A swallowable composite gel based on soy protein and rice starch and a method for its preparation

Abstract

The present application relates to a kind of swallowable composite gel based on soybean protein and rice starch and its preparation method and application.The method will be added in proportion to rice starch and soybean protein in deionized water mixing, and add different kinds and concentration of calcium salt, and prepare mixed system suspension.The suspension is preheated under constant temperature stirring at 60 DEG C, then quickly transferred to water bath and heated treatment.Cooling obtains soybean protein and rice starch composite gel containing different kinds and concentration of calcium salt.The present application makes full use of the physicochemical properties of protein and starch and its interaction, forms complex gel structure, thereby improving the texture and sensory characteristics of food.At the same time, by adding different calcium salt, the gel texture can be further adjusted and the nutritional value is strengthened, to meet the special needs of dysphagia population for food safety and suitable texture, to improve the effective scheme for the problem of dysphagia in elderly population, with good food application prospect.

Description

Technical Field

[0001] This invention relates to the field of food technology, and more specifically to an easily swallowable composite gel based on soybean protein and rice starch, and a method for its preparation. Background Technology

[0002] Dysphagia is a common condition among the elderly, leading to symptoms such as malnutrition, dehydration, and weight loss, and increasing the risk of complications such as accidental ingestion and choking. One way to reduce these risks is to develop foods that facilitate dysphagia. To this end, dysphagia foods should be nutritious, sensorily appealing, and possess safe texture and rheological properties. Existing dysphagia foods include purees, thickened liquids, and soft gels. Purees and thickened liquids, with their unformed appearance, are less likely to stimulate appetite in the elderly. Compared to purees or thickened liquids, soft gels, with their soft, stable, and supportive form and texture, may be more effective in stimulating appetite in the elderly. Therefore, soft gels hold potential in the development of texture-modified foods. However, designing nutritious and safe (meeting certain texture characteristics) soft gel foods remains a significant challenge!

[0003] Rice starch, derived from rice (a staple food for more than half the world's population), is inexpensive and provides essential digestible carbohydrates. Soy protein, a byproduct of vegetable oil processing, is abundant and provides nutrient-rich protein and essential amino acids. Furthermore, both rice starch and soy protein possess gelling properties, offering diverse textures. In improving gel quality, proteins and starches can effectively regulate gel-related behaviors through complex interactions. On one hand, this composite system fully utilizes the different physicochemical properties and functional characteristics of proteins and starches, forming complex gel structures through their interactions, thus improving the texture and sensory properties of food. On the other hand, as important sources of nutrition for the human body, the combination of protein and starch provides rich nutrition, meeting the body's needs for energy and nutrients.

[0004] Calcium salts are essential nutrients for elderly people with dysphagia and should be considered in the design of foods for this purpose to improve their nutritional value. Calcium is ubiquitous in food and is an important nutrient, especially for the elderly. As a cross-linking agent, calcium is also frequently used to improve the stability of gelled foods. The role of calcium depends on the type of calcium salt added. Calcium citrate, calcium carbonate, calcium gluconate, and calcium chloride, as alternative sources of calcium, show potential for high bioavailability. The bioavailability of calcium salts is influenced by multiple factors, including their solubility, degree of ionization, and interactions with other components in the food matrix. Therefore, selecting the appropriate type and concentration of calcium salt is crucial in the formulation design of foods for dysphagia. Summary of the Invention

[0005] The purpose of this invention is to provide an easy-to-swallow composite gel based on soybean protein and rice starch and its preparation method, in order to solve the following problems existing in the prior art: existing foods for difficulty swallowing are difficult to stimulate the appetite of the elderly and have low bioavailability, making it difficult to meet the nutritional needs of patients with difficulty swallowing.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] An easily swallowable composite gel based on soybean protein and rice starch and its preparation method, characterized by comprising the following steps:

[0008] (1) Preparation of a composite solution of soybean protein and rice starch: The ratio of rice starch to soybean protein is 1:1 to 1:3. Add it to deionized water, place it on a magnetic stirrer and stir until completely dissolved. Control the total solid content to 10%-15% to obtain a composite solution of soybean protein and rice starch.

[0009] (2) Preparation of calcium salt solutions of different types and concentrations: Different calcium salts, including calcium citrate (CCI), calcium carbonate (CCA), calcium gluconate (CGL) and calcium chloride (CCH), were placed on a magnetic stirrer with deionized water as solvent and stirred until completely dissolved. The solutions were then transferred to volumetric flasks, diluted to volume, and shaken well to prepare calcium salt solutions of four different calcium salts at 10-50 mmol.

[0010] (3) Preparation of soybean protein and rice starch composite gels containing different types and concentrations of calcium salt solutions: The different types of calcium salt solutions obtained in (2) were added to the composite solution of soybean protein and rice starch, and the suspension was stirred on a magnetic stirrer at a speed of 250 rpm / min for 1-3 h to ensure effective dispersion and hydration of rice starch and soybean protein. All the fully dispersed sample suspensions were preheated at 60 ℃ and stirred continuously for 10-20 min under constant temperature conditions. Then, the preheated samples were quickly transferred to a constant temperature water bath at 80-100 ℃ and heated for 30 min. The resulting gel was stored at 4 ℃ overnight, and then stored at room temperature for at least 30 min to obtain soybean protein and rice starch composite gels containing different types and concentrations of calcium salts.

[0011] Preferably, the ratio of rice starch to soybean protein in step (1) is fixed at 1:1.

[0012] Preferably, in step (1), the total solids content of the composite solution of soybean protein and rice starch is controlled at 12%.

[0013] Preferably, in step (2), calcium salt solutions of calcium citrate (CCI), calcium carbonate (CCA), calcium gluconate (CGL), and calcium chloride (CCH) with concentrations of 10 mmol, 20 mmol, and 30 mmol are prepared respectively.

[0014] Preferably, in step (3), different types of calcium salt solutions are added to the composite solution of soybean protein and rice starch, and the suspension is stirred on a magnetic stirrer at a speed of 250 rpm / min for 2 h to ensure effective dispersion and hydration of rice starch and soybean protein.

[0015] Preferably, in step (3), all the fully dispersed sample suspensions are preheated at 60 °C and continuously stirred for 20 min under constant temperature conditions. Then, the preheated samples are quickly transferred to a constant temperature water bath at 95 °C and heated for 30 min to obtain a composite gel of soybean protein and rice starch containing different types and concentrations of calcium salts.

[0016] This technical solution has the following beneficial technical effects:

[0017] (1) Calcium salt synergistic rice starch-soy protein composite gel is an effective means of regulating the texture and structure of foods with difficulty in swallowing. The combination of rice starch and soybean protein can construct a stable composite gel network while ensuring nutritional complementarity. Rice starch provides the source of carbohydrates, while soybean protein is rich in essential amino acids. The two interact during gel formation, forming a stable phase-separated network structure maintained by hydrogen bonds and disulfide bonds, giving the gel high water retention and soft texture, which is more in line with the requirements of foods with difficulty in swallowing for high water content and low hardness. On this basis, calcium salt is introduced to further change the protein conformation and starch gelatinization behavior through ion bridging and charge regulation, thereby regulating the microstructure, gel strength and rheological properties of the composite gel, so that the system can form a stable gel structure suitable for swallowing.

[0018] (2) After optimization using the methods of this study, the structural characteristics and nutritional functions of the calcium salt-rice starch-soybean protein composite gel were significantly improved. Different types and concentrations of calcium salts induce different aggregation modes and network structures in the composite system, thereby regulating the hardness, viscoelasticity and water-holding capacity of the gel, and enabling some systems to achieve a suitable IDSI swallowing grade.

[0019] (3) This study not only improves the texture, safety and nutritional value of foods with difficulty swallowing, but also provides a convenient and effective technical approach for developing nutritious, personalized and highly acceptable foods for special medical purposes. Attached Figure Description

[0020] Figure 1The results of fork tilt test and spoon tilt test on 3D printed soybean protein and rice starch composite gel containing different types and concentrations of calcium salts.

[0021] Figure 2 Evaluation results of the water-holding capacity of 3D-printed soybean protein and rice starch composite gels containing different types and concentrations of calcium salts;

[0022] Figure 3 Frequency scanning evaluation results of soybean protein and rice starch composite gels containing different types and concentrations of calcium salts;

[0023] Figure 4 Evaluation results of the three-interval thixotropic test (3ITT) of soybean protein and rice starch composite gel containing different types and concentrations of calcium salts;

[0024] Figure 5 The printability evaluation results of 3D printed soybean protein and rice starch composite gels containing different types and concentrations of calcium salts;

[0025] Figure 6 The results of confocal laser microscopy evaluation of 3D-printed soybean protein and rice starch composite gels containing different types and concentrations of calcium salts. Detailed Implementation

[0026] A clear and complete description of the technical solution is provided below for a specific embodiment of the present invention. It should be noted that the described embodiment represents only some, not all, implementations of the present invention.

[0027] This invention uses a rotational shear rheometer to evaluate the rheological properties of composite gels. Composite gels containing different types and concentrations of calcium salts are used as inks and printed using an extrusion syringe printer. The 3D-printed composite gels are then analyzed using confocal laser microscopy, water-holding capacity, and IDSI testing to examine their microstructural changes and determine their IDSI level to assess the gel's swallowing safety. The specific methods are as follows:

[0028] 1. Frequency scanning characteristics of the composite gel were measured:

[0029] The rheological properties of composite gels containing different types and concentrations of calcium salts were evaluated using a rotational shear rheometer equipped with a 35 mm parallel plate configuration (gap = 1 mm). The gels were equilibrated at room temperature for 1 h before testing. Storage modulus (G′), loss modulus (G″), and loss tangent (tan δ) were determined by frequency sweeps within the frequency range of 0.1–15 Hz at a temperature of 25 °C and a strain of 0.1%.

[0030] 2. The three-interval thixotropic properties of the composite gel were determined by the 3ITT test:

[0031] The rheological properties of RS-SPI composite gels containing different types and concentrations of calcium salts were evaluated using a rotational shear rheometer equipped with a 35 mm parallel plate configuration (gap = 1 mm). The gels were equilibrated at room temperature for 1 hour before testing. The 3ITT test included a three-step shear rate test. The first stage had a shear rate of 1 s⁻¹. -1 The duration of this phase is 200 s. Next, the second phase has a shear rate of 100 s. -1 The duration is 200 seconds. The third step applies the same conditions as the first step.

[0032] 3. 3D printing of composite gels:

[0033] Composite gels containing different types and concentrations of calcium salts were used as inks and printed using an extrusion syringe printer. The printed shape was a cross, the printing speed was 20 mm / s, the infill density was 50%, and the printing temperature was set to 25 ℃. Furthermore, the printability of the composite gels was evaluated by observing the clarity of the striations on the extrudate surface and the degree of collapse.

[0034] 4. Measurement of the microstructure of the composite gel after 3D printing:

[0035] The microstructure was observed using a Leica SP8 confocal microscope. The gel was sliced ​​into thin sections using a blade and stained with fluorescein isothiocyanate (FITC) and rhodamine B for 1 hour. Subsequently, the phase distribution behavior of proteins and starch in the gel was detected at 10x magnification using an FV3000 confocal scanning electron microscope. FITC was used to label starch and protein molecules, while rhodamine B was used to label protein molecules.

[0036] 5. Measurement of the water-holding capacity of the composite gel after 3D printing:

[0037] The water-holding capacity was determined using centrifugation. 1.0 g of the composite gel was weighed and centrifuged at 8000 × g for 30 min at 4 °C. The water-holding capacity (WHC) was calculated as the percentage of the mass of the gel after centrifugation relative to the mass of the initial gel.

[0038]

[0039] m0, m1, and m2 represent the mass of the centrifuge tube, the mass of the gel before centrifugation and the mass of the centrifuge tube, and the mass of the gel after centrifugation, respectively.

[0040] 6. IDSSI test of the composite gel after 3D printing:

[0041] Based on preliminary assessment, the composite gels of different proportions are tentatively classified as Grade 6 and Grade 5. Grade 6 samples will be evaluated through fork-pressure and spoon-pressure tests. Grade 5 samples will be evaluated through fork-pressure, fork-drop, and spoon-tilt tests. The fork-pressure and spoon-pressure tests involve pressing the gel sample with a fork or spoon and then pressing it with the thumb, observing the degree of gel deformation and whether the nail turns white. The fork-drop test involves placing the gel sample on a fork and observing the shape of the gel on the fork and its fluidity within the fork's gaps. The spoon-tilt test involves scooping the gel sample with a spoon and then gradually tilting the spoon to check for sample slippage and gel adhesion to the spoon. In the IDDSI test, a Grade 6 sample should flatten, deform, or crack under fork or spoon pressure, causing the nail to turn white, and should not return to its original shape after the pressure is removed. In the IDDSI test, a Grade 5 sample should deform under fork pressure without causing nail discoloration and should be able to stack on the fork without falling out of the gaps. When placed on a spoon and tilted, the Level 5 sample slides off easily without leaving any excessive residue.

[0042] Example 1

[0043] Rice starch and soy protein were added to deionized water at a fixed ratio of 1:1 and stirred on a magnetic stirrer until completely dissolved, maintaining a total solids content of 12%. Calcium citrate (CCI) was added to the solution at a concentration of 10 mmol. The resulting solution was stirred on a magnetic stirrer at 250 rpm / min for 2 h to ensure effective dispersion and hydration of the rice starch and soy protein. All well-dispersed sample suspensions were preheated at 60 °C and continuously stirred at a constant temperature for 20 min. Subsequently, the preheated samples were rapidly transferred to a 95 °C water bath and heated for 30 min to terminate the reaction. The resulting gel was stored overnight at 4 °C and then at room temperature for at least 30 min to obtain a soy protein and rice starch composite gel containing 10 mmol of calcium citrate (10 mmol CCI).

[0044] Example 2

[0045] Rice starch and soy protein were added to deionized water at a fixed ratio of 1:1 and stirred on a magnetic stirrer until completely dissolved, controlling the total solids content to 12%. Calcium citrate (CCI) was added to the solution at a concentration of 20 mmol. The resulting solution was stirred on a magnetic stirrer at a speed of 250 rpm / min for 2 h to ensure effective dispersion and hydration of rice starch and soy protein. All well-dispersed sample suspensions were preheated at 60 °C and continuously stirred under constant temperature for 20 min. Subsequently, the preheated samples were rapidly transferred to a constant temperature water bath at 95 °C and heated for 30 min to terminate the reaction. The resulting gel was stored at 4 °C overnight and then stored at room temperature for at least 30 min to obtain a soy protein and rice starch composite gel containing 20 mmol of calcium citrate (20 mmol CCI).

[0046] Example 3

[0047] Rice starch and soy protein were added to deionized water at a fixed ratio of 1:1 and stirred on a magnetic stirrer until completely dissolved, controlling the total solids content to 12%. Calcium citrate (CCI) was added to the solution at a concentration of 30 mmol. The resulting solution was stirred on a magnetic stirrer at 250 rpm / min for 2 h to ensure effective dispersion and hydration of the rice starch and soy protein. All well-dispersed sample suspensions were preheated at 60 °C and continuously stirred at a constant temperature for 20 min. Subsequently, the preheated samples were rapidly transferred to a 95 °C water bath and heated for 30 min to terminate the reaction. The resulting gel was stored overnight at 4 °C and then stored at room temperature for at least 30 min to obtain a soy protein and rice starch composite gel containing 30 mmol of calcium citrate (30 mmol CCI).

[0048] Example 4

[0049] Rice starch and soy protein were added to deionized water at a fixed ratio of 1:1 and stirred on a magnetic stirrer until completely dissolved, controlling the total solids content to 12%. Calcium carbonate (CCA) was added to the solution at a concentration of 10 mmol. The resulting solution was stirred on a magnetic stirrer at 250 rpm / min for 2 h to ensure effective dispersion and hydration of the rice starch and soy protein. All well-dispersed sample suspensions were preheated at 60 °C and continuously stirred under constant temperature for 20 min. Subsequently, the preheated samples were rapidly transferred to a 95 °C water bath and heated for 30 min to terminate the reaction. The resulting gel was stored overnight at 4 °C and then stored at room temperature for at least 30 min to obtain a soy protein and rice starch composite gel containing 10 mmol of calcium carbonate (10 mmol CCA).

[0050] Example 5

[0051] Rice starch and soy protein were added to deionized water at a fixed ratio of 1:1 and stirred on a magnetic stirrer until completely dissolved, controlling the total solids content to 12%. Calcium carbonate (CCA) was added to the solution at a concentration of 20 mmol. The resulting solution was stirred on a magnetic stirrer at 250 rpm / min for 2 h to ensure effective dispersion and hydration of the rice starch and soy protein. All well-dispersed sample suspensions were preheated at 60 °C and continuously stirred at a constant temperature for 20 min. Subsequently, the preheated samples were rapidly transferred to a 95 °C water bath and heated for 30 min to terminate the reaction. The resulting gel was stored overnight at 4 °C and then stored at room temperature for at least 30 min to obtain a soy protein and rice starch composite gel containing 20 mmol of calcium carbonate (20 mmol CCA).

[0052] Example 6

[0053] Rice starch and soy protein were added to deionized water at a fixed ratio of 1:1 and stirred on a magnetic stirrer until completely dissolved, controlling the total solids content to 12%. Calcium carbonate (CCA) was added to the solution at a concentration of 30 mmol. The resulting solution was stirred on a magnetic stirrer at 250 rpm / min for 2 h to ensure effective dispersion and hydration of the rice starch and soy protein. All well-dispersed sample suspensions were preheated at 60 °C and continuously stirred at a constant temperature for 20 min. Subsequently, the preheated samples were rapidly transferred to a 95 °C water bath and heated for 30 min to terminate the reaction. The resulting gel was stored overnight at 4 °C and then stored at room temperature for at least 30 min to obtain a soy protein and rice starch composite gel containing 30 mmol of calcium carbonate (30 mmol CCA).

[0054] Example 7

[0055] Rice starch and soy protein were added to deionized water at a fixed ratio of 1:1 and stirred on a magnetic stirrer until completely dissolved, controlling the total solids content to 12%. Calcium gluconate (CGL) was added to the solution at a concentration of 10 mmol. The resulting solution was stirred on a magnetic stirrer at 250 rpm / min for 2 h to ensure effective dispersion and hydration of the rice starch and soy protein. All well-dispersed sample suspensions were preheated at 60 °C and continuously stirred at a constant temperature for 20 min. Subsequently, the preheated samples were rapidly transferred to a 95 °C water bath and heated for 30 min to terminate the reaction. The resulting gel was stored overnight at 4 °C and then stored at room temperature for at least 30 min to obtain a soy protein and rice starch composite gel containing 10 mmol of calcium gluconate (10 mmol CGL).

[0056] Example 8

[0057] Rice starch and soy protein were added to deionized water at a fixed ratio of 1:1 and stirred on a magnetic stirrer until completely dissolved, controlling the total solids content to 12%. Calcium gluconate (CGL) was added to the solution at a concentration of 20 mmol. The resulting solution was stirred on a magnetic stirrer at 250 rpm / min for 2 h to ensure effective dispersion and hydration of the rice starch and soy protein. All well-dispersed sample suspensions were preheated at 60 °C and continuously stirred at a constant temperature for 20 min. Subsequently, the preheated samples were rapidly transferred to a 95 °C water bath and heated for 30 min to terminate the reaction. The resulting gel was stored overnight at 4 °C and then stored at room temperature for at least 30 min to obtain a soy protein and rice starch composite gel containing 20 mmol of calcium gluconate (20 mmol CGL).

[0058] Example 9

[0059] Rice starch and soy protein were added to deionized water at a fixed ratio of 1:1 and stirred on a magnetic stirrer until completely dissolved, controlling the total solids content to 12%. Calcium gluconate (CGL) was added to the solution at a concentration of 30 mmol. The resulting solution was stirred on a magnetic stirrer at 250 rpm / min for 2 h to ensure effective dispersion and hydration of the rice starch and soy protein. All well-dispersed sample suspensions were preheated at 60 °C and continuously stirred at a constant temperature for 20 min. Subsequently, the preheated samples were rapidly transferred to a 95 °C water bath and heated for 30 min to terminate the reaction. The resulting gel was stored overnight at 4 °C and then stored at room temperature for at least 30 min to obtain a soy protein and rice starch composite gel containing 30 mmol of calcium gluconate (30 mmol CGL).

[0060] Example 10

[0061] Rice starch and soy protein were added to deionized water at a fixed ratio of 1:1 and stirred on a magnetic stirrer until completely dissolved, controlling the total solids content to 12%. Calcium chloride (CCH) was added to the solution at a concentration of 10 mmol. The resulting solution was stirred on a magnetic stirrer at 250 rpm / min for 2 h to ensure effective dispersion and hydration of the rice starch and soy protein. All well-dispersed sample suspensions were preheated at 60 °C and continuously stirred at a constant temperature for 20 min. Subsequently, the preheated samples were rapidly transferred to a 95 °C water bath and heated for 30 min to terminate the reaction. The resulting gel was stored overnight at 4 °C and then stored at room temperature for at least 30 min to obtain a soy protein and rice starch composite gel containing 10 mmol of calcium chloride (10 mmol CCH).

[0062] Example 11

[0063] Rice starch and soy protein were added to deionized water at a fixed ratio of 1:1 and stirred on a magnetic stirrer until completely dissolved, controlling the total solids content to 12%. Calcium chloride (CCH) was added to the solution at a concentration of 20 mmol. The resulting solution was stirred on a magnetic stirrer at 250 rpm / min for 2 h to ensure effective dispersion and hydration of the rice starch and soy protein. All well-dispersed sample suspensions were preheated at 60 °C and continuously stirred at a constant temperature for 20 min. Subsequently, the preheated samples were rapidly transferred to a 95 °C water bath and heated for 30 min to terminate the reaction. The resulting gel was stored overnight at 4 °C and then stored at room temperature for at least 30 min to obtain a soy protein and rice starch composite gel containing 20 mmol of calcium chloride (20 mmol CCH).

[0064] Example 12

[0065] Rice starch and soy protein were added to deionized water at a fixed ratio of 1:1 and stirred on a magnetic stirrer until completely dissolved, controlling the total solids content to 12%. Calcium chloride (CCH) was added to the solution at a concentration of 30 mmol. The resulting solution was stirred on a magnetic stirrer at 250 rpm / min for 2 h to ensure effective dispersion and hydration of the rice starch and soy protein. All well-dispersed sample suspensions were preheated at 60 °C and continuously stirred at a constant temperature for 20 min. Subsequently, the preheated samples were rapidly transferred to a 95 °C water bath and heated for 30 min to terminate the reaction. The resulting gel was stored overnight at 4 °C and then stored at room temperature for at least 30 min to obtain a soy protein and rice starch composite gel containing 30 mmol of calcium chloride (30 mmol CCH).

[0066] Comparative Example 1

[0067] Rice starch and soy protein were added to deionized water at a fixed ratio of 1:1 and stirred on a magnetic stirrer until completely dissolved, controlling the total solids content to 12%. The resulting solution was then stirred on a magnetic stirrer at 250 rpm / min for 2 h to ensure effective dispersion and hydration of the rice starch and soy protein. All well-dispersed sample suspensions were preheated at 60 °C and continuously stirred at a constant temperature for 20 min. Subsequently, the preheated samples were rapidly transferred to a 95 °C water bath and heated for 30 min to terminate the reaction. The resulting gel was stored at 4 °C overnight and then at room temperature for at least 30 min to obtain a calcium-free soy protein and rice starch composite gel (Ctrl).

[0068] The performance of the soybean protein and rice starch composite gels containing different types and concentrations of calcium salts prepared in Examples 1-12 and Comparative Example 1 was tested, as follows:

[0069] 1. Frequency scanning evaluation results of soybean protein and rice starch composite gels containing different types and concentrations of calcium salts.

[0070] Result statement: From Figure 3As can be seen, compared with Comparative Example 1, the G′ values ​​of all samples exceeded the G″ values ​​across the entire frequency range, indicating that the composite gel possesses better network viscoelasticity. Furthermore, with increasing CCI and CCA concentrations (Examples 1-6), the G′ and G″ values ​​of the composite gel gradually increased. This is related to the fact that CCI and CCA are beneficial to gel network stability. Notably, CCA exhibited even higher G′ and G″ values. Conversely, with increasing CGL and CCH concentrations (Examples 7-12), the G′ and G″ values ​​of the composite gel gradually decreased. This is related to the fact that CGL and CCH reduce gel network stability. This is because CGL and CCH have a significant electrostatic shielding effect on starch and protein, leading to the disordered aggregation of starch and protein, forming a chaotic network structure. The results indicate that CCI and CCA can increase the viscoelasticity of the gel, which may be beneficial for the subsequent support deposition layer in the gel printing process; conversely, CGL and CCH reduce the viscoelasticity of the gel, which may be detrimental to the subsequent support deposition layer in gel printing. However, it is worth noting that higher viscoelasticity may lead to discontinuous extrusion, meaning that the extrusion process may repeatedly start and stop.

[0071] 2. 3ITT evaluation results of soybean protein and rice starch composite gels containing different types and concentrations of calcium salts.

[0072] Result presentation: Figure 4 The 3ITT plots of the three-interval thixotropic test are shown for composite gels of different types and concentrations. In the first stage, all gels maintained relatively good viscosity. The viscosity of composite gels containing CCI and CCA increased with increasing calcium salt concentration; conversely, the viscosity of composite gels containing CGL and CCH decreased with increasing calcium salt concentration. Overall, CCI and CCH have the effect of increasing viscosity, with CCI being more effective; CGL and CCH have the effect of decreasing gel viscosity. In the second stage, the viscosity of all samples decreased sharply, which is related to the destruction and deformation of the gel network structure caused by shear force. Under high shear strain, flexible starch and protein molecules will orient along the shear direction, resulting in a decrease in the system's conformational entropy and thus a decrease in viscosity. In the third stage, the viscosity of all samples recovered and gradually reached a stable state. This viscosity recovery is related to the self-healing of the physical cross-linking points of the gel network; that is, when the external force is removed, due to the reconstruction of the entangled structure of the physical network, the composite gel system partially or completely recovers, leading to an increase in conformational entropy and naturally gradually approaching the original viscosity. Compared to the first stage, the viscosity of all samples showed a significant decrease, but the overall viscosity trend remained consistent with the first stage. The higher viscosity recovered by composite gels containing CCI and CCA helped them withstand continuous extrusion loading in multi-printing, especially gels containing CCI. Conversely, the lower viscosity recovered by gels containing CGL and CCH was detrimental to continuous extrusion loading.

[0073] 3. Evaluation results of printability of 3D-printed soybean protein and rice starch composite gels containing different types and concentrations of calcium salts. Result statement: From Figure 5 As can be seen, the cross shape of the extruded material in Comparative Example 1 is not obvious, its layered structure is unclear, and there is significant collapse. This is related to its discontinuous network structure of gel breakage and weak gel strength, which makes the gel damaged during printing and difficult to recover, thus making it difficult to form a supportive geometry. However, with the increase of CCI and CCA concentrations, the cross shape of the 3D printed extruded material from the composite gel becomes more regular, the layered structure becomes clearer, and the support becomes better. This is related to CCI and CCA promoting the formation of a dense network structure, strong gel strength, and suitable viscosity of the composite gel. Furthermore, the surface of the extruded material containing CCI is smooth; while the extruded material containing CCA has a noticeable granular texture, and obvious traces of discontinuous extrusion can be seen. This may be attributed to the fact that the composite gel containing CCI has appropriate viscoelasticity and gel strength, enabling it to be continuously extruded by the 3D printer without any broken extrusion lines. The composite gel containing CCA has greater viscoelasticity and gel strength, exhibiting rigid gel texture characteristics, which may make it prone to internal cavities and irregular extrusion during printing, leading to discontinuous extrusion of the extruded material. Meanwhile, with increasing CGL and CCH concentrations, the cross-shaped structure of the 3D-printed extrudate from the composite gel gradually became less distinct, the layered structure became unclear, and significant collapse and water exudation occurred. This is related to the weak viscoelasticity and thixotropic recovery exhibited by the composite gel containing CGL and CCH. This leads to irreversible damage to CGL and CCH during extrusion, making it difficult to restore the gel structure and viscoelasticity. Simultaneously, the disruption of the gel network causes water trapped within it to precipitate, further reducing the support of the extrudate. Therefore, compared to CCA, CGL, and CCH, CCI helps to better regulate the gel's network, texture, and rheological properties, resulting in composite gels containing CCI exhibiting better printability, namely a smooth surface and good support and resolution.

[0074] 4. CLSM evaluation results of 3D-printed soybean protein and rice starch composite gels containing different types and concentrations of calcium salts.

[0075] like Figure 4As shown, compared to composite gels containing CCI, the CLSM images of 3D-printed extrudates containing CCI reveal a looser, more distorted, and more porous starch and protein network structure. Compared to composite gels containing CCA, the CLSM images of extrudates containing CCA appear to show a less dense network structure. However, the CLSM image characteristics of extrudates containing CGL and CCH are similar to those of composite gels containing CGL and CCH. Therefore, in 3D printing, composite gels containing CCI and CCA, which have better structure and gel strength, undergo considerable damage. Composite gels containing CGL and CCH, which have weaker structure and gel strength, appear to maintain a relatively intact network structure. Overall, 3D printing causes some damage to the network structure of composite gels, resulting in the loss of the original compact structure. This damage to the gel network structure reduces the gel strength of the composite gel, making the 3D-printed composite gel easier to swallow. This may be because the extrusion during 3D printing causes changes in the multi-scale structure of starch or protein in the composite gel, thus affecting the density of the gel network.

[0076] 5. IDDSI evaluation results of 3D-printed soybean protein and rice starch composite gels containing different types and concentrations of calcium salts.

[0077] Results description: IDSSI tests for all samples were performed from... Figure 1 As can be seen, in the fork-drop test, all samples except the 3D-printed extrudates of Examples 9 and 12 piled up into small mounds on the fork and did not flow through the gaps in the fork; in the spoon-tilt test, most left a small amount of residue on the spoon; and in the fork-press test, obvious fork pressing marks were shown. This indicates that all samples except the 3D-printed extrudates of Examples 9 and 12 can be classified as IDDSI Class 4; suitable for patients who cannot chew but are conscious of transporting food with their tongue; and suitable for people with limited swallowing ability but who can safely swallow highly viscous foods. However, for the 3D-printed extrudates of Examples 9 and 12, due to the extrusion action of 3D printing, they were unable to maintain a semi-solid self-supporting structure. Therefore, in the flow test, due to gravity, the 3D-printed extrudates of Examples 9 and 12 exhibited dripping phenomena. Therefore, the 3D printed extrudates of Examples 9 and 12 can be classified as IDDSI Level 3, suitable for people with weak swallowing ability but who can swallow moderately thick foods.

[0078] 6. Evaluation results of the water-holding capacity of 3D-printed soybean protein and rice starch composite gels containing different types and concentrations of calcium salts.

[0079] Result statement: From Figure 2As can be seen, compared with Comparative Example 1, the WHC of the 3D-printed gel extrudates still maintained a similar trend as before extrusion, but the WHC of the extrudates was significantly lower than before extrusion. This is related to the fact that 3D printing disrupts the network structure of the composite gel, leading to the release of water. However, it is worth noting that the WHC reduction of gels containing CCI and CCA after 3D printing was smaller, while the WHC reduction of gels containing CGL and CCH was more significant. In particular, the 3D-printed extrudates containing Examples 6 and 3 were difficult to measure WHC because they were difficult to maintain a semi-solid gel shape after centrifugation and formed a paste. This may be related to the weak water-binding ability of gels containing CGL and CCH, which makes it difficult for water to be bound and more likely to escape from the network. This is also consistent with the printability results of the 3D-printed extrudates, that is, obvious water separation was found on the composite gel extrudates of Examples 9 and 12. The results showed that 3D-printed products containing CCI and CCA still had good WHC. This high WHC helps patients with dysphagia to reduce saliva secretion and is also more conducive to food processing, transportation, and storage.

Claims

1. A process for the preparation of a swallowable composite gel based on soy protein and rice starch, characterized in that, Includes the following steps: (1) Preparation of a composite solution of soybean protein and rice starch: The ratio of rice starch to soybean protein is 1:1 to 1:

3. Add it to deionized water, place it on a magnetic stirrer and stir until completely dissolved. Control the total solid content to 10%-15% to obtain a composite solution of soybean protein and rice starch. (2) Preparation of calcium salt solutions of different types and concentrations: Different calcium salts, including calcium citrate (CCI), calcium carbonate (CCA), calcium gluconate (CGL), and calcium chloride (CCH), were placed on a magnetic stirrer with deionized water as solvent and stirred until completely dissolved. The solutions were then transferred to volumetric flasks, diluted to volume, and shaken well to prepare calcium salt solutions of four different calcium salts at 10-50 mmol. (3) Preparation of soybean protein and rice starch composite gels containing different types and concentrations of calcium salt solutions: The different types of calcium salt solutions obtained in (2) were added to the composite solution of soybean protein and rice starch, and the suspension was stirred on a magnetic stirrer at a speed of 250 rpm / min for 1-3 h to ensure effective dispersion and hydration of rice starch and soybean protein. All the fully dispersed sample suspensions were preheated at 60 ℃ and stirred continuously for 10-20 min under constant temperature conditions. Then, the preheated samples were quickly transferred to a constant temperature water bath at 80-100 ℃ and heated for 30 min. The resulting gel was stored at 4 ℃ overnight, and then stored at room temperature for at least 30 min to obtain soybean protein and rice starch composite gels containing different types and concentrations of calcium salts.

2. A process for the preparation of a swallowable composite gel based on soy protein and rice starch according to claim 1, characterized in that: In step (1), the ratio of rice starch to soybean protein is fixed at 1:

1.

3. A process for the preparation of a swallowable composite gel based on soy protein and rice starch as claimed in claim 1, wherein: In step (1), the total solids content of the compound solution of soybean protein and rice starch is controlled at 12%.

4. A process for the preparation of a swallowable composite gel based on soy protein and rice starch according to claim 1, characterized in that: In step (2), calcium salt solutions of calcium citrate (CCI), calcium carbonate (CCA), calcium gluconate (CGL), and calcium chloride (CCH) with concentrations of 10 mmol, 20 mmol, and 30 mmol were prepared, respectively.

5. A process for the preparation of a swallowable composite gel based on soy protein and rice starch according to claim 1, characterized in that: In step (3), different types of calcium salt solutions are added to the composite solution of soybean protein and rice starch, and the suspension is stirred on a magnetic stirrer at a speed of 250 rpm / min for 2 h to ensure effective dispersion and hydration of rice starch and soybean protein.

6. A process for the preparation of a swallowable composite gel based on soy protein and rice starch according to claim 1, characterized by: In step (3), all the fully dispersed sample suspensions were preheated at 60°C and stirred continuously for 20 min under constant temperature conditions. Then, the preheated samples were quickly transferred to a constant temperature water bath at 95°C and heated for 30 min to obtain a composite gel of soybean protein and rice starch containing different types and concentrations of calcium salts.

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