Cordyceps militaris-pectin composite gel 3D printing base material, and preparation method and application thereof

Abstract

The present application belongs to the field of food processing, and discloses a cordyceps militaris-pectin composite gel 3D printing base material and a preparation method and application thereof. In terms of 100 parts by weight of cordyceps militaris superfine powder, the base material contains 1-4 parts of pectin powder, 25-30 parts of isomaltulose, 80-120 parts of water, and 5-15 mL / 100 g of cordyceps militaris superfine powder of refined sunflower seed oil; the pectin is selected from low-ester sunflower pectin, citrus or apple pectin with a limited degree of esterification. The cordyceps militaris is uniformly mixed with 1wt%-4wt% pectin aqueous solution, and then is quenched and shaped after water bath conditioning. The obtained composite gel is excellent in shear thinning and elasticity, smooth in extrusion, and good in self-supporting property; when the addition amount of pectin powder is 2 parts, the printing deviation is as low as 0.86±0.15%, and when the addition amount of pectin powder is 4 parts, the height stability after 60 min is 98.92±0.19%, so the base material is suitable for high-precision cordyceps militaris functional 3D printing food preparation.

Description

Technical Field

[0001] This invention belongs to the field of food processing technology, and relates to a Cordyceps militaris-pectin composite gel 3D printing base material, its preparation method and application. Background Technology

[0002] Cordyceps militaris is rich in protein and polysaccharides. Cordyceps militaris protein possesses excellent water-holding, emulsifying, and gel-forming abilities, while Cordyceps militaris polysaccharides have thickening, water-retaining, and gel-stabilizing effects. Furthermore, cordycepin, a characteristic active ingredient in Cordyceps militaris, also exhibits anti-inflammatory and immunomodulatory effects, making it a promising candidate for application in the field of functional food 3D printing. Pectin, a plant-derived acidic heteropolysaccharide, combines gelling, thickening, water-retaining, and stabilizing functions, making it an ideal matrix for improving the rheological properties and molding stability of food 3D printing slurries. Combining Cordyceps militaris with pectin is expected to synergistically construct a food 3D printing composite gel system with excellent rheological properties and high molding stability.

[0003] In recent years, constructing composite gel systems using non-covalent interactions between polysaccharides and proteins to improve gel stability and suitability for 3D printing in food has become a research hotspot in this field. For example, Hu Qiuhui et al. disclosed a method for preparing a composite gel of enoki mushroom polysaccharide and soybean protein isolate (CN114409924A). This composite gel exhibits superior rheological properties, textural properties, and stability compared to the control group without added polysaccharides, and also shows improved digestibility and immune activity. Hu Qiuhui et al. also disclosed a method for preparing 3D-printed food based on Pleurotus eryngii matrix with added pectin and other colloidal substances (CN115336742A). Introducing colloidal substances into the Pleurotus eryngii matrix improved the gel-forming ability and 3D printing stability of the system. Zeng Yucheng et al. disclosed a 3D-printed food based on Auricularia auricula-judae with added xanthan gum (CN116250626A). The addition of xanthan gum significantly improved the rheological properties and extrusion performance of the Auricularia auricula-judae matrix, showing application potential in the field of easily swallowable foods.

[0004] However, the existing technologies mentioned above mostly use fruit and vegetable or edible fungi matrices combined with exogenous colloids to improve printing performance, and have not yet addressed the technical solutions for constructing a composite gel printing system with Cordyceps militaris as the main matrix and pectin as the core gelling agent. Although some studies have attempted to prepare gel foods by adding carrageenan, agar, etc. to Cordyceps militaris as a matrix and examining their 3D printing performance (see Teng X et al., Journal of Food Processing Engineering, 2019, 42(6):e13179), the printing fidelity and structural retention of the resulting products still need to be improved, and the interaction mechanism and compatibility between carrageenan, agar and Cordyceps militaris protein / polysaccharide are different from those of pectin, making it difficult to directly apply them.

[0005] In summary, there are currently no publicly available reports on the construction of food 3D printing composite gel matrix using Cordyceps militaris ultrafine powder and self-made low-ester pectin. This field still lacks a 3D printing matrix with Cordyceps militaris as the main functional ingredient, possessing both excellent printability and functional activity, and its preparation method. Summary of the Invention

[0006] To address the above technical problems, this invention provides a composite gel matrix using low-temperature ultrafine pulverized Cordyceps militaris as a functional matrix and synergistic thickening with self-made low-ester pectin and isomaltooligosaccharide. This composite gel matrix exhibits excellent extrusion flowability and self-supporting properties, making it suitable for the preparation of high-precision 3D printed foods. Furthermore, this invention provides a method for preparing the aforementioned matrix matrix and its application in 3D printed foods.

[0007] The Cordyceps militaris-pectin composite gel 3D printing base material provided by the present invention comprises, by weight, 100 parts of Cordyceps militaris ultrafine powder, 1-4 parts of pectin powder, 25-30 parts of isomaltooligosaccharide, and 80-120 parts of water.

[0008] It also includes: refined sunflower seed oil, the dosage of which is: refined sunflower seed oil: Cordyceps militaris ultrafine powder = (5~15) mL: 100g.

[0009] The pectin powder is selected from any one of low-ester sunflower pectin powder, low-ester citrus pectin powder, and low-ester apple pectin powder; the degree of esterification of the low-ester sunflower pectin is 30%~40%, the degree of esterification of the low-ester citrus pectin is 24%~30%, and the degree of esterification of the low-ester apple pectin is 27%~33%; the particle size of the Cordyceps militaris ultrafine powder is 8~12 μm.

[0010] Furthermore, the preparation method of Cordyceps militaris ultrafine powder is as follows: dried Cordyceps militaris with a moisture content of 6wt%~10wt% is coarsely pulverized intermittently at 10000~25000 r / min using a high-speed pulverizer, with each pulverization lasting 10~15 s, followed by cooling for 10~15 s after stopping the machine, and pulverizing for a total of 1~2 min to obtain Cordyceps militaris coarse powder; then the coarse powder is placed in a low-temperature ultrafine pulverizer and pulverized at 2~4℃ for 10~20 min to obtain Cordyceps militaris ultrafine powder with a particle size of 8~12 μm, corresponding to a sieve mesh size of 750~1500 mesh.

[0011] Preferably, the dried Cordyceps militaris has a moisture content of 8 wt%, the high-speed pulverizer rotates at 20,000 r / min, and the intermittent pulverization is performed for 15 seconds per pulverization, followed by a 15-second cooling stop, for a total of 2 minutes of pulverization. The powder is then passed through a 40-mesh sieve to obtain coarse Cordyceps militaris powder. The temperature in the low-temperature ultrafine pulverizer is 4℃, the pulverization time is 20 minutes, and the particle size of the Cordyceps militaris ultrafine powder is 10 μm, corresponding to a sieve mesh size of 1250 mesh.

[0012] Furthermore, the low-ester citrus pectin powder was prepared using the following method:

[0013] (1) Take dried peel of Newhall navel oranges from southern Jiangxi, pulverize it and pass it through a 60-mesh sieve to obtain dried navel orange peel powder;

[0014] (2) The navel orange peel powder obtained in step (1) was extracted with an aqueous solution of HCl or citric acid to a pH of 1.5-2.0 for 60-90 min at 80-90℃, filtered, and the filtrate was precipitated with anhydrous ethanol to obtain crude pectin.

[0015] (3) Prepare a 1wt% aqueous solution of crude pectin, adjust the pH to 11.0-12.0 with NaOH in an ice bath at 0-5℃, stir to remove esters, and then adjust the pH to 5.0-6.0 with HCl to terminate the reaction. After precipitation with ethanol, washing, drying at 60℃, and pulverizing through a 60-mesh sieve, a low-ester citrus pectin powder with an esterification degree of 24%-30% is obtained.

[0016] Low-ester apple pectin powder is prepared using the following method:

[0017] (1) Take dried peel from Yantai Fuji apples, crush it through a 60-mesh sieve to obtain apple peel powder;

[0018] (2) The apple peel powder obtained in step (1) was extracted with an aqueous solution of HCl or citric acid to a pH of 1.5-2.0 at 80-90℃ for 60-90 min, filtered, and crude pectin was obtained by adding anhydrous ethanol to the filtrate.

[0019] (3) Prepare a 1wt% aqueous solution of crude pectin, adjust the pH to 10.5-11.5 with NaOH in an ice bath at 0-5℃, stir to remove esters, and then adjust the pH to 5.0-6.0 with HCl to terminate the reaction. After precipitation with ethanol, washing, drying at 60℃, and pulverizing through a 60-mesh sieve, a low-ester apple pectin powder with an esterification degree of 27%-33% is obtained.

[0020] Further, the stirring and deesterification time in step (3) is 30~60 min; preferably, the stirring and deesterification time is 45 min.

[0021] This invention also provides a method for preparing a Cordyceps militaris-pectin composite gel 3D printing substrate, comprising the following steps:

[0022] Preparation of S1 Cordyceps militaris ultrafine powder: Dry Cordyceps militaris with a moisture content of 6wt%~10wt% was intermittently coarsely pulverized in a high-speed pulverizer for a total of 1~2 min to obtain Cordyceps militaris coarse powder; then the coarse powder was placed in a low-temperature ultrafine pulverizer and pulverized at 2~4℃ to obtain Cordyceps militaris ultrafine powder.

[0023] Preparation of S2 pectin solution: Pectin powder is slowly sprinkled into hot water at 95-100℃ while stirring at 300-500 r / min. After sprinkling, the stirring speed is adjusted to 80-150 r / min, and stirring is continued for 5-10 min until the pectin is fully dissolved, forming a uniform and transparent pectin solution. The solution is then cooled to 60-70℃ for later use. The concentration of the pectin solution is 1wt%-4wt%.

[0024] S3 Mixing Preparation: Add the Cordyceps militaris ultrafine powder, isomaltooligosaccharide, and refined sunflower seed oil obtained in S1 to the pectin solution obtained in S2 in sequence, and stir at 80~120 r / min until the mixture is uniform and fine and there are no visible particles to obtain the Cordyceps militaris-pectin mixture; wherein, the mass ratio of Cordyceps militaris ultrafine powder, pectin, isomaltooligosaccharide and water is 100:(1~4):(25~30):(80~120), and the material-to-liquid ratio of refined sunflower seed oil to Cordyceps militaris ultrafine powder is 0.05~0.15 mL / g;

[0025] S4 Water Bath Conditioning and Cold Refrigeration: After sealing the Cordyceps militaris-pectin mixture obtained in S3, it was treated in a water bath at 75~85℃ for 25~35 min. During the water bath, the container was sealed and covered to reduce moisture loss. After the treatment, it was quickly cooled to room temperature and then placed in a cold refrigeration at 2~6℃ to fix the shape, thus obtaining the Cordyceps militaris-pectin composite gel 3D printing base material.

[0026] Furthermore, in S3, the mass ratio of Cordyceps militaris ultrafine powder, pectin powder, isomaltooligosaccharide and water is 100:(1~4):(25~30):(80~120).

[0027] Preferably, the water bath treatment in S4 is a water bath at 80°C for 30 minutes, and the refrigeration is refrigeration at 4°C.

[0028] The application of the above-mentioned Cordyceps militaris-pectin composite gel 3D printing base material in the preparation of 3D printed food is also the key content to be protected by this invention.

[0029] Specifically, the conditions for 3D printing are as follows: ambient temperature 20~30℃, metal nozzle inner diameter 0.6~1.0 mm, printing speed 10~20 mm / s, infill density 75%~85%, layer height 0.5~1.5 mm, and extrusion temperature 30~40℃.

[0030] Preferably, the conditions for the above 3D printing are: ambient temperature 25℃, metal nozzle inner diameter 0.8 mm, printing speed 15 mm / s, infill density 80%, layer height 1.0 mm, and extrusion temperature 35℃.

[0031] The present invention achieves the following beneficial effects:

[0032] (1) To address the problem that Cordyceps militaris powder cannot simultaneously meet the requirements of "continuous extrusion" and "deposition shaping" in 3D printing, this invention constructs a food-grade Cordyceps militaris-pectin composite gel system. By introducing pectin to synergistically improve rheological properties, the use of non-food-grade additives is avoided. Combined with mild processes such as ultrafine grinding and low-temperature refrigeration, this invention provides a safe and simple new technology path for Cordyceps militaris structured foods.

[0033] (2) The addition of pectin significantly improves printing accuracy and structural stability. Introducing 2wt% citrus pectin can reduce the diameter and height deviation from more than 4% to about 0.9%, achieving an order-of-magnitude leap in accuracy; an addition of 4wt% can improve the structural height stability to 98.92%. The optimal addition window is 2wt% to 4wt%, which can be adapted to the application requirements of "high accuracy" and "high stability" respectively.

[0034] (3) Rheological studies confirmed that the system is dominated by elastic response (G′>G″, tanδ=0.2~0.4), and has both shear thinning (easy to extrude) and rapid rebound (easy to shape). The 4wt% addition group has the best structural strength, and the effect of adding too little is not significant, which proves that there is a clear threshold effect between the type and amount of pectin.

[0035] (4) Macroscopic texture and microstructure corroborate each other. The 4wt% citrus pectin group showed the best performance in all four indicators, including hardness and elasticity, and had the densest microstructure network. This confirms that pectin and Cordyceps militaris components synergistically construct a tight three-dimensional network, substantially enhancing the product's resistance to deformation and structural integrity. Attached Figure Description

[0036] Figure 1 The image shows the materials, 3D printing equipment, and the appearance of the printed cylinder of Cordyceps militaris-pectin composite gel.

[0037] Wherein: A: Cordyceps militaris-pectin composite gel state diagram; B: Top view of 3D printed cylinder; C: Food 3D printing equipment diagram; D: Head view of 3D printed cylinder; E and F: Complex geometric printing model diagrams;

[0038] Figure 2 Steady-state shear and oscillatory strain scanning results of Cordyceps militaris-pectin composite gel under different pectin types and addition amounts;

[0039] Wherein: A: The curve of apparent viscosity of the sample as a function of shear rate; B: The curve of storage modulus and loss modulus of sunflower pectin group as a function of shear strain; C: The curve of storage modulus and loss modulus of apple pectin group as a function of shear strain; D: The curve of storage modulus and loss modulus of citrus pectin group as a function of shear strain.

[0040] Figure 3Dynamic frequency scanning results of Cordyceps militaris-pectin composite gel under different pectin types and amounts;

[0041] Where, A: Energy storage modulus G′ varies with frequency; B: Loss modulus G″ varies with frequency; C: Loss tangent tanδ varies with frequency.

[0042] Figure 4 Figures showing the printing deviation and printing stability of 3D printed samples of Cordyceps militaris-pectin composite gel under different types and amounts of pectin.

[0043] A: Diameter and height deviation of the cylindrical printed sample; B: Height stability of the cylindrical printed sample after 60 minutes.

[0044] Figure 5 Textural properties of 3D-printed samples of Cordyceps militaris-pectin composite gel under different types and amounts of pectin;

[0045] Where A: Hardness diagram; B: Elasticity diagram; C: Adhesion diagram; D: Chewing diagram;

[0046] Figure 6 100x scanning electron microscope images of 3D printed samples of Cordyceps militaris-pectin composite gel under different types and amounts of pectin;

[0047] Wherein, A: 100x SEM image of group BK; B: 100x SEM image of group 1%K; C: 100x SEM image of group 2%K; D: 100x SEM image of group 4%K; E: 100x SEM image of group 1%G; F: 100x SEM image of group 2%G; G: 100x SEM image of group 4%G; H: 100x SEM image of group 1%P; I: 100x SEM image of group 2%P; J: 100x SEM image of group 4%P.

[0048] Figure 7 1000x scanning electron microscope images of 3D printed samples of Cordyceps militaris-pectin composite gel under different types and amounts of pectin;

[0049] A: 1000x SEM image of group BK; B: 1000x SEM image of group 1%K; C: 1000x SEM image of group 2%K; D: 1000x SEM image of group 4%K; E: 1000x SEM image of group 1%G; F: 1000x SEM image of group 2%G; G: 1000x SEM image of group 4%G; H: 1000x SEM image of group 1%P; I: 1000x SEM image of group 2%P; J: 1000x SEM image of group 4%P. Detailed Implementation

[0050] To enable those skilled in the art to better understand the present invention, the present invention will now be further described in conjunction with specific embodiments.

[0051] For ease of explanation, the blank control group without pectin powder is designated as group BK, the sample with low-ester sunflower pectin powder is designated as group K (K being the first letter of "sunflower"), the sample with low-ester citrus pectin powder is designated as group G (G being the first letter of "citrus"), and the sample with low-ester apple pectin powder is designated as group P (P being the first letter of "apple"). The pectin concentrations in each group (e.g., percentages in 1%K, 1%G, 1%P) are expressed as the mass-volume percentage concentration (w / w) of the pectin solution, i.e., the percentage of pectin powder mass to the total mass of the prepared pectin solution. "n%X" indicates a pectin concentration of n% (w / w) and the pectin source is group X. The amount of pectin powder added to the composite gel base is based on 100 parts of Cordyceps militaris ultrafine powder, formulated according to the weight ratio system of claim 1.

[0052] The preparation methods for Cordyceps militaris ultrafine powder, low-ester citrus pectin powder, and low-ester apple pectin powder are as follows:

[0053] 1.1 The preparation method of Cordyceps militaris ultrafine powder is as follows: take dried Cordyceps militaris with a moisture content of 8%, and use a high-speed pulverizer to perform intermittent coarse pulverization at 20000 r / min. Each pulverization lasts for 15 s, followed by a 15 s cooling period, and a total pulverization time of 2 min to obtain Cordyceps militaris coarse powder. Then, place the coarse powder in a low-temperature ultrafine pulverizer and pulverize it at 4℃ for 20 min to obtain Cordyceps militaris ultrafine powder with a particle size of 10 μm.

[0054] Low-ester sunflower seed pectin powder was purchased from Xinjiang Fufeng Biotechnology Co., Ltd. (Food Production License No.: SC20165010600072). The degree of esterification (DE) was 30% to 40%, which meets the definition range of low-ester pectin (DE≤50%) determined by titration method in GB 24804. It is used as the gel-forming main body of the composite gel base.

[0055] 1.2 Low-ester citrus pectin powder was prepared using the following method:

[0056] (1) Take dried peel of Newhall navel oranges from southern Jiangxi, pulverize it and pass it through a 60-mesh sieve to obtain dried navel orange peel powder;

[0057] (2) The dried orange peel powder obtained in step (1) was extracted with an aqueous solution of citric acid to pH 2.0 at 85°C for 85 min. The mixture was filtered while hot, and the filtrate was precipitated with 2 times the volume of anhydrous ethanol. The mixture was left to stand overnight and then filtered to obtain crude pectin.

[0058] (3) The crude pectin was prepared into a 1wt% aqueous solution. The pH was adjusted to 11.5 by slowly adding 2 mol / L NaOH solution under ice bath conditions at 0~5℃, and the mixture was stirred for 45 min to remove esters. Then, the pH was adjusted back to 5.5 with 2 mol / L HCl to terminate the reaction. Two volumes of anhydrous ethanol were added to precipitate the pectin. The precipitate was washed twice with ethanol, dried in an oven at 60℃, and pulverized through a 60-mesh sieve to obtain low-ester citrus pectin powder. The degree of esterification was determined to be 27.3% by titration.

[0059] 1.3 Low-ester apple pectin powder was prepared using the following method:

[0060] (1) Take dried peel from Yantai Fuji apples, crush it through a 60-mesh sieve to obtain apple peel powder;

[0061] (2) The apple peel powder obtained in step (1) was extracted with an aqueous solution of citric acid at pH 2.0 for 85 min at 85 °C. The mixture was filtered while hot, and the filtrate was precipitated with 2 times the volume of anhydrous ethanol. The mixture was left to stand overnight and then filtered to obtain crude pectin.

[0062] (3) Prepare a 1wt% aqueous solution of crude pectin. Adjust the pH to 10.5 by slowly adding 2 mol / L NaOH solution under ice bath conditions at 0~5℃ and stir for 45 min to remove esters. Then, adjust the pH to 5.5 with 2 mol / L HCl to terminate the reaction. Add 2 times the volume of anhydrous ethanol to precipitate the pectin. Wash twice with ethanol, dry in an oven at 60℃, and pulverize through a 60-mesh sieve to obtain low-ester apple pectin powder. The degree of esterification was determined to be 30.1% by titration.

[0063] Comparative Example 1

[0064] Add 10 g of Cordyceps militaris ultrafine powder, 3 g of isomaltooligosaccharide, and 1 mL of refined sunflower seed oil to 10 g of pure water, without adding pectin. Stir until the mixture is smooth and free of visible particles. Place the resulting mixture in a sealed container and incubate in a constant temperature water bath at 80°C for 30 min (keep the container sealed during the water bath to prevent moisture evaporation). After the water bath treatment, refrigerate at 4°C. The resulting sample is designated as group BK.

[0065] Example 1

[0066] Weigh 0.1 g of low-ester sunflower seed pectin powder and slowly sprinkle it into 10 g of 100℃ pure water under magnetic stirring at 500 r / min. Continue stirring until the pectin powder is completely dispersed, then reduce the stirring speed to 100 r / min and continue stirring for 10 min to fully dissolve the pectin and form a uniform and transparent 1wt% pectin solution. Then, add 10 g of Cordyceps militaris ultrafine powder, 3 g of isomaltooligosaccharide, and 1 mL of refined sunflower seed oil to the pectin solution in sequence, maintaining stirring at 100 r / min until the mixture is uniform, fine, and free of visible particles. Transfer the resulting mixture to a sealed container and treat it in a constant temperature water bath at 80℃ for 30 min (keeping the container sealed during the water bath to prevent moisture evaporation). After removal, refrigerate the resulting sample at 4℃ for later use to obtain Cordyceps militaris-pectin composite gel 1%K.

[0067] Example 2

[0068] The difference between this embodiment and Embodiment 1 is that the pectin powder is 0.2 g of low-ester sunflower disc pectin powder, and the other conditions remain unchanged, to obtain Cordyceps militaris-pectin composite gel 2%K.

[0069] Example 3

[0070] The difference between this embodiment and Embodiment 1 is that the pectin powder is 0.4 g of low-ester sunflower disc pectin powder, and the other conditions remain unchanged, to obtain Cordyceps militaris-pectin composite gel 4%K.

[0071] Example 4

[0072] The difference between this embodiment and Embodiment 1 is that the pectin powder is 0.1 g of low-ester citrus pectin powder, and the other conditions remain unchanged, to obtain Cordyceps militaris-pectin composite gel 1%G.

[0073] Example 5

[0074] The difference between this embodiment and Embodiment 1 is that the pectin powder is 0.2 g of low-ester citrus pectin powder, and the other conditions remain unchanged, resulting in Cordyceps militaris-pectin composite gel 2%G.

[0075] Example 6

[0076] The difference between this embodiment and Embodiment 1 is that the pectin powder is 0.4 g of low-ester citrus pectin powder, and the other conditions remain unchanged, resulting in Cordyceps militaris-pectin composite gel 4%G.

[0077] Example 7

[0078] The difference between this embodiment and Embodiment 1 is that the pectin powder is 0.1 g of low-ester apple pectin powder, and the other conditions remain unchanged, to obtain Cordyceps militaris-pectin composite gel 1%P.

[0079] Example 8

[0080] The difference between this embodiment and Embodiment 1 is that the pectin powder is 0.2 g of low-ester apple pectin powder, and the other conditions remain unchanged, resulting in Cordyceps militaris-pectin composite gel 2%P.

[0081] Example 9

[0082] The difference between this embodiment and Embodiment 1 is that the pectin powder is 0.4 g of low-ester apple pectin powder, and the other conditions remain unchanged, resulting in Cordyceps militaris-pectin composite gel 4%P.

[0083] Experimental Example 1: Rheological Properties Testing of Gels

[0084] The rheological properties of the composite gels prepared in Comparative Example 1 and Examples 1–9 were determined using a Kinexus Lab+ rotational rheometer. A parallel plate fixture with a diameter of 20 mm and a test spacing of 1000 μm was used. An appropriate amount of sample was placed on the lower plate, and after the rotor descended to the predetermined spacing, any sample overflowing from the edge of the plate was removed. Testing was performed after the sample had stabilized. The steady-state shear test temperature was 25 °C, and the shear rate range was 0.1–100 s⁻¹. -1 The oscillatory strain scanning range is 0.1% to 100%, and based on the strain scanning results, 0.5% strain in the linear viscoelastic region is selected for frequency scanning, with a frequency scanning range of 0.1 to 100 Hz. The storage modulus G′, loss modulus G″, and loss tangent tanδ are recorded.

[0085] Experimental Example 2: Printing Deviation of Printed Samples

[0086] The 3D printer used in the subsequent experiments was model FOODBOT-D1, branded by Hangzhou Shiyin Technology Co., Ltd.

[0087] The composite gels prepared in Comparative Example 1 and Examples 1-9 were respectively loaded into the storage tank of a food 3D printer. A cylindrical 3D model with a diameter of 20 mm and a height of 20 mm was constructed, and the 3D model was sliced. 3D printing was performed at room temperature, with a metal nozzle diameter of 0.8 mm, a printing speed of 15 mm / s, an infill density of 80%, a layer height of 1 mm, and an extrusion temperature of 35°C. The actual dimensions of the samples were recorded upon completion of printing and after 60 min of storage.

[0088] The deviation of the printed sample is calculated as deviation (%) = |L0 / L m -1|×100, where L m L0 represents the design value of the cylindrical 3D model, and L0 represents the actual measured value of the printed sample. The height stability of the printed sample is calculated as stability (%) = H 60 The calculation is / H0×100, where H0 is the sample height at 0 min after printing, and H...60 The height of the printed sample after 60 minutes.

[0089] Experiment Example 3: Texture determination of printed samples

[0090] The texture of 3D-printed cylindrical samples was determined using a texture analyzer. The test employed a 36 mm diameter P36 / R cylindrical probe, a compression ratio of 15%, a test speed of 2 mm / s, a trigger force of 5 g, and a 5 s interval between compressions. The hardness, elasticity, adhesiveness, and chewiness of the samples were recorded.

[0091] The 3D-printed sample was vacuum freeze-dried, and an appropriate amount of sample was cut and fixed onto the conductive adhesive on the stage. The internal cross-section of the sample was then subjected to ion sputtering gold sputtering treatment. The treated sample was placed under a scanning electron microscope and observed and images were acquired at 200x and 1000x magnifications at an accelerating voltage of 15 kV.

[0092] All rheological property tests, printing deviation and stability tests, texture determination, and SEM observations were performed at least three times. Results are expressed as mean ± standard deviation. One-way ANOVA was performed using SPSS 21.0 software, and the Waller-Duncan test was used for significance analysis, with a significance level of P < 0.05.

[0093] Figure 1 These images show the loading state of the Cordyceps militaris-pectin composite gel, the 3D printing equipment, and the top and side views of the printed cylinder. Figure 1 It can be seen that the prepared composite gel can be loaded into the barrel of a food 3D printer for extrusion printing, forming a cylindrical structure with a circular outline and a certain height after printing. The top and side views of the printed sample can be used to measure the actual diameter and height of the sample and compare them with the set cylindrical model dimensions. Complex model printing experiments were also conducted.

[0094] Table 1. Viscosity as a function of shear rate 0.1 38690 16740 18040 35480 13550 16700 18070 19950 25920 28150 1 5176 2444 2551 3731 2317 2843 2971 3229 4146 4609 10 361.6 192.6 222.6 319.9 312.5 305.5 282.8 255.5 413.4 411.1 100 6.237 16.12 10.6 13.83 17.6 15.84 13.13 8.892 13.1 16.72

[0095] Figure 2 A shows the variation of apparent viscosity as a function of shear rate for samples from different pectin-treated groups. Figure 2 As can be seen from A and Table 1, as the shear rate increases from 0.1 s⁻¹... -1 Gradually increase to 100 s -1 The apparent viscosity of each group of samples continued to decrease, indicating that the composite gels prepared in Comparative Example 1 and Examples 1-9 all have obvious shear-thinning characteristics.

[0096] At a low shear rate of 0.1 s -1Under the given conditions, the blank group had the highest apparent viscosity, reaching 38690 Pa. After adding different types and amounts of low-ester pectin, the apparent viscosity of the system showed different changes: low-ester sunflower disc pectin (K) group: 1% K (16740), 2% K (18040), 4% K (35480).

[0097] Low-ester citrus pectin (G) group: 1% G (13550), 2% G (16700), 4% G (18070); Low-ester apple pectin (P) group: 1% P (19950), 2% P (25920), 4% P (28150). For the same type of pectin, with increasing pectin addition, the reaction time increased by 0.1 s. -1 The apparent viscosity generally shows an increasing trend. When the shear rate increases to 1 s⁻¹, the viscosity increases. -1 The viscosity of each group decreased significantly; the shear rate continued to increase to 10 s⁻¹. -1 The viscosity decreased to the level of several hundred Pa; the shear rate reached 100 s⁻¹. -1 At that time, the viscosity of all samples dropped to a low level, the viscosity difference between groups narrowed significantly, and the apparent viscosity of each group gradually became closer.

[0098] Table 2 Modulus-Strain Scan

[0099] Combining the modulus-strain scan data in Table 2 and Figure 2 B~ Figure 2 The oscillatory strain scan results of different pectin systems show that in the low strain range (0.1% and 1% strain), the storage modulus (G′) of the blank group and each pectin-added sample is greater than the loss modulus (G″), and the changes in G′ and G″ with strain are relatively small, indicating that the samples in each group exhibit mainly elastic response under low strain conditions. As the shear strain gradually increases, both G′ and G″ decrease, and gradually approach or cross each other in the higher strain range, indicating that the original structure of the samples gradually weakens under large deformation.

[0100] Different types and amounts of pectin significantly affected the gel modulus. Under low strain (0.1%) conditions, Example 6 (4% G) had the highest storage modulus (G′) at 253,300 Pa, the highest among all groups; followed by Example 8 (2% P, 147,600 Pa) and Example 9 (4% P, 111,200 Pa). For the same type of pectin, within the experimental addition range, the storage modulus under low strain generally increased with increasing pectin addition.

[0101] Table 3 Modulus-Frequency Scan

[0102] Combining the modulus-frequency scan data in Table 3 and Figure 3A~ Figure 3 As shown in C, the storage modulus (G′) and loss modulus (G″) of the blank group and each pectin-added group samples generally showed an upward trend as the oscillation frequency increased. Within the tested full frequency range, all samples satisfied G′>G″ and tanδ<1, indicating that the Cordyceps militaris composite gel exhibited mainly elastic behavior and typical gel characteristics within the studied frequency range.

[0103] In the low-to-mid frequency range (0.1–10 Hz), the loss factor tanδ of most samples was concentrated between 0.2 and 0.4, which is consistent with the target elasticity range of this invention. This property is beneficial for maintaining structural stability and resisting self-weight collapse after the 3D printed preform is formed. The type and amount of pectin added have a significant impact on the gel modulus: In Example 6 (4% G), G′ and G″ remained at high levels at most test frequencies; the modulus of Example 9 (4% P) was also at a high level; the modulus of some low-pectin addition groups was lower than that of the blank group (BK group), indicating that adding a small amount of pectin does not necessarily improve the elasticity of the system, and the type and amount of pectin added need to be controlled.

[0104] When the frequency increases to the high-frequency region (100 Hz), the tanδ of some groups fluctuates, but the tanδ of all samples is still less than 1, and the system still maintains the elastic-dominant characteristic.

[0105] Figure 4 Figure A shows the diameter and height deviations of 3D-printed cylinders with different formulations. As can be seen from the figure, the diameter deviation of Comparative Example 1 is 4.21±0.42%, and the height deviation is 5.17±0.56%, both higher than the pectin-added group. After adding pectin, the overall diameter and height deviations of the printed samples decreased. Among them, Example 5 has the lowest diameter deviation (0.86±0.15%) and height deviation (0.92±0.26%); Example 6 has a diameter deviation (1.01±0.20%) and height deviation (0.95±0.34%); and Example 9 has a diameter deviation (1.07±0.17%) and height deviation (1.14±0.33%). Therefore, within the formulation range investigated in this experiment, the printed cylinder of Example 5 is closest in size to the designed model.

[0106] Figure 4 B shows the height stability of 3D printed samples with different formulations after 60 minutes. As can be seen from the figure, the height stability of Comparative Example 1 is 95.62 ± 0.41%. After adding pectin, the overall height stability of all groups of samples improved, with Example 3 at 97.98 ± 1.13%, Example 6 at 98.92 ± 0.19%, and Example 9 at 98.20 ± 0.49%. Example 6 has the highest height stability among all groups, indicating that this group of samples has minimal height loss after 60 minutes. In summary... Figure 4 A and Figure 4 As can be seen from B, Example 5 has a lower value in terms of initial print size deviation, while Example 6 has a higher value in terms of height retention after printing.

[0107] Table 4 Texture properties blank <![CDATA[99.07±2.59 cd ]]> <![CDATA[0.77±0.09 e ]]> <![CDATA[72.03±1.91 cd ]]> <![CDATA[61.8±0.17 cd ]]> 1%K <![CDATA[101.61±2.2 cd ]]> <![CDATA[0.79±0.05 de ]]> <![CDATA[71.74±2.3 cd ]]> <![CDATA[56.53±0.11 cd ]]> 2%K <![CDATA[100.48±3.68 cd ]]> <![CDATA[0.82±0.05 bcde ]]> <![CDATA[71.85±3.5 cd ]]> <![CDATA[59.13±0.16 cd ]]> 4%K <![CDATA[96±3.06 cd ]]> <![CDATA[0.81±0.06 bcde ]]> <![CDATA[66.53±2.6 cd ]]> <![CDATA[54.15±0.14 cd ]]> 1%G <![CDATA[102.26±3.32 cd ]]> <![CDATA[0.8±0.03 cde ]]> <![CDATA[69.84±2.77 cd ]]> <![CDATA[55.66±0.09 cd ]]> 2%G <![CDATA[126.95±4.88 c ]]> <![CDATA[0.78±0.03 e ]]> <![CDATA[93.69±4.01 bc ]]> <![CDATA[77.33±0.13 bc ]]> 4%G <![CDATA[166.36±5.38 ab ]]> <![CDATA[0.89±0.06 a ]]> <![CDATA[147.25±5.13 a ]]> <![CDATA[129.95±0.28 a ]]> 1%P <![CDATA[85.01±3.19 d ]]> <![CDATA[0.8±0.08 cde ]]> <![CDATA[58.91±2.56 d ]]> <![CDATA[47.13±0.2 d ]]> 2%P <![CDATA[112.28±2.66 c ]]> <![CDATA[0.83±0.06 bcd ]]> <![CDATA[79.72±2.47 c ]]> <![CDATA[66.48±0.13 c ]]> 4%P <![CDATA[144.97±3.66 b ]]> <![CDATA[0.89±0.05 a ]]> <![CDATA[110.9±3.28 b ]]> <![CDATA[99.37±0.15 b ]]>

[0108] Combining the texture test data in Table 4 and Figure 5 A~ Figure 5 D indicates that different types and amounts of low-ester pectin have a significant regulatory effect on the hardness, elasticity, adhesiveness, and chewiness of Cordyceps militaris 3D printed samples.

[0109] Figure 5 Figure A shows the hardness of 3D printed samples with different formulations. As can be seen from the figure, the hardness of samples in Examples 1-3 with different amounts of pectin is close to that of Comparative Example 1; the hardness of Examples 4-6 and Examples 7-9 generally increases with increasing pectin content. The hardness of Example 6 is 166.36±5.38 g, the highest among all groups; the hardness of Example 9 is 144.97±3.66 g, and the hardness of Example 5 is 126.95±4.88 g.

[0110] Figure 5 B shows the elasticity graphs of 3D printed samples with different formulations. The elasticity of each group of samples is mainly distributed between 0.77 and 0.89. Among them, the elasticity of Example 6 is 0.89±0.06 and the elasticity of Example 9 is 0.89±0.05. The elasticity values ​​of the two groups are relatively high.

[0111] Figure 5 C represents the adhesion properties of 3D printed samples with different formulations. The adhesion property of Example 6 was 147.25 ± 5.13 g, which was the highest value among all groups; the adhesion property of Example 9 was 110.90 ± 3.28 g, and the adhesion property of Example 5 was 93.69 ± 4.01 g.

[0112] Figure 5 D represents the chewiness of 3D-printed samples with different formulations. The chewiness of Example 6 was 129.95 ± 0.28 g, Example 9 was 99.37 ± 0.15 g, and Example 5 was 77.33 ± 0.13 g. (Summary) Figure 5 It can be seen that Example 6 exhibits high levels of hardness, elasticity, adhesiveness, and chewiness.

[0113] Figure 6The images show scanning electron microscope (SEM) images of 3D printed samples from different treatment groups under 100x magnification. As can be seen from the figures, the surface morphology of the printed lines and the continuity of the internal matrix differ under different pectin types and amounts. Under 100x magnification, the printed lines in Comparative Example 1 and some low-pectin-addition groups have relatively rough surfaces, with some irregularities in the line intersection areas; the printed lines in some citrus pectin groups and high-pectin-addition apple groups have relatively complete outlines, and the spacing between lines is more uniform.

[0114] Figure 7 Scanning electron microscope (SEM) images of 3D-printed samples from different treatment groups under 1000x magnification are shown. Large, irregularly shaped pores or cracks can be observed in Comparative Example 1 and some of the examples. With increasing pectin content in some groups, the number of large pores decreased, and the matrix morphology became more continuous. The internal morphology of Example 6 was relatively uniform and dense, with fewer large, irregular pores; the internal morphology of Example 9 was also relatively continuous. This microstructure is consistent with... Figure 4 The printing stability shown and Figure 5 Corresponding to the textural results shown, Example 6 exhibits high stability, hardness, adhesiveness, and chewiness.

[0115] Overall, the Cordyceps militaris-pectin composite gels prepared in Comparative Example 1 and Examples 1-9 all exhibited shear-thinning characteristics, with elastic response being dominant under low strain and dynamic frequency scanning conditions. The type and amount of pectin added affected the rheological properties, printing deviation, height stability, textural properties, and microstructure of the composite gels. Within the formulation range investigated in this experiment, Example 5 showed lower printing size deviation, while Example 6 exhibited relatively better printing height stability, key textural indices, and microstructural continuity.

Claims

1. A Cordyceps militaris-pectin composite gel 3D printing base material, characterized in that, By weight, it includes: 100 parts Cordyceps militaris, 1-4 parts pectin, 25-30 parts isomaltooligosaccharide, 80-120 parts water; It also includes: refined sunflower seed oil, the dosage of which is: refined sunflower seed oil: Cordyceps militaris ultrafine powder = (5~15) mL: 100 g.

2. The Cordyceps militaris-pectin composite gel 3D printing substrate according to claim 1, characterized in that, The pectin is selected from any one of low-ester sunflower disc pectin, low-ester citrus pectin and low-ester apple pectin; The degree of esterification of the low-ester sunflower pectin is 30%~40%; the degree of esterification of the low-ester citrus pectin is 24%~30%; and the degree of esterification of the low-ester apple pectin is 27%~33%.

3. The Cordyceps militaris-pectin composite gel 3D printing substrate according to claim 1, characterized in that, The Cordyceps militaris is used as a raw material in the form of ultrafine powder with a particle size of 8~12 μm. The preparation method of Cordyceps militaris ultrafine powder is as follows: dried Cordyceps militaris with a moisture content of 6wt%~10wt% is intermittently coarsely pulverized by a high-speed pulverizer to obtain Cordyceps militaris coarse powder; then the coarse powder is placed in a low-temperature ultrafine pulverizer and pulverized again at 2~4℃ to obtain Cordyceps militaris ultrafine powder with a particle size of 8~12 μm.

4. The Cordyceps militaris-pectin composite gel 3D printing substrate according to claim 2, characterized in that, When the pectin is used as a raw material in the form of low-ester citrus pectin powder or low-ester apple pectin powder, their preparation methods are as follows: The low-ester citrus pectin powder was prepared using the following method: (1) Take dried navel orange peel, crush and sieve it to obtain dried navel orange peel powder; (2) Adjust the pH of the aqueous solution to 1.5~2.0, add the dried navel orange peel powder from (1), extract at 80~90℃ for 60~90 min, filter, and precipitate the filtrate with anhydrous ethanol to obtain crude pectin; (3) Prepare a 1wt% aqueous solution of crude pectin, adjust the pH to 11.0-12.0 in an ice bath at 0-5℃, stir to remove esters, and then adjust the pH to 5.0-6.0 to terminate the reaction. After precipitation with ethanol, washing, drying, pulverizing and sieving, a low-ester citrus pectin powder with an esterification degree of 24%-30% is obtained. The low-ester apple pectin powder was prepared using the following method: (1) Take dried apple peel, crush and sieve it to obtain dried apple peel powder; (2) Adjust the pH of the aqueous solution to 1.5~2.0, add the dried apple peel powder from (1), extract at 80~90℃ for 60~90 min, filter, and precipitate the filtrate with anhydrous ethanol to obtain crude pectin; (3) Prepare a 1wt% aqueous solution of crude pectin, adjust the pH to 10.5-11.5 in an ice bath at 0-5℃, stir to remove esters, and then adjust the pH to 5.0-6.0 to terminate the reaction. After precipitation with ethanol, washing, drying, pulverizing and sieving, a low-ester apple pectin powder with an esterification degree of 27%-33% is obtained.

5. The Cordyceps militaris-pectin composite gel 3D printing substrate according to claim 4, characterized in that, The stirring and deesterification time mentioned in (3) is 30~60 min.

6. The method for preparing the 3D printing base material of Cordyceps militaris-pectin composite gel according to any one of claims 1 to 5, characterized in that, Includes the following steps: S1 Preparation of Cordyceps militaris ultrafine powder: Dry Cordyceps militaris with a moisture content of 6wt%~10wt% was intermittently coarsely pulverized using a high-speed pulverizer for a total of 1~2 min to obtain Cordyceps militaris coarse powder; then the coarse powder was placed in a low-temperature ultrafine pulverizer and pulverized at 2~4℃ to obtain Cordyceps militaris ultrafine powder with a particle size of 8~12 μm. S2 Preparation of pectin solution: Slowly sprinkle pectin powder into hot water at 95-100℃ while stirring at 300-500 r / min, then adjust the stirring speed to 80-150 r / min and continue stirring for 5-10 min until the pectin is fully dissolved to obtain a uniform and transparent pectin solution, and cool it to 60-70℃; wherein the pectin solution is an aqueous solution with a mass percentage concentration of 1%-4% prepared by dissolving pectin powder in hot water; S3 Mixing Preparation: Add the Cordyceps militaris ultrafine powder obtained in S1 to the pectin solution obtained in S2, then add isomaltooligosaccharide and refined sunflower seed oil in sequence, and stir at 80~120 r / min until the mixture is uniform and fine and there are no visible particles to obtain the Cordyceps militaris-pectin mixture. S4 Water Bath Conditioning and Cold Refrigeration Molding: The Cordyceps militaris-pectin mixture obtained in S3 is treated in a sealed water bath at 75~85℃ for 25~35min, then cooled to room temperature, and then placed in a cold refrigeration at 2~6℃ to fix the shape, thus obtaining the Cordyceps militaris-pectin composite gel 3D printing base material. The proportions of each raw material are as described in claim 1.

7. The method for preparing the 3D printing base material of Cordyceps militaris-pectin composite gel according to claim 6, characterized in that, The pectin powder is low-ester citrus pectin powder; the Cordyceps militaris ultrafine powder is 100 parts, and the pectin powder is 4 parts.

8. The method for preparing the 3D printing base material of Cordyceps militaris-pectin composite gel according to claim 6, characterized in that, The pectin powder is low-ester apple pectin powder; the Cordyceps militaris ultrafine powder is 100 parts, and the pectin powder is 4 parts.

9. The application of the Cordyceps militaris-pectin composite gel 3D printing base material according to any one of claims 1 to 5 in the preparation of 3D printed food.

10. The application according to claim 9, characterized in that, The 3D printing conditions are: ambient temperature 20~30℃, metal nozzle inner diameter 0.6~1.0 mm, printing speed 10~20 mm / s, infill density 75%~85%, layer height 0.5~1.5 mm, and extrusion temperature 30~40℃.

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