Method for improving 3D printing characteristics of starch gel by rapeseed protein high internal phase emulsion

Abstract

The invention discloses a method for improving 3D printing characteristics of starch gel through rapeseed protein high internal phase emulsion, and belongs to the technical field of food 3D printing. According to the method, modified rapeseed protein-quercetin compound stable high-internal-phase emulsion and starch gel are used as raw materials, the high-internal-phase emulsion is mixed with starch paste according to different proportions, and 3D printing is carried out. By adding the modified rapeseed protein-quercetin compound high internal phase emulsion, the viscosity of starch paste can be effectively reduced, the printing precision is improved, the phenomena such as chapping caused by moisture evaporation of gel are relieved, and the 3D printing characteristics of the starch gel are improved. According to the novel technology disclosed by the invention, room-temperature extrusion of the starch gel can be realized, the surface of a product is prevented from being cracked and hard, slow release of active ingredients can be realized, and the swallowing difficulty of the product is reduced. The method is easy to operate, the quality of printed products is good, and meanwhile application of the rapeseed protein and the starch gel thereof in the field of food 3D printing can be expanded.

Description

Technical Field

[0001] This invention belongs to the field of food 3D printing technology, specifically relating to a method and application of improving the 3D printing properties of starch gel with rapeseed protein high internal phase emulsion. Background Technology

[0002] 3D printing, also known as additive manufacturing, primarily utilizes three-dimensional modeling technology to stack materials together, ultimately forming products with more complex and refined structures and appearances. During the 3D printing process, material is smoothly extruded from a needle under high shear force and stacked layer by layer according to a selected three-dimensional model under the control of a computer program. The printing material must possess sufficient supporting strength to prevent the product structure from collapsing and to maintain stability under specific conditions. Compared to traditional methods, 3D printing can achieve more complex and refined product structures and effectively reduce resource consumption and raw material costs, laying the foundation for its application in personalized nutrition and food development.

[0003] Starch, the second most abundant polysaccharide organic compound in nature, is a major energy source for humans and has been widely used in the field of food 3D printing. Patent CN119097075 discloses a low glycemic index 3D-printed starch gel and its preparation method. This patent utilizes a secondary encapsulation of an alcohol-soluble protein-polyphenol complex in the starch gel to achieve controlled release of polyphenols and enhance their efficacy. CN115886238B discloses a method for preparing a composite Dendrobium officinale starch gel 3D-printed material. The obtained starch-based gel not only possesses the physiological activity of Dendrobium officinale but also exhibits good extrudability, flowability, and structural self-supporting ability. CN114191601A discloses a technology for preparing starch gel hemostatic materials based on 3D printing technology. The obtained hemostatic material has good liquid absorption, hemostatic efficiency, and cell compatibility. Therefore, starch gel occupies an important position in the field of 3D printing. However, natural starch gelatinization has disadvantages such as high viscosity, easy retrogradation, and poor water retention. This requires higher extrusion temperatures and pressures for starch paste during 3D printing. During storage, the starch in the gel undergoes a retrogradation reaction, which can significantly increase the hardness of 3D printed products, making them more difficult to chew and swallow. In addition, the evaporation of moisture from the starch gel during storage can lead to the formation of a hard, cracked shell on the surface of 3D printed products, severely hindering its application in food 3D printing. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of starch gels, such as high viscosity, easy retrogradation, and poor water retention, by providing a method for improving the 3D printing properties of starch gels using a rapeseed protein high internal phase emulsion. This involves adding an appropriate amount of rapeseed protein high internal phase emulsion to a starch paste to prepare a mixed gel. By reducing the viscosity of the starch paste and increasing the water retention of the gel, the 3D printing properties of the starch gel are improved. This technology can serve as a method for obtaining high-quality starch gel 3D printed products, with the aim of further expanding the application of starch gels in the field of food 3D printing.

[0005] To achieve the above-mentioned objectives, the present invention provides a method for improving the 3D printing properties of starch gel using rapeseed protein high internal phase emulsion, which is carried out according to the following steps:

[0006] (1) Preparation of modified rapeseed protein-quercetin complex: First, whey protein, zein and rapeseed protein were mixed in a mass ratio of 1:1:0.2 to prepare a deionized water solution with a total mass concentration of 1%. Then, quercetin with a final concentration of 5 mg / mL was added. The pH of the mixed solution was adjusted to 12 using 1 mol / L alkaline solution and stirred thoroughly for 3 h (maintaining the pH of the system at 12). The pH of the mixed solution was then adjusted to 7 using 0.1 mol / L citric acid. After centrifugation, ultrafiltration desalting and freeze drying, the modified rapeseed protein-quercetin complex was obtained.

[0007] (2) Preparation of high internal phase emulsion: The complex in step (2) was fully dissolved in phosphate buffer at pH 7.5 at a ratio of 10:1 (g / L), and then 4 times the volume of rapeseed oil was added. The mixture was then prepared using a high-speed disperser (10000r / min, 30s).

[0008] (3) Preparation of hot starch paste: Add starch to deionized water at a ratio of 200:1 (g / L), place it in boiling water and heat for 30 minutes. Stir constantly during the heating process to ensure that the starch is heated evenly and fully gelatinized to obtain hot starch paste.

[0009] (4) Preparation of mixed gel: The high internal phase emulsion obtained in step (2) is added to the hot starch paste obtained in step (3) at a mass ratio of 10%-50% while stirring (1000r / min, 15min) to obtain mixed gels with different addition ratios of high internal phase emulsion.

[0010] (5) 3D Printing: Add the mixed gel to the barrel, select the cylindrical model, and perform 3D printing using a gas extrusion 3D printer, with an extrusion pressure of 0-100 kg / cm². 2 The extrusion temperature was 25℃, the nozzle diameter was 0.90mm, the fill rate was 75%, and the moving speed was 30mm / s, resulting in a 3D printed product.

[0011] (6) Evaluation of 3D printed product characteristics: The improvement effect of high internal phase emulsion on the 3D printing characteristics of starch gel was evaluated from the perspectives of optimal extrusion pressure, product printing accuracy, and surface drying crack characteristics, based on the optimal extrusion pressure for smooth extrusion and good molding of mixed gel.

[0012] The alkaline solution in step (1) is a mixture of sodium hydroxide and potassium hydroxide in a 1:1 molar ratio.

[0013] The rapeseed oil in step (2) is rapeseed oil containing 0.2 mg / mL of vitamin D3.

[0014] The height of the circular tube model in step (5) is 1cm, the outer diameter is 2cm, and the inner diameter is 1cm.

[0015] Compared with the prior art, the beneficial effects of the present invention are:

[0016] (1) This invention is the first to use high internal phase emulsion to improve the 3D printing characteristics of starch gel. It can not only reduce the viscosity of starch paste to realize room temperature extrusion of starch gel, but also effectively slow down the evaporation rate of water on the gel surface and avoid the formation of dry cracks and hard shells on the surface of printed products.

[0017] (2) The present invention prepares modified rapeseed protein into a highly introverted emulsion to improve the 3D printing properties of starch gel, which can broaden the application field of rapeseed protein in food processing.

[0018] (3) The appropriate addition of high internal phase emulsion can increase the resistant starch content of starch gel and also achieve the intestinal slow release of active ingredients (such as quercetin and vitamin D3). Attached Figure Description

[0019] Figure 1 The effect of high internal phase emulsion on the room temperature extrusion and 3D printing properties of starch gel;

[0020] Figure 2 The effect of high internal phase emulsion on surface cracking of starch gel 3D printed products;

[0021] Figure 3 Drop and tilt tests of starch gel with 30% high internal phase emulsion added;

[0022] Figure 4 Press test of starch gel fork with 30% high internal phase emulsion added. Detailed Implementation

[0023] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below.

[0024] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0025] The room-temperature extrudability of starch gels was evaluated by adjusting the air pump pressure of the 3D printer (0-100 kg / cm²). 2 To determine the effect of high internal phase emulsion on the room temperature extrudability of starch gel.

[0026] The calculation of the printing accuracy of the product was based on the method reported by Ji Shengyang (Ji Shengyang. Construction of cassava starch composite gel system for 3D printing and its programmed deformation study in 4D printing [D]. 2023). The influence of high internal phase emulsion on the 3D printing accuracy of starch gel was evaluated using the parameter differences between the 3D product and the printed model. The printing accuracy (PA) of the gel was calculated according to the following formula:

[0027]

[0028] In the formula, x, y, and z are the outer diameter, inner diameter, and height of the 3D printed product, respectively; x0, y0, and z0 are the outer diameter, inner diameter, and height of the 3D printed model, respectively, and the units of the parameters are all cm.

[0029] Surface cracking is a common phenomenon in the storage of starch gel products and is usually used as an important indicator of shelf life for hydrogel products. To simulate the impact of commodity storage on starch gel 3D printed products, the printed products were stored in a constant temperature and humidity chamber at 25°C for 48 hours. An air circulation system was used to accelerate the evaporation of moisture from the gel surface. The effect of rapeseed protein-quercetin complex high internal phase emulsion on starch surface cracking during storage was quickly assessed by visual observation.

[0030] The in vitro digestion characteristics of the high internal phase emulsion and its starch-mixed gel were determined according to the method of Shao et al. (Shao F, Zhang Y, Wan X. et al., Improving the properties of whey protein isolate-zein nanoogels with novel acidifiers: Re-dispersity, stability and quercetin bioavailability. International Journal of Biological Macromolecules, 2024, 266: 137567). The calculation of the proportions of rapidly digestible starch (RDS), slowly digestible starch (SDS), and resistant starch (RS) was based on the research of Shao Feng (Shao Feng. Study on the inhibitory effect of rutin and quercetin on the in vitro digestion of buckwheat starch and noodles [D]. 2021). All parameters are expressed as percentages (%).

[0031] Swallowing dysphagia assessment included drip and tilt tests and a pressure test. The drip and tilt tests, based on international standards for dysphagia-related foods, categorized foods into seven levels: thin, slightly thick, moderately thick, medium thick, very thick, light, and regular. The effects of high internal phase emulsions on the swallowing properties of starch gels were analyzed using a spoon and fork.

[0032] Example 1

[0033] Whey protein, zein, and rapeseed protein were mixed in a mass ratio of 1:1:0.2 to prepare a 1% deionized water solution. Quercetin was then added to a final concentration of 5 mg / mL. The pH of the solution was adjusted to 12 using a 1 mol / L alkaline solution (sodium hydroxide and potassium hydroxide mixed in a 1:1 molar ratio). The solution was stirred thoroughly for 3 hours (maintaining pH 12). The pH was then adjusted to 7 using 0.1 mol / L citric acid. After centrifugation, ultrafiltration desalting, and freeze-drying, a modified rapeseed protein-quercetin complex was obtained. The complex was dissolved in a phosphate buffer solution at a ratio of 10:1 (g / L) at pH 7.5. Four volumes of active rapeseed oil (containing 0.2 mg / mL vitamin D3) were added, and a high internal phase emulsion was prepared using a high-speed disperser (10000 rpm, 30 s). Starch was added to deionized water at a ratio of 200:1 (g / L), and heated in boiling water for 30 minutes with constant stirring to ensure uniform heating and complete gelatinization, thus preparing a hot starch paste. The high internal phase emulsion was then added to the hot starch paste at a mass ratio of 10%, while stirring continuously (using an electric stirrer at 1000 rpm for 15 minutes) to obtain a mixed gel containing 10% high internal phase emulsion. This mixed gel was then placed into a barrel, and a cylindrical model (1 cm high, 2 cm outer diameter, 1 cm inner diameter) was selected for 3D printing using a gas extrusion 3D printer with an extrusion pressure of 0-100 kg / cm². 2 The extrusion temperature was 25℃, the nozzle diameter was 0.90mm, the fill rate was 75%, and the moving speed was 30mm / s, resulting in a 3D printed product of starch gel with a 10% high internal phase emulsion. The effect of adding 10% high internal phase emulsion on the 3D printing properties of starch gel was evaluated from the perspectives of optimal extrusion pressure and printing accuracy for smooth extrusion and good shaping of the mixed gel.

[0034] Example 2

[0035] A high internal phase emulsion was added to the hot starch paste at a mass ratio of 20%, and mixed with an electric stirrer (1000 rpm, 15 min) while being added, to obtain a mixed gel with 20% high internal phase emulsion. The remaining steps were the same as in Example 1. The effect of adding 20% ​​high internal phase emulsion on the 3D printing properties of the starch gel was evaluated.

[0036] Example 3

[0037] A high internal phase emulsion was added to the hot starch paste at a mass ratio of 30%, and mixed with an electric stirrer (1000 rpm, 15 min) while being added, to obtain a mixed gel with 30% high internal phase emulsion. The remaining steps were the same as in Example 1. The effect of adding 30% high internal phase emulsion on the 3D printing properties of the starch gel was evaluated.

[0038] Example 4

[0039] A high internal phase emulsion was added to the hot starch paste at a mass ratio of 40%, and mixed with an electric stirrer (1000 rpm, 15 min) while being added, to obtain a mixed gel with 40% high internal phase emulsion. The remaining steps were the same as in Example 1. The effect of adding 40% high internal phase emulsion on the 3D printing properties of the starch gel was evaluated.

[0040] Example 5

[0041] A high internal phase emulsion was added to the hot starch paste at a mass ratio of 50%, and mixed with an electric stirrer (1000 rpm, 15 min) while being added, to obtain a mixed gel with 50% high internal phase emulsion. The remaining steps were the same as in Example 1. The effect of adding 50% high internal phase emulsion on the 3D printing properties of the starch gel was evaluated.

[0042] Comparative Example 1

[0043] Except for the absence of modified rapeseed protein-quercetin in the high inward emulsion, the remaining steps were the same as in Example 1: starch gel was prepared, extrusion temperature was set to 80°C, and pure starch gel product printed at 80°C was obtained by 3D printing, and its printing characteristics were evaluated.

[0044] Comparative Example 2

[0045] Except for the absence of modified rapeseed protein-quercetin in the high inward emulsion, the remaining steps were the same as in Example 1: starch gel was prepared, extrusion temperature was set to 50°C, and pure starch gel product printed at 50°C was obtained by 3D printing, and its printing characteristics were evaluated.

[0046] Comparative Example 3

[0047] Except for the absence of modified rapeseed protein-quercetin in the high inward emulsion, the remaining steps were the same as in Example 1: starch gel was prepared, extrusion temperature was set to 25°C, and pure starch gel product printed at 25°C was obtained by 3D printing, and its printing characteristics were evaluated.

[0048] Figure 1 Table 1 shows the effect of high internal phase emulsion on the room temperature extrusion and 3D printing properties of starch gel.

[0049] Figure 1 The figures show the longitudinal and transverse views of 3D-printed starch gel products with different proportions of high internal phase emulsion at room temperature. Table 1 shows the printing parameters and accuracy. As can be seen from the figures and table, Comparative Examples 1-3 show the products printed from pure starch gel without high internal phase emulsion at extrusion temperatures of 80°C, 50°C, and 25°C, respectively, with the corresponding optimal extrusion pressures being 25 kg / cm². 2 55kg / cm 2 and 75kg / cm 2The results indicate that starch paste at higher temperatures (80°C) is easier to extrude, but has poor formability and very low printing accuracy (11.31%). Starch paste at room temperature (25°C) solidifies, making extrusion difficult. After adding different proportions of high internal phase emulsion, the starch gels in all embodiments could be successfully extruded at room temperature. The optimal extrusion pressure gradually decreased with increasing high internal phase emulsion addition ratio, but excessively high addition ratios would impair the starch gel's formability, leading to decreased printing accuracy. The printed product with a high internal phase emulsion addition ratio of 30% showed good formability, and the optimal printing pressure was 35 kg / cm². 2 The pressure range is approximately 23% of the maximum pressure range of the equipment; although the printing accuracy of starch gel is 95% after adding 10% (Example 1), its optimal printing pressure is relatively high (85 kg / cm²). 2 The addition of starch gel causes significant wear and tear on the equipment; the printing accuracy of starch gel decreases rapidly after the addition ratio exceeds 30% (Example 3), and the mixed gel with an addition ratio of 50% (Example 5) cannot even form a stable self-supporting structure.

[0050] Table 1. Effects of adding high internal phase emulsion on room temperature extrusion and 3D printing properties of starch gel.

[0051]

[0052] Figure 2 The effect of high internal phase emulsion on surface cracking of starch gel 3D printed products.

[0053] Surface cracking is a common phenomenon during the storage of starch gel products and is usually used as an important indicator of shelf life for hydrogel products. To simulate the impact of product storage on 3D-printed starch gel products, comparative examples 2, 1 (10% high internal phase emulsion added), and 3 (30% high internal phase emulsion added) printed with pure starch gel at 50°C were selected and stored in a constant temperature and humidity chamber (with an air circulation system to accelerate the evaporation of moisture from the gel surface) for 48 hours. The surface cracking of the products was then visually observed. The results are as follows: Figure 2 As shown, in comparison, the printed products of Examples 2 and 1 both exhibited a hardened, cracked shell (multiple cracks or fissures) on their surfaces. However, no cracking was observed on the surfaces of the circular, butterfly, turtle, and "D" shaped products printed in Example 3. This indicates that the 30% high internal phase emulsion effectively prevents the rapid evaporation of moisture from the starch gel, thus preventing the formation of a hardened, cracked shell. In conclusion, the 30% high internal phase emulsion effectively improves the surface cracking of starch gel, meaning it can extend the shelf life of 3D printed gel products.

[0054] Tables 2 and 3 show the effect of 30% high internal phase emulsion on the in vitro digestibility of starch gel 3D printed products.

[0055] The product from Example 3, which exhibited the best printing effect, was selected for in vitro digestion experiments. Table 2 shows the effect of 30% high internal phase emulsion on the release rate and bioavailability of quercetin and vitamin D3 in the starch gel 3D printed product. As can be seen from the table, the starch gel structure significantly reduces the release of quercetin and vitamin D3 from the high internal phase emulsion in the stomach and significantly slows down the release rate of the active ingredients in the intestine, achieving the purpose of sustained release of the active ingredients. Notably, the protective effect of the starch gel can also significantly improve the bioavailability of the active ingredients (p<0.05). Table 3 shows the effect of 30% high internal phase emulsion on the digestible starch composition of the starch gel 3D printed product. As can be seen from the table, after adding the high internal phase emulsion, the proportion of rapidly digestible starch in the starch gel significantly decreased (p<0.05), while the proportion of resistant starch significantly increased (p<0.05). This means that the high internal phase emulsion reduces the digestion rate of the starch gel, indicating that this product has certain potential in regulating blood glucose levels.

[0056] Table 2. Effects of 30% high internal phase emulsion on the release rate and bioavailability of quercetin and vitamin D3 in 3D printed products.

[0057]

[0058] Note: ** indicates p < 0.01; * indicates p < 0.05

[0059] Table 3. Effect of 30% high internal phase emulsion on starch composition of starch gel 3D printed products

[0060]

[0061] Note: * indicates <0.05

[0062] Figure 3 and Figure 4 The effect of adding 30% high internal phase emulsion on the swallowing properties of starch gel.

[0063] Figure 3 To evaluate the swallowing characteristics of a starch gel containing 30% high internal phase emulsion, drop and tilt tests were conducted. According to international standards for foods with dysphagia, foods are classified into seven levels: thin, slightly thick, moderately thick, medium thick, very thick, light, and regular. Drop tests were performed using a spoon, and tilt tests were performed using a fork. Results are as follows: Figure 3As shown. Comparative Example 2 (0h) presents a viscous paste that adheres to the bottom of spoons and forks and does not drip when tilted, classifying it as a lightweight type. Example 3 (0h) drips from the bottom of spoons and forks during the tilt test, classifying it as a highly viscous type, indicating that 30% high internal phase emulsion can effectively reduce the swallowing difficulty of starch gel, making it suitable for people with severely weakened tongue control. After being left at room temperature for 3 hours, Comparative Example 2 forms a distinct solid form and drips during the tilt test with a fork. This is mainly because the solidification of the starch gel reduces the gel's viscosity, but the increased gel hardness increases the swallowing difficulty, classifying it as a conventional type. This also indicates that being left at room temperature increases the swallowing difficulty of starch gel products. The effect of being left at room temperature for 3 hours on Example 3 is minimal, remaining at a highly viscous level, indicating that the addition of 30% high internal phase emulsion can reduce the impact of storage on the swallowing characteristics of starch gel.

[0064] Figure 4 Press test of starch gelatinized forks with 30% high internal phase emulsion. Results are as follows. Figure 4 As shown, after the fork pressing test, all samples from Comparative Examples 2 and 3 could not return to their original shape and could be cut or broken into small pieces by the fork. Specifically, when Comparative Example 2 was pressed after being left at room temperature for 3 hours, the thumbnail turned white, but no whitening of the thumbnail was observed when pressing other samples. This indicates that Comparative Example 2, left at room temperature for 3 hours, had the highest swallowing difficulty, which is consistent with the results of the tilting test. Figure 4 This indicates that room temperature storage increases the difficulty of swallowing starch gel foods, while the addition of a high internal phase emulsion can effectively improve this deterioration. Therefore, the addition of 30% high internal phase emulsion can reduce the difficulty of swallowing starch gels and extend the shelf life of starch gel products.

[0065] The invention has been described through embodiments that are currently considered to be the most preferred and practical. It should be understood that the invention is not limited to the disclosed embodiments. Rather, its purpose is to cover various modifications and equivalent arrangements within the spirit and scope of the appended claims, the scope of which is to be interpreted in the broadest possible sense to include all such modifications and equivalent structures permitted under the law.

Claims

1. A method for improving the 3D printing properties of starch gel using rapeseed protein high internal phase emulsion, the following steps are performed: (1) Preparation of modified rapeseed protein-quercetin complex: First, whey protein, zein and rapeseed protein were mixed in a mass ratio of 1:1:0.2 to prepare a deionized water solution with a total mass concentration of 1%. Then, quercetin with a final concentration of 5 mg / mL was added. The pH of the mixed solution was adjusted to 12 using 1 mol / L alkaline solution and stirred thoroughly for 3 h (maintaining the pH of the system at 12). The pH of the mixed solution was then adjusted to 7 using 0.1 mol / L citric acid. After centrifugation, ultrafiltration desalting and freeze drying, the modified rapeseed protein-quercetin complex was obtained. (2) Preparation of high internal phase emulsion: The complex in step (2) was fully dissolved in phosphate buffer at pH 7.5 at a ratio of 10:1 (g / L), and then 4 times the volume of rapeseed oil was added. The mixture was then prepared using a high-speed disperser (10000r / min, 30s). (3) Preparation of hot starch paste: Add starch to deionized water at a ratio of 200:1 (g / L), place it in boiling water and heat for 30 minutes. Stir constantly during the heating process to ensure that the starch is heated evenly and fully gelatinized to obtain hot starch paste. (4) Preparation of mixed gel: The high internal phase emulsion obtained in step (2) is added to the hot starch paste obtained in step (3) at a mass ratio of 10%-50% while stirring (1000r / min, 15min) to obtain mixed gels with different addition ratios of high internal phase emulsion. (5) 3D Printing: Add the mixed gel to the barrel, select the cylindrical model, and perform 3D printing using a gas extrusion 3D printer, with an extrusion pressure of 0-100 kg / cm². 2 The extrusion temperature was 25℃, the nozzle diameter was 0.90mm, the filling rate was 75%, and the moving speed was 30mm / s to obtain the 3D printed product.

2. The method for improving the 3D printing properties of starch gel using rapeseed protein high internal phase emulsion according to claim 1, characterized in that... The alkaline solution in step (1) is a mixture of sodium hydroxide and potassium hydroxide in a 1:1 molar ratio.

3. The method for improving the 3D printing properties of starch gel using rapeseed protein high internal phase emulsion according to claim 1, characterized in that... The rapeseed oil in steps (1) and (2) is rapeseed oil containing 0.2 mg / mL of vitamin D3.

4. The method for improving the 3D printing properties of starch gel using rapeseed protein high internal phase emulsion according to claim 1, characterized in that... The height of the circular tube model in step (5) is 1cm, the outer diameter is 2cm, and the inner diameter is 1cm.

Images