

[0015] (1) Using the pan coating method, make pills from the fine powder of the internal active ingredient and the binder, and dry.

[0016] (2) Alternately spray sodium alginate solution and chitosan solution on the product of step (1) multiple times, and add an anti-adhesive, and freeze-dry to obtain porous slow-release coating layer microspheres.

[0017] (3) Dissolve the outer hydrophobic layer material in a solvent to obtain a mixed solution, spray the mixed solution on the surface of the porous sustained-release coating layer microspheres in step (2) to coat the hydrophobic layer, and dry to obtain the sustained-release floating calcium formate additive.

[0018] Preferably, in the step (1), the binder is a liquid, and the liquid includes water, aqueous glucose solution, aqueous starch solution or serum emulsion; in the pan coating method, the internal active ingredient and the binder are alternately added in batches, the rotation speed is 20 - 40 rpm, the humidity is ≤70%, the temperature is 25 - 30 °C, and the size of the pills is continuously corrected.

[0019] Preferably, in the step (2), the concentrations of the sodium alginate solution and the chitosan solution are each independently 5 - 10% (w / v), and the solvent of the chitosan solution is 2 - 4 wt% acetic acid or hydrochloric acid aqueous solution; the anti-adhesive is talc or magnesium stearate; the dosage of the anti-adhesive is 0.5 - 3 wt% of the total amount of sodium alginate and chitosan; the temperature during the pill-making process is 60 - 80 °C, the humidity is 50 - 70%; the conditions for freeze-drying are -10 to -40 °C, the vacuum degree is 10 - 40 Pa, and the time is 4 - 10 h.

[0020] Preferably, in the step (3), the solvent is at least one of dichloromethane, chloroform, tetrahydrofuran, dimethylformamide, benzene and toluene; the concentration of the outer hydrophobic layer material in the mixed solution is 28 - 50 wt%, and the drying temperature is 25 - 45 °C.

[0021] Using sodium alginate as the coating material for the core layer of calcium formate (Ca(HCOO)₂) has the following advantages. The sodium alginate solution wraps around the surface of the calcium formate particles, enabling the hydration release of Ca 2+ , directly triggering the gelation of sodium alginate, enhancing the binding force between the core layer and the intermediate layer. The amino group in the chitosan polymer reacts with the carboxyl group in sodium alginate to further form a high-strength gel network, improving the binding strength of the intermediate coating layer; in addition, the solubility of chitosan and sodium alginate is different at different pH values. Chitosan can dissolve when the solution pH ≤ 6.5, and sodium alginate dissolves under neutral to slightly alkaline conditions. The different dissolution properties enable the calcium formate particles to have a sustained-release performance, which has a good therapeutic effect on fish and shrimp in aquaculture; furthermore, sodium alginate and chitosan copolymerize to form a composite gel, which forms a porous network structure after freeze-drying, reducing the overall density of the particles and endowing the particles with floating or slow-sinking properties; the outer hydrophobic layer has a good stabilizing effect on protecting the inner structure.

[0022] Beneficial effects:

[0023] 1. The slow-release floating calcium formate additive for aquaculture of the present invention is a particulate matter with a core-shell three-layer structure. Calcium formate is wrapped inside, the middle layer is a porous elastic pressure-resistant sodium alginate-chitosan gel, which has light weight and floating performance; and the outer layer is a hydrophobic layer to prevent the particulate matter from dissolving in water. Through the structural design of the present invention, the calcium formate additive is endowed with floating and slow-release properties. The surface waterproof layer prevents dissolution in water, and the middle light material realizes controllable buoyancy and slow-release performance. The floating performance of the additive is convenient for observing the dosage during feeding in aquaculture, avoiding waste and improving the utilization rate of calcium formate raw materials. The middle slow-release layer and the water-repellent layer of the outer layer are environmentally friendly materials, which will not cause the problem of microplastic residues. At the same time, less release occurs in the stomach and precise release occurs in the intestine for such structure materials, which has a significant effect on improving enteritis of fish and the like.

[0024] 2. In the process of preparing the slow-release floating calcium formate additive for aquaculture of the present invention, the traditional Chinese medicine pan-making method is adopted to make pills. This process is mature, and the cohesiveness of calcium formate is good, which is also beneficial for making pills, and the particle size of the pills is controllable. Then, sodium alginate is sprayed on the surface of the prepared pills. Sodium alginate combines with calcium ions in calcium formate to form a gel on the surface of the calcium formate pills. Chitin and sodium alginate will also form a composite gel material, which improves the coating strength of the composite gel in the middle layer. Then, through freeze-drying, the composite gel in the middle layer forms a porous elastic structure, reducing the density of the calcium formate additive particulate matter and endowing the particulate matter with floating or slow-sinking performance. After spraying the hydrophobic layer material on the outer layer, the dissolution rate of the calcium formate additive in water can be reduced, avoiding the loss of calcium formate and water pollution. At the same time, polylactic acid and lipids have low density, which can reduce the density of the particulate matter. The overall density of the slow-release floating calcium formate additive for aquaculture of the present invention is 0.6 - 0.8 g / cm 3 , the slow-sinking time is 30 - 50 min; the dissolution loss rate is less than 5% after soaking in water for 1 - 3 h, and after stirring simulation at 200 - 500 rpm for 5 - 10 min, the integrity rate > 90%. The structural design is ingenious and the application effect is good. Specific Embodiments

[0025] Next, the technical solutions in the embodiments of the present invention will be described clearly and completely. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0026] Example 1

[0027] This embodiment provides a sustained-release floating calcium formate additive for aquaculture. The sustained-release floating calcium formate additive is a particulate with a particle size of 2.0 mm. The particulate sequentially includes an internal active ingredient, an intermediate porous sustained-release coating layer, and an outer hydrophobic layer from the inside to the outside. The mass percentages of the three layers are 90 wt%, 7 wt%, and 3 wt% respectively. The internal active ingredient is calcium formate, and it also contains 2 wt% of the disintegrant starch, and the porous sustained-release coating layer is used to wrap the internal active ingredient.

[0028] The material of the porous sustained-release coating layer is a sodium alginate-chitosan composite porous material with a mass ratio of 3:1. The material of the outer hydrophobic layer is a polylactic acid and fat with a mass ratio of 8:3.

[0029] The preparation method of the sustained-release floating calcium formate additive for aquaculture in this embodiment includes the following steps:

[0030] (1) Weigh the raw materials according to the above formula, and use the pan pelletization method in a pill-making machine. The pan pelletization method is to alternately pan in the internal active ingredient and the binder (a 3 wt% starch solution). The parameters are: rotation speed 30 rpm, humidity 50%, temperature 28°C; and correct the size of the pills. After the pill-making is completed, dry them in the air.

[0031] (2) Alternately spray a 10% (w / v) sodium alginate solution and a 5% (w / v) chitosan solution into the product of step (1) in a pill-making machine. The solvent of the chitosan solution is a 3 wt% acetic acid aqueous solution; and add 0.5 - 3 wt% of talc anti-sticking agent in portions to the total amount of sodium alginate and chitosan. The temperature during the pill-making process is 70°C, and the operating humidity is 50%; freeze-dry to obtain porous sustained-release coating layer microspheres. The conditions for freeze-drying are -20°C, vacuum degree 20 Pa, and time 6 h.

[0032] (3) Dissolve the outer hydrophobic layer in chloroform to obtain a 40 wt% mixed solution, and then spray the mixed solution in portions on the surface of the porous sustained-release coating layer microspheres obtained in step (2) in a pill-making machine to coat the hydrophobic layer, and dry at 30°C to obtain the sustained-release floating calcium formate additive.

[0033] The slow-sinking time of the sustained-release floating calcium formate additive obtained in this example is 40 min, and the overall density is 0.7 g / cm 3 , and the dissolution loss rate is less than 5% after soaking for 2 h; after simulating stirring at 350 rpm for 8 min, the integrity rate > 90%.

[0034] Example 2

[0035] This embodiment provides a slow-release floating calcium formate additive for aquaculture. The slow-release floating calcium formate additive is particulate matter with a particle size of 0.5 mm. The particulate matter sequentially includes an internal active ingredient, an intermediate porous slow-release coating layer, and an outer hydrophobic layer from the inside to the outside. The mass percentages of the three are 88 wt%, 9 wt%, and 3 wt% respectively. The active ingredient is calcium formate fine powder passing through a 200-mesh sieve and 2 wt% of disintegrant starch of calcium formate. The porous slow-release coating layer is used to wrap the internal active ingredient.

[0036] The material of the porous slow-release coating layer is a sodium alginate-chitosan composite porous material with a mass ratio of 2:1. The material of the outer hydrophobic layer includes 7:2 polylactic acid and fat by mass.

[0037] The preparation method of the slow-release floating calcium formate additive for aquaculture in this embodiment includes the following steps.

[0038] (1) Weigh the raw materials according to the above formula and use the pan pelletization method in a pill-making machine. The pan pelletization method is to gradually and layer by layer incorporate the internal active ingredient and the binder water, and use centrifugal force to make pills. The parameters are: rotation speed 20 rpm, humidity 50%, temperature 30 °C; and continuously correct the size of the pills.

[0039] (2) Spray 5% (w / v) sodium alginate and 5% (w / v) chitosan solution alternately multiple times into the product of step (1). The solvent of the chitosan solution is 3 wt% acetic acid aqueous solution; and add 0.5 wt% of magnesium stearate anti-adhesive agent, which is the total amount of sodium alginate and chitosan, in portions. The temperature during the pill-making process is 80 °C, and the operating humidity is 50%; freeze-dry to obtain porous slow-release coating layer microspheres. The conditions for freeze-drying are -40 °C, vacuum degree 10 Pa, and time 5 h.

[0040] (3) Dissolve the outer hydrophobic layer in a solvent to obtain a mixed solution with a mass percentage concentration of 40 wt%. Spray the mixed solution in portions on the surface of the porous slow-release coating layer microspheres obtained in step (2) to coat the hydrophobic layer, and dry at 30 °C to obtain the slow-release floating calcium formate additive.

[0041] The sedimentation time of the slow-release floating calcium formate additive obtained in this example is 30 min, and the overall density is 0.6 g / cm 3 , and the slow sedimentation time is 30 min; the dissolution loss rate is less than 5% after soaking for 1 h, and the integrity rate is > 90% after stirring simulation at 200 rpm for 10 min.

[0042] Example 3

[0043] This embodiment provides a sustained-release floating calcium formate additive for aquaculture. The sustained-release floating calcium formate additive is a particulate matter with a particle size of 1.5 mm. The particulate matter sequentially includes an internal active ingredient, an intermediate porous sustained-release coating layer, and an outer hydrophobic layer from the inside to the outside, and the mass percentages of the three are 93 wt%, 5 wt%, and 2 wt% respectively. The internal active ingredient is calcium formate and 2 wt% of disintegrant starch of calcium formate, and the porous sustained-release coating layer is used to wrap the internal active ingredient.

[0044] The material of the porous sustained-release coating layer is a sodium alginate-chitosan composite porous material with a mass ratio of 4:1. The material of the outer hydrophobic layer is a lipid and polylactic acid with a mass ratio of 8:3. The lipid is a hydrogenated fat and beeswax with a mass ratio of 1:3.

[0045] The preparation method of the sustained-release floating calcium formate additive for aquaculture in this embodiment includes the following steps.

[0046] (1) Weigh the raw materials according to the above formula, and use the pan pelletization method in a pill-making machine. The pan pelletization method is to alternately pan in the internal active ingredient and the binder (1 wt% serum emulsion), and the parameters are: rotation speed 40 rpm, humidity 70%, temperature 30 °C; and correct the size of the pills, and dry at a low temperature of 40 °C after the pill-making is completed.

[0047] (2) Spray the 10% (w / v) sodium alginate and 5% (w / v) chitosan solution alternately multiple times on the product of step (1). The solvent of the chitosan solution is 3 wt% hydrochloric acid aqueous solution; and add 2 wt% of talc anti-adhesive agent of the total amount of sodium alginate and chitosan in portions. The temperature during the pill-making process is 60 °C, and the operating humidity is 40%; freeze-dry to obtain the porous sustained-release coating layer microspheres, and the conditions for freeze-drying are -40 °C, vacuum degree 40 Pa, and time 8 h.

[0048] (3) Dissolve the outer hydrophobic layer in chloroform to obtain a mixed solution with a concentration of 28 wt%, and spray the mixed solution on the surface of the porous sustained-release coating layer microspheres obtained in step (2) in portions to coat the hydrophobic layer, and dry at 45 °C to obtain the sustained-release floating calcium formate additive.

[0049] The sedimentation time of the sustained-release floating calcium formate additive obtained in this example is 30 min, and the overall density is 0.8 g / cm 3 , and the slow sedimentation time is 30 min; the dissolution loss rate after soaking for 1 h is 2%, and after stirring simulation at 200 rpm for 10 min, the integrity rate is 93%.

[0050] Example 4

[0051] This embodiment provides a sustained-release floating calcium formate additive for aquaculture. The sustained-release floating calcium formate additive is a particulate matter with a particle size of 3 mm. The particulate matter sequentially includes an internal active ingredient including calcium formate and talcum powder, an intermediate porous sustained-release coating layer, and an outer hydrophobic layer from the inside to the outside. The mass percentages of the three layers are 90 wt%, 5 wt%, and 5 wt% respectively. The porous sustained-release coating layer is used to wrap the internal active ingredient.

[0052] The material of the porous sustained-release coating layer is a sodium alginate-chitosan composite porous material with a mass ratio of 5:1. The material of the outer hydrophobic layer is a polylactic acid and lipid with a mass ratio of 7:3. The lipid is hydrogenated fat. The internal active ingredient, the porous sustained-release coating layer, and the outer hydrophobic layer.

[0053] The preparation method of the sustained-release floating calcium formate additive for aquaculture in this embodiment includes the following steps.

[0054] (1) Weigh the raw materials according to the above formula and use the pan pelletization method in a pill-making machine. The pan pelletization method is to alternately pan in the internal active ingredient and the binder (3 wt% starch solution). The parameters are: rotation speed 20 rpm, humidity 40%, temperature 25 °C. And correct the size of the pills, and dry them at a low temperature of 45 °C after the pill-making is completed.

[0055] (2) Sprinkle the 8% (w / v) sodium alginate and 7% (w / v) chitosan solution alternately in batches on the product of step (1). The solvent of the chitosan solution is 3 wt% acetic acid aqueous solution. And add 2 wt% of talcum powder anti-sticking agent to the total amount of sodium alginate and chitosan in batches. The temperature during the pill-making process is 80 °C, and the operating humidity is 40%. Freeze-dry to obtain the porous sustained-release coating layer microspheres. The conditions for freeze-drying are -20 °C, a vacuum degree of 10 Pa, and a time of 7 h.

[0056] (3) Dissolve the outer hydrophobic layer in a solvent to obtain a 50 wt% mixed solution, and spray the mixed solution on the surface of the porous sustained-release coating layer microspheres obtained in step (2) in batches to coat the hydrophobic layer, and dry at 35 °C to obtain the sustained-release floating calcium formate additive.

[0057] The sedimentation time of the sustained-release floating calcium formate additive obtained in this example is 40 min, and the overall density is 0.76 g / cm 3 , and the slow sedimentation time is 40 min; the dissolution loss rate is less than 5% after soaking for 2 h, and the integrity rate is > 90% after stirring simulation at 200 rpm for 10 min.

[0058] Example 5

[0059] This embodiment provides a sustained-release floating calcium formate additive for aquaculture. The sustained-release floating calcium formate additive is a particulate matter with a particle size of 2 mm. The particulate matter sequentially includes an internal active ingredient, an intermediate porous sustained-release coating layer, and an outer hydrophobic layer from the inside to the outside, and the mass percentages of the three are 90 wt%, 8 wt%, and 2 wt% respectively. The internal active ingredient is calcium formate, and also contains 1 wt% of disintegrant talc powder of calcium formate. The porous sustained-release coating layer is used to wrap the internal active ingredient.

[0060] The material of the porous sustained-release coating layer is a sodium alginate-chitosan composite porous material with a mass ratio of 4:1. The material of the outer hydrophobic layer is a mixture of polylactic acid and lipid with a mass ratio of 7:2. The lipid is a 1:1 mixture of fat and beeswax.

[0061] The preparation method of the sustained-release floating calcium formate additive for aquaculture in this embodiment includes the following steps.

[0062] (1) Weigh the raw materials according to the above formula, and use the pan pelletization method in a pelletizer. The pan pelletization method is to alternately pan in the internal active ingredient and the binder (a 3 wt% starch solution). The parameters are: rotation speed 40 rpm, humidity 50%, temperature 30 °C. And correct the size of the pellets. After the pelletization is completed, dry them in the air.

[0063] (2) Spray the 7% (w / v) sodium alginate and 6% (w / v) chitosan solution alternately in batches onto the product of step (1). The solvent of the chitosan solution is a 3 wt% acetic acid aqueous solution. And add 1 wt% of talc anti-sticking agent of the total amount of sodium alginate and chitosan in batches. The temperature during the pelletization process is 70 °C, and the operating humidity is 60%. Freeze-dry to obtain porous sustained-release coating layer microspheres. The conditions for freeze-drying are -10 °C, a vacuum degree of 10 Pa, and a time of 8 h.

[0064] (3) Dissolve the outer hydrophobic layer in a solvent to obtain a 35 wt% mixed solution. Spray the mixed solution onto the surface of the porous sustained-release coating layer microspheres obtained in step (2) in batches to coat the hydrophobic layer, and dry at 30 °C to obtain the sustained-release floating calcium formate additive.

[0065] The sedimentation time of the sustained-release floating calcium formate additive obtained in this example is 40 min, and the overall density is 0.7 g / cm 3 , and the slow sedimentation time is 40 min. The dissolution loss rate is less than 5% after soaking for 1 h. After stirring simulation at 300 rpm for 7 min, the integrity rate > 90%.

[0066] Example 6

[0067] This embodiment provides a sustained-release floating calcium formate additive for aquaculture. The sustained-release floating calcium formate additive is a particulate with a particle size of 2 mm. The particulate sequentially includes an internal active ingredient, an intermediate porous sustained-release coating layer, and an outer hydrophobic layer from the inside to the outside, and the mass percentages of the three layers are 90 wt%, 7 wt%, and 3 wt% respectively. The internal active ingredient is calcium formate, and it also contains 2 wt% of disintegrant starch based on calcium formate. The porous sustained-release coating layer is used to wrap the internal active ingredient.

[0068] The material of the porous sustained-release coating layer is a sodium alginate-chitosan composite porous material with a mass ratio of 3:1. The material of the outer hydrophobic layer is a polylactic acid and lipid with a mass ratio of 8:3.

[0069] The preparation method of the sustained-release floating calcium formate additive for aquaculture in this embodiment includes the following steps.

[0070] (1) Weigh the raw materials according to the above formula, and use the pan pelletization method in a pill-making machine. The pan pelletization method is to alternately pan in the internal active ingredient and the binder (3 wt% starch solution). The parameters are: rotation speed 20 rpm, humidity 50%, temperature 30 °C. And correct the size of the pills. After the pill-making is completed, dry them in the air.

[0071] (2) Gradually and alternately spray 10% (w / v) sodium alginate solution and 10% (w / v) chitosan solution into the product of step (1). The solvent of the chitosan solution is 3 wt% acetic acid aqueous solution. And gradually add 0.5 wt% of talcum powder anti-sticking agent based on the total amount of sodium alginate and chitosan. The temperature during the pill-making process is 60 °C, and the operating humidity is 60%. The conditions for freeze-drying are -10 °C, vacuum degree 10 Pa, and time 8 h.

[0072] (3) Dissolve the outer hydrophobic layer in dichloromethane to obtain a mixed solution with a concentration of 40 wt%. Then, spray the mixed solution into the microspheres of the porous sustained-release coating layer obtained in step (2) in a pill-making machine in batches to coat the hydrophobic layer, and dry it at 45 °C to obtain the sustained-release floating calcium formate additive.

[0073] The sedimentation time of the sustained-release floating calcium formate additive obtained in this embodiment is 30 - 50 min, the overall density is 0.6 - 0.8 g / cm 3 , and the slow sedimentation time is 30 - 50 min; the dissolution loss rate is less than 5% after soaking for 1 - 3 h. After stirring simulation at 200 - 500 rpm for 5 - 10 min, the integrity rate > 90%.

[0074] The above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A slow-release floating calcium formate additive for aquaculture, characterized in that, The sustained-release floating calcium formate additive is a particulate matter, which sequentially includes an internal active ingredient, a porous sustained-release coating layer, and an outer hydrophobic layer from the inside to the outside. The porous sustained-release coating layer is used to wrap the internal active ingredient; the internal active ingredient includes calcium formate.

2. The sustained-release floating calcium formate additive for aquaculture according to claim 1, wherein: The material of the porous sustained-release coating layer is a sodium alginate-chitosan composite porous material; the material of the outer hydrophobic layer includes lipids and polylactic acid. The internal active ingredient also contains a disintegrant, and the disintegrant is starch or talcum powder.

3. The sustained-release floating calcium formate additive for aquaculture according to claim 1 or 2, characterized in that: The mass percentages of the internal active ingredient, the porous sustained-release coating layer, and the outer hydrophobic layer of the sustained-release floating calcium formate additive are 88-93 wt%, 5-9 wt%, and 2-5 wt% respectively, and the particle size of the sustained-release floating calcium formate additive is 0.5-4 mm.

4. The slow-release floating calcium formate additive for aquaculture according to claim 2, wherein: The lipids include fat and / or beeswax; the mass ratio of sodium alginate to chitosan in the porous sustained-release coating layer is 2-5:1, and the mass ratio of polylactic acid to lipids in the outer layer is 7-8:2-3.

5. The slow-release floating calcium formate additive for aquaculture according to claim 1, characterized in that: The overall density of the sustained-release floating calcium formate additive is 0.6-0.8 g / cm 3 , and the slow-settling time is 30-50 min.

6. The slow-release floating calcium formate additive for aquaculture according to claim 1, wherein: The dissolution loss rate of the sustained-release floating calcium formate additive after being soaked in water for 1-3 h is less than 5%, and the integrity rate is >90% after being stirred and simulated at 200-500 rpm for 5-10 min.

7. The preparation method of the sustained-release floating calcium formate additive for aquaculture according to any one of claims 1-6, characterized in that: It includes the following steps: (1) Using the pan coating method to make pills from the fine powder of the internal active ingredient and a binder, and drying. (2) Alternately spraying a sodium alginate solution and a chitosan solution multiple times onto the product of step (1), and adding an anti-adhesive agent, and freeze-drying to obtain porous sustained-release coating layer microspheres. (3) Dissolving the outer hydrophobic layer material in a solvent to obtain a mixed solution, spraying the mixed solution onto the surface of the porous sustained-release coating layer microspheres in step (2) to coat the hydrophobic layer, and drying to obtain the sustained-release floating calcium formate additive.

8. The preparation method of the sustained-release floating calcium formate additive for aquaculture according to claim 7, characterized in that: In step (1), the binder is a liquid, and the liquid includes water, an aqueous glucose solution, an aqueous starch solution, or a serum emulsion; the pan coating method is to alternately pan in the internal active ingredient and the binder in batches, with a rotation speed of 20-40 rpm, a humidity ≤70%, a temperature of 25-30 °C, and continuously correcting the size of the pills.

9. The preparation method of the sustained-release floating calcium formate additive for aquaculture according to claim 7, characterized in that: In step (2), the concentrations of the sodium alginate solution and the chitosan solution are each independently 5-10% (w / v), and the anti-adhesive agent is talcum powder or magnesium stearate; the dosage of the anti-adhesive agent is 0.5-3 wt% of the total amount of sodium alginate and chitosan; the temperature during the pill-making process is 60-80 °C, and the humidity is 50-70%; the freeze-drying conditions are -10~-40 °C, the vacuum degree is 10-40 Pa, and the time is 4-10 h.

10. The preparation method of the sustained-release floating calcium formate additive for aquaculture according to claim 7, wherein: In step (3), the solvent is at least one of dichloromethane, chloroform, tetrahydrofuran, dimethylformamide, benzene, and toluene. The concentration of the outer hydrophobic layer material in the mixed solution is 28-50 wt%, and the drying temperature is 25-45 °C.