A shepherd's purse gel for 3D printing with high freeze-thaw stability and preparation method thereof

Abstract

The present invention belongs to the technical field of food 3D printing, and discloses a 3D printing shepherd's purse gel with high freeze-thaw stability and a preparation method thereof. The present invention uses pea protein and galactomannan as raw materials, and fixes shepherd's purse powder to a protein-polysaccharide mixed gel network by a thermal crosslinking method, so that the shepherd's purse gel has significant rheological properties and gel properties, overcomes the problem that the slurry plasticity is poor after the shepherd's purse raw material is crushed, the viscosity is low, and there is no printing performance, and the shepherd's purse gel is given good freeze-thaw stability, so that the 3D printing accuracy of the shepherd's purse gel after freeze-thaw is greater than 95%, and the stability is more than 92%, which improves the standardization degree of the printing substrate, and reduces the loss of functional components and flavor quality of shepherd's purse after gel freeze-thaw. The prepared printing system not only has the advantages of natural environmental protection, can fully broaden the utilization of plant resources, and achieve sustainable development, but also has the potential for personalized customization of special medical food for special populations with nutritional fortification and health benefits.

Description

Technical Field

[0001] The invention belongs to the technical field of food 3D printing, and more specifically relates to a shepherd's purse gel for 3D printing with high freeze-thaw stability and a preparation method thereof. Background Art

[0002] 3D printing technology is an intelligent molding technology that uses computer programs to digitize complex processing processes and realize high-precision geometric models. Food 3D printing technology combines 3D printing with food manufacturing to construct complex structures, which can promote the sustainable development of food production, simplify the supply chain, and reduce resource waste. Fruits and vegetables, as an important part of human diet, can provide carbohydrates, vitamins, minerals, bioactive substances, etc. for the human body. Applying fruit and vegetable raw materials to food 3D printing can promote the development of healthy ingredients and achieve accurate allocation of personalized or dietary nutritional needs. However, due to the problems of low viscosity and weak mechanical strength of fruit and vegetable raw materials, it is difficult to achieve 3D printing. For example, fruits and vegetables with high water content have strong slurry fluidity and do not have printing rheological properties; fruits and vegetables with high fiber content have large slurry particles that are easy to clog the printing nozzle. In addition, in order to improve the efficiency of food 3D printing and the standardization of the printing system, freezing and refrigeration technology is used in the production and preparation of printing matrices, but temperature fluctuations during freezing and refrigeration will cause freeze-thaw phenomena, resulting in reduced printing performance of food matrix materials, loss of nutrients, and deterioration of flavor quality. Therefore, improving the freeze-thaw stability of fruit and vegetable matrix printing materials is of great significance for the precise formulation of 3D printing to meet personalized nutrition.

[0003] Shepherd's purse (Capsellabursa-pastoris) is a herbaceous plant of the genus Capsella in the cruciferous family, and enjoys the reputation of "the best wild vegetables". Studies have shown that shepherd's purse is rich in protein, cellulose, polyphenols, flavonoids, polysaccharides, alkaloids, vitamin C, amino acids and other active ingredients, among which the content of vitamin C and carotene is much higher than that of similar vegetables, and has the medicinal value of lowering blood lipids, anti-inflammatory, antioxidant, hypoglycemic, antibacterial and other medicinal values. With shepherd's purse as raw material, shepherd's purse can be developed into a healthy leisure food with delicate taste, unique flavor, soft and delicious, and rich in nutrition through 3D printing, so that consumers can not only take nutrition after eating, but also achieve the effect of improving intelligence and health. However, after the shepherd's purse raw material is crushed, the slurry has poor plasticity and low viscosity, does not have printing rheological properties, and the functional components and flavor quality of shepherd's purse are seriously lost after freeze-thaw. Therefore, how to prepare a shepherd's purse gel printing matrix with high freeze-thaw stability is the focus of research by those skilled in the art.

[0004] Invention patent CN 114409924A discloses a Flammulina velutipes polysaccharide-soy protein gel suitable for 3D printing and its preparation method, which achieves the purpose of high-protein food processing, customized food structure, and functional food nutrition. Invention patent CN 115708539A discloses a composite food ink and 3D printing method suitable for high-precision printing, which can achieve microfilament printing at the level of hundreds of microns, improving the external visual beauty and taste of printed food. The above patents use single components such as non-starch polysaccharides, proteins, starch, etc. to mix with each other to prepare composite gels, and can only prepare high-precision high-protein printing systems, and do not involve freeze-thaw stability. Therefore, the above patents do not have the rheological properties and other properties required for 3D printing extrusion and molding.

[0005] Invention patent CN 117502656A discloses a 3D printed high-protein-polysaccharide easy-to-swallow food and its preparation method, which uses a variety of hydrophilic colloids such as cellulose derivatives, which are not easily accepted by consumers, and although its composition types are diverse, it can only provide high-protein characteristics. Invention patent CN 117064054A discloses fruit and vegetable powder-protein gel for 3D printing and its preparation method and application, which uses 180-220℃ high temperature and 0.5-2.0MPa high pressure to treat fruits and vegetables, resulting in serious loss of fruit and vegetable flavor, and the heat-sensitive nutrients in fruits and vegetables will also be severely destroyed, leaving only the color and printing performance of fruits and vegetables.

[0006] Invention patent CN 117297072A discloses a chickpea protein-based high internal phase emulsion with high freeze-thaw stability based on interface regulation, and its preparation method and application, which improves the stability of flavor components embedded in the oil phase in the emulsion gel after freeze-thaw. Invention patent CN 114027392A discloses a double-network pea protein hydrogel with high freeze-thaw stability and its preparation method, which improves the stability of the water in the network structure in the hydrogel. The above patents do not have high printing performance, which is significantly different from the material properties requirements of the 3D printing system, such as rheological properties and gel properties.

[0007] Therefore, how to provide a shepherd's purse gel for 3D printing with high freeze-thaw stability and a preparation method thereof is a problem that needs to be urgently solved by those skilled in the art. Summary of the invention

[0008] In order to overcome the shortcomings and deficiencies in the prior art, the present invention provides a shepherd's purse gel for 3D printing with high freeze-thaw stability and a preparation method thereof. The shepherd's purse gel not only has 3D printing characteristics and high freeze-thaw stability, but also has the characteristic flavor and nutritional quality of shepherd's purse, and can expand the 3D printing food materials of fruits and vegetables, improve the efficiency of food 3D printing and the standardization of the printing system, promote the diversified development of the shepherd's purse processing industry chain, and develop 3D printed food that meets the appearance, taste, and health requirements.

[0009] In order to achieve the above object, the present invention adopts the following technical solution:

[0010] One of the purposes of the present invention is to provide a method for preparing shepherd's purse gel for 3D printing with high freeze-thaw stability, comprising the following steps:

[0011] (1) dispersing pea protein in water, adjusting the pH to 7-8, homogenizing, and fully hydrating to obtain a pea protein suspension;

[0012] (2) adding galactomannan to the pea protein suspension, mixing evenly, homogenizing at high speed, sealing with plastic wrap, and heating in a water bath to obtain a pea protein-galactomannan mixed solution;

[0013] (3) cleaning the shepherd's purse and removing the roots, cutting into sections, ultrasonically treating, draining, vacuum microwave-far infrared combined drying, ultrafine grinding, sieving, and obtaining shepherd's purse powder;

[0014] (4) mixing the shepherd's purse powder with the pea protein-galactomannan mixed solution, homogenizing at high speed, performing a water bath thermal cross-linking reaction, and cooling at room temperature to obtain the shepherd's purse gel for 3D printing.

[0015] Preferably, the homogenization time in step (1) is 5 to 10 minutes, and sufficient hydration is achieved by magnetic stirring at 600 to 800 rpm for 4 to 6 hours.

[0016] Preferably, the concentration of pea protein in the pea protein suspension in step (1) is 0.02-0.06 g / mL.

[0017] Preferably, the galactomannan in step (2) is selected from one of fenugreek gum, guar gum, spiny bean gum and locust bean gum.

[0018] Preferably, the concentration of the galactomannan in the pea protein suspension in step (2) is 0.04-0.08 g / mL.

[0019] The beneficial effects of the above technical scheme are: improving the viscoelasticity of the gel system with galactomannan having a mannose backbone and galactose side groups, and improving the stability of the shepherd's purse gel network topological structure during the freezing and thawing process of the system by interacting with pea protein with high surface activity, thereby reducing the loss of shepherd's purse's nutrient components and flavor quality.

[0020] Preferably, the speed of the high-speed homogenization in step (2) is 7000-10000 rpm, the time is 5-10 min, and the temperature of the water bath heating is 82-88° C., and the time is 10-20 min.

[0021] Preferably, the specific operation of step (3) is: clean the shepherd's purse and remove the roots, cut it into 2-3 cm segments, treat it at an ultrasonic power of 6 W / g for 20 minutes, drain it, vacuum microwave dry it at a microwave power of 6 W / g until the moisture content at the conversion point is 50% to 70%, transfer it to a far-infrared dryer, dry the shepherd's purse at a temperature of 58 to 62° C. until the moisture content is less than 10%, and ultrafine grind the dried shepherd's purse, and pass it through an 80-mesh sieve to obtain shepherd's purse powder.

[0022] The beneficial effects of the above technical scheme are: vacuum microwave-far infrared combined drying is adopted, with good uniformity, high drying efficiency, high retention of flavor quality, nutrients and color, and the shepherd's purse powder prepared under the combined drying conditions is used in the 3D printing system, which not only has the typical flavor and characteristic nutrients of shepherd's purse, but also the protein-polysaccharide mixed gel can protect the shepherd's purse system to have high printing performance before and after freezing and thawing.

[0023] Preferably, the mass ratio of the shepherd's purse powder to the pea protein-galactomannan mixed solution in step (4) is 1:4.

[0024] Preferably, it is characterized in that the speed of the high-speed homogenizer in step (4) is 7000-10000 rpm, the time is 3-5 min, the temperature of the water bath is 82-88°C, the time is 3-5 min, and the cooling time at room temperature is 3-4.5 h.

[0025] The second purpose of the present invention is to provide a shepherd's purse gel for 3D printing with high freeze-thaw stability prepared by the above method. After freezing and thawing, the main acting force of the shepherd's purse gel is transformed from hydrophobic interaction to disulfide bond. The microscopic porosity of the gel before and after freezing and thawing is 23.14-28.08%, and the average diameter of the microscopic pores before and after freezing and thawing is 20.85-27.20 μm.

[0026] The third purpose of the present invention is to provide the application of the above-mentioned shepherd's purse gel for 3D printing with high freeze-thaw stability in the field of food 3D printing. Under the printing conditions of nozzle diameter 0.84 mm, printing temperature 25°C, nozzle movement speed 15 mm / s, and filling rate 100%, the printing accuracy before and after freeze-thaw is more than 95%, and the stability is more than 92%.

[0027] It can be seen from the above technical solution that, compared with the prior art, the present invention provides a shepherd's purse gel for 3D printing with high freeze-thaw stability and a preparation method thereof, which has the following beneficial effects:

[0028] (1) The present invention uses pea protein and galactomannan as raw materials, fixes shepherd's purse powder into a protein-polysaccharide mixed gel network by a thermal cross-linking method, and makes the shepherd's purse gel have significant rheological properties and gel properties, overcomes the problems of poor plasticity, low viscosity and poor printing performance of the slurry after the shepherd's purse raw material is crushed, and gives the shepherd's purse gel good freeze-thaw stability, so that the 3D printing accuracy of the shepherd's purse gel after freeze-thaw is greater than 95%, and the stability is more than 92%, thereby improving the standardization degree of the printing substrate and reducing the loss of functional components and flavor quality of the shepherd's purse after the gel is frozen and thawed.

[0029] (2) In the present invention, galactomannan with different branching ratios and pea protein are used to form a gel network structure with different pore densities and pore characteristics through the mutual conversion between hydrophobic interaction and disulfide bonds, so as to regulate the gel pores and water freedom, promote the shepherd's purse powder to be tightly fixed in the gel network, reduce the influence of environmental factors on the nutritional components and flavor of shepherd's purse, and avoid the obvious increase of microscopic pores and porosity in the gel during the freeze-thaw process, maintain the stability of the gel network topological structure, reduce the water loss rate, and show good freeze-thaw stability. In addition, the addition ratio of different galactomannan and pea protein makes the gel structure and texture characteristics adjustable, which can meet the needs of different products.

[0030] (3) The high freeze-thaw stability shepherd's purse gel prepared by the present invention is suitable for making 3D printed products of various shapes. The printed products have uniform and fine texture, green color, high precision and stability, good printing effect, and realize the personalized customization of 3D printed fruit and vegetable-based foods. The amino acid ratio of pea protein in the printed products is balanced, and contains lysine lacking in cereals. Galactomannan, as a new functional dietary fiber, can be highly fermented and utilized by intestinal flora. Prebiotics, in addition, shepherd's purse has a unique flavor and rich nutrients, and is suitable for special groups with protein dietary intake needs, low intestinal absorption capacity, chewing and swallowing difficulties, etc. The prepared printing system not only has the advantages of being natural and environmentally friendly, can fully broaden the utilization of plant resources, and achieve sustainable development, but also has the potential for personalized customization of special medical foods for special groups with nutritional fortification and health benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0032] Figure 1 This is a 3D printing molding effect diagram of shepherd's purse gel before and after freezing and thawing in Example 3.

[0033] Figure 2 This is the microstructure of shepherd's purse gel before and after freeze-thawing in Example 3. DETAILED DESCRIPTION

[0034] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] Example 1

[0036] A method for preparing shepherd's purse gel for 3D printing with high freeze-thaw stability comprises the following steps:

[0037] Pea protein was dispersed in water, the pH was adjusted to 7, the concentration was set to 0.05 g / mL, homogenized for 5 min, and magnetically stirred at 600 rpm for 4 h to fully hydrate it to obtain a pea protein suspension. Guar gum was added to the pea protein suspension at a concentration of 0.05 g / mL, homogenized at 10000 rpm for 5 min, sealed with plastic wrap, and heated in a water bath at 88°C for 20 min to obtain a pea protein-guar gum mixed solution. Shepherd's purse was washed, roots were removed, cut into 2-3 cm segments, treated at 6 W / g ultrasonic power for 20 min, dried under 6 W / g microwave conditions to a moisture content of 60% at the conversion point, dried under infrared temperature of 60°C to a moisture content of less than 10%, and the dried shepherd's purse was crushed at high speed and passed through an 80-mesh sieve to obtain shepherd's purse powder. Shepherd's purse powder and pea protein-guar gum solution were mixed in a mass ratio of 1:4, homogenized at 10,000 rpm for 3 minutes, placed in a water bath at 88°C for 3 minutes, and allowed to cool for 4 hours to obtain shepherd's purse gel for 3D printing with high freeze-thaw stability.

[0038] The hydrophobic interaction in the gel was determined to be the main force, the consistency coefficient was 1497.45, the yield stress was 1776.75Pa, the gel strength was 134.00g, the microporosity was 26.11%, and the average micropore diameter was 23.05μm. The gel after freeze-thaw was determined to have disulfide bonds as the main force, the consistency coefficient was 1453.60, the yield stress was 1633.89Pa, the gel strength was 114.67g, the microporosity was 26.84%, and the average micropore diameter was 26.18μm. The 3D printing material was added to the printing barrel, and the cylinder was selected to prepare the 3D printed product under the parameters of nozzle diameter 0.84mm, printing temperature 25℃, nozzle movement speed 15mm / s, and filling rate 100%. Before freezing and thawing, the accuracy of the 3D printed product was 96.61%, and the stability after 6 hours of standing was 93.59%; after freezing and thawing, the accuracy of the 3D printed product was 96.44%, and the stability after 6 hours of standing was 92.75%. The bioaccessibility loss rates of polyphenols and carotenoids were 1.39% and 2.29%, respectively.

[0039] Example 2

[0040] A method for preparing shepherd's purse gel for 3D printing with high freeze-thaw stability comprises the following steps:

[0041] Pea protein was dispersed in water, the pH was adjusted to 7, the concentration was set to 0.04 g / mL, homogenized for 5 min, and magnetically stirred at 600 rpm for 4 h to fully hydrate it to obtain a pea protein suspension. Guar gum was added to the pea protein suspension at a concentration of 0.06 g / mL, homogenized at 10000 rpm for 5 min, sealed with plastic wrap, and heated in a water bath at 88°C for 20 min to obtain a pea protein-guar gum mixed solution. Shepherd's purse was washed, roots were removed, cut into 2-3 cm segments, treated at 6 W / g ultrasonic power for 20 min, dried under 6 W / g microwave conditions to a moisture content of 60% at the conversion point, dried under infrared temperature of 60°C to a moisture content of less than 10%, and the dried shepherd's purse was crushed at high speed and passed through an 80-mesh sieve to obtain shepherd's purse powder. Shepherd's purse powder and pea protein-guar gum solution were mixed in a mass ratio of 1:4, homogenized at 10,000 rpm for 3 minutes, placed in a water bath at 88°C for 3 minutes, and allowed to cool for 4 hours to obtain shepherd's purse gel for 3D printing with high freeze-thaw stability.

[0042] The hydrophobic interaction in the gel was determined to be the main force, the consistency coefficient was 1829.04, the yield stress was 2062.35Pa, the gel strength was 156.67g, the microporosity was 24.69%, and the average diameter of the micropores was 21.91μm. The gel after freeze-thaw was determined to have hydrophobic interaction as the main force, the consistency coefficient was 1744.33, the yield stress was 2001.13Pa, the gel strength was 143.33g, the microporosity was 28.08%, and the average diameter of the micropores was 27.20μm. The 3D printing material was added to the printing barrel, and the cylinder was selected to prepare the 3D printing product under the parameters of nozzle diameter 0.84mm, printing temperature 25℃, nozzle movement speed 15mm / s, and filling rate 100%. Before freezing and thawing, the accuracy of the 3D printed product was 98.09%, and the stability after 6 hours of standing was 95.74%; after freezing and thawing, the accuracy of the 3D printed product was 97.16%, and the stability after 6 hours of standing was 95.45%. The bioaccessibility loss rates of polyphenols and carotenoids were 3.64% and 2.08%, respectively.

[0043] Example 3

[0044] A method for preparing shepherd's purse gel for 3D printing with high freeze-thaw stability comprises the following steps:

[0045] Pea protein was dispersed in water, the pH was adjusted to 7, the concentration was set to 0.03 g / mL, homogenized for 5 min, and magnetically stirred at 800 rpm for 4 h to fully hydrate it to obtain a pea protein suspension. Guar gum was added to the pea protein suspension at a concentration of 0.07 g / mL, homogenized at 10000 rpm for 5 min, sealed with plastic wrap, and heated in a water bath at 88°C for 20 min to obtain a pea protein-guar gum mixed solution. Shepherd's purse was washed, roots were removed, cut into 2-3 cm segments, treated at 6 W / g ultrasonic power for 20 min, dried under 6 W / g microwave conditions to a moisture content of 60% at the conversion point, dried under infrared temperature of 60°C to a moisture content of less than 10%, and the dried shepherd's purse was crushed at high speed and passed through an 80-mesh sieve to obtain shepherd's purse powder. Shepherd's purse powder and pea protein-guar gum solution were mixed in a mass ratio of 1:4, homogenized at 10,000 rpm for 3 minutes, placed in a water bath at 88°C for 3 minutes, and allowed to cool for 4 hours to obtain shepherd's purse gel for 3D printing with high freeze-thaw stability.

[0046] The hydrophobic interaction in the gel was determined to be the main force, the consistency coefficient was 2164.55, the yield stress was 2449.95Pa, the gel strength was 176.67g, the microporosity was 23.14%, and the average diameter of the micropores was 20.85μm. The gel after freeze-thaw was determined to have hydrophobic interaction as the main force, the consistency coefficient was 2210.51, the yield stress was 2395.74Pa, the gel strength was 182.67g, the microporosity was 27.24%, and the average diameter of the micropores was 24.71μm. The 3D printing material was added to the printing barrel, and the cylinder was selected to prepare the 3D printing product under the parameters of nozzle diameter 0.84mm, printing temperature 25℃, nozzle movement speed 15mm / s, and filling rate 100%. Before freezing and thawing, the accuracy of the 3D printed product was 98.36%, and the stability after standing for 6 hours was 94.34%; after freezing and thawing, the accuracy of the 3D printed product was 98.31%, and the stability after standing for 6 hours was 94.31%, and the bioaccessibility loss rates of polyphenols and carotenoids were 4.81% and 3.78%, respectively.

[0047] Comparative Example 1

[0048] A shepherd's purse gel for 3D printing and a preparation method thereof, comprising the following steps:

[0049] Locust bean gum was dispersed in water to a concentration of 0.08 g / mL, homogenized at 7000 rpm for 5 min, sealed with plastic wrap, and heated in a water bath at 85°C for 20 min. Shepherd's purse was washed, roots were removed, cut into 2-3 cm segments, treated at 6 W / g ultrasonic power for 20 min, dried under 6 W / g microwave conditions until the moisture content at the conversion point was 60%, and dried under infrared temperature of 60°C until the moisture content was less than 10%, and the dried shepherd's purse was crushed at high speed and passed through an 80-mesh sieve to obtain shepherd's purse powder. Shepherd's purse powder and locust bean gum solution were mixed in a mass ratio of 1:4, homogenized at 10000 rpm for 3 min, placed in a water bath at 85°C for 3 min, and allowed to cool for 4 h to obtain shepherd's purse gel.

[0050] The yield stress of the gel was 921.11Pa, the gel strength was 72.67g, the microporosity was 17.61%, and the average diameter of the micropores was 35.50μm. The yield stress of the gel after freeze-thaw was 858.42Pa, the gel strength was 60.55g, the microporosity was 20.37%, and the average diameter of the micropores was 37.92μm. The 3D printing material was added to the printing barrel, and the cylinder was selected. The 3D printing product was prepared under the parameters of nozzle diameter 0.84mm, printing temperature 25℃, nozzle movement speed 15mm / s, and filling rate 100%. Before freeze-thaw, the accuracy of the 3D printing product was 90.83%, and the stability after standing for 6h was 76.32%; after freeze-thaw, the accuracy of the 3D printing product was 86.64%, the stability after standing for 6h was 70.77%, and the bioaccessibility loss rates of polyphenols and carotenoids were 12.44% and 13.53%, respectively.

[0051] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the scheme disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0052] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing shepherd's purse gel for 3D printing with high freeze-thaw stability, characterized in that: The following steps are involved: (1) dispersing pea protein in water, adjusting the pH to 7-8, homogenizing, and fully hydrating to obtain a pea protein suspension; (2) adding galactomannan to the pea protein suspension, mixing evenly, homogenizing at high speed, sealing with plastic wrap, and heating in a water bath to obtain a pea protein-galactomannan mixed solution; (3) cleaning the shepherd's purse and removing the roots, cutting into sections, ultrasonically treating, draining, vacuum microwave-far infrared combined drying, ultrafine grinding, sieving, and obtaining shepherd's purse powder; (4) The shepherd's purse powder is mixed with the pea protein-galactomannan mixed solution, homogenized at high speed, subjected to a water bath thermal cross-linking reaction, and cooled at room temperature to obtain a shepherd's purse gel for 3D printing.

2. The method for preparing a shepherd's purse gel for 3D printing with high freeze-thaw stability according to claim 1, characterized in that: The homogenization time in step (1) is 5 to 10 minutes, and sufficient hydration is achieved by magnetic stirring at 600 to 800 rpm for 4 to 6 hours; The concentration of pea protein in the pea protein suspension in step (1) is 0.02-0.06 g / mL.

3. The method for preparing a shepherd's purse gel for 3D printing with high freeze-thaw stability according to claim 1, characterized in that: The galactomannan in step (2) is selected from one of fenugreek gum, guar gum, spiny bean gum and locust bean gum.

4. The method for preparing a shepherd's purse gel for 3D printing with high freeze-thaw stability according to claim 1, characterized in that: The concentration of the galactomannan in the pea protein suspension in step (2) is 0.04-0.08 g / mL.

5. The method for preparing a shepherd's purse gel for 3D printing with high freeze-thaw stability according to claim 1, characterized in that: The speed of the high-speed homogenization in step (2) is 7000-10000 rpm, the time is 5-10 min, and the temperature of the water bath heating is 82-88° C., and the time is 10-20 min.

6. The method for preparing a shepherd's purse gel for 3D printing with high freeze-thaw stability according to claim 1, characterized in that: The specific operation of step (3) is as follows: clean the shepherd's purse and remove the roots, cut it into 2-3 cm segments, treat it at an ultrasonic power of 6 W / g for 20 minutes, drain it, vacuum microwave dry it at a microwave power of 6 W / g until the moisture content at the conversion point is 50% to 70%, transfer it to a far-infrared dryer, dry the shepherd's purse at a temperature of 58 to 62° C. until the moisture content is less than 10%, and ultrafine grind the dried shepherd's purse and pass it through an 80-mesh sieve to obtain shepherd's purse powder.

7. The method for preparing a shepherd's purse gel for 3D printing with high freeze-thaw stability according to claim 1, characterized in that: The mass ratio of the shepherd's purse powder to the pea protein-galactomannan mixed solution in step (4) is 1:

4.

8. The method for preparing a shepherd's purse gel for 3D printing with high freeze-thaw stability according to claim 1, characterized in that: The speed of the high-speed homogenization in step (4) is 7000-10000 rpm, the time is 3-5 min, the temperature of the water bath is 82-88° C., the time is 3-5 min, and the cooling time at room temperature is 3-4.5 h.

9. A shepherd's purse gel for 3D printing with high freeze-thaw stability prepared according to the method according to any one of claims 1 to 8, characterized in that: After freezing and thawing, the main force of shepherd's purse gel changes from hydrophobic interaction to disulfide bond. The microscopic porosity of the gel before and after freezing and thawing is 23.14-28.08%, and the average diameter of the microscopic pores before and after freezing and thawing is 20.85-27.20μm.

10. The use of the shepherd's purse gel for 3D printing with high freeze-thaw stability according to claim 9 in the field of food 3D printing, characterized in that: Under the printing conditions of nozzle diameter 0.84mm, printing temperature 25℃, nozzle movement speed 15mm / s, and filling rate 100%, the printing accuracy before and after freeze-thaw is more than 95%, and the stability is more than 92%.

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