Polyphenol-wheat starch gel as well as preparation method and application thereof in 3D printing

Abstract

The invention discloses polyphenol-wheat starch gel as well as a preparation method and application thereof in 3D printing. The polyphenol-wheat starch gel is obtained by gelatinizing starch-polyphenol suspension at the temperature of 55-70 DEG C in a heat preservation manner; the starch-polyphenol suspension liquid is obtained by uniformly stirring gelatinized polyphenol starch suspension liquid, wheat starch and waxy wheat starch, wherein the wheat starch and the waxy wheat starch are mixed according to the mass ratio of (9: 1)-(6: 4); the gelatinized polyphenol starch suspension is obtained by mixing a mixed starch suspension and polyphenol, heating to 50-65 DEG C, uniformly stirring, and cooling to room temperature; the mixed starch suspension is obtained by mixing wheat starch and waxy wheat starch, adding water at room temperature and uniformly stirring. The preparation cost of the gel is relatively low, protein does not need to be added to influence the product quality, the printing temperature is relatively low, the content of resistant starch in the product is high, the gel has good mechanical strength and extrudability, a 3D printing product with high printing precision can be prepared, and the requirement for personalized customization of food is met.

Description

Technical Field

[0001] The present invention relates to a 3D printing food raw material, in particular to a polyphenol-wheat starch gel and its preparation method and application in 3D printing, belonging to the technical field of food processing. Background Art

[0002] In recent years, the incidence of diet-related chronic metabolic diseases has been showing an increasing trend year by year. In the field of modern food science and nutrition, the demand for nutritious and healthy diets has become increasingly significant. Research shows that consuming resistant starch can effectively regulate the metabolism of blood glucose and lipids in the human body, reduce the intestinal pH value, and increase the quantity and abundance of beneficial bacteria in the intestine, playing a preventive role in diseases caused by nutritional imbalances such as obesity, diabetes, cardiovascular diseases, and metabolic syndrome. Among them, the complex formed by the interaction of starch with other food components is a new type of resistant starch with relatively high nutritional value.

[0003] Resistant starch is mainly divided into 4 categories, namely physically entrapped starch (RS1), resistant starch granules (RS2), retrograded starch (RS3), and modified starch (RS4). The content of physically entrapped starch or resistant starch granules in natural grains and legumes and other foods generally accounts for about 1%-10% of the total starch content, and the content of resistant starch in native starches such as corn starch, potato starch, cassava starch, and rice starch is generally less than 5%. Therefore, it is difficult to meet the application requirements by only extracting and separating resistant starch from natural starches. Retrograded starch and modified starch are the main ways to increase the content of resistant starch in starch at present.

[0004] The preparation methods of resistant starch are classified into chemical modification methods, physical treatment methods, and enzyme treatment methods according to different treatment means. However, although the chemical modification method can change the properties of starch to improve resistance, there are potential safety hazards. For example, the residue of chemical reagents threatens human health, and at the same time, it will cause environmental pollution. Moreover, the reaction conditions are difficult to accurately control, resulting in unstable product quality. The physical treatment method has too high energy consumption, does not conform to the trend of energy conservation and environmental protection, and the treatment effect is limited. The content of the obtained resistant starch is not high and the stability is poor, and it is easily affected by time and storage conditions. In the enzyme treatment method, the production cost of enzymes is high, which limits large-scale application. In addition, the stability of enzymes is poor, and their activity is easily interfered by factors such as temperature, pH value, and metal ions, and it is also difficult to preserve. Strict conditions need to be controlled during the reaction process, increasing the complexity of the process. These problems have restricted the efficient preparation and wide application of resistant starch to a certain extent.

[0005] 3D printing technology is considered an innovative food production mode that eliminates the need for unique-shaped molds and may open up more design options. However, in recent years, the application of 3D printing technology in food has been relatively limited, probably because the properties of food raw materials are difficult to meet the mechanical properties required for 3D printing. Most food raw materials have deficiencies such as low mechanical strength, high water content, poor taste, and difficulty in preserving the processed products. Wheat starch is a potential raw material for 3D printing inks, but wheat starch-based inks have problems such as difficult extrusion and poor formability, and the products after 3D printing have low precision, poor stability, and low resistant starch content. These defects have limited the application of wheat starch in 3D printing to a certain extent. How to improve wheat starch or add other components to obtain better sensory properties and mechanical strength of the products is of great significance for promoting the food 3D printing industry.

[0006] CN202410668960.9 A processing method for low glycemic index starchy foods that can achieve complex 3D printed food shapes. This technology first prepares pregelatinized high amylose starch from high amylose starch, then configures it with corn starch into a starch suspension, adds protein to the obtained starch suspension to make a composite gel, and finally prints the composite gel according to the designed pattern through a 3D printer to obtain a starchy food with a complex food shape and a low glycemic index. However, the raw material of high amylose corn starch (amylose content ≥ 50%, preferably 70%) required by this technology has a high acquisition cost and limited commercial supply. The high-concentration calcium chloride used may remain after centrifugation, posing a food safety hazard. The ethanol precipitation step increases the process complexity and production cost. The added soy / pea protein is likely to introduce a beany smell, and the high-concentration protein may be overly sticky and elastic, affecting the texture of the product. Moreover, high-temperature printing (≥ 80°C) may cause some thermosensitive proteins to deform and inactivate. Summary of the Invention

[0007] To overcome the above problems existing in the prior art, a polyphenol-wheat starch gel with relatively low cost, no need to add protein to affect the product quality, relatively low printing temperature, high resistant starch content in the product, good mechanical strength, and good extrudability and forming stability, and a preparation method thereof are provided.

[0008] Another object of the present invention is to provide the application of the polyphenol-wheat starch gel in 3D printing.

[0009] The above invention objects are achieved by the following technical solutions:

[0010] A polyphenol-wheat starch gel is obtained by gelatinizing a starch-polyphenol suspension at a temperature of 55-70°C; the starch-polyphenol suspension is obtained by uniformly stirring a gelatinized polyphenol starch suspension with wheat starch and waxy wheat starch mixed in a mass ratio of (9:1)-(6:4); the gelatinized polyphenol starch suspension is obtained by mixing a mixed starch suspension with polyphenols, heating to 50-65°C, stirring evenly, and cooling to room temperature; the mixed starch suspension is obtained by mixing wheat starch and waxy wheat starch in a mass ratio of (9:1)-(6:4), adding water at room temperature, and stirring evenly, and controlling the mass concentration of wheat starch and waxy wheat starch to be 3-6%.

[0011] To further achieve the object of the present invention, preferably, the polyphenol is ferulic acid, caffeic acid, gallic acid or protocatechuic acid.

[0012] Preferably, the mass ratio of the wheat starch to the waxy wheat starch is (5:1)-(1:1).

[0013] Preferably, in the gelatinized polyphenol starch suspension, the mass concentration of the polyphenol is 1.25-5%.

[0014] Preferably, the stirring time when heating to 50-65°C is 30-45 min, and the rotation speed is 250-600 rpm.

[0015] Preferably, in the mixed starch suspension, the mass concentration of wheat starch and waxy wheat starch is 20-25%.

[0016] Preferably, the gelatinization of the starch-polyphenol suspension at a temperature of 55-70°C is to add the starch-polyphenol suspension into the printer loading cylinder, set the 3D printing temperature to 55-70°C, and wait for the 3D printer temperature to rise to the set printing temperature for gelatinization.

[0017] Preferably, the heat preservation time is 10-15 min.

[0018] The preparation method of the polyphenol-wheat starch gel includes the following steps:

[0019] 1) Mix wheat starch and waxy wheat starch in a mass ratio of (9:1)-(6:4), add water at room temperature, and stir evenly to obtain a mixed starch suspension with a mass concentration of 3-6%;

[0020] 2) Mix the mixed starch suspension with polyphenols, heat to 50-65°C, stir evenly, and cool to room temperature to obtain a gelatinized polyphenol starch suspension;

[0021] 3) Stir the gelatinized polyphenol starch suspension evenly with wheat starch and waxy wheat starch mixed in a mass ratio of (9:1)-(6:4) to obtain a starch-polyphenol suspension;

[0022] 4) Keep the starch-polyphenol suspension at a temperature of 55 - 70 °C for gelatinization to obtain polyphenol-wheat starch gel.

[0023] Regarding the application of the polyphenol-wheat starch gel described above in 3D printing, select a 3D model to print the polyphenol-wheat starch gel. The nozzle diameter of the 3D model is 0.6 - 1.0 mm, and the printing speed is controlled at 25 - 45 mm / s.

[0024] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0025] 1) The present invention selects natural wheat starch and waxy wheat starch as raw materials, which are safe and non-toxic, widely used in food processing and production, and have been commercially produced with low production costs. Moreover, the compounding method of natural wheat starch and waxy wheat starch is green, efficient, and highly operable. After compounding, the gel properties of starch can be significantly improved.

[0026] 2) The present invention compounds wheat starch and waxy wheat starch. The highly branched amylopectin of waxy wheat starch endows the material with excellent shear thinning properties to ensure uniform extrusion of the material and reduce blockage. At the same time, the strong water retention of waxy wheat starch delays water loss and inhibits aging, and the rigid supporting effect of wheat starch effectively prevents the collapse of the printed structure. The two work together to significantly improve the printing accuracy and achieve the precise printing and preparation of complex structure products.

[0027] 3) The high-temperature stability of wheat starch in the present invention is complementary to the low-temperature rapid gelatinization property of waxy wheat starch, enhancing the thermal stability and mechanical stability of the material, reducing shrinkage and deformation during printing, and finally achieving the effect of the stability of 3D printed products. It can print complex food structures, realize personalized 3D printed food, and broaden the application scope of food 3D printing.

[0028] 4) The present invention greatly increases the content of resistant starch by loading polyphenols with wheat starch gel, which is beneficial to delaying the occurrence of metabolic syndrome, diabetes, and cardiovascular diseases, and is conducive to the preparation of personalized 3D printed functional foods.

[0029] 5) Compared with the Chinese patent application CN202410668960.9, the present invention does not require high-price high amylose corn starch, does not cause food safety hazards due to the use of high-concentration calcium chloride, and will not easily affect the product quality due to the addition of soy / pea protein. Moreover, the printing temperature is significantly reduced. The 3D printed products of the present invention have relatively low costs, do not require the addition of protein to affect the product quality, and have a relatively low printing temperature. Description of the Drawings

[0030] Figure 1Effect diagrams of the compound wheat starch gels of Comparative Example 1 (not loaded with polyphenols) and Examples 1-4 loaded with gallic acid, caffeic acid, ferulic acid and protocatechuic acid respectively at 0 h after 3D printing.

[0031] Figure 2 Effect diagrams of the compound wheat starch gels of Comparative Example 1 (not loaded with polyphenols) and Examples 1-4 loaded with gallic acid, caffeic acid, ferulic acid and protocatechuic acid respectively at 24 h after 3D printing.

[0032] Figure 3 3D printing effect diagrams of the waxy wheat starch gel of Comparative Example 2 not loaded with polyphenols and the wheat starch gel of Comparative Example 3 not loaded with wheat starch. Detailed implementation manners

[0033] The present invention will be further described below in conjunction with the accompanying drawings and embodiments. It should be understood that the embodiments are for better explaining the present invention, but not for limiting the present invention.

[0034] Aiming at the problems existing in the prior art, the present invention uses wheat starch as the raw material, especially selects waxy wheat starch and wheat starch for mixing and compounding, and adds them in two times in the form of such a mixture. Adding the mixture at a low mass concentration first is beneficial for the starch to be partially gelatinized and swollen and evenly dispersed in the water phase during subsequent heating, avoiding the aggregation and precipitation of starch molecules during 3D printing, and at the same time enabling the polyphenols to be dispersed in the starch matrix and initially combined with the starch, so as to better form a stable complex with the starch in the subsequent stage; then adding the waxy wheat starch and wheat starch at a higher mass concentration can further increase the starch mass concentration on the basis of the first low mass concentration, helping the polyphenol-starch suspension to gelatinize in the printer loading cylinder to form a polyphenol-wheat starch gel with a more solid three-dimensional network structure, enhancing the mechanical properties and stability of the product. Moreover, adding in two times avoids uneven gelatinization of the polyphenol-starch suspension in the printer loading cylinder caused by high-concentration mixing at one time, affecting the 3D printing effect.

[0035] Based on the above ideas, a polyphenol-wheat starch gel provided by the present invention is obtained by holding and gelatinizing a starch-polyphenol suspension at a temperature of 55-70 °C; the starch-polyphenol suspension is obtained by uniformly stirring a gelatinized polyphenol starch suspension with wheat starch and waxy wheat starch mixed in a mass ratio of (9:1)-(6:4); the gelatinized polyphenol starch-polyphenol suspension is obtained by mixing a mixed starch suspension with polyphenols, heating to 50-65 °C and stirring evenly, and then cooling to room temperature; the mixed starch suspension is obtained by mixing wheat starch and waxy wheat starch in a mass ratio of (9:1)-(6:4), adding water at room temperature and stirring evenly, and controlling the mass concentration of wheat starch and waxy wheat starch to be 3-6%.

[0036] In the present invention, the combination of wheat starch and waxy wheat starch makes use of the complementary characteristics of the high-temperature stability of wheat starch and the low-temperature rapid gelation characteristics of waxy wheat starch. Wheat starch has a good rigid supporting effect, which can effectively prevent the collapse of the printed structure. The highly branched amylopectin of waxy wheat starch endows the molding material with excellent shear-thinning characteristics, which can ensure the uniform extrusion of the material during the 3D printing process and avoid blockage. Moreover, the strong water retention of waxy wheat starch can delay water loss and inhibit product aging. Therefore, in the present invention, wheat starch and waxy wheat starch should be compounded in a ratio of (9:1) to (6:4). Further preferably, the mass ratio of wheat starch to waxy wheat starch in the present invention is (5:1) to (1:1).

[0037] In the raw materials of the present invention, the polyphenols are common choices in the art, and are preferably ferulic acid, caffeic acid, gallic acid or protocatechuic acid.

[0038] According to the purpose of the invention, the present invention can determine the concentration of polyphenols in the gelatinized polyphenol starch-polyphenol suspension and the mass concentration of wheat starch and waxy wheat starch in the mixed starch suspension in combination with the requirements of the reaction. Preferably, the mass concentration of polyphenols in the gelatinized polyphenol starch-polyphenol suspension is controlled to be 1.25 - 5%; in the mixed starch suspension, the mass concentration of wheat starch and waxy wheat starch is 20 - 25%.

[0039] As for the heating and stirring method in the technical measures, it can be selected according to the purpose of the invention and conventional practices. Preferably, the heating temperature in the present invention is 50 - 65°C, the stirring time is 30 - 45 min, and the rotation speed is 250 - 600 rpm.

[0040] To simplify the steps, the present invention can directly use polyphenol-wheat starch gel for printing. The specific method is to directly add the starch-polyphenol suspension into the loading cylinder of the printer, set the 3D printing temperature to 55 - 70°C, wait for the temperature of the 3D printer to rise to the set printing temperature, and after heat preservation and gelatinization to obtain the polyphenol-wheat starch gel, select a 3D model for printing. Preferably, the nozzle diameter of the 3D model is 0.6 - 1.0 mm, the printing speed is controlled at 25 - 45 mm / s, and the heat preservation time is 10 - 15 min.

[0041] The present invention utilizes the characteristics of waxy wheat starch with high freeze-thaw stability and low aging degree to improve the accuracy and stability of the products after 3D printing of wheat starch; in the way of hot extrusion 3D printing, the content of resistant starch is increased by loading polyphenols, and the compounding of polyphenols and starch can improve the antioxidant property and extend the shelf life of the products, and can also enhance the gel network structure by binding with starch molecules through hydrogen bonds to improve the mechanical strength of the printed products, thereby developing healthy and safe anti-digestible foods. Through testing, it is found that the 3D printing accuracy and stability of single wheat starch gel and single waxy wheat starch gel are both poor.

[0042] Test methods involved in the examples:

[0043] (1) Precision and stability of 3D printed samples

[0044] In the prior art, the precision of 3D printing is often quantified by dimensional deviation (such as laser scanning or image analysis), and the stability is measured by the deformation rate or texture analyzer. To facilitate the measurement and calculation of the precision and stability of 3D printed samples, the present invention selects a 3D printed model as a three-dimensional Tetris block with the same length and width (which can be regarded as the side length of a square) and different heights. A vernier caliper is used to measure the side length / height deviation of the printed sample. Although it is slightly inferior to laser scanning in terms of precision, its low cost and easy operation characteristics highly match the actual needs of food 3D printing. Moreover, this method is consistent with the dimensional accuracy test principle in the 3D printing standards of ISO / ASTM 52902, ASTM F3637-22, and ISO2768-1, and is feasible. The side length and height of the sample after 3D printing at 0 h and 24 h are measured with a vernier caliper. The precision of 3D printing can be represented by the deviation of the side length and height between the printed sample and the model. The calculation formula is as follows:

[0045]

[0046] In the formula: E 1 and E h are the relative deviations of the side length and height respectively, with the unit of %; S 1 and S h are the side length and height of the sample after printing at 0 h respectively, with the unit of mm; T 1 and T h are the designed values of the model side length and height respectively, with the unit of mm; E a is the average value of the relative deviations of the side length and height, which is the precision, with the unit of %.

[0047] The stability of 3D printing is represented by the deviation of the side length / height between the sample after printing for 24 h and the sample after printing at 0 h. Let C a represent the average value of the relative deviations of the side length and height, which is the stability, with the unit of %.

[0048] (2) Digestibility test

[0049] Enzymes from Sigma (porcine pancreatic α-amylase: P-7545 and amyloglucosidase: A-3360) are used to analyze the contents of rapidly digestible starch (RDS), slowly digestible starch (SDS), and resistant starch (RS) by referring to the steps proposed by Englyst.

[0050] Example 1: A method for preparing gallic acid-wheat starch gel and its 3D printing application, including the following steps:

[0051] (1) Mix wheat starch and waxy wheat starch in a mass ratio of 6:4, add water at room temperature and stir evenly to obtain a wheat and waxy wheat mixed starch suspension with a mass percentage of 3%;

[0052] (2) Add gallic acid to the wheat and waxy wheat mixed starch suspension, control the mass percentage of gallic acid to be 1.25%, heat at 50 °C, stir evenly at a speed of 250 rpm for 30 min, and cool to room temperature to obtain a low-concentration partially gelatinized starch suspension containing gallic acid;

[0053] (3) Continue to add wheat starch and waxy wheat starch with a mass ratio of 6:4 to the partially gelatinized starch suspension in step (2) to obtain a uniform starch-gallic acid suspension with a starch mass percentage of 20% (the mass content of starch in the suspension);

[0054] (4) Add the above starch-gallic acid suspension to the printer loading cylinder, set the printing temperature to 55 °C, wait for the printer temperature to rise to the set printing temperature and keep it warm for 10 min to make the starch-gallic acid suspension gelatinize to form gallic acid-wheat starch gel. Select the printing model as a three-dimensional Tetris, with a length of 45 mm, a width of 45 mm, and a height of 20 mm. The nozzle diameter of the printer is 0.6 mm, and the printing speed is 25 mm / s for printing.

[0055] (5) The designed value T of the side length of the 3D printed product Tetris model 1 is 45.00 mm, and the designed value T of the model height h is 20.00 mm. After printing for 0 h, the side lengths S of the length and width 1 are 46.10 mm, and the height S h is 21.50 mm. After printing for 24 h, the side lengths of the length and width are 41.80 mm, and the height is 18.10 mm. The relative deviation of the side length can be obtained through the calculation formula The relative deviation of the height 3D printing accuracy Similarly, the 3D printing stability C can be obtained through calculation a = 88%. After digestion performance testing, the resistant starch content of the product in this example is 55%; the accuracy of the 3D printed product is 95%, the stability is 88%, and the resistant starch content is 55%.

[0056] Example 2

[0057] (1) Mix wheat starch and waxy wheat starch in a mass ratio of 7:3, add water at room temperature and stir evenly to obtain a wheat and waxy wheat mixed starch suspension with a mass percentage of 4%;

[0058] (2) Add caffeic acid to the wheat and waxy wheat mixed starch suspension, control the mass percentage of caffeic acid to be 2.50%, heat at 55 °C, stir evenly at a rotation speed of 400 rpm for 35 min, and cool to room temperature to obtain a low-concentration partially gelatinized starch suspension containing caffeic acid;

[0059] (3) Continue to add wheat starch and waxy wheat starch with a mass ratio of 7:3 to the partially gelatinized starch suspension in step (2) to obtain a uniform starch-caffeic acid suspension with a starch mass percentage of 20% (the mass content of starch in the suspension);

[0060] (4) Add the above suspension to the printer loading cylinder, set the printing temperature to 60 °C, wait for the printer temperature to rise to the set printing temperature and keep it warm for 12 min to gelatinize the starch-caffeic acid suspension to form caffeic acid-wheat starch gel. Select the printing model as a three-dimensional Tetris, with a length of 45 mm, a width of 45 mm, and a height of 20 mm. The nozzle diameter of the printer is 0.7 mm, and the printing speed is 30 mm / s for printing.

[0061] Tested by the method of Example 1, the accuracy of the 3D printed product is 96%, the stability is 90%, and the resistant starch content is 60%.

[0062] Example 3

[0063] (1) Mix and compound wheat starch and waxy wheat starch according to a mass ratio of 8:2, add water at room temperature and stir evenly to obtain a wheat and waxy wheat mixed starch suspension with a mass percentage of 5%;

[0064] (2) Add ferulic acid to the wheat and waxy wheat mixed starch suspension, control the mass percentage of ferulic acid to be 3.75%, heat at 60 °C, stir evenly at a rotation speed of 500 rpm for 40 min, and cool to room temperature to obtain a low-concentration partially gelatinized starch suspension containing ferulic acid;

[0065] (3) Continue to add wheat starch and waxy wheat starch with a mass ratio of 8:2 to the partially gelatinized starch suspension in step (2) to obtain a uniform starch-ferulic acid suspension with a starch mass percentage of 25% (the mass content of starch in the suspension);

[0066] (4) Add the above suspension to the printer's loading cylinder, set the printing temperature to 65 °C, wait for the printer temperature to rise to the set printing temperature and then keep it warm for 13 min to gelatinize the starch-ferulic acid suspension to form ferulic acid-wheat starch gel. Select the printing model as a three-dimensional Tetris, with a length of 45 mm, a width of 45 mm, and a height of 20 mm. The nozzle diameter of the printer is 0.8 mm, and the printing speed is 35 mm / s for printing.

[0067] Tested by the method of Example 1, the accuracy of the 3D printed product is 97%, the stability is 92%, and the resistant starch content is 65%.

[0068] Example 4: A method for preparing 3D printed wheat starch gel loaded with protocatechuic acid and having anti-digestibility, comprising the following steps:

[0069] (1) Mix and compound wheat starch and waxy wheat starch in a mass ratio of 9:1, add water at room temperature and stir evenly to obtain a 6% (by mass) wheat and waxy wheat mixed starch suspension;

[0070] (2) Add 5.0% (by mass) protocatechuic acid to the wheat and waxy wheat mixed starch suspension, heat at 65 °C, stir evenly at a speed of 600 rpm for 45 min, and cool to room temperature to obtain a low-concentration partially gelatinized starch suspension containing protocatechuic acid;

[0071] (3) Continuously add wheat starch and waxy wheat starch with a mass ratio of 9:1 to the partially gelatinized starch suspension in step (2) to obtain a uniform starch-protocatechuic acid suspension with a starch mass percentage of 25% (the mass content of starch in the suspension);

[0072] (4) Add the above suspension to the printer's loading cylinder, set the printing temperature to 70 °C, wait for the printer temperature to rise to the set printing temperature and then keep it warm for 15 min to gelatinize the starch-protocatechuic acid suspension to form protocatechuic acid-wheat starch gel. Select the printing model as a three-dimensional Tetris, with a length of 45 mm, a width of 45 mm, and a height of 20 mm. The nozzle diameter of the printer is 0.9 mm, and the printing speed is 35 mm / s for printing.

[0073] Tested by the method of Example 1, the accuracy of the 3D printed product is 94%, the stability is 85%, and the resistant starch content is 57%.

[0074] Comparative Example 1

[0075] (1) Mix and compound wheat starch and waxy wheat starch in a mass ratio of 8:2, add water at room temperature and stir evenly to obtain a 3% (by mass) wheat and waxy wheat mixed starch suspension;

[0076] (2) Heat and stir the above mixture suspension evenly at 60 °C for 30 min, and cool it to room temperature to obtain a low-concentration gelatinized starch suspension;

[0077] (3) Continuously add wheat starch and waxy wheat starch with a mass ratio of 8:2 to the suspension in step (2) to obtain a uniform starch suspension with a starch mass percentage of 25%;

[0078] (4) Add the above suspension to the printer loading cylinder, set the printing temperature to 70 °C, wait for the printer temperature to rise to the set printing temperature and then keep it warm for 15 min to gelatinize the starch suspension to form a starch gel. Select the printing model as a three-dimensional Tetris, with a length of 45 mm, a width of 45 mm, and a height of 20 mm. The nozzle diameter of the printer is 0.6 mm, and the printing speed is 25 mm / s for printing.

[0079] Tested by the method of Example 1, the accuracy of the 3D printing product is 90%, the stability is 80%, and the resistant starch content is 30%.

[0080] Comparative Example 2: A method for preparing a 3D printed waxy wheat starch gel, comprising the following steps:

[0081] (1) Add water to waxy wheat starch at room temperature and stir evenly to obtain a waxy wheat starch suspension with a mass percentage of 3%;

[0082] (2) Heat and stir the above waxy wheat starch suspension evenly at 60 °C for 30 min, and cool it to room temperature to obtain a low-concentration gelatinized starch suspension;

[0083] (3) Continuously add waxy wheat starch to the suspension in step (2) to obtain a uniform starch suspension with a mass percentage of 25%;

[0084] (4) Add the above waxy wheat starch suspension to the printer loading cylinder, set the printing temperature to 70 °C, wait for the printer temperature to rise to the set printing temperature and then keep it warm for 15 min to gelatinize the waxy wheat starch suspension to form a waxy wheat starch gel. Select the printing model as a three-dimensional Tetris, with a length of 45 mm, a width of 45 mm, and a height of 20 mm. The nozzle diameter of the printer is 0.7 mm, and the printing speed is 30 mm / s for printing.

[0085] Comparative Example 3: A method for preparing a 3D printed wheat starch gel, comprising the following steps:

[0086] (1) Add water to wheat starch at room temperature and stir evenly to obtain a wheat starch suspension with a mass percentage of 3%;

[0087] (2) Heat and stir the above wheat starch suspension evenly at 60 °C for 30 min, and cool it to room temperature to obtain a low-concentration gelatinized starch suspension;

[0088] (3) Continuously add wheat starch to the suspension in step (2) to obtain a uniform starch suspension with a mass percentage of 25%;

[0089] (4) Add the above wheat starch suspension into the printer loading cylinder, set the printing temperature to 70 °C, wait for the printer temperature to rise to the set printing temperature and keep it warm for 15 min to gelatinize the wheat starch suspension to form a wheat starch gel. Select the printing model as a three-dimensional Tetris, with a length of 45 mm, a width of 45 mm, and a height of 20 mm. The nozzle diameter of the printer is 0.8 mm, and the printing speed is 35 mm / s for printing.

[0090] Figure 1 The figures show the 3D printed wheat starch gels of Comparative Example 1 (not loaded with polyphenols) and Examples 1-4 loaded with gallic acid, caffeic acid, ferulic acid, and protocatechuic acid at 0 h after 3D printing. In Comparative Example 1, the edges of the printed structure are blurred, the corners are not distinct, there is a slight collapse, and the printing layers are not obvious, indicating that the rheology and precision of the gel without added polyphenols are poor; in Example 1, the edges of the printed structure are clear, the corners are relatively sharp, there is no collapse, the surface is smooth, the printing layers are obvious, and the model details are complete; in Example 2, the edges of the printed structure are straight, there is no collapse, the surface is smooth with a slight gloss, the printing layers are obvious, and the 3D printing precision is good; in Example 3, the corners of the printed structure are the most distinct, the edges are sharp, there is no collapse or deformation, the surface is smooth and has uniform reflection, the model details are completely presented, and the printing accuracy reaches 97%; in Example 4, the edges of the printed structure are clear and straight, there is no collapse, the surface is smooth, the printing layers are obvious, and the printing accuracy is 94%.

[0091] Figure 2Effect diagrams of the compound wheat starch gels loaded with gallic acid, caffeic acid, ferulic acid, and protocatechuic acid in Examples 1-4 and Comparative Example 1 (unloaded with polyphenols) 24 h after 3D printing. In Comparative Example 1, the 3D printing structure was deformed, the edges were blunt, the corners were not distinct, there was obvious collapse, and the printing layers were blurred, indicating that the gel without added polyphenols had poor stability; in Example 1, the 3D printing edges were slightly blunt, the height decreased slightly but still maintained good shape integrity, and the printing layers were visible; in Example 2, the 3D printing edges were relatively clear, the height decreased slightly but still maintained good shape integrity, and the printing layers were obvious; in Example 3, the 3D printing edges remained relatively sharp, the height changed little, the shape remained intact, the printing layers were obvious, and the surface glossiness had no obvious change compared with 0 h; in Example 4, the 3D printing edges were slightly rounded and blunt, the height decreased slightly but still maintained good shape integrity, and the printing layers were visible. Compared with Comparative Example 1, Examples 1-4 could still maintain good shape and structural integrity 24 h after 3D printing.

[0092] The printing accuracy of Comparative Example 1 was 90%, the stability was 80%, and the resistant starch content was 30%; while the printing accuracy of Example 1 was 95%, the stability was 88%, and the resistant starch content was 55%; the printing accuracy of Example 2 was 96%, the stability was 90%, and the resistant starch content was 60%; the printing accuracy of Example 3 was 97%, the stability was 92%, and the resistant starch content was 65%; the printing accuracy of Example 4 was 94%, the stability was 85%, and the resistant starch content was 57%. Compared with Comparative Example 1 without added polyphenols, Examples 1, 2, 3, and 4 significantly improved the printing accuracy, stability, and resistant starch content of the 3D printing products due to the addition of polyphenols. This is because polyphenols can bind to starch molecules to form a more stable gel network structure, enhance the mechanical strength of the printing material, thereby improving the forming accuracy and anti-deformation ability; and polyphenols can inhibit the activity of α-amylase, delay starch digestion, and increase the resistant starch content.

[0093] Figure 33D printing effect diagrams of the waxy wheat starch gel without polyphenol loading in Comparative Example 2 and the wheat starch gel without loading in Comparative Example 3. The results show that 3D printing of Comparative Example 2 could not be formed, and 3D printing of Comparative Example 3 showed cracking phenomena, indicating that the 3D printing effects of the uncompounded waxy wheat starch gel and wheat starch gel were poor. The reason why Comparative Example 2 could not be formed was that although waxy wheat starch had high freeze-thaw stability and low retrogradation degree, its molecular structure was mainly composed of amylopectin, and the formed gel network was relatively loose and the mechanical strength was insufficient. During the 3D printing process, the gel could not provide enough support force, resulting in the difficulty of maintaining the shape of the extruded material, which was prone to collapse or flow deformation. The reason for the cracking in Comparative Example 3 was that wheat starch was mainly composed of amylose and was prone to retrogradation during cooling and storage, resulting in an increase in gel hardness and brittleness. After 3D printing, the gel rapidly lost water and shrank due to aging, and cracks appeared on the surface or the internal structure collapsed; and wheat starch might have too high viscosity or too strong elasticity during the printing process, resulting in difficult extrusion or ineffective layered stacking after extrusion, affecting the forming accuracy.

[0094] Compared with the Chinese invention patent application CN202410668960.9, the present invention does not require high-price high-amylose corn starch, does not need to use high-concentration calcium chloride that poses food safety hazards, nor will it easily affect the product quality due to the addition of soy / pea protein. Moreover, the printing temperature is significantly reduced. The cost of the 3D printing product of the present invention is relatively low, there is no need to add protein to affect the product quality, and the printing temperature is relatively low.

[0095] The above content is a further detailed description of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is only limited to these descriptions. For those skilled in the art of the present invention, without departing from the concept of the present invention, several equivalent substitutions or obvious variations can be made, and as long as the performance or use is the same, they should all be regarded as belonging to the protection scope of the present invention.

Claims

1. A polyphenol-wheat starch gel, characterized in that: The starch-polyphenol suspension is obtained by gelatinizing the starch-polyphenol suspension at a temperature of 55-70°C; the starch-polyphenol suspension is obtained by uniformly stirring the gelatinized polyphenol starch suspension with wheat starch and waxy wheat starch mixed in a mass ratio of (9:1) to (6:4); the gelatinized polyphenol starch suspension is obtained by mixing the mixed starch suspension with polyphenols, heating to 50-65°C, stirring evenly, and cooling to room temperature; the mixed starch suspension is obtained by mixing wheat starch and waxy wheat starch in a mass ratio of (9:1) to (6:4), adding water at room temperature and stirring evenly, and controlling the mass concentration of the wheat starch and the waxy wheat starch to be 3-6%.

2. The polyphenol-wheat starch gel according to claim 1, characterized in that The polyphenol is ferulic acid, caffeic acid, gallic acid or protocatechuic acid.

3. The polyphenol-wheat starch gel according to claim 1, characterized in that The mass ratio of the wheat starch to the waxy wheat starch is (5:1) to (1:1).

4. The polyphenol-wheat starch gel according to claim 1, characterized in that The mass concentration of polyphenols in the gelatinized polyphenol starch suspension is 1.25-5%.

5. The polyphenol-wheat starch gel according to claim 1, characterized in that The stirring time during heating to 50-65° C. is 30-45 min, and the rotation speed is 250-600 rpm.

6. The polyphenol-wheat starch gel according to claim 1, characterized in that In the mixed starch suspension, the mass concentration of wheat starch and waxy wheat starch is 20-25%.

7. The polyphenol-wheat starch gel according to claim 1, characterized in that The starch-polyphenol suspension is kept warm and gelatinized at a temperature of 55-70° C. by adding the starch-polyphenol suspension into a printer loading barrel, setting the 3D printing temperature to 55-70° C., and waiting for the 3D printer temperature to rise to the set printing temperature for keeping warm and gelatinizing.

8. The polyphenol-wheat starch gel according to claim 7, characterized in that The insulation time is 10-15 minutes.

9. The method for preparing the polyphenol-wheat starch gel according to claim 1, characterized in that The steps include: 1) mixing wheat starch and waxy wheat starch in a mass ratio of (9:1) to (6:4), adding water at room temperature and stirring evenly to obtain a mixed starch suspension with a mass concentration of 3-6%; 2) mixing the mixed starch suspension with polyphenols, heating to 50-65° C. and stirring evenly, and cooling to room temperature to obtain a gelatinized polyphenol starch suspension; 3) The gelatinized polyphenol starch suspension is uniformly stirred with wheat starch and waxy wheat starch mixed in a mass ratio of (9:1) to (6:4) to obtain a starch-polyphenol suspension; 4) The starch-polyphenol suspension is kept at a temperature of 55-70° C. to gelatinize to obtain a polyphenol-wheat starch gel.

10. Use of the polyphenol-wheat starch gel according to any one of claims 1 to 7 in 3D printing, wherein the polyphenol-wheat starch gel is selected to be printed in a 3D model, the nozzle diameter of the 3D model is 0.6-1.0 mm, and the printing speed is controlled to be 25-45 mm / s.

Images