A high-quality gelatin special bone particle anhydrous high-efficiency preparation method

Abstract

The application relates to a high-quality gelatin special bone particle anhydrous high-efficiency preparation method, and belongs to the technical field of livestock product by-product processing. The method comprises the following steps: crushing livestock raw bones in sequence through three-stage crushing units, controlling single-stage crushing ratio, obtaining middle bone particles with a particle size of 45-50 mm, and keeping the broken bone particle section as a jagged angular structure; defatting the middle bone particles at 60-70 DEG C under normal pressure with n-hexane, and separating liquid and solid to obtain defatted middle bone particles; performing fourth-stage fine crushing on the defatted middle bone particles to a particle size of 6-20 mm, and obtaining high-quality gelatin special bone particles and bone powder through grading screening. The defatting operation is moved to the 45-50 mm medium particle size stage, the fine crushing is performed after defatting to realize accurate control of the final particle size, the residual oil rate is less than or equal to 2%, the crude protein content is greater than or equal to 30%, the yield of the 6-20 mm target bone particles is increased from 45-50% to more than 60% on average, the fine powder yield is reduced from 30-35% to less than 20% on average, and the high-value full utilization of bone raw materials is realized.

Description

Technical Field

[0001] This application relates to the field of livestock product by-product processing technology, and in particular to a method for the anhydrous and efficient preparation of high-quality gelatin-specific bone granules. Background Technology

[0002] Gelatin, a protein mixture obtained from the partial hydrolysis of collagen, is an important natural polymer material due to its unique property—thermally reversible gelation (it dissolves in hot water, cools to form a gel, and remelts upon heating). Thanks to its excellent biocompatibility, biodegradability, and multifunctionality, gelatin is widely used in the food industry (as a gelling agent and stabilizer), the pharmaceutical field (in the manufacture of capsules and hemostatic materials), and industrial products (photosensitive materials and cosmetics).

[0003] The key to producing high-quality gelatin lies in the processing quality of bone raw materials—specifically, bone granules. Bone granules typically come from the bones of animals such as cattle, sheep, mules, and horses, and the core processing step is degreasing. In the last century, China introduced hydraulic degreasing production lines, represented by equipment from APV and Alfa Laval. This process involves mixing the material with hot water in a cooker and maintaining a high temperature of 85-95℃ for 6-12 minutes, causing most of the bone fat to melt and be discharged with the hot water. The mixture is then centrifuged at high speed using a horizontal screw press, ultimately controlling the residual oil content of the bone granules to ≤2%.

[0004] However, this traditional cooking and washing process has significant drawbacks. On the one hand, the high-temperature cooking process severely damages the crude protein in the bones, leading to a decrease in the nutritional value of the raw materials, which in turn affects the yield and quality of the subsequent gelatin. On the other hand, this method is a high-water-consuming process, which generates a large amount of oily organic wastewater, resulting in high treatment costs and enormous environmental pressure.

[0005] To address the aforementioned issues, those skilled in the art have begun exploring anhydrous degreasing technologies. For example, patent application CN107513466A, entitled "A Production Process and System for Low-Temperature Atmospheric Pressure Extraction of Bone Oil," proposes an anhydrous degreasing process using n-hexane as a solvent. This process effectively removes bone fat while avoiding the shortcomings of traditional hydraulic degreasing, significantly reducing water consumption and wastewater discharge. More importantly, it significantly preserves the crude protein content in the bone raw material, laying a solid foundation for the subsequent production of high-quality gelatin.

[0006] However, in actual production, it has been found that to ensure sufficient solvent penetration and maintain a stable residual oil content (≤2%), manufacturers are often forced to use finer particle sizes. While this approach ensures effective degreasing, it directly leads to a significant decrease in the yield of bone granules with the target particle size (6-20mm) and an abnormally high content of fine powder (<6mm). In the raw material cost structure of gelatin production, the purchase price of bone granules is typically more than 45% higher than that of bone meal. The decrease in the yield of high-value bone granules and the increase in the yield of low-value bone meal directly weaken the economic benefits and overall utilization rate of raw materials for enterprises. 6-20mm bone granules are currently what most bone gelatin manufacturers are pursuing. Relatively smaller bone granules have a larger surface area, bringing many benefits to subsequent production processes.

[0007] Therefore, how to resolve the inherent contradiction between degreasing efficiency and target particle size retention, while maintaining the existing advantages of anhydrous degreasing process (low residual oil and high protein retention), improve the yield of 6-20mm bone particles and reduce the yield of bone meal, thereby reducing the conversion of bone particles to bone meal at the source and realizing the high-value full utilization of bone raw materials, has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0008] The technical problem to be solved by this application is to address the inherent contradiction between the degreasing efficiency and target particle size retention of the existing anhydrous hexane degreasing process. While maintaining the existing advantages of the anhydrous degreasing process (low residual oil and high protein retention), the yield of 6-20mm bone particles is increased while the yield of bone meal is reduced, thereby achieving high-value full utilization of bone raw materials.

[0009] This application discloses a method for the anhydrous and efficient preparation of high-quality gelatin-specific bone granules, comprising the following steps: (1) Multi-stage crushing of animal raw bones: Animal raw bones are crushed sequentially through three-stage crushing units, and the single-stage crushing ratios i1≤3.0, i2≤2.5, and i3≤2.5 are controlled to obtain bone particles with a particle size of 45-50mm; the single-stage crushing ratio refers to the ratio of the maximum feed particle size to the maximum discharge particle size; The first stage of crushing is coarse crushing: animal bones with a feed size ≤300mm are crushed into bone blocks with a particle size of 100-120mm, and the single-stage crushing ratio i1≤3.0; The second stage of crushing is medium crushing: the bone blocks obtained from the first stage of crushing are crushed to bone particles with a diameter of 60-75mm, and the single-stage crushing ratio i2≤2.5; The third stage of crushing is fine crushing: the bone particles obtained from the second stage of crushing are crushed to the target bone particles with a final particle size of 45-50mm, the single-stage crushing ratio i3≤2.5, and the cross-section of the crushed bone particles maintains an uneven angular structure. (2) Low temperature and normal pressure degreasing: The target bone particles obtained in step (1) are degreased under normal pressure at 60-70℃ with hexane as solvent, and then separated by liquid-solid separation to obtain the degreased bone particles and a mixed solution containing hexane, oil and water. (3) Post-processing: The defatted bone particles obtained in step (2) are subjected to fourth-stage fine crushing to target bone particles with a particle size of 6-20mm, with a single-stage crushing ratio of i4≤2.5; and after grading and screening, high-quality gelatin-specific bone particles and bone powder are obtained respectively.

[0010] Further, in step (1), the first-stage crushing adopts a low-speed, high-torque crusher with a discharge port diameter of 120mm; the second-stage crushing adopts a jaw crusher or a cone crusher with a discharge port gap of 60-75mm; and the third-stage crushing adopts a double-roll crusher with a roll gap of 45-50mm.

[0011] Furthermore, the fourth-stage fine crushing in step (3) adopts a double-roll crusher with the roller gap adjusted to 8-10mm.

[0012] Furthermore, the degreasing in step (2) is carried out in an extraction tank, and the upper end of the extraction tank is provided with a gaseous discharge port; the gaseous discharge port is connected to a gaseous condensation and recovery mechanism through a pipeline.

[0013] Furthermore, the defatting time in step (2) is 1-4 hours.

[0014] Furthermore, the animal bones are those of cattle, sheep, mules, horses, or pigs.

[0015] Furthermore, the mixed solution obtained in step (2) is heated to vaporize and condense all the liquid n-hexane for recovery, and the remaining solution is water-containing oil.

[0016] The inventive mechanism of this application is as follows: This application addresses the industry problem of existing anhydrous degreasing processes that, in pursuit of degreasing efficiency, necessitate refining particle size, resulting in a low yield of target-size bone particles. It creatively proposes a two-stage synergistic process: "medium particle size control before degreasing – precise fine crushing after degreasing." The core innovation lies in moving the degreasing operation forward to the 45-50mm medium particle size stage, preventing the disintegration of fine bone particles within the degreasing tank due to mechanical collision and micro-crack propagation. The specific mechanism is as follows: (i) Multi-stage crushing before defatting: Constructing an angular structure that is "crushed but not broken," laying the foundation for high yield. This application employs a three-stage crushing process before defatting, strictly limiting the crushing ratio of each stage to achieve "crushing without shattering" of bone particles, minimizing the generation of fine powder while achieving an intermediate particle size of 45-50mm. First-stage coarse crushing: A low-speed, high-torque crusher is used to crush animal raw bones with a feed size ≤300mm into bone blocks with a particle size of 100-120mm, with a single-stage crushing ratio i1 ≤ 3.0. This stage is mainly characterized by tearing and bending fracture, forming rough bone blocks with initial fracture surfaces along the natural cleavage planes of the bone, exposing the microscopic porous structure inside the bone, and providing initial channels for solvent penetration. The crushing ratio is strictly controlled in this stage to avoid over-crushing large bones at once, resulting in a large amount of fine powder.

[0017] Second-stage medium crushing: Jaw or cone crushers are used to crush 100-120mm bone blocks to 60-75mm, with a single-stage crushing ratio i2 ≤ 2.5. Through compression crushing, the bone particles are further split along the micro-cracks or natural bone seams created in the previous stage, while preserving their angularity. Because the crushing ratio is controlled within 2.5, the energy input is gentle, and the bone particles mainly crack along cleavage planes rather than being pulverized, thus controlling the fine powder yield from the source.

[0018] The third stage of fine crushing: A double-roll crusher is used to crush 60-75mm aggregate particles to 45-52mm, with a single-stage crushing ratio i3≤2.5. Quasi-static crushing ensures that the aggregate particles maintain an irregular, angular structure with high surface roughness, providing ample microscopic penetration channels for subsequent degreasing. Compared to impact crushing, the quasi-static crushing method of double-roll crushing results in a very low fine powder yield, and the cross-sectional morphology is more conducive to solvent wetting.

[0019] Conventional crushing typically employs hammer crushers or impact crushers for the fine crushing stage, using impact force to pulverize materials. The resulting product has a high proportion of fine powder and irregular particle shape. This application specifies the use of a double-roll crusher for the third-stage fine crushing, utilizing quasi-static pressure to fracture the aggregate particles. The resulting product has a low proportion of fine powder and a cross-section exhibiting an "irregular angular structure"—this structure forms the microscopic channels for solvent penetration during subsequent low-temperature degreasing.

[0020] The key point of this step is setting the crushing endpoint before degreasing at 45-50mm, instead of the traditional 6-20mm. This "moderate crushing" strategy has the following advantages: 1. Larger particle size results in higher mechanical strength when subjected to stirring and liquid flow impact in the degreasing tank, significantly reducing the risk of disintegration; 2. The angular structure is fully preserved, and the specific surface area is sufficient to ensure solvent penetration efficiency, achieving the required residual oil rate without relying on excessive crushing; 3. Higher material bulk density in the degreasing tank, better liquid permeability, reduced stirring energy consumption, and less equipment wear.

[0021] (ii) Low-temperature and atmospheric-pressure defatting: Ensuring defatting efficiency while preserving protein activity. The 45-50mm intermediate bone particles obtained in step (I) are degreased for 1-4 hours under low temperature and normal pressure conditions of 60-70℃ using n-hexane as a solvent. Then, after liquid-solid separation, the degreased bone particles and a mixed solution containing n-hexane, oil and water are obtained.

[0022] The key point of this step is: 1. Compared to fine bone fragments of 6-20mm, 45-52mm bone particles have better impact and wear resistance in the degreasing tank, and produce very little secondary fine powder due to mechanical collision during the degreasing process; 2. Low temperature conditions (60-70℃) prevent thermal denaturation of collagen and protect the microstructure of the edges from thermal stress damage. 3. The rough, angular structure at the front end provides ample solvent wetting channels, ensuring degreasing efficiency; 4. After defatting, the bone particles become slightly more brittle due to the extraction of oil, which provides favorable conditions for the subsequent fourth-stage crushing—making them easier to crush and reducing crushing energy consumption.

[0023] (III) Fourth-stage fine crushing after defatting: Precisely control the final particle size to achieve high yield. The degreased 45-50mm intermediate aggregate particles are subjected to a fourth-stage fine crushing using a double-roll crusher with the roller gap adjusted to 8-10mm, crushed to a final particle size of 6-20mm, with a single-stage crushing ratio i4≤2.5.

[0024] The key innovation of this step lies in postponing the fine crushing of the final particle size after degreasing. In traditional processes, 6-20mm fine bone particles are largely converted into fine powder during degreasing due to the propagation of internal micro-cracks and mechanical collisions. This application, however, postpones the fine crushing stage, allowing the degreasing operation to deal with 45-52mm bone particles with higher mechanical strength. The 6-20mm bone particles formed after degreasing no longer need to undergo the harsh conditions inside the degreasing tank, thus maximizing the preservation of the integrity of the target particle size. Simultaneously, the increased brittleness of the bone particles after degreasing allows the use of a double-roll crusher with quasi-static pressure to maintain the angular structure of the cross-section, resulting in an extremely low yield of fine powder.

[0025] Compared with the prior art, this application has the following beneficial effects: 1. Significantly improved bone particle yield: By postponing fine crushing, secondary disintegration losses during the degreasing process are avoided. The yield of finished bone particles with a target particle size of 6-20mm has increased from 45-50% in the traditional process to an average of over 60%, and the yield of fine powder has decreased from 30-35% to an average of less than 20%, resulting in significant economic benefits.

[0026] 2. Excellent core indicators: The low-temperature defatting process ensures that the residual oil content of bone particles is ≤2%, the moisture content is ≤8%, and the crude protein content is ≥30%.

[0027] 3. The degreasing process is gentler and more efficient: The degreasing target is medium-sized bone particles of 45-52mm, which has a higher bulk density and better liquid permeability compared to fine bone particles of 6-20mm. The material flowability in the extraction tank is better, the stirring energy consumption is reduced by 15-20%, and the equipment wear is reduced.

[0028] 4. Uniform and stable product quality: The four-stage crushing process ensures that the final aggregate particle size distribution is highly concentrated in the target range of 6-20mm, with regular particle shape. The yield fluctuation between batches is controlled within ±3%, which significantly improves product consistency and the user experience of downstream users.

[0029] 5. Achieve high-value full utilization of bone resources: This process, through precise control of the crushing sequence, maximizes the conversion of bone raw materials into high-value bone pellets (main product). The bone pellets are used for the production of high-quality gelatin, and a small amount of bone meal can be used as a by-product of feed additives, thus achieving high-value utilization of bone resources. Attached Figure Description

[0030] The above and other objects, features and advantages of this application will become more apparent from the more detailed description of exemplary embodiments thereof in conjunction with the accompanying drawings, wherein the same reference numerals generally represent the same components in the exemplary embodiments thereof.

[0031] Figure 1 The diagram shown is a schematic diagram of high-quality gelatin-specific bone particles with a size of 6-20mm obtained in Embodiment 1 of this application. Detailed Implementation

[0032] The embodiments of this application will be described in more detail below with reference to the examples. The following examples are for illustrative purposes only and should not be considered as limiting the scope of this application. Unless otherwise stated, the methods used in the examples are conventional methods in the art, and the reagents used are commercially available. Those skilled in the art can make various modifications and changes based on this application, and these modifications and changes also fall within the protection scope of this application. Example 1

[0033] This embodiment provides a high-efficiency anhydrous preparation method for high-quality gelatin-specific bone granules, including the following steps: (1) Multi-stage fracture of animal bones Fresh beef bones are taken, and after removing visible meat and tendons, raw bones with a feed size ≤300mm are fed into the crushing system for three-stage crushing: First-stage coarse crushing: A low-speed, high-torque twin-shaft shear crusher is used, with a discharge diameter of 120mm, to crush raw bone into bone blocks with a particle size of 100-120mm. Based on the ratio of the maximum feed particle size to the maximum discharge particle size, the single-stage crushing ratio i1 = 300 / 120 = 2.5 ≤ 3.0. This stage is mainly characterized by tearing and bending fractures, resulting in bone blocks with rough cross-sections that expose the microscopic porous structure within the bone structure.

[0034] Second-stage medium crushing: A jaw crusher is used, with the discharge port gap adjusted to 60-75mm, to crush the first-stage output into bone particles with a diameter of 60-75mm. The single-stage crushing ratio i2 = 120 / 75 = 1.6 ≤ 2.5. Testing showed that the bone particles in this stage maintained intact edges and corners, exhibiting fresh fracture surfaces, with a fine powder (<6mm) yield of approximately 2%.

[0035] The third stage of fine crushing: A double-roll crusher is used, with the roller gap adjusted to 45-50mm. The output from the second stage is crushed to intermediate aggregate particles with a diameter of 45-50mm. The single-stage crushing ratio i3=75 / 50=1.5≤2.5. Through quasi-static pressure crushing, the aggregate particles maintain an irregular angular structure with a high surface roughness. After screening, the crushed product contains 92.3% intermediate aggregate particles of 45-50mm, 2.5% fine powder (<6mm), and 5.2% aggregate particles >50mm (which can be returned to the third stage for further crushing).

[0036] (2) Low-temperature and normal-pressure degreasing The 45-50 mm intermediate bone particles obtained in step (1) were loaded into an extraction tank, and hexane solvent was added (solvent to bone particle mass ratio of 4:1). The tank was then degreased at 65°C and atmospheric pressure for 2.5 h. During the degreasing process, the gaseous outlet at the top of the extraction tank was connected to a condensation recovery mechanism via a pipeline to achieve solvent recycling. After degreasing, liquid-solid separation was performed to obtain the degreased intermediate bone particles and a mixed solution containing hexane, oil, and water.

[0037] (3) Post-processing The defatted intermediate bone particles obtained in step (2) were subjected to a fourth-stage fine crushing using a double-roll crusher with the roller gap adjusted to 8-10 mm, crushing to the target particle size of 6-20 mm. The single-stage crushing ratio i4 = 50 / 20 = 2.5 ≤ 2.5. After grading and screening, high-quality gelatin-specific bone particles of 6-20 mm were obtained (e.g., Figure 1 (as shown) and bone meal byproducts <6mm.

[0038] Test results: Yield of target bone particles (6-20mm): 61.2% Fine powder (<6mm) yield: 19.5% Residual oil content: 1.7% Moisture content: 7.4% Crude protein content: 31.5% Example 2 (Lower limit of defatting temperature) This embodiment is basically the same as Embodiment 1, except that the degreasing temperature is adjusted to 60℃.

[0039] (2) Low-temperature and normal-pressure degreasing The 45-50 mm intermediate bone particles obtained in step (1) were loaded into an extraction tank, and hexane solvent was added. The mixture was degreased at 60°C and normal pressure for 2.5 h.

[0040] Test results: Yield of target bone particles (6-20mm): 61.8% Fine powder (<6mm) yield: 18.9% Residual oil content: 1.9% Moisture content: 7.6% Crude protein content: 31.8% The results showed that at a degreasing temperature of 60°C, the residual oil rate could still be controlled below 2%, and the yield was slightly higher than that of Example 1, but the degreasing efficiency was slightly lower (the residual oil rate was slightly higher).

[0041] Example 3 (Upper Limit of Degreasing Temperature) This embodiment is basically the same as Embodiment 1, except that the degreasing temperature is adjusted to 70℃.

[0042] (2) Low-temperature and normal-pressure degreasing The 45-50 mm intermediate bone particles obtained in step (1) were loaded into an extraction tank, and hexane solvent was added. The mixture was degreased at 70°C and normal pressure for 2.5 h.

[0043] Test results: Yield of target bone particles (6-20mm): 60.5% Fine powder (<6mm) yield: 20.1% Residual oil content: 1.5% Moisture content: 7.2% Crude protein content: 30.9% The results showed that the degreasing effect was better (lower residual oil rate) at a degreasing temperature of 70℃, but the yield decreased slightly (possibly due to the slight embrittlement of the bone grain edges caused by high temperature).

[0044] Example 4 (Lower limit of defatting time) This embodiment is basically the same as Embodiment 1, except that the defatting time is adjusted to 1 hour.

[0045] (2) Low-temperature and normal-pressure degreasing The 45-50 mm intermediate bone particles obtained in step (1) were loaded into an extraction tank, and hexane solvent was added. The mixture was then degreased at 65°C and normal pressure for 1 hour.

[0046] Test results: Yield of target bone particles (6-20mm): 62.5% Fine powder (<6mm) yield: 18.2% Residual oil content: 2.0% Moisture content: 7.8% Crude protein content: 31.6% The results showed that with a defatting time of 1 hour, the residual oil rate just reached the critical value of 2%, but the bone particle yield was the highest.

[0047] Example 5 (Upper Limit of Degreasing Time) This embodiment is basically the same as Embodiment 1, except that the defatting time is adjusted to 4 hours.

[0048] (2) Low-temperature and normal-pressure degreasing The 45-50 mm intermediate bone particles obtained in step (1) were loaded into an extraction tank, and hexane solvent was added. The mixture was then degreased at 65°C and normal pressure for 4 hours.

[0049] Test results: Yield of target bone particles (6-20mm): 59.2% Fine powder (<6mm) yield: 21.5% Residual oil content: 1.4% Moisture content: 7.0% Crude protein content: 31.0% The results showed that the degreasing effect was the best (lowest residual oil rate) at a degreasing time of 4 hours, but the yield decreased significantly (possibly due to the collision and breakage of bone particles caused by prolonged stirring).

[0050] Example 6 (Second-stage crushing uses a cone crusher) This embodiment is basically the same as embodiment 1, except that the second-stage crushing uses a cone crusher.

[0051] (1) Multi-stage fracture of animal bones First-stage coarse crushing: Same as in Example 1.

[0052] Secondary crushing: A cone crusher is used, with the discharge port gap adjusted to 60-75mm, to crush the first-stage output into aggregate particles with a diameter of 60-75mm, achieving a single-stage crushing ratio i2≤2.5. Testing showed that the aggregate particles maintained their angular integrity during this stage, with a fine powder (<6mm) yield of approximately 2.5%.

[0053] Third-stage fine crushing: Same as Example 1.

[0054] Post-processing: Same as in Example 1.

[0055] Test results: Yield of target bone particles (6-20mm): 60.8% Fine powder (<6mm) yield: 19.6% Residual oil content: 1.8% Moisture content: 7.5% Crude protein content: 31.3% The results show that using a cone crusher for secondary crushing is as effective as using a jaw crusher.

[0056] Example 7 (Upper limit of the third-stage crushing roller gap) This embodiment is basically the same as Embodiment 1, except that the gap of the third-stage crushing roller is adjusted to 50mm.

[0057] (1) Multi-stage fracture of animal bones First and second stage crushing: Same as in Example 1.

[0058] The third stage of pre-crushing: A double-roll crusher is used, with the roller gap adjusted to 50mm, to crush the second-stage output into intermediate aggregate particles with a particle size of 45-50mm (upper limit 50mm). Screening results show that 90.5% of the crushed product consists of 45-50mm intermediate aggregate particles, 3.0% of fine powder (<6mm), and 6.5% of aggregate particles >50mm.

[0059] Post-processing: Same as in Example 1.

[0060] Test results: Yield of target bone particles (6-20mm): 59.8% Fine powder (<6mm) yield: 20.5% Residual oil content: 1.9% Moisture content: 7.6% Crude protein content: 31.1% The results showed that when the roller gap was adjusted to 10 mm, the yield of target bone particles decreased slightly, but was still within an acceptable range.

[0061] Example 8 (Lower limit of the third-stage crushing roller gap) This embodiment is basically the same as Embodiment 1, except that the gap of the third-stage crushing roller is adjusted to 45mm.

[0062] (1) Multi-stage fracture of animal bones First and second stage crushing: Same as in Example 1.

[0063] The third stage of pre-crushing: A double-roll crusher is used, with the roller gap adjusted to 45mm, to crush the second-stage output into intermediate aggregate particles with a particle size of 45-50mm (lower limit 45mm). Screening results show that 93.2% of the crushed product consists of 45-50mm intermediate aggregate particles, 2.2% is fine powder (<6mm), and 4.6% is aggregate particles >50mm.

[0064] Test results: Yield of target bone particles (6-20mm): 60.2% Fine powder (<6mm) yield: 20.3% Residual oil content: 1.7% Moisture content: 7.4% Crude protein content: 31.2% The results showed that when the roller gap was adjusted to 8 mm, the yield of the target bone particles was comparable to that of Example 1, but the fine powder content was slightly higher.

[0065] Comparative Example 1 (Single-stage crushing) This comparative example is basically the same as Example 1, except that single-stage crushing is used instead of three-stage crushing, and the material is crushed to 6-20mm before degreasing.

[0066] (1) Single-stage fragmentation of animal bones Fresh beef bones with a feed size ≤300mm were directly crushed using a hammer crusher. The crusher parameters were adjusted to achieve a target product size of 6-20mm. Testing revealed that 52.3% of the crushed product was 6-20mm target bone particles, 36.8% was fine powder (<6mm), and 10.9% was >20mm bone particles (requiring rework).

[0067] (2) Low temperature and normal pressure degreasing: Same as in Example 1.

[0068] (3) Post-processing: Same as in Example 1.

[0069] Test results: Yield of target bone particles (6-20mm): 36.5% Fine powder (<6mm) yield: 43.2% Residual oil content: 1.9% Moisture content: 7.8% Crude protein content: 30.8% Conclusion: Single-stage high crushing ratio crushing (using a hammer crusher with concentrated impact energy) resulted in a large number of bone particles being over-crushed into fine powder, and further disintegration due to the expansion of internal microcracks during degreasing. The target bone particle yield decreased by about 25 percentage points compared with Example 1 (from about 60% in Example 1 to 36.5%), while the fine powder yield increased significantly, verifying the necessity of multi-stage cascade crushing.

[0070] Comparative Example 2 (two-stage crushing, the second-stage crushing ratio is too large) This comparative example is basically the same as Example 1, except that it uses two-stage crushing (omitting the first stage and merging the original first and second stages), and is crushed to 6-20mm before degreasing.

[0071] (1) Two-stage fragmentation of animal bones First-stage crushing: Fresh beef bones with a feed size ≤300mm are crushed into bone pieces with a discharge diameter of 60-75mm using a jaw crusher with a discharge diameter of 80mm. The single-stage crushing ratio i1 = 300 / 75 = 4.0 is calculated based on the ratio of the maximum feed size to the maximum discharge size.

[0072] Second-stage crushing: A double-roll crusher is used, with the roller gap adjusted to 12.5mm. The first-stage output is crushed to the target aggregate particle size of 6-20mm. Based on the ratio of the maximum feed particle size to the maximum output particle size, the single-stage crushing ratio i2 = 75 / 20 = 3.75.

[0073] Tests showed that 68.5% of the crushed product was composed of target bone particles between 6-20mm, 21.3% was fine powder (<6mm), and 10.2% was bone particles >20mm.

[0074] (2) Low temperature and normal pressure degreasing: Same as in Example 1.

[0075] (3) Post-processing: Same as in Example 1.

[0076] Test results: Yield of target bone particles (6-20mm): 44.8% Fine powder (<6mm) yield: 30.5% Residual oil content: 1.8% Moisture content: 7.6% Crude protein content: 30.5% Conclusion: Two-stage crushing with an excessively high crushing ratio resulted in numerous microcracks inside the bone particles, which further disintegrated during the degreasing and stirring process. The yield of fine powder increased significantly compared to the crushed product (from 21.3% to 30.5%), and the target bone particle yield decreased by approximately 14 percentage points compared to Example 1. This verifies the necessity of three-stage crushing and controlling the single-stage crushing ratio.

[0077] Comparative Example 3 (using three-stage crushing but with a loose crushing ratio) This comparative example is basically the same as Example 1, except that it uses three-stage crushing but allows for a wider crushing ratio, and the material is crushed to 45-50mm before degreasing.

[0078] (1) Three-stage fragmentation of animal bones First-stage coarse crushing: Same as in Example 1, but the single-stage crushing ratio i1=3.5 (discharge port diameter is increased to 85mm).

[0079] Second-stage medium crushing: single-stage crushing ratio i2=3.0 (discharge port gap widened to 85mm).

[0080] Third-stage pre-crushing: single-stage crushing ratio i3=2.5 (roller gap 50mm), to obtain 45-50mm intermediate aggregate particles.

[0081] Tests showed that 85.5% of the crushed product was composed of medium-sized aggregate particles (45-50mm), 8.5% was composed of fine powder (<6mm), and 6.0% was composed of aggregate particles (>50mm).

[0082] (2) Low temperature and normal pressure degreasing: Same as in Example 1.

[0083] (3) Post-processing: Same as in Example 1 (fourth-stage fine crushing to 6-20mm).

[0084] Test results: Yield of target bone particles (6-20mm): 51.3% Fine powder (<6mm) yield: 28.0% Residual oil content: 1.8% Moisture content: 7.5% Crude protein content: 30.6% Conclusion: Even with three-stage crushing and a pre-degreasing size of 45-50 mm, relaxing the single-stage crushing ratio still leads to an increase in microcracks inside the intermediate bone particles, resulting in more fine powder being generated during the fourth-stage crushing and degreasing process. The target bone particle yield is reduced by about 8 percentage points compared to Example 1, verifying that the contribution of the "low single-stage crushing ratio" to the yield has a gradient dependence.

[0085] Comparative Example 4 (Level 3 fragmentation but without maintaining angular structure) This comparative example is basically the same as Example 1, except that the third-stage crushing uses a high-speed rotating hammer crusher to destroy the angular structure.

[0086] (1) Three-stage fragmentation of animal bones (third-stage destruction of edges and corners) First and second stage crushing: Same as in Example 1.

[0087] The third stage of pre-crushing: A high-speed hammer crusher (3000 r / min) is used to crush the second-stage output to intermediate aggregate particles with a particle size of 45-50 mm. Upon observation, the aggregate particles have a rounded cross-section, the angular structure is destroyed, and the surface is relatively smooth.

[0088] Tests showed that 90.2% of the crushed product consisted of medium-sized aggregate particles (45-50mm), 5.5% consisted of fine powder (<6mm), and 4.3% consisted of aggregate particles (>50mm).

[0089] (2) Low temperature and normal pressure degreasing: Same as in Example 1.

[0090] (3) Post-processing: Same as in Example 1.

[0091] Test results: Yield of target bone particles (6-20mm): 58.2% Fine powder (<6mm) yield: 21.0% Residual oil content: 2.5% Moisture content: 7.9% Crude protein content: 30.2% Conclusion: Although the three-stage crushing controlled the crushing ratio, the high-speed crushing in the third stage disrupted the angular structure, leading to a decrease in degreasing efficiency (residual oil content exceeding the standard by 2.5%) and a reduction in yield. This verifies the importance of maintaining the angular structure of the bone particle cross-section for degreasing efficiency.

[0092] Comparative Example 5 (High-Temperature Degreasing) This comparative example is basically the same as Example 1, except that the degreasing temperature is high (85°C).

[0093] (2) High temperature degreasing The target bone particles were loaded into an extraction tank, and hexane solvent was added. The mixture was then degreased at 85°C and normal pressure for 2.5 hours.

[0094] Test results: Yield of target bone particles (6-20mm): 54.5% Fine powder (<6mm) yield: 25.8% Residual oil content: 1.5% Moisture content: 7.3% Crude protein content: 24.2% Conclusion: Although high-temperature defatting can ensure the defatting effect, the crude protein content is significantly reduced (from 31% to 24%). At the same time, the high temperature makes the edges of bone particles brittle, and more fine powder is generated during defatting stirring and subsequent sieving, resulting in a decrease in yield.

[0095] Comparative Example 6 (Defatting time too short) This comparative example is basically the same as Example 1, except that the defatting time is adjusted to 0.5h.

[0096] (2) Low-temperature and normal-pressure degreasing The target bone particles were loaded into an extraction tank, and hexane solvent was added. The mixture was then degreased at 65°C and normal pressure for 0.5 hours.

[0097] Test results: Yield of target bone particles (6-20mm): 62.8% Fine powder (<6mm) yield: 17.5% Residual oil content: 2.8% Moisture content: 8.1% Crude protein content: 31.2% Conclusion: The defatting time was too short (0.5h), resulting in an excessive residual oil rate (2.8%). Although the yield was the highest, the product was unqualified.

[0098] Comparative Example 7 (excessive defatting time) This comparative example is basically the same as Example 1, except that the defatting time is adjusted to 6 hours.

[0099] (2) Low-temperature and normal-pressure degreasing The target bone particles were loaded into an extraction tank, and hexane solvent was added. The mixture was then degreased at 65°C and normal pressure for 6 hours.

[0100] Test results: Yield of target bone particles (6-20mm): 55.2% Fine powder (<6mm) yield: 25.0% Residual oil content: 1.3% Moisture content: 6.8% Crude protein content: 30.5% Conclusion: Excessive defatting time (6h) caused bone particles to collide and break during prolonged stirring, resulting in increased fine powder yield and decreased overall yield. Results Analysis

[0101] The results of the embodiments and comparative examples were analyzed: 1. Regarding the control of the ratio between tertiary crushing and single-stage crushing Comparing Example 1 with Comparative Examples 1-3, it can be seen that: Single-stage crushing (Comparative Example 1) resulted in a target aggregate yield of only 36.5%, while the fine powder yield was as high as 43.2%. Two-stage crushing with an excessive crushing ratio (Comparative Example 2) resulted in a target aggregate yield of 46.8% and a fine powder yield of 32.5%. The target aggregate yield was 51.3% and fine powder yield was 28.0% for tertiary crushing with an open crushing ratio (Comparative Example 3). The present application achieves a target bone particle yield of 61.2% and a fine powder yield of 19.5% by controlling the single-stage crushing ratio and fine crushing after defatting (Example 1) through three-stage crushing and controlling the single-stage crushing ratio.

[0102] The above comparison proves that dispersing the total crushing ratio into three stages of progressive crushing with low crushing ratios, and placing the final particle size fine crushing after degreasing, is the key to controlling the fine powder yield and improving the target bone particle yield from the source.

[0103] 2. Regarding the preservation of angular structures Comparing Example 1 and Comparative Example 4, we can see that: Comparative Example 4 used high-speed crushing to destroy the angular structure. Although the crushing particle size was well controlled (yield 58.2%), the degreasing efficiency decreased (residual oil rate exceeded the standard by 2.5%). Example 1 maintains the angular structure and has good degreasing efficiency (residual oil rate 1.7%).

[0104] The above comparison proves that maintaining the angular structure of the bone particle cross-section is a necessary condition to ensure efficient degreasing without refining the particle size.

[0105] 3. Regarding defatting temperature Comparing Examples 1-3 with Comparative Example 5, we can see that: Although high-temperature defatting (85℃, Comparative Example 5) had a good defatting effect (residual oil rate 1.5%), the crude protein content was significantly reduced (24.2%), and the thermal embrittlement of bone particles led to a decrease in yield (54.5%). Low-temperature defatting (60-70℃, Examples 1-3) ensures the defatting effect while maintaining the crude protein content above 30% and the yield above 60%.

[0106] The above comparison proves that low-temperature defatting at 60-70℃ is the optimal range for balancing defatting efficiency, protein retention, and yield.

[0107] 4. Regarding defatting time Comparing Examples 1, 4, and 5 with Comparative Examples 6 and 7, it can be seen that: The defatting time was too short (0.5h, comparative example 6) which resulted in an excessive residual oil content (2.8%). Excessive defatting time (6 hours, Comparative Example 7) resulted in a decrease in yield (55.2%). A defatting time of 1-4 hours (Examples 1, 4, 5) can achieve a better yield while ensuring the defatting effect.

[0108] The above comparison proves that a degreasing time of 1-4 hours is a reasonable process window.

[0109] Based on the analysis of the results of the above embodiments and comparative examples, it can be concluded that: 1. The three-stage crushing and control of the single-stage crushing ratio in the technical solution of this application can effectively avoid over-crushing and ensure the final bone particle yield from the source.

[0110] 2. The preservation of the angular structure of the bone particle cross-section in the technical solution of this application provides sufficient specific surface area and penetration channels for subsequent degreasing, so that the degreasing efficiency can still be guaranteed without refining the particle size.

[0111] 3. The low-temperature degreasing (60-70℃) in this application's technical solution can ensure the degreasing effect (residual oil rate ≤2%), avoid the damage of crude protein to high temperature (crude protein content ≥30%), and avoid the yield decrease caused by the thermal embrittlement of bone particles.

[0112] 4. The technical solution of this application places the final particle size fine crushing after degreasing, so that the degreasing operation is faced with 45-50mm intermediate bone particles with higher mechanical strength, avoiding the disintegration and loss of 6-20mm fine bone particles in the degreasing tank. This is the core innovation for achieving a breakthrough improvement in the yield of target bone particles.

[0113] 5. Through the synergistic effect of the above-mentioned features, the technical solution of this application, while maintaining the existing advantages of the anhydrous degreasing process, increases the yield of 6-20mm target particle size bone particles from 45-50% in the traditional process to an average of over 60%, and reduces the fine powder yield from 30-35% to an average of less than 20%, resulting in significant economic benefits.

[0114] The various embodiments of this application have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or improvement of the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A method for the anhydrous and efficient preparation of high-quality gelatin-specific bone granules, characterized in that, Includes the following steps: (1) Multi-stage crushing of animal raw bones: Animal raw bones are crushed sequentially through three-stage crushing units, and the single-stage crushing ratios i1≤3.0, i2≤2.5, and i3≤2.5 are controlled to obtain bone particles with a particle size of 45-50mm; the single-stage crushing ratio refers to the ratio of the maximum feed particle size to the maximum discharge particle size; The first stage of crushing is coarse crushing: animal bones with a feed size ≤300mm are crushed into bone blocks with a particle size of 100-120mm, and the single-stage crushing ratio i1≤3.0; The second stage of crushing is medium crushing: the bone blocks obtained from the first stage of crushing are crushed to bone particles with a diameter of 60-75mm, and the single-stage crushing ratio i2≤2.5; The third stage of crushing is fine crushing: the bone particles obtained from the second stage of crushing are crushed to the target bone particles with a final particle size of 45-50mm, the single-stage crushing ratio i3≤2.5, and the cross-section of the crushed bone particles maintains an uneven angular structure. (2) Low temperature and normal pressure degreasing: The target bone particles obtained in step (1) are degreased under normal pressure at 60-70℃ with hexane as solvent, and then separated by liquid-solid separation to obtain the degreased bone particles and a mixed solution containing hexane, oil and water. (3) Post-processing: The defatted bone particles obtained in step (2) are subjected to fourth-stage fine crushing to target bone particles with a particle size of 6-20mm, with a single-stage crushing ratio of i4≤2.5; and after grading and screening, high-quality gelatin-specific bone particles and bone powder are obtained respectively.

2. The method for preparing high-quality gelatin-specific bone granules using anhydrous methods according to claim 1, characterized in that, In step (1), the first-stage crushing adopts a low-speed, high-torque crusher with a discharge port diameter of 120mm; the second-stage crushing adopts a jaw crusher or a cone crusher with a discharge port gap of 60-75mm; the third-stage crushing adopts a double-roll crusher with a roll gap of 45-50mm.

3. The method for preparing high-quality gelatin-specific bone granules using anhydrous methods according to claim 1, characterized in that, The fourth-stage fine crushing in step (3) uses a double-roll crusher with the roller gap adjusted to 8-10mm.

4. The method for preparing high-quality gelatin-specific bone granules using anhydrous methods according to claim 1, characterized in that, The degreasing in step (2) is carried out in an extraction tank, the upper end of which is provided with a gaseous discharge port; the gaseous discharge port is connected to a gaseous condensation and recovery mechanism through a pipeline.

5. The method for preparing high-quality gelatin-specific bone granules anhydrous efficiently according to claim 1, characterized in that, The defatting time in step (2) is 1-4 hours.

6. The method for preparing high-quality gelatin-specific bone granules using anhydrous methods according to claim 1, characterized in that, The animal bones mentioned are those of cattle, sheep, mules, horses, or pigs.

7. The method for preparing high-quality gelatin-specific bone granules in anhydrous form according to claim 1, characterized in that, The mixed solution obtained in step (2) is heated to vaporize and condense all the liquid n-hexane for recovery, and the remaining solution is water-containing oil.

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