Oyster shell calcium gel and its preparation method

Abstract

This invention provides oyster shell calcium gel and its preparation method, belonging to the field of health food technology. The invention involves mixing and dissolving oyster shell powder with a lactic acid solution to obtain an oyster shell calcium lactate solution; mixing the oyster shell calcium lactate solution, chitosan, and gelatin to obtain a gel liquid; and mixing the gel liquid with a Na2CO3 solution and allowing it to stand to obtain oyster shell calcium gel. This invention uses chitosan and gelatin as base materials and oyster shells as the calcium source to prepare a high-calcium, jelly-like calcium gel, different from currently available tablets and oral calcium supplements. The oyster shell calcium gel prepared by this invention has high calcium content, good stability, easy absorption, good bioactivity, and few gastrointestinal side effects. It is portable, easy to use, easy to chew, and has a chewy and smooth texture. Furthermore, its components are simple, the raw materials are readily available, and the product has high added value. The production process of this invention is simple to operate, environmentally friendly, and has excellent prospects for widespread application.

Description

Technical Field

[0001] This invention belongs to the field of health food technology, and particularly relates to an oyster shell gel calcium and its preparation method. 。 Background Technology

[0002] Calcium plays a vital role in maintaining the normal physiological functions of human bones, muscles, nerves, and cardiovascular system. Oysters are the world's largest farmed shellfish and one of my country's four major farmed shellfish. Currently, domestic oyster farming mainly focuses on the edible parts, while the inedible shells are discarded as waste, causing environmental pollution and wasting resources.

[0003] Oyster shells are multi-layered microstructures formed naturally through mineralization under the regulation of bio-organic macromolecules such as proteins and polysaccharides. These shells are primarily composed of calcium carbonate. Organic matter such as proteins and polysaccharides accounts for only about 5%, while calcium carbonate comprises 90%–95% of the total mass of the oyster shell, with a calcium content of approximately 40%, making it an excellent natural source of calcium. Research on preparing various food-grade and pharmaceutical-grade calcium supplements from oyster shells has received widespread attention. Oyster calcium carbonate chewable tablets, oyster shell calcium chewable tablets, Longmu Zhuanggu granules, oyster calcium carbonate granules, and oyster calcium carbonate capsules are already available on the market.

[0004] The aforementioned oyster shell calcium supplements all use oyster shells processed into powder as a direct calcium source, with calcium carbonate as the calcium supplement component. However, calcium carbonate supplements require stomach acid to break down and release calcium. 2+ Oyster shell calcium supplements need to be digested and absorbed properly. The CO2 produced during this process can cause belching, constipation, and abdominal discomfort. Excessive or long-term use can lead to rebound gastric acid secretion, making them unsuitable for patients with gastrointestinal diseases such as gastric ulcers. Furthermore, oyster shell calcium supplements in tablet, powder, and capsule forms often have a fishy smell, poor taste and texture, and are difficult to swallow, which can lead to an unpleasant experience for consumers and cause psychological resistance.

[0005] Chinese patent CN 110024895 A discloses an oyster calcium gel candy and its preparation method. Although the dosage form has been improved, the oyster calcium component is still insoluble calcium carbonate, which will have the problem of uneven dispersion. The improved gel-type calcium supplement also has the problems of side effects and poor taste. Summary of the Invention

[0006] In view of this, the purpose of this invention is to provide oyster shell gel calcium and its preparation method, so as to overcome the problems of existing calcium supplement products, such as fishy smell, poor taste and texture, difficulty in swallowing, and side effects.

[0007] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0008] This invention provides a method for preparing oyster shell calcium gel, comprising the following steps:

[0009] 1) Mix and dissolve oyster shell powder with lactic acid solution to obtain oyster shell calcium lactate solution;

[0010] 2) Mix oyster shell calcium lactate solution, chitosan and gelatin to obtain a gel solution;

[0011] 3) Mix the gel solution with Na2CO3 solution and let it stand to obtain oyster shell calcium gel.

[0012] Preferably, the ratio of oyster shell powder to lactic acid solution is 1g:(15-40)mL.

[0013] Preferably, the mass ratio of chitosan to gelatin is (1-3):(1-3).

[0014] Preferably, the concentration of the Na2CO3 solution is 0.5-2.5 mol / L.

[0015] Preferably, the mixing temperatures in steps 2) and 3) are 40-90°C.

[0016] Preferably, the oyster shell powder has a mesh size of 80-120; the lactic acid solution has a concentration of 1-3 mol / L; and the dissolution time is 20-40 min.

[0017] Preferably, the ratio of the oyster shell calcium lactate solution, chitosan, and gelatin is (40-60) mL: (0.5-1.5) g: (0.5-1.5) g.

[0018] Preferably, the mixing process in steps 2) and 3) is accompanied by stirring, the stirring speed is 200-400 rpm, the stirring time in step 2) is 10-30 min, and the stirring time in step 3) is 40-80 min.

[0019] Preferably, the settling time is 18-30 hours.

[0020] The present invention also provides a method for preparing oyster shell gel calcium as described above, resulting in oyster shell gel calcium.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] This invention uses non-toxic, safe, and biocompatible gelatin and chitosan as gelling agents. Gelatin is insoluble in cold water but soluble in hot water, and the gel it prepares exhibits reversible temperature-dependent changes. Chitosan is readily soluble in acidic environments but has poor solubility in neutral or alkaline conditions, and possesses functions such as lowering lipids, promoting gastrointestinal motility, regulating intestinal health, and promoting calcium absorption. The oyster shell gel prepared using a gelatin-chitosan mixture is not only easy to chew and has a smooth texture, but also protects the gastrointestinal tract and promotes calcium absorption. Oyster shells are dissolved in lactic acid to prepare calcium lactate, which has advantages over calcium carbonate in terms of good solubility, easy absorption, and easy dispersion. Using this oyster shell calcium lactate solution as a calcium source ensures that the calcium in the prepared oyster shell gel is not only well dispersed in the gel but also easily absorbed.

[0023] The oyster shell gel prepared by this invention has a high calcium content, good stability, is easily absorbed, has good bioactivity, and few gastrointestinal side effects. It is portable, easy to use, easy to chew, and has a chewy and smooth texture. Furthermore, its ingredients are simple, the raw materials are readily available, the preparation process is simple, and the product has high added value. As a calcium supplement, its raw materials and jelly-like gel form offer better taste and easier calcium absorption compared to commercially available calcium carbonate tablets, capsules, and powders, and it also has a protective function for the gastrointestinal tract, providing consumers with a better choice for calcium supplementation. The production process of this invention is simple, environmentally friendly, and has excellent prospects for widespread application. Attached Figure Description

[0024] Figure 1 Effect of the mass ratio of mixed gelling agents (CS:GEL) on the strength of oyster shell calcium gel;

[0025] Figure 2 Effect of the mass ratio of mixed gelling agent (CS:GEL) on the stability of oyster shell gel calcium (from left to right, the mass ratios of mixed gelling agent (CS:GEL) added are 2:0, 3:1, 2:1, 1:1, 1:2, 1:3, and 0:2, respectively);

[0026] Figure 3 The effect of the solid-liquid ratio of oyster shell lactic acid solution on the strength of oyster shell calcium gel;

[0027] Figure 4 Effect of solid-liquid ratio of oyster shell lactic acid solution on the stability of oyster shell gel calcium (from left to right, the solid-liquid ratios of oyster shell and lactic acid solution are 1:40, 1:35, 1:30, 1:25, 1:20, and 1:15, respectively).

[0028] Figure 5 The effect of temperature on the strength of oyster shell gel calcium gel;

[0029] Figure 6The effect of temperature on the stability of oyster shell gel calcium (from left to right, the temperatures are 40, 50, 60, 70, 80, and 90℃).

[0030] Figure 7 The effect of Na2CO3 concentration on the strength of oyster shell gel calcium gel;

[0031] Figure 8 Effect of Na2CO3 concentration on the stability of oyster shell gel calcium (from left to right, representing Na2CO3 concentrations of 0, 0.5, 1.0, 1.5, 2.0, and 2.5 mol / L respectively);

[0032] Figure 9 SEM images of oyster shell calcium gel (a, b, and c are electron microscope images of oyster shell calcium gel magnified at 50x, 500x, and 5000x respectively).

[0033] Figure 10 Fecal samples from rats in each group 14 days after administration of oyster shell calcium gel;

[0034] Figure 11 Micro-CT analysis of the distal femur of SD rats in each experimental group (a is a 3D cross-sectional image of the trabeculae; b is a 2D coronal image from CT scan; c is a 3D reconstructed image of the femur). Detailed Implementation

[0035] This invention provides a method for preparing oyster shell calcium gel, comprising the following steps:

[0036] 1) Mix and dissolve oyster shell powder with lactic acid solution to obtain oyster shell calcium lactate solution;

[0037] 2) Mix oyster shell calcium lactate solution, chitosan and gelatin to obtain a gel solution;

[0038] 3) Mix the gel solution with Na2CO3 solution and let it stand to obtain oyster shell calcium gel.

[0039] In this invention, oyster shell powder is mixed and dissolved with a lactic acid solution to obtain an oyster shell calcium lactate solution. The preferred method for preparing the oyster shell powder is to wash, dry, and pulverize oyster shells to obtain the powder. The mesh size of the oyster shell powder is preferably 80-120 mesh, more preferably 90-110 mesh. The concentration of the lactic acid solution is preferably 1-3 mol / L, more preferably 1.5-2.5 mol / L. The preferred mixing ratio of oyster shell powder to lactic acid solution is 1 g:(15-40) mL, more preferably 1 g:(20-35) mL. The preferred mixing temperature is 40-90℃, more preferably 50-70℃. The preferred dissolution time is 20-40 min, more preferably 25-35 min.

[0040] In this invention, an oyster shell calcium lactate solution, chitosan, and gelatin are mixed to obtain a gel solution; the preferred mass ratio of chitosan to gelatin is (1-3):(1-3), more preferably (1.5-2.5):(1.5-2.5); the preferred mixing method is to first slowly add chitosan to the oyster shell calcium lactate solution, and then add gelatin; the preferred ratio of the oyster shell calcium lactate solution, chitosan, and gelatin is (40-60) mL:(0.5-1.5) g:(0.5-1.5) g. The preferred mixing temperature is 40-90℃, more preferably 50-70℃; the mixing process is accompanied by stirring, the stirring speed is preferably 200-400 rpm, more preferably 250-350 rpm; the stirring time is preferably 10-30 min, more preferably 15-25 min.

[0041] In this invention, oyster shell calcium gel is obtained by mixing a gel solution with a Na2CO3 solution and allowing it to stand. The concentration of the Na2CO3 solution is preferably 0.5-2.5 mol / L, more preferably 1-2 mol / L. The amount of Na2CO3 solution added is preferably 3-7 mL, more preferably 4-6 mL. The mixing temperature is preferably 40-90℃, more preferably 50-70℃. The mixing process is accompanied by stirring, and the stirring speed is preferably 200-400 rpm, more preferably 250-350 rpm. The stirring time is preferably 40-80 min, more preferably 50-70 min. The standing method is preferably natural cooling followed by standing at room temperature, and the standing time is preferably 18-30 h, more preferably 20-26 h.

[0042] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0043] Example 1

[0044] Oyster shells were washed, dried, and pulverized into 100-mesh powder. Oyster shell calcium lactate solution was prepared by dissolving the powder in 2 mol / L lactic acid solution for 30 minutes at a solid-liquid ratio of 1:30 (g / mL) and a controlled temperature of 60℃. In 50 mL of the oyster shell calcium lactate solution, chitosan was slowly added to the system at 70℃, followed by gelatin. The total mass of chitosan and gelatin added was 2 g, with a chitosan-to-gelatin mass ratio of 3:1. The mixture was stirred at 300 rpm for 20 minutes to dissolve and mix thoroughly to prepare a gel. In the above gel reaction system, while maintaining the above reaction temperature and stirring speed, 5 mL of 1 mol / L Na₂CO₃ solution was added, and the reaction was stirred for 60 minutes. The reaction product was collected into a plastic graduated cup, sealed, allowed to cool naturally, and allowed to stand at room temperature for 24 hours to obtain oyster shell calcium gel.

[0045] Example 2

[0046] Oyster shells were washed, dried, and pulverized into 80-mesh powder. Oyster shell calcium lactate solution was prepared by dissolving the powder in 1 mol / L lactic acid solution for 20 minutes at a solid-liquid ratio of 1:40 (g / mL) and a controlled temperature of 40℃. In 60 mL of the oyster shell calcium lactate solution, chitosan was slowly added first, followed by gelatin, at a controlled temperature of 60℃. The total mass of chitosan and gelatin added was 3 g, with a chitosan-to-gelatin mass ratio of 2:1. The mixture was stirred at 400 rpm for 15 minutes to dissolve and mix thoroughly, preparing a gel. In the above gel reaction system, while maintaining the above reaction temperature and stirring speed, 4 mL of 2.5 mol / L Na₂CO₃ solution was added, and the mixture was stirred for 70 minutes. The reaction product was collected into a plastic graduated cup, sealed, allowed to cool naturally, and allowed to stand at room temperature for 20 hours to obtain oyster shell calcium gel.

[0047] Example 3

[0048] Oyster shells were washed, dried, and pulverized into 120-mesh powder. Oyster shell calcium lactate solution was prepared by dissolving the powder in 3 mol / L lactic acid solution for 40 min at a solid-liquid ratio of 1:25 (g / mL) and a controlled temperature of 50℃. In 40 mL of the oyster shell calcium lactate solution, chitosan was slowly added first, followed by gelatin, at a controlled temperature of 40℃. The total mass of chitosan and gelatin added was 2.5 g, with a chitosan-to-gelatin mass ratio of 1:2. The mixture was stirred at 350 rpm for 25 min to dissolve and mix thoroughly to prepare a gel. In the above gel reaction system, while maintaining the above reaction temperature and stirring speed, 6 mL of 2 mol / L Na₂CO₃ solution was added, and the mixture was stirred for 50 min. The reaction product was collected into a plastic graduated cup, sealed, allowed to cool naturally, and allowed to stand at room temperature for 26 h to obtain oyster shell calcium gel.

[0049] Experimental Example 1

[0050] Effect of the mass ratio of mixed gelling agents (CS:GEL) on the strength and stability of calcium gel:

[0051] Weigh an appropriate amount of 100-mesh oyster shell powder and add 2 mol / L lactic acid solution at a solid-liquid ratio of 1:25 (mass:volume) to the oyster shell lactic acid solution. Stir and react at 60℃ and 300 rpm for 30 min, then filter and divide into multiple 50 mL portions of oyster shell calcium lactate solution. At 60℃ and 300 rpm, add chitosan slowly to the oyster shell calcium lactate solution according to mixing gel mass ratios of 2:0, 3:1, 2:1, 1:1, 1:2, 1:3, and 0:2, respectively. Then add gelatin, with a total added mass of 2 g of chitosan and gelatin. Stir and dissolve until uniformly mixed. Then add 5 mL of 1 mol / L Na2CO3 solution and continue stirring for 1 h. After gently stirring with a glass rod to remove bubbles, transfer 20 mL of the reaction mixture to a plastic graduated cup, seal and allow to cool naturally for 24 h to obtain oyster shell calcium gel. The gel strength of the calcium gel was determined using a TAXTPlus food property analyzer with a 0.5-inch cylindrical polyoxymethylene black probe. After the product was stored at room temperature for half a month, the stability of the calcium gel was analyzed based on the precipitation of calcium gel.

[0052] Experimental results: The effect of the mass ratio of mixed gelling agent (CS:GEL) on the strength of calcium gel is as follows: Figure 1 As shown, the gel strength of calcium gel changes significantly with the mass ratio of the mixed gelling agent. As the CS:GEL ratio decreases, the gel strength decreases, and in some cases, the gel strength of calcium gel prepared in a gel system without chitosan drops to zero.

[0053] The effect of the mass ratio of mixed gelling agents (CS:GEL) on the stability of calcium gel is as follows: Figure 2 As shown, calcium lactate precipitation occurred in all calcium gel systems with CS:GEL ratios of 2:0, 1:1, 1:2, and 0:2 after half a month. The CS:GEL 2:0 system showed more white solid calcium precipitation on the gel surface, while the CS:GEL 1:1 and 1:2 systems showed only small amounts of calcium precipitation. The CS:GEL 0:2 system showed a small amount of white calcium precipitation that settled at the bottom of the sample. In contrast, calcium gel products with CS:GEL ratios of 3:1, 2:1, and 1:3 showed no calcium precipitation and exhibited good stability. Considering both gel strength and stability, a CS:GEL ratio of 3:1 or 2:1 was determined.

[0054] Experiment Example 2

[0055] The effect of the solid-liquid ratio of oyster shell lactic acid solution on the strength and stability of calcium gel:

[0056] Weigh out appropriate amounts of 100-mesh oyster shell powder and add 2 mol / L lactic acid solution at solid-liquid ratios (mass:volume) of oyster shell lactic acid solution of 1:40, 1:35, 1:30, 1:25, 1:20, and 1:15 respectively. Stir and react at 60℃ and 300 rpm for 30 min, then filter and take 50 mL of each oyster shell calcium lactate solution. At 60℃ and 300 rpm, add chitosan first, then gelatin, at a CS:GEL ratio of 2:1, with a total added mass of 2 g of chitosan and gelatin. Stir and dissolve until homogeneous. Then add 5 mL of 1.0 mol / L Na₂CO₃ solution and continue stirring for 1 h. After gently stirring with a glass rod to remove bubbles, transfer 20 mL of the reaction mixture to a graduated plastic cup, seal, and allow to cool naturally for 24 h to obtain oyster shell calcium gel. Determine the gel strength of the calcium gel and observe and analyze its stability after half a month of storage.

[0057] Experimental results: The effect of the solid-liquid ratio of oyster shell lactic acid solution on the gel strength of calcium gel is as follows: Figure 3 As shown, increasing the solid-liquid ratio increases the calcium ion concentration in the gel system. When the solid-liquid ratio is less than 1:35, the gel strength of the system decreases as the solid-liquid ratio increases, and the gel strength is the lowest when the solid-liquid ratio is 1:35. When the solid-liquid ratio is greater than 1:35, the gel strength of the calcium gel increases significantly with the increase of the solid-liquid ratio of the oyster shell lactic acid solution.

[0058] The effect of the solid-liquid ratio of oyster shell lactic acid solution on the stability of calcium gel is as follows: Figure 4 As shown, calcium gels prepared with solid-liquid ratios of 1:20 and 1:15 exhibited calcium precipitation after half a month of storage. The calcium gel prepared with a solid-liquid ratio of 1:20 mainly precipitated a large amount of white calcium on the gel surface, with less precipitation inside. The calcium gel prepared with a solid-liquid ratio of 1:15 precipitated not only a large amount of white calcium on the surface but also a large amount of relatively large white calcium deposits inside the gel. No calcium precipitation was observed in calcium gels prepared with solid-liquid ratios of 1:40, 1:35, 1:30, and 1:25 after half a month of storage. Considering both gel strength and stability, a solid-liquid ratio of 1:25 was determined to be optimal for the oyster shell lactic acid solution used in the preparation of the calcium gel.

[0059] Experimental Example 3

[0060] The effect of temperature on the strength and stability of calcium gel:

[0061] Weigh an appropriate amount of 100-mesh oyster shell powder and add 2 mol / L lactic acid solution at a solid-liquid ratio of 1:25 (mass:volume). Stir and react at 60℃ and 300 rpm for 30 min, then filter and dispense into multiple 50 mL portions of oyster shell calcium lactate solution. At different temperatures (40, 50, 60, 70, 80, 90℃) and 300 rpm, add chitosan first, then gelatin, at a CS:GEL ratio of 2:1. Stir until dissolved and mixed thoroughly. Then add 5 mL of 1 mol / L Na₂CO₃ solution and continue stirring for 1 h. After gently stirring with a glass rod to remove bubbles, transfer 20 mL of the reaction mixture to a graduated plastic cup, seal, and allow to cool naturally for 24 h to obtain oyster shell calcium gel. Determine the gel strength of the calcium gel and observe and analyze its stability after half a month of storage.

[0062] Experimental results: The effect of temperature on the strength of calcium gel is as follows Figure 5 As shown, the strength of the calcium gel prepared at temperatures below 70℃ increases with increasing temperature; while the strength of the calcium gel prepared at temperatures above 70℃ decreases with increasing temperature, reaching its maximum at 70℃.

[0063] The effect of temperature on the stability of calcium gel, such as Figure 6 As shown, after half a month of storage, the calcium gels prepared at 40, 80, and 90℃ all exhibited varying degrees of white calcium precipitation on the gel surface. The calcium gel prepared at 40℃ showed only a small amount of white calcium precipitation; the calcium gel prepared at 80℃ showed a larger amount of precipitated calcium, while the calcium gel prepared at 90℃ showed a smaller amount of precipitated calcium. The calcium gels prepared at 50, 60, and 70℃ all showed calcium precipitation, indicating good stability. Considering both gel strength and stability, the optimal preparation temperature for calcium gels was determined to be 70℃.

[0064] Experiment Example 4

[0065] Effect of Na2CO3 concentration on the strength and stability of calcium gel:

[0066] Weigh an appropriate amount of 100-mesh oyster shell powder and add 2 mol / L lactic acid solution at a solid-liquid ratio of 1:25 (mass:volume). Stir and react at 60℃ and 300 rpm for 30 min, then filter and divide into multiple 50 mL portions of oyster shell calcium lactate solution. At 70℃ and 300 rpm, slowly add chitosan first, then gelatin, at a CS:GEL ratio of 2:1, to each oyster shell calcium lactate solution. Stir and dissolve thoroughly. Then add 5 mL of Na₂CO₃ solution with concentrations of 0, 0.5, 1.0, 1.5, 2.0, and 2.5 mol / L respectively. Continue stirring and reacting for 1 h. After gently stirring with a glass rod to remove bubbles, transfer 20 mL of the reaction mixture to a graduated plastic cup, seal, and allow to cool naturally for 24 h to obtain oyster shell calcium gel. Determine the gel strength of the calcium gel and observe and analyze its stability after half a month of storage.

[0067] The effect of Na2CO3 concentration on the strength of calcium gel is as follows: Figure 7 As shown, except for a slight decrease in gel strength when the added Na2CO3 concentration was 1.0 mol / L, the overall trend was that the gel strength increased significantly with increasing Na2CO3 concentration.

[0068] The effect of Na2CO3 concentration on the stability of calcium gel is as follows: Figure 8 As shown, when Na₂CO₃ concentrations were added at 2.0 and 2.5 mol / L, the prepared calcium gels showed significant white calcium precipitation after half a month of storage. When Na₂CO₃ concentration was added at 1.5 mol / L, a small amount of white calcium also appeared on the surface of the prepared calcium gel. The stability of the calcium gel decreased with increasing Na₂CO₃ concentration, with relatively good stability observed at Na₂CO₃ concentrations of 0, 0.5, and 1.0 mol / L. Considering both gel strength and stability, the optimal Na₂CO₃ concentration for calcium gel preparation was determined to be 0.5 mol / L.

[0069] Experimental Example 5

[0070] Orthogonal experiments were used to determine the optimal preparation process conditions:

[0071] Orthogonal array design: using L9(3) 4 The orthogonal design scheme was used to further optimize the preparation process conditions of oyster shell calcium gel. The parameters were: A (mixed gel mass ratio), B (temperature / ℃), and C (Na₂CO₃ concentration / mol·L⁻¹). -1 D (solid-liquid ratio of oyster shell lactic acid solution / g·mL) -1 Orthogonal experiments were conducted, and the optimal values ​​of each preparation factor determined by single factors were used to determine the orthogonal experimental level values ​​of each factor. The values ​​are shown in Table 1.

[0072] Table 1. Orthogonal Factor Level Table

[0073]

[0074] Orthogonal experiment and results analysis:

[0075] Using gel strength as the performance index of calcium gel, the experiment was conducted according to the orthogonal experimental design table. An appropriate amount of 100-mesh oyster shell powder was weighed, and 2 mol / L lactic acid solution was added according to the solid-liquid ratio (mass:volume) of the oyster shell lactic acid solution in the design. The mixture was stirred and dissolved at 60℃ and 300 rpm for 30 min, and then filtered to obtain 50 mL of oyster shell calcium lactate solution. At a certain temperature and 300 rpm, a certain proportion of mixed gelling agent was added to the system, first slowly adding chitosan, then gelatin. The total mass of chitosan and gelatin added was 2 g. After stirring and dissolving evenly, 5 mL of a certain concentration of Na2CO3 solution was added, and the reaction was continued for 1 h. After gently stirring with a glass rod to remove bubbles, 20 mL of the reaction mixture was transferred to a plastic graduated cup, sealed, and allowed to cool naturally for 24 h to obtain oyster shell calcium gel. The gel strength index was measured using a texture analyzer. The range analysis of the experimental results is shown in Table 2, and the SPSS variance significance analysis of the experimental results is shown in Table 3.

[0076] Table 2 shows that the optimal gel strength of 36.576 g is achieved under the following process conditions: a mixed gel mass ratio (CS:GEL) of 3:1, a temperature of 70℃, a sodium carbonate concentration of 1.0 mol / L, and a solid-liquid ratio of oyster shell lactic acid solution of 1:30. Range analysis of the experimental results also shows that the optimal process condition combination is A1B2C2D2, consistent with the previous analysis. Comparing the R values, the order of influence of the four factors on the strength index is: mixed gel mass ratio > temperature > sodium carbonate concentration > solid-liquid ratio of oyster shell lactic acid solution. SPSS variance analysis in Table 3 shows that only the mixed gel mass ratio and temperature have a significant impact on the gel strength of the calcium gel, while the sodium carbonate concentration and the solid-liquid ratio of the oyster shell lactic acid solution have no significant effect.

[0077] Table 2. Orthogonal experimental scheme and results for the preparation process of oyster shell calcium gel.

[0078]

[0079]

[0080] Table 3. Statistical analysis of variance of orthogonal experiment results.

[0081]

[0082]

[0083] aR² = 0.648 (Adjusted R² = 0.491)

[0084] Example 6

[0085] Determination of calcium content and morphological characterization of oyster shell gel prepared under optimal preparation conditions:

[0086] Weigh an appropriate amount of 100-mesh oyster shell powder and add 2 mol / L lactic acid solution at a solid-liquid ratio of 1:30 (mass:volume). Stir and react at 60℃ and 300 rpm for 30 min, then filter and take 50 mL of oyster shell calcium lactate solution. At 70℃ and 300 rpm, slowly add chitosan first, then gelatin, at a CS:GEL ratio of 3:1. The total mass of chitosan and gelatin added is 2 g. Stir and dissolve until homogeneous. Then add 5 mL of 1 mol / L Na₂CO₃ solution and continue stirring for 1 h. After gently stirring with a glass rod to remove bubbles, transfer 20 mL of the reaction mixture to a graduated plastic cup, seal, and allow to cool naturally for 24 h to obtain a high-performance, pale yellow, slightly transparent oyster shell calcium gel. The calcium content and morphology of the calcium gel were determined and analyzed.

[0087] Calcium content was determined by EDTA titration. The specific procedure is as follows: Take 0.1 mL of oyster shell calcium lactate solution, dilute it, and take 25 mL. Titrate the calcium ions with 0.00125 mol / L EDTA standard solution, and calculate the calcium ion concentration in the oyster shell calcium lactate solution.

[0088] The formula for calculating calcium ion concentration is: C Ca2+ =C×V×D / 25

[0089] Where C Ca2+ C is the calcium ion concentration in the oyster shell calcium lactate solution, in mol / L; V is the concentration of the EDTA standard solution, in mol / L; D is the volume of EDTA standard solution consumed, in mL; and D is the dilution factor.

[0090] The formula for calculating the calcium content in calcium gel is: m Ca2+ =C Ca2+ ×V1×M×V2 / (V1+V3)

[0091] Where m Ca2+ V1 represents the calcium content of each sample, in mg; V2 represents the volume of oyster shell lactic acid solution used in gel preparation (50 mL); V3 represents the volume of gel poured into the sample cup after the reaction (20 mL); V4 represents the volume of solution added to the system during gel preparation (5 mL); M represents the relative atomic mass of Ca (40.078 g·mol⁻¹). -1 .

[0092] The optimal preparation process for 20 mL of oyster shell calcium gel was determined to contain 277 mg of calcium. Generally, 100 mL of milk contains 90-120 mg of calcium. Therefore, consuming 20 mL of oyster shell calcium gel prepared under optimal conditions is equivalent to the calcium intake from drinking a 250 mL glass of milk.

[0093] The morphology of calcium gel was observed using scanning electron microscopy (SEM). The samples were treated with a metal coating method, and the specific operation was as follows: conductive adhesive was attached to a copper sample truncated cone, a small amount of the sample to be tested was attached to the conductive adhesive, and the excess sample was blown away with a rubber bulb. Then the sample truncated cone was placed in a gold sputtering machine for gold sputtering treatment. The treated sample truncated cone was placed in the instrument for measurement, and the morphology of calcium gel was observed at different magnifications.

[0094] SEM images of oyster shell calcium gel are shown below. Figure 9 As shown. From Figure 9 As can be seen, the appearance of calcium gel contains many pores of varying sizes, with the diameter of most pores ranging from 0 to 50 μm. The surface of the pores is smooth and blocky, while the internal structure of the pores is wrinkled and uneven.

[0095] Experimental Example 7

[0096] Chronic toxicity test of oyster shell calcium gel prepared under optimal preparation conditions:

[0097] Oyster shell calcium gel with a calcium content of 13.85 mg / mL, prepared under optimal processing conditions, was used in a chronic toxicity experiment on rats. Female SD rats aged 6-8 months and weighing 500±25g were randomly divided into four groups of six rats each after one week of acclimatization in the animal facility. The rats were administered calcium gel via gavage at normal (0 mL), low (2 mL), medium (4 mL), and high (6 mL) doses, once daily for 14 consecutive days. The rats' condition was observed daily, and changes in body weight and food intake were recorded. Physical characteristics, behavior, food intake, fecal characteristics, and weight changes were also observed. The dietary formula for the rats during the experiment contained the following nutrients: crude protein >18%, crude fat >4%, crude fiber <5%, crude ash <8%, moisture <10%, calcium 1.0-1.8%, and phosphorus 0.6-1.2%.

[0098] Experimental results: such as Figure 10 As shown. By Figure 10 It can be seen that during the experiment, there were no significant differences in appearance, behavior, food intake, fecal shape and weight among the rats in each group, and no deaths or other abnormalities were observed in the rats in each group during the experiment.

[0099] Experimental Example 8

[0100] The osteoporosis treatment effect of oyster shell calcium gel prepared under optimal preparation process conditions:

[0101] Oyster shell calcium gel with a calcium content of 13.85 mg / mL, prepared under optimal processing conditions, was used to conduct an experiment on the calcium supplementation effect in osteoporosis. Female SD rats aged 6-8 months and weighing 500±25g were used. After one week of acclimatization in the animal facility, bilateral ovariectomy was performed to establish an osteoporosis model. The rats were randomly divided into a sham-operated group, a model group, and a calcium gel preparation group (4 mL / kg / d of calcium gel, equivalent to a calcium dose of 55 mg / kg / d), with 6 rats in each group. Two days after surgery, the rats were administered calcium gel via gavage once daily for 8 weeks. Afterward, the rats were euthanized by cervical dislocation under anesthesia. The left femur (including the femoral head and medial and lateral condyles) was immediately and completely dissected, soft tissue was removed, and the contents were placed in physiological saline for examination.

[0102] Micro-CT scanning was used to perform femoral μCT imaging experiments. The scanning parameters were: X-ray tube current 362μA, voltage 69KV, scanning the entire object, scanning resolution 9.00μm, exposure time 1200ms, and scanning angle 180 degrees.

[0103] Experimental results: such as Figure 11 As shown. By Figure 11 μCT scan results showed that, compared with the sham-operated group, the cortical bone of rats in the model group was thinner and the trabeculae were thinner; oyster shell gel calcium treatment improved osteoporotic rats to some extent and promoted bone formation.

[0104] As can be seen from the above embodiments and experimental examples, the oyster shell calcium gel prepared by the method of the present invention has good strength and stability, high calcium content, porous appearance, few side effects, easy absorption, and good biological activity.

[0105] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing oyster shell gel calcium, characterized by, Includes the following steps: 1) Mix and dissolve oyster shell powder with lactic acid solution to obtain oyster shell calcium lactate solution; 2) Mix oyster shell calcium lactate solution, chitosan and gelatin to obtain a gel solution; 3) Mix the gel solution with Na2CO3 solution and let it stand to obtain oyster shell calcium gel; The ratio of oyster shell powder to lactic acid solution is 1g:(15-40)mL; The mass ratio of chitosan to gelatin is (1-3):(1-3); The concentration of the Na₂CO₃ solution is 0.5-2.5 mol / L; The mixing temperatures in steps 2) and 3) are 40-90℃, respectively.

2. The method of claim 1, wherein the oyster shell gel calcium is prepared by the steps of: The oyster shell powder has a mesh size of 80-120; the concentration of the lactic acid solution is 1-3 mol / L; and the dissolution time is 20-40 min.

3. The method for preparing oyster shell calcium gel according to claim 1, characterized in that, The ratio of the oyster shell calcium lactate solution, chitosan, and gelatin is (40-60) mL: (0.5-1.5) g: (0.5-1.5) g.

4. The method for preparing oyster shell calcium gel according to claim 1, characterized in that, The mixing process in steps 2) and 3) is accompanied by stirring, the stirring speed is 200-400 rpm, the stirring time in step 2) is 10-30 min, and the stirring time in step 3) is 40-80 min.

5. The method for preparing oyster shell calcium gel according to claim 1, characterized in that, The settling time is 18-30 hours.

6. Oyster shell calcium gel prepared by the method of any one of claims 1-5.

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