A method for preparing a collagen powder

Abstract

The application discloses a collagen powder preparation method and relates to the technical field of food processing. The collagen powder is prepared from animal skins through the following steps: cooking and extraction, colloidal mill circulating grinding, disc type three-phase centrifugal separation, residue recycling, high-pressure homogenization and spray drying; in the cooking and extraction stage, the high-shear stirring is adopted to destroy the winding structure of collagen fibers and improve the protein dissolution efficiency; the colloidal mill is matched with an online particle size feedback system to realize uniform material particle size; the disc type three-phase centrifuge is used to realize the separation of fat phase, protein solution phase and residue phase; the residual protein is recovered from the residue through secondary extraction with hot water, and is added into the protein solution; the trace fat is dispersed through high-pressure homogenization; the heat-resistant flavoring agent is compounded to cover the fishy smell; and then, drying, cooling, iron removal through screening, nitrogen filling and sealing are carried out to obtain the collagen powder. The process is stable, the raw material is easy to obtain, the protein content of the finished product is greater than or equal to 83.5%, and the fat is less than or equal to 0.30%, so the collagen powder can be applied to the fields of food, health products, cosmetics and biomedical materials.

Description

Technical Field

[0001] This invention relates to the field of food processing technology, and in particular to a method for preparing collagen powder. Background Technology

[0002] Collagen is a major structural protein in animal connective tissue, widely found in skin, bone, tendons, and other tissues. It possesses a unique triple helix structure and excellent biocompatibility, biodegradability, and low immunogenicity, making it valuable in food, health products, cosmetics, and biomedical materials. With the rapid development of the health industry, collagen powder, as a high-protein, low-fat, and easily absorbed nutritional supplement, is experiencing continuous market demand growth.

[0003] Currently, the main extraction methods for animal-derived collagen include acid extraction, alkaline extraction, enzymatic extraction, and hot water extraction. Each method has significant drawbacks. Acid and alkaline extraction can damage the amino acid structure, enzymatic hydrolysis is complex and costly, and traditional hot water extraction is inefficient and incompletely separates fat from protein, resulting in a high fat content in the product. Separation techniques after collagen extraction often involve filtration or centrifugation, leading to the disposal of residual protein in the resulting solid residue, resulting in low recycling rates.

[0004] Therefore, there is a need to develop a method for preparing collagen powder with high extraction efficiency, good separation effect, and full resource utilization to meet the needs of industrial production and market application. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a method for preparing collagen powder, comprising the following steps: (1) Cooking extraction: Thawed animal skin is put into a refining tank equipped with a shearing and stirring device, and water is added to a material-to-liquid ratio of 1: (1.5~2.0). The temperature is raised to 85~95℃ for cooking, while shearing and stirring are turned on at a speed of 800~1500rpm and maintained for 15~30min. The strong mechanical shearing action destroys the entanglement structure of collagen fiber bundles, increases the contact area between fibers and water, and enhances the heat and mass transfer efficiency. (2) Grinding with a colloid mill: The liquid obtained in step (1) is pumped into a colloid mill and ground into a slurry. The grinding discharge temperature is controlled to be ≤95℃ and the D90 particle size is ≤80μm. The colloid mill is equipped with an online particle size detection device, a circulating pump and a feedback control system. Preferably, the online particle size detection device collects the particle size distribution data of the slurry after grinding in real time. When the D90 particle size is >80μm, the feedback control system automatically triggers the circulation pump to return the slurry to the colloid mill through the return pipeline for secondary grinding until the D90 particle size is ≤80μm. This ensures stable particle size distribution between batches, providing uniform pretreatment materials for subsequent three-phase centrifugal separation, and fundamentally improving the controllability of the process and the stability of product quality.

[0006] (3) Disc-type three-phase centrifugal separation: The slurry from step (2) is kept at a temperature of ≥65℃ by a plate heat exchanger and pumped to a disc-type three-phase centrifuge to separate into fat phase, protein solution phase and centrifugal residue phase.

[0007] Preferably, the disc-type three-phase centrifuge has a drum speed of 5500~6500 rpm and a separation factor of 7500~8500 g, achieving efficient separation of the fat phase, protein solution phase and centrifugation residue phase simultaneously in a single separation operation.

[0008] Preferably, after the centrifuged residue phase described in step (3) is utilized for resource recovery, it enters a high-pressure homogenization process. The resource recovery specifically involves: putting the centrifuged residue into a hot water extraction tank, adding hot water at 90~100℃ at a material-to-liquid ratio of 1:2, and stirring for 30~60 minutes at a stirring speed of 30~60 rpm; after extraction, pumping the extracted slurry into a screw press to separate it into hot water extract and pressing residue; adding the hot water extract and the protein solution from step (3) together into a temporary storage tank, stirring until the system is uniform and stable, and then pumping it into a high-pressure homogenizer for homogenization, thereby realizing the recovery and reuse of residual protein in the residue.

[0009] Preferably, the mass ratio of the hot water extract to the protein solution in step (3) is 1:(5~8).

[0010] Preferably, the fat phase is collected and used to refine industrial oil, and the centrifuged residue can be directly used as feed or organic fertilizer raw material, or the remaining pressing residue after hot water extraction of the centrifuged residue can be used as feed or organic fertilizer raw material.

[0011] (4) High-pressure homogenization: The protein solution from step (3) is pumped into a high-pressure homogenizer for homogenization. The homogenization pressure is 15~25MPa, and the homogenization is repeated 2~4 times to fully disperse the fat particles in the liquid into tiny droplets, and the protein encapsulates the fat to form a stable emulsion system.

[0012] Preferably, step (4) further includes adding a heat-resistant flavor enhancer to the temporary storage tank, mixing it with the protein solution, and then pumping it into a high-pressure homogenizer; the heat-resistant flavor enhancer is selected from one or more of yeast extract, disodium 5'-ribonucleotide, and hydrolyzed plant protein, and the mass ratio of the amount of the heat-resistant flavor enhancer added to the protein solution is (0.05~1):1000.

[0013] The intense shearing action of high-pressure homogenization ensures that the flavor enhancer and protein matrix are thoroughly and evenly mixed, effectively masking the fishy and gamey smell of collagen powder derived from animal skin.

[0014] (5) Spray drying: After high-pressure homogenization, the liquid material enters a centrifugal spray drying tower to dry into collagen powder; the inlet temperature of the spray drying tower is 165±5℃ and the outlet temperature is 55~65℃.

[0015] Preferably, the preparation method further includes cooling the spray-dried collagen powder in a fluidized bed to ≤35°C, passing it through a 60-80 mesh sieve, removing iron with a magnetic rod, and then sealing it in nitrogen-filled packaging.

[0016] Preferably, the animal skin is one or more of pigskin, cowhide, chicken skin, and sheepskin in any proportion.

[0017] The collagen powder prepared by the above method has a protein content of ≥83.5%, fat content of ≤0.30%, peptides with a molecular weight distribution of 1000~10000Da accounting for ≥60%, ash content of ≤2.0%, and moisture content of ≤7.0%. It can be used to prepare food, health products, cosmetics, and biomedical materials.

[0018] Compared with the prior art, the present invention has the following advantages: 1. High-shear stirring at 800-1500 rpm is introduced during the cooking and extraction stage. This strong mechanical shearing action disrupts the entanglement of collagen fiber bundles, increases the contact area between the fibers and water, and enhances heat and mass transfer efficiency. Compared to static cooking or low-speed stirring, high-shear stirring allows collagen fibers to disperse rapidly and swell fully, significantly improving protein dissolution rate.

[0019] 2. After a second extraction with hot water, the centrifuged residue is reused in the high-pressure homogenization process, thus realizing the recovery and reuse of residual protein in the residue.

[0020] 3. By adjusting key parameters such as cooking temperature, shearing speed, and homogenization pressure, the method of this invention can take into account the differences in fiber characteristics and collagen content of various animal skin raw materials such as pigskin, cowskin, chickenskin, and sheepskin, and prepare collagen powder with a protein content of ≥83.5% and fat content of ≤0.30%, which can be used as a material in the fields of food, health products, cosmetics, and biomedicine. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the preparation method of collagen powder according to the present invention. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. The following examples and comparative cases are for illustrative purposes only and are not intended to limit the scope of protection of this invention.

[0023] It should be noted that, unless otherwise specified, the experimental methods described in the following implementation plan are all conventional methods, and the reagents and materials described are all commercially available unless otherwise specified.

[0024] Example 1: Preparation of porcine skin-derived collagen powder Take 500 kg of frozen pigskin that has passed inspection and quarantine, and thaw it in a 4℃ thawing room for 24 hours until the core temperature reaches 0~4℃. After thawing, rinse the surface with clean water to remove residual hair, bloodstains and fat lumps, drain and weigh to obtain 485 kg of raw skin.

[0025] Step 1: Extraction by steaming or boiling The above raw hides were put into a 1500L extraction tank equipped with a shearing and stirring device, and 750kg of tap water was added. The temperature was raised to 90℃ for steaming and extraction. At the same time, the shearing and stirring was turned on and the speed was set to 1200rpm. After maintaining this for 20 minutes, a milky white viscous liquid was obtained.

[0026] Step 2: Grinding with a colloid mill The cooked broth is pumped into a colloid mill, the grinding disc gap is adjusted to 50μm, the cooling jacket circulating water is turned on, and the grinding outlet temperature is 92℃. The online particle size analyzer monitors the D90 value in real time: after the first grinding, D90 = 120μm > 80μm, the feedback control system automatically triggers the secondary grinding circuit, and the slurry is returned to the colloid mill; after the second grinding, D90 = 72μm ≤ 80μm, and the slurry is sent to the broth mixing and heat preservation unit.

[0027] Step 3: Disc-type three-phase centrifugal separation The slurry from step 2 is heated to a temperature above 70°C using a plate heat exchanger and then pumped to a disc-type three-phase centrifuge for three-phase separation. The disc-type three-phase centrifuge is set to a drum speed of 6000 rpm, with a separation factor of approximately 8000 g. After separation, approximately 48 kg of fatty phase, approximately 980 kg of protein solution phase, and approximately 185 kg of centrifugation residue are obtained. The fatty phase is collected and stored for use in the crude refining of industrial oil; the protein solution phase undergoes a high-pressure homogenization process; and the centrifugation residue phase is used for resource utilization.

[0028] Step 4: Resource utilization of residue The centrifuged residue from step 3 was placed into a hot water extraction tank, and 370 kg of 90°C hot water was added. The mixture was heated using a steam jacket, maintaining a temperature of 90±2°C, and stirred at 45 rpm for 45 minutes. After extraction, the extract was pumped into a screw press for solid-liquid separation, collecting approximately 340 kg of hot water extract, which was then pumped into a temporary storage tank at a specific mass ratio. Approximately 210 kg of pressing residue was retained and can be used as feed or organic fertilizer raw material.

[0029] Step 5: High-pressure homogenization Pump the 980 kg protein solution from step 3 into a temporary storage tank, add 140 kg of the hot water extract obtained in step 4, and add 0.5 kg of baker's yeast extract. Maintain the temperature at 75-80°C and stir at 80 rpm for 15 minutes until the system is homogeneous and stable.

[0030] The mixture was then pumped into a high-pressure homogenizer for homogenization at a pressure of 20 MPa. The homogenizer was circulated and homogenized three times until there were no visible oil droplets, no layering, and no sediment, and the system appeared as a uniform milky white.

[0031] Step 6: Spray drying The high-pressure homogenized liquid was pumped into a centrifugal spray drying tower for drying. The feed rate was controlled to maintain the inlet air temperature at 165℃ and the outlet air temperature at 60℃. The centrifugal atomizer rotor speed was 18000 rpm. After drying, the powder was collected by a cyclone separator, yielding approximately 156 kg of milky white, odorless collagen powder.

[0032] Step 7: Post-processing and Packaging After spray drying, the collagen powder is cooled to 30°C in a fluidized bed, sieved through a 70-mesh screen, and then removed by a magnetic rod iron remover (the mass of which is negligible). Finally, it is sealed in a nitrogen-filled packaging machine, with the residual oxygen content in the packaging bag being ≤3%.

[0033] Example 2: Preparation of bovine hide collagen Take 600 kg of frozen cowhide that has passed inspection and quarantine, and thaw it in a 4℃ thawing room for 36 hours until the core temperature reaches 0~4℃. After thawing, rinse the surface with clean water to remove residual hair, bloodstains and subcutaneous fat layer. After draining, weigh to obtain 582 kg of clean cowhide material.

[0034] Step 1: Extraction by steaming or boiling The above-mentioned cleaned cowhide material was put into a 2000L extraction tank equipped with a high-shear stirring device, 1164kg of tap water was added, the temperature was raised to 95℃ for steaming and extraction, and the shear stirring was turned on for 30 minutes with the speed set at 1500rpm.

[0035] Step 2: Grinding with a colloid mill After cooking, the liquid is pumped into a colloid mill for grinding. The gap between the grinding discs is adjusted to 50 μm, and the cooling jacket circulating water is turned on. After two grindings, the D90 particle size of the slurry is 68 μm, and the grinding discharge temperature is 93℃.

[0036] Step 3: Disc-type three-phase centrifugal separation The slurry from step 2 was heated in a plate heat exchanger to maintain a temperature above 68°C, and then pumped to a disc-type three-phase centrifuge for three-phase separation. The drum speed of the disc-type three-phase centrifuge was set to 6500 rpm, and the separation factor was approximately 8500g. The separated product was: Approximately 72 kg of fat phase, approximately [amount missing] of protein solution phase, and approximately 394 kg of centrifugation residue phase were collected and stored for use in crude refining of industrial oil; the protein solution phase was subjected to a high-pressure homogenization process; and the centrifugation residue phase was used for resource utilization.

[0037] Step 4: Resource utilization of residue The centrifuged residue obtained in step 3 was placed into a hot water extraction tank, and 788 kg of 100°C hot water was added. The tank was heated using a steam jacket, maintaining the temperature at 90-100°C, and stirred at 60 rpm for 60 minutes. After extraction, the extract was pumped into a screw press for solid-liquid separation, collecting approximately 720 kg of hot water extract and approximately 455 kg of pressing residue.

[0038] Step 5: High-pressure homogenization The 1280 kg protein solution obtained in step 3 was pumped into a temporary storage tank, and 160 kg of the hot water extract obtained in step 4 was added. At the same time, 1.28 kg of disodium 5'-inosinate was added, and the mixture was stirred at 80 rpm for 20 min until the system was homogeneous and stable. Then, the mixture was pumped into a high-pressure homogenizer for homogenization. The homogenization pressure was set to 25 MPa, and the homogenization was repeated 3 times until the liquid was visually free of oil droplets, layering, and sediment, and the system was uniformly milky white.

[0039] Step 6: Spray drying The homogenized liquid material was pumped into a centrifugal spray drying tower for drying. The feed rate was controlled to maintain the inlet air temperature at 170℃ and the outlet air temperature at 65℃, with the centrifugal atomizer rotating at 18000 rpm. After drying, approximately 198 kg of milky white, odorless collagen powder was obtained.

[0040] Step 7: Post-processing and Packaging After spray drying, the collagen powder is cooled to 35°C in a fluidized bed, sieved through an 80-mesh screen, and then removed by a magnetic rod iron remover (the mass of which is negligible). Finally, it is sealed in a nitrogen-filled packaging machine, with the residual oxygen content in the packaging bag being ≤3%.

[0041] Example 3: Preparation of chicken skin-derived collagen Take 500 kg of frozen chicken skin that has passed inspection and quarantine, and thaw it in a 4℃ thawing room for 18 hours until the core temperature reaches 0~4℃. After thawing, rinse the surface with clean water to remove residual hair, blood, and subcutaneous fat. After draining, weigh to obtain approximately 465 kg of clean chicken skin.

[0042] Step 1: Extraction by steaming or boiling The above-mentioned cleaned chicken skin material was put into a 1500 L extraction tank equipped with a shearing and stirring device, 698 kg of tap water was added, the temperature was raised to 85℃ for steaming and extraction, and the shearing and stirring was turned on at the same time, with the speed set to 800 rpm and maintained for 30 min.

[0043] Step 2: Grinding with a colloid mill After cooking, the liquid is pumped into a colloid mill. The gap between the grinding discs is adjusted to 60 μm, and the cooling jacket circulating water is turned on. Because the chicken skin fibers are softer, the grinding efficiency is slightly lower than that of pig skin. After three grindings, the D90 particle size of the slurry is 78 μm, and the discharge temperature is 88℃.

[0044] Step 3: Disc-type three-phase centrifugal separation The slurry from step 2 is heated to a temperature above 65°C using a plate heat exchanger and then pumped to a disc-type three-phase centrifuge for three-phase separation. The disc-type three-phase centrifuge is set to a drum speed of 5500 rpm, with a separation factor of approximately 7500 g. The separated slurry yields approximately 58 kg of a fatty phase, approximately 850 kg of a protein solution phase, and approximately 155 kg of centrifugation residue. The fatty phase is collected and stored for use in the crude refining of industrial oil; the protein solution phase undergoes a high-pressure homogenization process; and the centrifugation residue phase is used for resource utilization.

[0045] Step 4: Resource utilization of residue The centrifuged residue from step 3 was placed into a hot water extraction tank, and 310 kg of 90°C hot water was added. The mixture was heated using a steam jacket to maintain a temperature of 90-95°C, and stirred at 30 rpm for 60 min.

[0046] After extraction, the extracted slurry is pumped into a screw press for solid-liquid separation. Approximately 285 kg of hot water extract is collected and directly pumped into the emulsification and blending unit. Approximately 175 kg of pressing residue can be used as feed or organic fertilizer raw material.

[0047] Step 5: High-pressure homogenization The 850 kg protein solution obtained in step 3 was pumped into a temporary storage tank, and 140 kg of the hot water extract obtained in step 4 and 0.43 kg of brewer's yeast extract were added. The temperature was maintained at 75±5℃, and the mixture was stirred at 80 rpm for 15 min until the system was homogeneous and stable. The mixture was then pumped into a high-pressure homogenizer for homogenization at a pressure of 15 MPa, and homogenized 4 times until no oil droplets, layering, or sedimentation were visible, and the system appeared uniformly milky white.

[0048] Step 6: Spray drying The homogenized liquid material was pumped into a centrifugal spray dryer for drying. The feed rate was controlled to maintain the inlet air temperature at 160℃ and the outlet air temperature at 55℃. The centrifugal atomizer rotor rotated at 18,000 rpm. After drying, the powder was collected by a cyclone separator, yielding approximately 138 kg of collagen powder.

[0049] Step 7: Post-processing and Packaging After spray drying, the collagen powder is cooled to 30°C in a fluidized bed, sieved through a 60-mesh screen, and then removed by a magnetic rod separator to remove any possible metallic foreign matter (the mass of which is negligible). Finally, it is sealed in a nitrogen-filled packaging machine, with the residual oxygen content in the packaging bag being ≤3%.

[0050] Example 4: Preparation of sheepskin-derived collagen Take 400 kg of frozen sheepskin that has passed inspection and quarantine, and thaw it in a 4℃ thawing room for 30 hours until the core temperature reaches 0~4℃. After thawing, rinse the surface with clean water to remove residual hair, bloodstains and subcutaneous fat layer. After draining, weigh to obtain approximately 382 kg of clean sheepskin material.

[0051] Step 1: Extraction by steaming or boiling The cleaned sheepskin material was put into a 1500 L extraction tank equipped with a high-shear stirring device, 764 kg of tap water was added, and the temperature was raised to 95°C for steaming and extraction. At the same time, the shear stirring was turned on and the speed was set to 1500 rpm for 15 minutes.

[0052] Step 2: Grinding with a colloid mill After cooking, the liquid is pumped into a colloid mill, the grinding disc gap is adjusted to 40 μm, the cooling jacket circulating water is turned on, and after secondary grinding, the slurry D90 particle size is 72 μm, and the grinding discharge temperature is 93℃.

[0053] Step 3: Disc-type three-phase centrifugal separation The slurry from step 2 is heated to a temperature above 68°C using a plate heat exchanger and then pumped to a disc-type three-phase centrifuge for three-phase separation. The disc-type three-phase centrifuge is set to a drum speed of 6500 rpm, with a separation factor of approximately 8500 g. After separation, approximately 35 kg of a fatty phase, approximately 1020 kg of a protein solution phase, and approximately 165 kg of centrifugation residue are obtained. The fatty phase is collected and stored for use in the crude refining of industrial oil; the protein solution phase undergoes a high-pressure homogenization process; and the centrifugation residue phase is used for resource utilization.

[0054] Step 4: Resource utilization of residue The centrifuged residue obtained in step 3 was placed into a hot water extraction tank, and 330 kg of 100°C hot water was added. The tank was heated using a steam jacket to maintain the temperature at 95-100°C, and the mixture was stirred at 60 rpm for 30 minutes. After extraction, the extract was pumped into a screw press for solid-liquid separation, and approximately 305 kg of hot water extract and approximately 185 kg of pressing residue were collected.

[0055] Step 5: High-pressure homogenization The 1020 kg protein solution obtained in step 3 was pumped into a temporary storage tank, and 127 kg of the hot water extract obtained in step 4 and 0.41 kg of disodium 5'-ribonucleotides were added. The mixture was stirred at 80 rpm for 20 min until the system was homogeneous and stable. The mixture was then pumped into a high-pressure homogenizer for homogenization at a pressure of 25 MPa. The homogenization was repeated twice until the mixture was visually free of oil droplets, stratification, and sediment, and the system appeared uniformly milky white.

[0056] Step 6: Spray drying The homogenized liquid material was pumped into a centrifugal spray dryer for drying. The feed rate was controlled to maintain a stable inlet air temperature of 170℃ and an outlet air temperature of 65℃, with the centrifugal atomizer rotating at 18,000 rpm. Approximately 152 kg of collagen powder was obtained after drying.

[0057] Step 7: Post-processing and Packaging After spray drying, the collagen powder is cooled to 35°C in a fluidized bed, sieved through an 80-mesh screen, and then removed by a magnetic rod iron remover (the mass of which is negligible). Finally, it is sealed in a nitrogen-filled packaging machine, with the residual oxygen content in the packaging bag being ≤3%.

[0058] Example 5: Preparation of porcine skin-derived collagen The difference between this embodiment and embodiment 1 is that the residue resource utilization process described in step (4) is omitted, that is, the centrifugal residue is not subjected to secondary hot water extraction and reuse, but is directly treated as a by-product.

[0059] Take 500 kg of frozen pigskin that has passed inspection and quarantine, and thaw it in a 4℃ thawing room for 24 hours until the core temperature reaches 0~4℃. After thawing, rinse the surface with clean water to remove residual hair, bloodstains and fat lumps, drain and weigh to obtain 485 kg of raw skin.

[0060] Step 1: Extraction by steaming or boiling The raw hides were put into a 1500 L extraction tank equipped with a shearing and stirring device, and 750 kg of tap water was added. The temperature was raised to 90°C for steaming and extraction. At the same time, the shearing and stirring was turned on, and the speed was set to 1200 rpm for 20 min. The liquid gradually changed from turbid to milky white viscous slurry with no obvious fiber clumps.

[0061] Step 2: Grinding with a colloid mill After cooking, the liquid is pumped into a colloid mill, the grinding disc gap is adjusted to 50 μm, the cooling jacket circulating water is turned on, and after secondary grinding, the slurry D90 particle size is 72 μm, and the grinding discharge temperature is 92℃.

[0062] Step 3: Disc-type three-phase centrifugal separation The slurry from step 2 is heated to a temperature above 70°C using a plate heat exchanger and then pumped to a disc-type three-phase centrifuge for three-phase separation. The disc-type three-phase centrifuge is set to a drum speed of 6000 rpm, with a separation factor of approximately 8000 g. After separation, approximately 48 kg of a fatty phase, approximately 980 kg of a protein solution phase, and approximately 185 kg of centrifuge residue are obtained. The fatty phase is collected and stored for use in the crude refining of industrial oil; the protein solution phase is subjected to a high-pressure homogenization process; and the centrifuge residue phase is directly treated as a byproduct without further hot water extraction or reuse.

[0063] Step 4: High-pressure homogenization The protein solution from step 3 was directly pumped into a temporary storage tank, and the temperature was maintained at 75-80℃. The mixture was stirred at 80 rpm for 15 minutes until the system was homogeneous and stable. Subsequently, the protein solution was directly pumped into a high-pressure homogenizer for homogenization at a pressure of 20 MPa. The homogenization was repeated 3 times until no oil droplets, layering, or precipitation were visible, and the system appeared uniformly milky white.

[0064] Step 5: Spray drying The high-pressure homogenized liquid was pumped into a centrifugal spray drying tower for drying. The feed rate was controlled to maintain the inlet air temperature at 165℃ and the outlet air temperature at 60℃. The centrifugal atomizer rotor rotated at 18,000 rpm. After drying, the powder was collected by a cyclone separator, yielding approximately 124 kg of milky white collagen powder with a fishy odor.

[0065] Step 6: Post-processing and Packaging After spray drying, the collagen powder is cooled to 30°C in a fluidized bed, sieved through a 70-mesh screen, and then removed by a magnetic rod iron remover (the mass of which is negligible). Finally, it is sealed in a nitrogen-filled packaging machine, with the residual oxygen content in the packaging bag being ≤3%.

[0066] The main components of the collagen powders prepared in Examples 1-5 were tested, and the test results and product yields are shown in the table below.

[0067] The test results of Examples 1-5 show that the process of the present invention has good adaptability to four major animal hide raw materials: pigskin, cowhide, chicken skin, and sheepskin. Among them, the product yield of cowhide raw material in Example 2, when the upper limit parameter is used, is 34.0% and the total protein yield is 80.2%. Even when the lower limit parameter is used for chicken skin raw material, the product yield is 29.8% and the protein yield is 72.3%.

[0068] Compared to Example 5 (without residue recycling), Example 1 (with residue recycling) under the same raw materials and parameters resulted in a 6.2% increase in product yield and an 18.2% increase in total protein yield.

[0069] Comparative Example 1 The same raw materials and process methods as in Example 1 were used, except that a conventional high-temperature cooking process was used for extraction.

[0070] Take 500 kg of frozen pigskin that has passed inspection and quarantine, and thaw it in a 4℃ thawing room for 24 hours until the core temperature reaches 0~4℃. After thawing, rinse the surface with clean water to remove residual hair, bloodstains and fat lumps, drain and weigh to obtain 485 kg of raw skin.

[0071] Step 1: Extraction by steaming or boiling The raw hides were placed into a 1500L extraction tank. Without turning on the shearing and stirring, 730kg of tap water was added, and the temperature was raised to 90℃ for steaming and extraction.

[0072] After cooking, the liquid showed obvious fiber clump aggregation, with a large number of undispersed collagen fiber bundles floating on the surface, and the viscosity of the liquid was significantly higher than that of the same period in Example 1.

[0073] Step 2: Grinding with a colloid mill After cooking, the liquid is pumped into a colloid mill, the grinding disc gap is adjusted to 50μm, the cooling jacket circulating water is turned on, the grinding outlet temperature is 94℃, and after 6 cycles of grinding, the D90 particle size is reduced to 78μm.

[0074] Step 3: Disc-type three-phase centrifugal separation The slurry from step 2 was heated in a plate heat exchanger to maintain a temperature above 70°C, and then pumped to a disc-type three-phase centrifuge for three-phase separation. The drum speed of the disc-type three-phase centrifuge was set to 6000 rpm, and the separation factor was approximately 8000 g. After separation, approximately 53 kg of fat phase, approximately 798 kg of protein solution phase, and approximately 363 kg of centrifugation residue were obtained.

[0075] Step 4: Resource utilization of residue The centrifuged residue from step 3 was placed into a hot water extraction tank, and 726 kg of 90°C hot water was added. The tank was heated using a steam jacket, maintaining a temperature of 90±2°C, and stirred at 45 rpm for 45 minutes. After extraction, the extract was pumped into a screw press for solid-liquid separation, collecting approximately 445 kg of hot water extract and approximately 644 kg of pressing residue.

[0076] Step 5: High-pressure homogenization Pump the 798 kg protein solution obtained in step 3 into a temporary storage tank, add 150 kg of the hot water extract obtained in step 4, and add 0.43 kg of baker's yeast extract. Maintain the temperature at 75~80℃ and stir at 80 rpm for 15 min until the system is uniform and stable.

[0077] The mixture was then pumped into a high-pressure homogenizer for homogenization at a pressure of 20 MPa. After three cycles of homogenization, trace amounts of flocculent matter were still visible in the air.

[0078] Step 6: Spray drying The high-pressure homogenized liquid was pumped into a centrifugal spray drying tower for drying. The feed rate was controlled to maintain the inlet air temperature at 165℃ and the outlet air temperature at 60℃. The centrifugal atomizer rotor rotated at 18,000 rpm. After drying, the powder was collected by a cyclone separator, yielding approximately 130 kg of pale yellow, odorless collagen powder.

[0079] Step 7: Post-processing and Packaging After spray drying, the collagen powder is cooled to 30°C in a fluidized bed, sieved through a 70-mesh screen, and then removed by a magnetic rod iron remover (the mass of which is negligible). Finally, it is sealed in a nitrogen-filled packaging machine, with the residual oxygen content in the packaging bag being ≤3%.

[0080] Comparative Example 2 Take 500 kg of frozen pigskin that has passed inspection and quarantine, and thaw it in a 4℃ thawing room for 24 hours until the core temperature reaches 0~4℃. After thawing, rinse the surface with clean water to remove residual hair, bloodstains and fat lumps, drain and weigh to obtain 485 kg of raw skin.

[0081] Step 1: Extraction by steaming or boiling The raw hides were placed into a 1500L extraction tank equipped with a shearing and stirring device, 730kg of tap water was added, the temperature was raised to 90℃ for steaming and extraction, the shearing and stirring was turned on at 2500rpm and maintained for 15min.

[0082] Through the observation window of the refining tank, it can be seen that at a speed of 2500 rpm, the liquid is violently churning, and a fine bubble layer of 5-8 cm thickness forms on the surface. The temperature of the liquid rises rapidly from room temperature to 90℃, with a maximum temperature of 98-102℃. After stirring is stopped for 15 minutes, the liquid turns light brown in color and has a slight burnt smell. The liquid's fluidity is close to that of clear water, and it becomes completely clear after standing for 1 minute, with a small amount of brown sediment at the bottom.

[0083] Step 2: Grinding with a colloid mill After cooking, the liquid was pumped into the colloid mill, and the gap between the grinding discs was adjusted to 50 μm. The cooling jacket circulating water was turned on. Due to the significant decrease in the viscosity of the feed liquid, cavitation occurred in the feed pump of the colloid mill, and the feed flow rate needed to be reduced to 70% of that in Example 1. The grinding discharge temperature was 96°C. Due to the excessive degradation of proteins into small molecule peptides and free amino acids caused by ultra-high shear, the viscosity of the liquid decreased, and the shear grinding efficiency of the colloid mill decreased instead. After 4 cycles of grinding, the D90 particle size was 76 μm.

[0084] Step 3: Disc-type three-phase centrifugal separation The slurry from step 2 was heated in a plate heat exchanger to maintain a temperature above 70°C, and then pumped to a disc-type three-phase centrifuge for three-phase separation. The drum speed of the disc-type three-phase centrifuge was set to 6000 rpm, and the separation factor was approximately 8000 g. After separation, approximately 52 kg of fat phase, approximately 920 kg of protein solution phase, and approximately 210 kg of centrifugation residue were obtained.

[0085] Step 4: Resource utilization of residue The centrifuged residue from step 3 was placed into a hot water extraction tank, and 420 kg of 90°C hot water was added. The tank was heated using a steam jacket, maintaining a temperature of 90±2°C, and stirred at 45 rpm for 45 minutes. After extraction, the extract was pumped into a screw press for solid-liquid separation, collecting approximately 335 kg of hot water extract and approximately 285 kg of pressing residue.

[0086] Step 5: High-pressure homogenization Pump the 920 kg protein solution obtained in step 4 into a temporary storage tank, add 140 kg of the hot water extract obtained in step 4, and add 0.43 kg of baker's yeast extract. Maintain the temperature at 75~80℃ and stir at 80 rpm for 15 min until the system is uniform and stable.

[0087] The mixture was then pumped into a high-pressure homogenizer for homogenization at a pressure of 20 MPa. After three homogenizations, there was no visible oil droplets or stratification, but the liquid was grayish-white with slight flocculent suspension. This may be due to excessive protein degradation, resulting in a molecular weight distribution that is biased towards smaller molecules and reduced emulsification capacity. Even with high-pressure homogenization, it is difficult to form a stable protein-fat emulsion system.

[0088] Step 6: Spray drying The homogenized liquid material was pumped into a centrifugal spray drying tower for drying. The feed rate was controlled to maintain a stable inlet air temperature of 165℃ and an outlet air temperature of 60℃. The centrifugal atomizer rotor speed was 18000 rpm. During the spray drying process, due to the low viscosity of the liquid material and poor atomization effect, some large droplets were not fully dried and adhered to the wall. A small amount of brownish adhering material was found on the inner wall of the drying tower. After drying, the powder was collected by a cyclone separator, yielding approximately 110 kg of pale yellow collagen powder with a burnt smell.

[0089] Step 7: Post-processing and Packaging The spray-dried collagen powder was cooled to 30°C in a fluidized bed and passed through a 70-mesh sieve. Approximately 15 kg of brown lumps, which were too hard to pass through the sieve, were observed; about 95 kg of powder passed through the sieve. After removing any possible metallic foreign objects from the sieved product using a magnetic rod separator, the product was sealed in a nitrogen-filled packaging machine, ensuring that the residual oxygen content inside the packaging bag was ≤3%.

[0090] Comparative Example 3: Preparation of Collagen Powder by Enzymatic Extraction Take 500 kg of frozen pigskin that has passed inspection and quarantine, and thaw it in a 4℃ thawing room for 24 hours until the core temperature reaches 0~4℃. After thawing, rinse the surface with clean water to remove residual hair, bloodstains and fat lumps, drain and weigh to obtain 485 kg of raw skin.

[0091] Step 1: Enzymatic extraction The raw hides were placed in a 1500 L enzymatic hydrolysis tank, and 970 kg of 0.5 mol / L acetic acid solution (material-to-liquid ratio approximately 1:2) was added. The pH was adjusted to 2.5, and 4.85 kg of pepsin (enzyme activity 1:10000) was added. The mixture was extracted at a constant temperature of 37℃ with stirring at 60 rpm for 24 h. After enzymatic hydrolysis, the temperature was raised to 85℃ and held for 15 min to inactivate the enzyme, and then cooled to room temperature.

[0092] During the enzymatic hydrolysis process, it was observed that the solution gradually became clearer from 0 to 4 hours, the collagen fibers began to swell, and the viscosity slowly increased; from 4 to 12 hours, the fibers gradually degraded into soluble peptides, and the solution became a pale yellow viscous liquid; from 12 to 24 hours, the enzymatic hydrolysis was nearly complete, the viscosity of the solution stabilized, and it became a pale yellow transparent liquid with a slight sour taste.

[0093] Step 2: Filtration and Separation The enzymatically hydrolyzed solution was pumped into a plate and frame filter press and filtered using a 200-mesh filter cloth to separate it into filtrate and filter residue. Due to the high viscosity of the enzymatically hydrolyzed solution, the filtration speed was slow, requiring approximately 4 hours to complete the filtration. The filtrate weighed approximately 920 kg and was a pale yellow, transparent liquid. The filter residue weighed approximately 180 kg, containing about 60% water, and was a paste-like consistency with a sour, putrid odor.

[0094] Step 3: High-pressure homogenization The filtrate was pumped into a temporary storage tank, and the temperature was maintained at 75-80℃. The mixture was stirred at 80 rpm for 15 minutes until homogeneous. 0.5 kg of heat-resistant baker's yeast extract was then added. The mixture was then pumped into a high-pressure homogenizer for homogenization at a pressure of 20 MPa, and homogenized three times. After homogenization, the mixture was milky white, but after standing for 2 hours, a small amount of oil floated on the surface.

[0095] Step 4: Spray drying The homogenized liquid material was pumped into a centrifugal spray drying tower for drying. The feed rate was controlled to maintain the inlet air temperature at 165℃ and the outlet air temperature at 60℃. The centrifugal atomizer rotor rotated at 18,000 rpm. After drying, the powder was collected by a cyclone separator, yielding approximately 121 kg of milky white collagen powder with a strong fishy odor.

[0096] Step 5: Post-processing and Packaging After spray drying, the collagen powder is cooled to 30°C in a fluidized bed, sieved through a 70-mesh screen, and then removed by a magnetic rod iron remover (the mass of which is negligible). Finally, it is sealed in a nitrogen-filled packaging machine, with the residual oxygen content in the packaging bag being ≤3%.

[0097] Comparative Example 4: Preparation of Collagen Powder by Alkali Extraction Take 500 kg of frozen pigskin that has passed inspection and quarantine, and thaw it in a 4℃ thawing room for 24 hours until the core temperature reaches 0~4℃. After thawing, rinse the surface with clean water to remove residual hair, bloodstains and fat lumps, drain and weigh to obtain 485 kg of raw skin.

[0098] Step 1: Alkali extraction The above raw material skin was put into an alkaline hydrolysis tank with a volume of 1500 L, and 970 kg of 1.0 mol / L sodium hydroxide solution was added (the material-to-liquid ratio was about 1:2). The pH was adjusted to 12.0, and the mixture was stirred and extracted at room temperature (25±2℃) for 48 h at a stirring speed of 60 rpm.

[0099] During the alkaline hydrolysis process: from 0 to 12 h, the liquid gradually turns dark yellow, the surface of the pigskin becomes slippery, and the collagen fibers begin to swell; from 12 to 24 h, the fibers gradually degrade, the viscosity of the liquid increases and then decreases, and it becomes a dark yellow turbid liquid; from 24 to 48 h, the alkaline hydrolysis tends to be complete, the liquid is grayish-brown, has a strong alkaline taste, and some amino acids racemic.

[0100] After alkaline hydrolysis, the pH was adjusted to 7.0 with 6 mol / L hydrochloric acid to neutralize the precipitate, which produced a large amount of sodium chloride salting out. The precipitate was then removed by centrifugation.

[0101] Step 2: Filtration and Separation The neutralized liquid was pumped into a plate and frame filter press and filtered using a 200-mesh filter cloth. Due to the large amount of sodium chloride precipitate produced after neutralization, the filter cloth frequently became clogged and needed to be replaced multiple times. The filtration time was approximately 6 hours, and the filtrate was approximately 850 kg, which was a grayish-brown turbid liquid. The filter residue was approximately 220 kg, which was a grayish-white paste with a strong alkaline taste.

[0102] Step 3: High-pressure homogenization The filtrate was pumped into a temporary storage tank, and the temperature was maintained at 75-80℃. The mixture was stirred at 80 rpm for 15 minutes until homogeneous. The solution was then pumped into a high-pressure homogenizer for homogenization at a pressure of 20 MPa, and homogenized three times. After homogenization, the solution was grayish-white and separated into layers after standing for 1 hour.

[0103] Step 4: Spray drying The homogenized feed solution was pumped into a centrifugal spray drying tower for drying. The feed rate was controlled to maintain a stable inlet air temperature of 165℃ and an outlet air temperature of 60℃. The centrifugal atomizer rotor speed was 18,000 rpm. Due to the high salt content and high conductivity of the feed solution, severe wall adhesion occurred during the spray drying process, with scale reaching a thickness of 2-3 mm on the tower wall. The tower needed to be shut down for cleaning, reducing drying efficiency by approximately 30%. After drying, the powder was collected by a cyclone separator, yielding approximately 97 kg of grayish-white collagen powder with a slightly alkaline odor.

[0104] Step 5: Post-processing and Packaging The spray-dried collagen powder was cooled to 30°C via a fluidized bed and then sieved through a 70-mesh sieve. Approximately 25 kg of the residue remained on the sieve; this residue was a grayish-white, hard agglomerated mass with an alkaline taste. Approximately 72 kg passed through the sieve. After removing any potential metallic impurities using a magnetic rod separator, the product was sealed in a nitrogen-filled packaging machine, ensuring a residual oxygen content of ≤3% within the packaging bag.

[0105] The main components of the collagen powders prepared in Comparative Examples 1-4 were tested, and the test results and product yields are shown in the table below.

[0106] Comparative Example 1, lacking shear action, failed to disrupt the entangled structure of collagen fiber bundles, resulting in a significantly reduced protein dissolution rate, high liquid viscosity, 6 cycles in the colloid mill, and the highest fat content. Comparative Example 2, however, suffered from excessively high rotation speed (2500 rpm), generating mechanical shear heat that caused localized temperatures exceeding 100°C. This led to collagen thermal denaturation, the unwinding and breakage of the triple helix structure into small peptides and free amino acids, a burnt odor, and a protein content reduced to 72.5% with a molecular weight distribution of only 45.2%. Furthermore, excessive protein degradation decreased emulsification capacity. This demonstrates that 800–1500 rpm can effectively disperse fiber bundles to improve extraction efficiency while avoiding excessive protein denaturation and damage.

[0107] Comparative Example 3: Enzymatic extraction is time-consuming and requires chemical reagents such as acetic acid and pepsin, increasing raw material costs. The product has a high fat content of 1.85%, poor emulsification stability, and oil floats after standing for 2 hours. Comparative Example 4: Alkaline extraction causes racemic degradation of essential amino acids such as lysine and arginine, resulting in a protein content of only 65.0%. Neutralization produces a large amount of NaCl, leading to an ash content as high as 4.5%. Spray drying suffers from severe wall adhesion and reduced efficiency, and the product has a grainy texture after dissolution.

[0108] In comparison, the present invention requires no chemical reagents during the cooking process, has a short processing time, ensures that all product indicators meet the standards, and has sufficient safety margin. It is significantly superior to existing technologies in terms of efficiency, cost, quality, and environmental protection.

[0109] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present invention, various equivalent transformations can be made to the technical solution of the present invention (such as changing the raw material ratio, adjusting the process parameters, replacing equivalent materials, etc.). All such equivalent transformations fall within the protection scope of the present invention.

Claims

1. A method for preparing collagen powder, characterized in that, Includes the following steps: (1) Cooking extraction: Put the thawed animal skin into the extraction tank equipped with a shearing and stirring device, add water to the material-to-liquid ratio of 1: (1.5~2.0), heat to 85~95℃ for cooking, and at the same time turn on the shearing and stirring, with a speed of 800~1500rpm, and maintain for 15~30min. (2) Grinding with a colloid mill: The liquid obtained in step (1) is pumped into a colloid mill and ground into a slurry. The grinding discharge temperature is controlled to be ≤95℃ and the D90 particle size is ≤80μm. The colloid mill is equipped with an online particle size detection device, a circulating pump and a feedback control system. (3) Disc-type three-phase centrifugal separation: The slurry from step (2) is kept at a temperature of ≥65℃ by a plate heat exchanger and pumped to a disc-type three-phase centrifuge to separate into a fat phase, a protein solution phase, and a centrifugal residue phase; (4) High pressure homogenization: After the protein solution from step (3) is pumped into a temporary storage tank with a stirring device for temporary storage, it is pumped into a high pressure homogenizer for homogenization. The homogenization pressure is 15~25MPa, and the homogenization is repeated 2~4 times until there is no visible oil droplets, no layering, and no sediment. (5) Spray drying: After high pressure homogenization, the liquid material enters a centrifugal spray drying tower to dry into collagen powder; the inlet air temperature of the spray drying tower is 165±5℃, the outlet air temperature is 55~65℃, and the centrifugal atomizer disc rotation speed is 18000rpm.

2. The method for preparing collagen powder according to claim 1, characterized in that, In step (2), the online particle size detection device collects the particle size distribution data of the slurry after grinding in real time. When the D90 particle size is >80μm, the feedback control system automatically triggers the circulation pump to return the slurry to the colloid mill through the return pipeline for secondary grinding until the D90 particle size is ≤80μm.

3. The method for preparing collagen powder according to claim 1, characterized in that, The disc-type three-phase centrifuge described in step (3) has a drum rotation speed of 5500~6500rpm and a separation factor of 7500~8500g.

4. The method for preparing collagen powder according to claim 1, characterized in that, After the centrifuged residue phase described in step (3) is utilized for resource recovery, it enters a high-pressure homogenization process. The resource recovery specifically involves: Centrifuged residue is put into a hot water extraction tank, and hot water at 90~100℃ is added at a material-to-liquid ratio of 1:

2. The mixture is stirred and extracted for 30~60 minutes at a stirring speed of 30~60 rpm. After extraction, the extracted slurry is pumped into a screw press to separate it into hot water extract and pressing residue. The hot water extract is pumped into a temporary storage tank containing the protein solution from step (3). After stirring until the system is uniform and stable, it is pumped into a high-pressure homogenizer for homogenization.

5. The method for preparing collagen powder according to claim 4, characterized in that, The mass ratio of the hot water extract to the protein solution in step (3) is 1:(5~8).

6. The method for preparing collagen powder according to claim 1, characterized in that, Step (4) also includes adding a heat-resistant flavor enhancer to the temporary storage tank, mixing it with the protein solution, and then pumping it into a high-pressure homogenizer; the heat-resistant flavor enhancer is selected from one or more of yeast extract, disodium 5'-ribonucleotide, and hydrolyzed vegetable protein, and the mass ratio of the amount of the heat-resistant flavor enhancer added to the protein solution is (0.05~1):1000.

7. The method for preparing collagen powder according to claim 1, characterized in that, The preparation method further includes cooling the spray-dried collagen powder in a fluidized bed to ≤35℃, passing it through a 60~80 mesh sieve, removing iron with a magnetic rod, and then sealing it in nitrogen-filled packaging.

8. The method for preparing collagen powder according to claim 1, characterized in that, The animal skin is one or more of the following: pigskin, cowhide, chicken skin, and sheepskin, or in any proportion: multiple types.

9. A collagen powder, characterized in that, It is prepared by the preparation method of collagen powder as described in any one of claims 1 to 8.

10. The application of the collagen powder according to claim 9 in the preparation of food, health products, cosmetics and biomedical materials.

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