A printing method of a cassava starch-based 3D printing material

Abstract

The application discloses a kind of based on cassava starch 3D printing material printing method, belong to food 3D printing technical field.The method includes: (1) cassava starch is added to water, is placed in high pressure micro jet and is treated to obtain starch suspension liquid;(2) in starch suspension liquid, protein, fatty acid and polysaccharide are added, stirred uniformly, then ultrasonic treatment is carried out to obtain pretreatment material;(3) pretreatment material is heated, so that starch is completely gelatinized and then loaded into 3D printer material cylinder, after gel cooling, 3D printing is carried out.The present application uses cassava starch as base material, and the microstructure of cassava starch can be broken by ultrahigh pressure micro jet treatment, and the intermolecular interaction is enhanced by ultrasonic treatment;Through the above process improvement, the printing accuracy of 3D printing product is greatly improved, and can reach more than 95%.

Description

Technical Field

[0001] This invention relates to the field of food 3D printing technology, specifically to a printing method based on cassava starch as a 3D printing material. Background Technology

[0002] 3D printing is a technology that uses digital model files as a basis and adhesive materials to construct objects layer by layer. It belongs to the category of rapid prototyping technology. Food 3D printing technology integrates multiple technologies such as food processing technology and digital technology, and has the advantages of safety, nutrition, personalization, and diverse shapes. It can optimize food components according to different nutritional components and formulas, and conveniently and quickly manufacture healthy foods that meet the needs of different groups of people, thereby improving food quality and enriching food varieties.

[0003] 3D printing materials are the foundation of 3D printing. Using starch as a raw material for food 3D printing is currently a major research direction. Cassava starch is a powdered product obtained by extracting starch from cassava and then dehydrating and drying it. Compared to starches from other root vegetables, it has a lower gelatinization temperature, higher viscosity, and lower price, making it widely used in food formulation, beverage, and confectionery production. As an indispensable component of food processing, starch is attracting increasing attention. However, using pure starch as a raw material for printing results in disadvantages such as poor mechanical strength, low printing accuracy, and poor shape retention, making it difficult to meet consumer demands.

[0004] Currently, starch complex gels are often prepared by adding raw materials such as proteins and lipids to change their rheological properties, or by using sodium chloride solution and microwave post-treatment to enhance the cross-linking of starch gels, resulting in a uniform and dense starch complex gel system, which is then used to improve the strength and accuracy of starch gel 3D printing.

[0005] Patent document CN 106666800 A discloses a method for preparing a 3D printing material based on potato starch. This material is composed of potato starch, protein, water, and butter, which are mixed, gelatinized, kneaded, and then 3D printed. Protein reduces the adhesiveness of the gelatinized potato starch, while butter increases the material's lubricity. During the gelatinization of the potato starch, the protein and the small starch molecules produced by gelatinization cross-link, forming a gel with excellent elasticity and plasticity. This gel interacts with the butter to form a network of small molecule supports with high elasticity, toughness, plasticity, and mechanical strength, meeting the requirements of 3D printing.

[0006] Patent document CN 108208768 A discloses a 3D-printed food material based on potato starch. The raw materials include: potato starch, protein, water, butter, polysaccharides, and organic salts. Sodium carboxymethyl cellulose and chitosan can bind the various components of the material and form cross-links with the protein. The cross-linked material improves the mechanical strength of the material in the presence of inorganic calcium ions.

[0007] Current research on starch gel 3D printing materials focuses on improving the mechanical strength of the material, while product precision still needs improvement. Pullulan, an extracellular polysaccharide secreted by *Bacillus buddingus*, is readily soluble in water and possesses excellent adhesive properties, making it widely used in food and textile industries. However, to date, there have been no reports indicating that pullulan can be used as a raw material to improve the precision of cassava starch gel 3D printing. Furthermore, some post-processing methods, such as microwave and sodium chloride treatment, do not significantly improve the accuracy of starch gel 3D printing, thus limiting the application of starch-based materials in 3D printing.

[0008] Therefore, selecting new raw materials or developing a novel material pretreatment method to improve the printing accuracy of starch-based materials has become an urgent problem to be solved. Summary of the Invention

[0009] The purpose of this invention is to provide a printing method for 3D printing materials based on cassava starch. By pre-treating the materials, the printing accuracy of starch-based 3D printing materials is improved, thereby solving the technical problems of low printing accuracy and poor shape retention of existing starch 3D printing materials.

[0010] To achieve the above objectives, the present invention adopts the following technical solution:

[0011] A printing method based on cassava starch 3D printing material includes the following steps:

[0012] (1) Add cassava starch to water and treat it in a high-pressure microjet to obtain a starch suspension;

[0013] (2) Add protein, fatty acid and polysaccharide to starch suspension, stir evenly, and then perform ultrasonic treatment to obtain pretreated material;

[0014] (3) Heat the pretreated material to make the starch completely gelatinized and then put it into the material cylinder of the 3D printer. After the gel cools, 3D printing is performed.

[0015] The raw materials, by weight percentage, include: 13-20% tapioca starch, 1%-5% protein, 2%-9% fatty acids, 0.02%-0.06% polysaccharides, and the remainder is water.

[0016] Protein can reduce the viscosity of cassava starch and increase the elastic modulus of the system, thereby giving the printed product stronger support. Preferably, the protein is casein, pea protein, whey protein, or rapeseed protein.

[0017] Fatty acids can increase the lubricity and mechanical strength of products. Studies have shown that the chain length and unsaturation of fatty acids affect the printing accuracy of products; as the carbon chain length decreases and the degree of unsaturation increases, the printing accuracy of the product improves accordingly. Preferably, the fatty acid is linolenic acid, lauric acid, or linoleic acid.

[0018] Polysaccharides can bind together the components of a material and can interact with starch molecules, especially short-chain amylopectin and amylose, increasing the mechanical strength of the system. Preferably, the polysaccharide is pullulan.

[0019] More preferably, the raw materials, by weight percentage, include: 15% tapioca starch, 2% casein, 2.94% linolenic acid, 0.06% pullulan, and the balance being water. The combination of these materials forms a material that meets the requirements for 3D printing.

[0020] In step (1), the present invention uses cassava starch as a substrate, and ultra-high pressure micro-jet treatment can increase the breakage of the microstructure of cassava starch, which is conducive to the formation of starch-lipid-protein ternary complex.

[0021] Preferably, the high-pressure microjet treatment pressure is 60–150 MPa.

[0022] Even better, the high-pressure microjet processing pressure is 100MPa.

[0023] In step (2), the mixing of all raw materials followed by ultrasonic treatment helps to improve the uniformity of material mixing, enhance intermolecular interactions, and promote the formation of a uniform and dense gel structure after water bath heating of the starch complex. Studies have shown that the ultrasonic treatment in this step, combined with the ultra-high pressure microjets in step (1), significantly improves the printing accuracy of the 3D printing material.

[0024] Preferably, the ultrasonic treatment power is 50-200W and the time is 20-40min.

[0025] More preferably, the ultrasonic treatment power is 200W and the time is 30min.

[0026] In step (3), the materials are mixed and heated in a water bath to gelatinize the starch. After the starch is completely gelatinized, it is loaded into the 3D printer. When the gel cools to room temperature, the desired model is selected for 3D printing.

[0027] Preferably, the heating temperature is 90-100℃. During the heating process, the material is stirred.

[0028] The beneficial effects of this invention are as follows:

[0029] (1) This invention uses cassava starch as a base material. High-pressure microfluidic treatment can increase the microstructure breakage of cassava starch, which is beneficial to the formation of starch-lipid-protein ternary complexes. The addition of casein, linolenic acid and low concentration of pullulan can reduce the viscosity of cassava starch, increase the elastic modulus, and give the printed material higher rigidity. Ultrasonic pretreatment can promote the formation of a uniform and dense gel structure after water bath heating of the starch complex. Through the above process improvements, the printing accuracy of 3D printed products is greatly improved, reaching more than 95%, and the shape can be maintained intact for 2-3 hours.

[0030] (2) The 3D printing material formula does not contain food additives and preservatives that are harmful to human health, thus ensuring the safety of the printed products.

[0031] (3) The starch composite gel provided by the present invention has high printing precision and can be processed into 3D printed products with different shapes and novel features, which enriches the 3D printed products, realizes the automated, personalized and diversified production of products, and expands the application of starch food 3D printing in the food industry. Attached Figure Description

[0032] Figure 1 The images show actual 3D printed products prepared from the raw materials under the conditions of Example 1. a, b, and c are respectively the Zhejiang University Qiushi Eagle, the Butterfly Dress, and the Cube.

[0033] Figure 2 To investigate the effects of different proteins on the accuracy of 3D printing of cassava starch gel composites.

[0034] Figure 3 To investigate the effect of different fatty acids on the accuracy of 3D printing of cassava starch gel composites.

[0035] Figure 4 To investigate the effect of different concentrations of pullulan on the accuracy of 3D printing of cassava starch gel composites.

[0036] Figure 5 To investigate the effect of different ultrasonic pretreatment times on the accuracy of 3D printing of cassava starch gel composites.

[0037] Figure 6 The effect of different jet pressures on the pretreatment of cassava starch on printing accuracy.

[0038] Figure 7The effect of different microjet pressure pretreatments on the microstructure of cassava was investigated. In the figure, a represents cassava starch that has not undergone microjet pressure pretreatment, b represents cassava starch that has undergone microjet pressure pretreatment at 30 MPa, c represents cassava starch that has undergone microjet pressure pretreatment at 60 MPa, d represents cassava starch that has undergone microjet pressure pretreatment at 100 MPa, and e represents cassava starch that has undergone microjet pressure pretreatment at 150 MPa.

[0039] Figure 8 The effects of high-pressure microfluidic treatment combined with ultrasonic treatment, high-pressure microfluidic treatment alone, and ultrasonic treatment alone on improving product printing accuracy were investigated.

[0040] Note: The groups marked with different letters in the above figure have significant differences, i.e., P < 0.05. Detailed Implementation

[0041] The present invention will be further described below with reference to specific embodiments. These embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Any modifications or substitutions made to the methods, steps, or conditions of the present invention without departing from the spirit and essence of the invention are within the scope of the invention.

[0042] Unless otherwise specified, the experimental methods used in the following examples are conventional methods; the materials and reagents used are commercially available unless otherwise specified.

[0043] Cassava starch (CAS: 9005-25-8), casein (CAS: 9000-71-9), pea protein (CAS: 222400-29-5), rapeseed protein (rapeseed seeds were dehulled, crushed, and passed through an 80-mesh sieve. After defatting with petroleum ether for 8 hours, the seeds were dried and sieved again. The defatted rapeseed meal was dissolved in distilled water at a ratio of 1:10 (w / v). The pH was adjusted to 8.0 with NaOH (1 mol / L). The mixture was centrifuged at 4°C and 8000g for 20 minutes. The supernatant was collected, and the pH was adjusted to 4.5 with HCl (1 mol / L). After standing for 1 hour, the mixture was further centrifuged at 4°C and 8000g for 20 minutes. Centrifuge at 000g for 20 minutes to obtain a precipitate, then dialyze (100kDa), freeze-dry to obtain rapeseed protein, soy protein isolate (CAS: 9010-10-0), whey protein isolate (CAS: 84082-51-9), linolenic acid (CAS: 463-40-1), lauric acid (CAS: 143-07-7), palmitic acid (CAS: 57-10-3), stearic acid (CAS: 57-11-4), oleic acid (CAS: 112-80-1), linoleic acid (CAS: 60-33-3), pullulan (CAS: 9057-02-7).

[0044] High-pressure microfluidic homogenizer (Nanogenizer-110P), 3D printer (Foodbot-S2), ultrasonic instrument (JY92-IIDN).

[0045] Example 1: Precision 3D Printing of Cassava Starch Compound

[0046] 1. Preparation method

[0047] Weigh 15g of tapioca starch, add 85g of water to prepare a starch suspension, and then subject it to high-pressure microjets at a pressure of 100MPa. Next, add 2g of casein, 2.94g of linolenic acid, and 0.06g of pullulan, and stir for 30 minutes. Then, perform ultrasonic pretreatment at 200W for 30 minutes. Finally, heat in a 100℃ water bath for 10 minutes, and then load the mixture into the feed cylinder of a 3D printer. After the gel cools, proceed with 3D printing. The printer nozzle diameter is 0.84mm, the moving speed is 30mm / s, the filling speed is 40mm / s, and the infill rate is 80%.

[0048] 2. Performance Testing

[0049] The 3D printed model is a cuboid measuring 30 (length) × 30 (width) × 15 (height) mm. The total percentage error is calculated after measuring the length, width, and height of the printed product using calipers, thus determining the printing accuracy. The specific calculation formula is as follows:

[0050]

[0051] Tests showed that the printing accuracy of the 3D-printed cuboid under the above conditions was 98.25%.

[0052] 3. Application

[0053] Replace the 3D printing model, prepare the raw materials under the above conditions, and load them into the 3D printer for 3D printing. Figure 1 As shown, the 3D printed products all exhibited high precision, with smooth sample surfaces, no obvious collapse, and sharp edges.

[0054] Example 2: Effects of different proteins on the accuracy of 3D printing of cassava starch gel complex

[0055] In Example 1, casein was replaced with pea protein, rapeseed protein, soy protein isolate, and whey protein isolate, while other conditions remained unchanged.

[0056] The results are as follows Figure 2 As shown, the addition of different proteins has a significant impact on the printing accuracy of the product. It can be found that the product with the addition of soy protein isolate has the lowest printing accuracy, while the product with the addition of casein has the highest printing accuracy.

[0057] Example 3: Effects of different fatty acids on the accuracy of 3D printing of cassava starch gel composites

[0058] In Example 1, linolenic acid was replaced with lauric acid, palmitic acid, stearic acid, oleic acid, and linoleic acid, while other conditions remained unchanged.

[0059] The results are as follows Figure 3 As shown, the addition of oils with different chain lengths and degrees of unsaturation has a significant impact on the printing accuracy of the product. The product with added linolenic acid has the highest printing accuracy. In addition, it can be found that as the degree of unsaturation increases, the printing accuracy of the product also gradually improves.

[0060] Example 4: Effect of different concentrations of pullulan on the accuracy of 3D printing of cassava starch gel composites

[0061] The amount of pullulan added in Example 1 was adjusted (0g, 0.02g, 0.04g, 0.06g, 0.08g), while other conditions remained unchanged.

[0062] The results are as follows Figure 4 As shown, compared with the sample without pullulan, the printing accuracy of the products prepared with pullulan was improved. As the pullulan content increased from 0.02% to 0.06%, the printing accuracy of the products gradually increased, while when the pullulan content reached 0.08%, the printing accuracy of the products showed a downward trend.

[0063] Example 5: Effect of different ultrasonic treatment conditions on the accuracy of 3D printing of cassava starch gel composite.

[0064] The ultrasound pretreatment time in Example 1 was changed (0, 10, 20, 30, 40 min), while other conditions remained unchanged.

[0065] The results are as follows Figure 5 As shown, compared with the samples that have not undergone ultrasonic treatment, the printing accuracy of the products prepared from the ultrasonically treated suspensions is increased. As the ultrasonic time increases from 10 min to 30 min, the printing accuracy of the products gradually increases, but when the ultrasonic time reaches 40 min, the printing accuracy of the products shows a decreasing trend.

[0066] Example 6: Effect of different high-pressure microjets on the accuracy of 3D printing of cassava starch gel composites

[0067] The high-pressure microjet treatment pressure in Example 1 was changed (0, 30, 60, 100, 150 MPa), while other conditions remained unchanged.

[0068] The results are as follows Figure 6As shown, compared with cassava starch that has not undergone microfluidic pretreatment, the printing accuracy of products prepared from starch treated with microfluidics at different pressures is improved. As the microfluidic pressure increases from 30 MPa to 100 MPa, the printing accuracy of the products gradually increases, while when the pressure reaches 150 MPa, the printing accuracy shows a decreasing trend.

[0069] like Figure 7 As shown, high-pressure microjet pretreatment leads to the disruption of the microstructure of cassava starch.

[0070] Example 7: The impact of high-pressure microfluidic treatment combined with ultrasonic treatment, high-pressure microfluidic treatment alone, and ultrasonic treatment alone on improving product printing accuracy.

[0071] The high-pressure microfluidic treatment and ultrasonic treatment conditions in Example 1 were removed, while other conditions remained unchanged. The results showed that the printing accuracy of the product was 87.33%.

[0072] The printing accuracy of the cassava starch gel composite treated only by high-pressure microfluidics was 92.32%, an improvement of 4.99%. The printing accuracy of the cassava starch gel composite treated only by ultrasound was 91.75%, an improvement of 4.42%. The printing accuracy of the cassava starch gel composite treated by both high-pressure microfluidics and ultrasound was 98.25%, an improvement of 10.92%, significantly higher than the combined improvement achieved by using high-pressure microfluidics and ultrasound pretreatment alone. Figure 8 ).

[0073] The above results indicate that high-pressure microjets and ultrasonic pretreatment have a synergistic effect, which can significantly improve the printing accuracy of the product.

Claims

1. A printing method of a cassava starch-based 3D printing material, characterized by, The method comprises the following steps: (1) adding cassava starch into water, and placing in a high-pressure microfluidizer to obtain a starch suspension; the high-pressure microfluidizer treatment pressure is 60-150 MPa; (2) adding protein, fatty acid and polysaccharide into the starch suspension, stirring uniformly, and then performing ultrasonic treatment to obtain a pretreated material; the ultrasonic treatment power is 50-200 W, and the time is 20-40 min; (3) heating the pretreated material to completely gelatinize the starch, and then loading into a 3D printer material cylinder, and performing 3D printing after gel cooling. The raw materials include, in mass percentage, cassava starch 13-20%, protein 1-5%, fatty acid 2-9%, polysaccharide 0.02-0.06%, and the balance is water; the protein is casein, pea protein, whey protein or rapeseed protein; the fatty acid is linolenic acid, lauric acid or linoleic acid; and the polysaccharide is pullulan.

2. The printing method of the cassava starch-based 3D printing material according to claim 1, characterized by, The raw materials include, in mass percentage, cassava starch 15%, casein 2%, linolenic acid 2.94%, pullulan 0.06%, and the balance is water.

3. The printing method of the cassava starch-based 3D printing material according to claim 1, characterized by, The high-pressure microfluidizer treatment pressure is 100 MPa.

4. The printing method of the cassava starch-based 3D printing material according to claim 1, characterized by, The ultrasonic treatment power is 200 W, and the time is 30 min.

5. The printing method of the cassava starch-based 3D printing material according to claim 1, characterized by, In step (3), the heating temperature is 90-100 DEG C.

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