Oat protein composite hydrogel ink for dysphagia and its preparation method and application in 3D printing

Abstract

The present application relates to a kind of oat protein composite hydrogel ink suitable for dysphagia and its preparation method and application in 3D printing.The hydrogel ink is made of the following raw materials: oat protein-inulin Maillard reaction covalent complex, kappa-carrageenan and xanthan gum, and the balance is water.The present application uses inulin to modify oat protein, combined with solid-phase thermal Maillard reaction, improves the hydration dispersibility, water retention and heat-induced gelation of oat protein, so that the oat protein system which is difficult to form stable gel structure can maintain the layered stacking form after printing.Then, a specific amount of carrageenan, xanthan gum and purified water is used, which not only ensures the controllable shear thinning property during 3D printing, but also ensures the high cohesiveness and low adhesion when eaten by dysphagia patients, reducing the risk of aspiration and asphyxia for dysphagia patients.

Description

Technical Field

[0001] This invention relates to the technical field of 3D printed hydrogels for patients with swallowing disorders, specifically to an oat protein composite hydrogel ink suitable for patients with swallowing disorders, its preparation method, and its application in 3D printing. Background Technology

[0002] Dysphagia in the elderly has become a significant issue affecting their nutritional intake, quality of life, and safe eating. Patients with dysphagia often struggle to safely consume regular solid foods due to weakened throat muscles, impaired neurological coordination, or sequelae of underlying diseases. Current clinical and elderly care settings often employ liquid diets, homogenized diets, and pureed foods to reduce the risk of aspiration and choking. However, these foods generally suffer from limited visual appeal, insufficient flavor release, weak textural layers, and a poor dining experience. Long-term consumption can easily reduce appetite and potentially exacerbate the risk of malnutrition.

[0003] Food 3D printing technology can process nutritionally functional pastes or gels into three-dimensional structures that more closely resemble the appearance of natural foods through extrusion molding and layer-by-layer stacking. This provides a new pathway for personalized nutritional design, appearance reshaping, and texture control of foods for dysphagia. 3D printing materials used in dysphagia foods not only need to meet the processing requirements of continuous extrusion and post-printing shape retention, but also the texture requirements necessary for safe swallowing.

[0004] Oat protein has good nutritional value and the advantage of being a plant source, and oats are well accepted by the elderly. However, natural oat protein isolate has problems such as low solubility, easy particle aggregation, uneven dispersion, and rough texture during processing. When used directly in extrusion 3D printing of food, it is prone to problems such as discontinuous extrusion, insufficient interlayer support, and molding collapse.

[0005] Furthermore, 3D printing of swallowable foods places mutually restrictive demands on the rheological properties of the materials: under high shear conditions within the nozzle, the material should have low apparent viscosity to enable low-pressure, continuous, and uniform extrusion; after leaving the nozzle and depositing on the printing platform, the material should rapidly recover high static structural strength to maintain the three-dimensional morphology of the stacked layers. For foods with swallowing difficulties, the material should also avoid significant water separation, excessive adhesion, and breakage after oral processing to prevent free water or broken particles from increasing the risk of aspiration.

[0006] Therefore, there is an urgent need to construct a composite hydrogel system that combines the nutritional properties of plant proteins, controllable shear thinning characteristics (low apparent viscosity under high shear and rapid recovery of self-supporting ability under static conditions), and swallowing safety texture characteristics, in order to solve the problem of insufficient applicability of natural plant protein-based materials in 3D printing of foods for elderly people with swallowing disorders. Summary of the Invention

[0007] Therefore, the purpose of this invention is to provide an oat protein composite hydrogel ink suitable for people with swallowing disorders, its preparation method and its application in 3D printing, so as to solve the problem that existing printed swallowable foods are difficult to simultaneously possess controllable shear thinning properties and high cohesiveness and low adhesion when consumed by people with swallowing disorders.

[0008] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0009] An oat protein composite hydrogel ink suitable for people with swallowing disorders is made from the following raw materials in weight percentages: 19.0~21.0% oat protein isolate-inulin Maillard reaction covalent complex, 0.7~0.9% κ-carrageenan and 0.6~0.8% xanthan gum, with the balance being purified water; the oat protein isolate-inulin Maillard reaction covalent complex is prepared by reacting oat protein isolate with inulin via a solid-phase dry heat Maillard reaction.

[0010] This invention selects oat protein isolate-inulin Maillard reaction covalent complex as the main nutritional and structural basis of hydrogel ink. Solid-phase dry heat Maillard reaction is used to improve the functional properties of oat protein isolate. Combined with specific amounts of carrageenan, xanthan gum and purified water, it not only ensures the controllable shear thinning properties during 3D printing, but also ensures high cohesiveness and low adhesion when consumed by patients with swallowing disorders, reducing the risk of aspiration and choking in patients with swallowing disorders.

[0011] This invention modifies oat protein isolate with inulin and combines it with solid-phase dry heat Maillard reaction. This not only reduces protein particle aggregation and improves solubility and water retention, but more importantly, it significantly enhances the gel-forming ability of the oat protein system. This allows the oat protein system, which is originally difficult to form a stable gel structure, to maintain a layered stacked morphology after printing. This avoids the problem of unmodified oat protein system collapsing into a protein liquid state after printing, and provides a foundation for the subsequent construction of 3D printed hydrogels that can be stably extruded, deposited and stacked.

[0012] Preferably, during the solid-phase dry heat Maillard reaction, the mass ratio of oat protein isolate to inulin is 1:(2~2.5), and the purity of the inulin is above 90%. The inulin is food-grade low-polymerization inulin or fructooligosaccharide-type inulin, with an average degree of polymerization of DP 2~20. Purity refers to the proportion of reactive oligosaccharides with free reducing end groups in the inulin to more than 90% of the total mass of the inulin. More preferably, the inulin is food-grade short-chain inulin.

[0013] Food-grade low-polymerization inulin or fructooligosaccharide-type inulin is selected. Compared to high-polymerization inulin, it has a higher proportion of end groups and better hydration and dispersibility. Under weakly alkaline pH, controlled humidity solid-phase dry heat, and high molecular contact frequency conditions, the reactive end groups can undergo Maillard initial condensation and subsequent rearrangement reactions with the free amino groups of amino acid residues such as lysine in oat protein, thereby forming protein-inulin glycosylation products. Since the reactivity of inulin is lower than that of monosaccharides, using mild controlled humidity dry heat reaction conditions can control the reaction to a stage where functional properties are improved without excessive browning.

[0014] Preferably, the solid-phase dry thermal Maillard reaction is carried out at a temperature of 50–60°C, a relative humidity of 75%–82%, a reaction time of 24–48 h, and a pH of 7.5–8.5.

[0015] Oat protein systems are generally not suitable for 3D printing. This invention controls the mass ratio of oat protein isolate to inulin and uses a solid-phase dry heat method to perform Maillard modification on oat protein isolate. The Maillard modification is carried out under specific pH, temperature, humidity and reaction time conditions, so that oat protein and inulin undergo a moderate Maillard glycosylation reaction. This improves the gel-forming ability and structural stability of oat protein without excessive browning or producing obvious unpleasant flavor.

[0016] The appropriate Maillard reaction stage can be comprehensively judged by the decrease in free amino content, grafting degree, protein solubility, particle size, browning index A420, and color difference ΔE. Preferably, the free amino content decreases by 25% to 45%, the grafting degree is 20% to 45%, the protein solubility is not less than 60%, the browning index A420 is not higher than 0.15, and the color difference ΔE is not higher than 8.

[0017] Preferably, the oat protein isolate-inulin Maillard reaction covalent complex is prepared by mixing oat protein isolate, inulin and deionized water to prepare a mixed solution with a total solids content of 10-15%, adjusting the pH to 7.5-8.5, freeze-drying and then performing a solid-phase dry heat Maillard reaction.

[0018] The oat protein isolate-inulin Maillard reaction covalent complex was prepared using the following method:

[0019] Step 1: Add oat protein isolate and inulin to deionized water at a mass ratio of 1:(2~2.5) to prepare a mixed solution with a total solids mass fraction of 10~15%. Adjust the pH to 7.5~8.5 and freeze-dry to obtain lyophilized powder.

[0020] Step 2: Place the freeze-dried powder in a container containing a saturated salt solution and perform a solid-phase dry heat reaction at a relative humidity of 75%–82% and a temperature of 50–60°C for 24–48 h to obtain an oat protein isolate-inulin Maillard reaction covalent complex.

[0021] The second technical solution of the present invention is:

[0022] A method for preparing an oat protein composite hydrogel ink suitable for people with swallowing disorders includes the following steps: mixing oat protein isolate-inulin Maillard reaction covalent complex according to the following weight percentages: 19.0~21.0% oat protein isolate-inulin Maillard reaction covalent complex, 0.7~0.9% κ-carrageenan and 0.6~0.8% xanthan gum, with the balance being purified water, and then sequentially subjecting the mixture to hydration, degassing, heat treatment and cooling to obtain the composite hydrogel ink.

[0023] Preferably, the hydration process involves first pre-dry mixing the oat protein isolate-inulin Maillard reaction covalent complex, κ-carrageenan, and xanthan gum to obtain a mixed powder, and then mixing the mixed powder with purified water at 70-80°C and stirring at a high speed of 4000-6000 rpm for 2-3 minutes.

[0024] Preferably, the degassing is centrifugal degassing or vacuum degassing; the heat treatment is heating in a water bath at 87~93°C for 10~13 min; the cooling is rapid cooling in an ice-water bath; after cooling, an equilibration process is also included, which consists of refrigerating at 4°C overnight and equilibrating at room temperature for 30~35 min before 3D printing. Degassing is to reduce the impact of air bubbles on the continuity of printed lines and the forming accuracy. Subsequent heating is to promote further homogenization of the system. Further rapid cooling in an ice-water bath and refrigerating at 4°C overnight are to enable the system to form a stable pre-gel structure. The purpose of refrigeration equilibration is to achieve full hydration and structural stability, while the ink just taken out of the ice-water bath may still be in a non-equilibrium state in terms of its internal moisture distribution, polymer chain entanglement, and other microstructures.

[0025] The third technical solution of the present invention is:

[0026] A 3D-printed hydrogel suitable for people with swallowing disorders is prepared by 3D printing using the above-mentioned oat protein composite hydrogel ink; the hydrogel has a cohesiveness of 0.6~1.0 and an adhesion of 0.4~0.5 mJ.

[0027] Preferably, the 3D printing conditions are as follows: injection barrel temperature is 25-30°C; nozzle diameter is 0.6-1.0 mm; layer height is 0.5-0.8 mm; printing speed is 10-20 mm / s; and the printing platform is a cool platform with a temperature of 15-25°C.

[0028] A method for preparing a 3D-printed hydrogel suitable for individuals with swallowing disorders, comprising the following steps:

[0029] After equilibration at room temperature, the composite hydrogel ink was transferred into the syringe of the 3D printer. It was allowed to stand for 10 minutes to defoam, and the syringe temperature was maintained at 25–30°C to ensure the system remained extrudable before printing. The printing parameters were set as follows: nozzle diameter 0.6–1.0 mm, layer height 0.5–0.8 mm, and printing speed 10–20 mm / s. The material was continuously extruded through the nozzle and deposited onto a cooled printing platform, where it was stacked layer by layer to form the desired three-dimensional dietary shape. The nozzle diameter, layer height, and printing speed could be adjusted within the above range based on the composite hydrogel's water content, particle dispersion, and the desired printing shape.

[0030] The fourth technical solution of the present invention is:

[0031] Application of a 3D-printed hydrogel suitable for people with swallowing disorders in personalized 3D-printed swallowing diets for patients with swallowing disorders.

[0032] The technical solution of the present invention achieves the following beneficial technical effects:

[0033] 1. Compared to the unmodified oat protein isolate / inulin physical mixing system, this invention significantly improves the hydration and dispersibility, water-holding capacity, and gel-forming ability of oat protein through a moderate Maillard reaction between oat protein isolate and inulin. The unmodified oat protein system easily forms unsupported, liquid-like aggregates after printing, making it difficult to maintain the layered structure and intended shape. After Maillard modification, the system forms a more stable gel structure, significantly reducing the height loss rate after printing and significantly improving line continuity and shape retention.

[0034] 2. Compared with systems lacking xanthan gum, the 3D-printed composite hydrogel of the present invention has more obvious shear-thinning properties and better low-shear cohesive structure, which is beneficial to reduce extrusion resistance and improve the integrity of the food bolus during swallowing.

[0035] 3. Compared with systems lacking κ-carrageenan, the 3D printing composite hydrogel of the present invention has better self-supporting ability after printing deposition, which helps to reduce interlayer settlement, flow and collapse, and improve the retention of printed shape.

[0036] 4. The 3D printed composite hydrogel of the present invention, combined with the IDDSI spoon tilt test, fork drop test and fork pressure test, evaluates the texture grade of printed food and can be used to prepare personalized diets for elderly people with dysphagia. Attached Figure Description

[0037] Figure 1 The 3D printing molding effects of different 3D printing hydrogel systems in Experimental Example 2 of this invention;

[0038] Figure 2 The results of IDDSI swallowing level tests for different 3D printed hydrogel systems in Experimental Example 3 of this invention are shown. Detailed Implementation

[0039] The purpose and effects of Maillard modification of oat protein isolate in this invention:

[0040] First, the Maillard reaction product of oat protein isolate and inulin is used to improve the functional properties of oat protein, especially its gelling ability and self-supporting capacity after printing. Natural oat protein isolate has poor hydration and dispersibility, and significant particle aggregation. When used alone or directly mixed with inulin, it is difficult to form a continuous gel network with sufficient strength. After printing, it tends to flow and collapse as a liquid, failing to maintain its three-dimensional morphology. Through moderate Maillard glycosylation, hydrophilic segments of inulin are introduced into the surface of oat protein molecules, improving the protein's hydration and dispersion, reducing particle aggregation, and enhancing its gel-forming ability and water-holding stability after heating. This transforms oat protein from a difficult-to-print liquid system into a gel-type printing matrix with structure-retaining capabilities.

[0041] Second, Maillard modification unifies the nutritional and processing properties of oat protein. Oat protein isolate provides the nutritional basis of plant protein, while inulin provides the properties of water-soluble dietary fiber. If the two are only physically mixed, the main result is a nutritional blend. However, after appropriate glycosylation, the hydration dispersibility, water-holding stability, and blend uniformity of the system can be further improved.

[0042] Third, κ-carrageenan is used in this invention as a component for post-printing morphology retention and interlayer support, while xanthan gum is used to improve bolus cohesion under shear thinning, continuous extrusion, and low-shear conditions. These three components are not simply added together, but rather work together to achieve a balance between extrudability, morphology retention, and swallowing textural stability in the composite hydrogel, based on Maillard modification that improves protein dispersion.

[0043] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0044] Example 1

[0045] The oat protein composite hydrogel ink of this embodiment, suitable for individuals with swallowing disorders, is made from the following raw materials by weight percentage: 20% oat protein isolate-inulin Maillard reaction covalent complex, 0.8% κ-carrageenan, and 0.7% xanthan gum, with the balance being purified water; wherein, the oat protein isolate-inulin Maillard reaction covalent complex is prepared by reacting oat protein isolate with inulin via a solid-phase dry heat Maillard reaction. For the specific preparation method, please refer to Example 2.

[0046] Example 2

[0047] The preparation method of the oat protein composite hydrogel ink suitable for people with swallowing disorders in this embodiment adopts the following steps:

[0048] Step 1: Preparation of oat protein isolate-inulin Maillard reaction covalent complex

[0049] (1) Oat protein isolate and inulin (short-chain inulin produced by Henan Beixiang Trading Co., Ltd., with a purity of ≥95% and an average degree of polymerization DP of 2-9) were added to deionized water at a mass ratio of 1:2 to prepare a mixed solution with a total solids mass fraction of 10%. The pH was adjusted to about 8.0 with 0.1 mol / L NaOH solution. The mixture was stirred thoroughly to hydrate and disperse it evenly. The mixed solution was then freeze-dried to obtain a loose and uniform freeze-dried powder.

[0050] (2) Place the above freeze-dried powder in a sealed container or constant temperature and humidity equipment containing saturated salt solution, and control the relative humidity of the reaction environment at about 79%. Perform solid-phase dry heat Maillard reaction at 60°C for 48 hours to obtain oat protein isolate-inulin Maillard reaction covalent complex.

[0051] Step 2: Prepare composite hydrogel ink

[0052] Weigh out 20g of oat protein isolate-inulin Maillard reaction covalent complex (20.0% of the system), 0.8g of κ-carrageenan, 0.7g of xanthan gum, and 78.5g of purified water by weight percentage. First, dry-mix the three powders thoroughly. Then, add purified water at approximately 75°C and mechanically stir at 5000 rpm for 3 minutes to ensure complete hydration, dispersion, and formation of a homogeneous mixture. After centrifugation and degassing, heat in a 90°C water bath for 10 minutes; then rapidly cool in an ice-water bath and refrigerate overnight at 4°C. Before printing, remove and equilibrate at room temperature for 30 minutes to obtain the composite hydrogel ink of Example 1.

[0053] The 3D-printed hydrogel suitable for people with swallowing disorders in this embodiment is prepared using the following method:

[0054] The composite hydrogel ink was loaded into a 3D printing syringe, the syringe temperature was controlled at 25-30°C, the nozzle diameter was 0.8 mm, the layer height was 0.6 mm, the printing speed was 15 mm / s, and the printing was carried out layer by layer extrusion on a cool platform.

[0055] Comparative Example 1

[0056] The preparation method of the 3D printing hydrogel in this comparative example is basically the same as that in Example 2, except that the oat protein isolate-inulin Maillard reaction covalent complex used in the preparation of the composite hydrogel ink is replaced with 6.67g of oat protein isolate + 13.33g of inulin, which are physically mixed only, and the total solids account for 20.0%.

[0057] Comparative Example 2

[0058] The preparation method of the 3D printing hydrogel in this comparative example is basically the same as that in Example 2, except that xanthan gum is not added when preparing the composite hydrogel ink.

[0059] Comparative Example 3

[0060] The preparation method of the 3D printing hydrogel in this comparative example is basically the same as that in Example 2, except that κ-carrageenan is not added when preparing the composite hydrogel ink.

[0061] Table 1. Formulation design for each experimental group

[0062]

[0063] Experimental Example 1: Characterization of Maillard Modification Effects

[0064] This experimental example characterized the oat protein isolate-inulin Maillard reaction covalent complex prepared in Example 1 and the unmodified oat protein isolate / inulin physical mixture of Comparative Example 1. All tests were performed in triplicate. The results in Table 2 show that a moderate Maillard reaction significantly improves the hydration, dispersibility, and water-holding capacity of the oat protein system, while maintaining the degree of browning within an acceptable range.

[0065] Maillard modification characterization: The degree of modification was evaluated using free amino content, grafting degree, protein solubility, water-holding capacity, average particle size D50, browning index A420, and color difference ΔE. The grafting degree can be calculated based on the percentage decrease in free amino content, and combined with the browning index and color difference to determine whether it is in the appropriate Maillard stage.

[0066] Free amino content: Accurately weigh 40 mg of modified protein and dissolve it in 1 mL of methanol. Add 2.5 mL of 20% SDS, 25 mL of 0.1 mol / L borax, and 100 μL of β-mercaptoethanol. Make up to 50 mL with distilled water. This is the reagent for the o-phthalaldehyde method and should be prepared immediately before use.

[0067] Dilute the protein hydrolysate 50-fold, then add 200 μL of the diluted solution to 4 mL of OPA reagent. Mix well and react at room temperature for 2 min. Measure the absorbance at 340 nm. Use 200 μL of water added to the o-phthalaldehyde method reagent as a blank. Plot a standard curve using L-leucine and calculate the concentration of free amino groups in the hydrolysate.

[0068] Grafting rate determination: 40 mg of o-phthalaldehyde (OPA) was dissolved in 1 mL of methanol solution. 2.5 mL of 20% (w / v) SDS solution, 25 mL of 0.1 mol / L sodium tetraborate solution, and 200 μL of β-mercaptoethanol were added to the solution, and the volume was adjusted to 50 mL with deionized water to obtain the OPA reagent. The lyophilized powder of the LF-Lac covalent complex was dissolved in deionized water to prepare a 0.5 mg / mL LF-Lac covalent complex solution. 4 mL of o-phthalaldehyde (OPA) reagent was added to two test tubes, one containing 200 μL of the sample solution and the other containing 200 μL of deionized water as a blank. The tubes were mixed and incubated at room temperature for 2 min. The absorbance was measured at 340 nm. The grafting rate was calculated using the following formula:

[0069] Grafting rate (DG) % =

[0070] Where A0 is the net absorbance of free amino groups in the sample solution before grafting, and A1 is the net absorbance of free amino groups in the sample solution after grafting; the net absorbance of free amino groups in the sample solution before and after grafting is calculated as the difference between the absorbance of the sample and the absorbance of the blank sample.

[0071] Browning index: Take 0.5g of oat protein-inulin reaction products treated with different drying times, add 30% methanol, grind and make up to 40mL, stir at 40℃ for 30min, centrifuge at 7156g for 10min, take the supernatant and make up to 50mL with 30% methanol, and measure the absorbance value at 420nm to represent the browning index (melanoidin content).

[0072] Color difference measurement: Oat protein before and after modification was compressed into tablets, and three points were randomly selected to measure the color difference. The brightness (L*), red-green color (a*), and yellow-blue color (b*) of the tablet surface were recorded, and the color difference value (ΔE) was calculated. Three replicates were performed.

[0073]

[0074] In the formula, ΔL, Δa, and Δb represent the differences between the L*, a*, and b* values ​​of the oat protein tablets before and after modification and the L*, a*, and b* values ​​of the calibration plate, respectively.

[0075] Protein solubility: Weigh 200 mg of the complex, add 4 mL of distilled water, stir with a magnetic stirrer at 60 °C, then centrifuge at 5000 rpm for 10 minutes, and use a BCA kit to determine the protein content of the supernatant and calculate the protein solubility.

[0076] Gel strength: Puncture strength was tested using a texture analyzer with a P / 0.5 cylindrical probe (12.7 mm in diameter). The test mode was set to puncture mode, with a speed of 1.0 mm / s before, during, and after the test, a trigger force of 5 g, and a puncture deformation of 50%. Before testing, the prepared composite hydrogel samples were equilibrated at room temperature for 30 min to ensure stable results. Each sample was measured in at least three parallel trials, and the maximum peak force (g) during the puncture process was recorded as the gel strength.

[0077] Table 2. Changes in the functional properties of the oat protein-inulin system before and after Maillard modification.

[0078]

[0079] Table 2 shows that under mild, controlled humidity and dry heat conditions, oat protein isolate and inulin underwent a moderate Maillard glycosylation reaction. This reaction not only reduced protein particle aggregation and improved solubility and water-holding capacity, but more importantly, it significantly enhanced the gel-forming ability of the oat protein system, providing a foundation for the subsequent construction of stable extruded, deposited, and stacked 3D-printed hydrogels. Although the unmodified oat protein / inulin physical mixture had the same total solids content, the resulting gel remained primarily a highly fluid protein liquid, making it difficult to form a stable three-dimensional structure.

[0080] The rationale for using inulin in the Maillard modification of this invention lies in the following: This invention preferably uses low-polymerization-degree inulin or fructooligosaccharide-type inulin, with a higher proportion of end groups than high-polymerization-degree inulin. Furthermore, under conditions of pH 7.5–8.5, 50–60°C, 75%–82% relative humidity, and solid-phase dry heat, the protein and inulin molecules are in full contact, which promotes mild glycosylation between the free amino groups of oat protein and the reactive end groups of inulin. This pathway is more gradual than monosaccharide reactions, which is beneficial for controlling color and flavor changes, allowing the product to possess both dietary fiber properties and processing functionality.

[0081] Experiment Example 2: Rheological Properties and 3D Printing Quality

[0082] This experiment measured the rheological properties and 3D printing quality of Example 1 and Comparative Examples 1-3. The results are shown in Table 3.

[0083] Rheological testing: The shear viscosity, shear thinning index, and static storage modulus G′ of the samples were evaluated using a rotational rheometer. The test temperature was 25°C, and the samples were equilibrated at 25°C for 30 min before testing. The shear rate range for steady-state shear testing was 0.1–100 s⁻¹, and the shear viscosity data were fitted using a power-law model to obtain the shear thinning index n. Dynamic oscillation testing was conducted within the linear viscoelastic region of the samples, with a strain set at 1% and a frequency sweep range of 0.1–10 Hz. The storage modulus at 1 Hz was used as the evaluation index for static support capacity. Each group of samples was tested in triplicate, and the results are expressed as the average value.

[0084] 3D printing evaluation: Observe whether the sample is continuously extruded under the set printing conditions, and whether clogging or breakage occurs.

[0085] Table 3. Rheological properties of materials in each test group and evaluation of 3D printing quality.

[0086]

[0087] As shown in Table 3, Example 1 exhibits a high zero-shear viscosity, a low shear thinning index, and a high static storage modulus, indicating that it has strong structural support capabilities in a static state and good flow adaptability during high-shear extrusion.

[0088] Compared to Comparative Example 1, the total amount of oat protein-inulin related components in both groups was 20.0%. However, the zero-shear viscosity and static storage modulus of Example 1 were significantly higher than those of Comparative Example 1, while the shear thinning index was significantly lower. Therefore, the difference in printing continuity and morphology retention cannot be attributed to the difference in solid content, but mainly to the improvement in hydration dispersibility, particle size, and gelation caused by Maillard modification. Comparative Example 1, due to the lack of glycosylation modification, had poor functional properties of natural oat protein, resulting in significant collapse after printing. Compared to Comparative Example 2, the addition of xanthan gum improved shear thinning and extrusion stability; compared to Comparative Example 3, κ-carrageenan significantly improved the self-supporting ability after deposition (e.g., ...). Figure 1 (As shown).

[0089] Experimental Example 3: Texture characteristics, water separation rate, and IDDSI swallowing grade evaluation of hydrogels.

[0090] To evaluate swallowing safety, in addition to hardness and cohesiveness, this experimental case further recorded the results of three operational tests: adhesion, water separation rate, and IDDSI, as shown in Table 4. Figure 2 As shown. For foods with swallowing difficulties in the elderly, higher cohesiveness helps maintain the integrity of the food bolus, lower adhesion helps reduce the risk of residue in the pharynx or on the spoon surface, and lower water separation rate helps reduce the risk of aspiration caused by free water.

[0091] Texture and Swallowing Safety Assessment: A texture analyzer was used for TPA testing to record hardness, cohesiveness, and adhesion. Adhesion was expressed as the absolute value of adhesion work; a higher value indicates a higher risk of residue on the spoon surface or oral cavity. Water separation rate was calculated as the ratio of the mass of water separated after a certain storage time to the initial mass of the sample. IDDSI evaluation included spoon tilt test, fork drip test, and fork pressure test, and was assessed based on whether the sample slid off completely, whether it stuck to the sides or formed strings, whether it dripped from the fork crevices, and whether it retained a complete fork tooth imprint after fork pressure.

[0092] Table 4. Texture characteristics and swallowing safety related indicators of 3D-printed hydrogels in each experimental group

[0093]

[0094] From Table 4 and Figure 2 It can be seen that Example 1 has moderate hardness, high cohesiveness, and low adhesion, combining good printing structural stability and swallowing bolus integrity, making it suitable as a 3D printing matrix for foods with swallowing difficulties in the elderly. Comparative Example 1 does not meet the IDDSI 4 standard; its hardness and cohesiveness are significantly low, its gelation and structural stability are insufficient, and its printing support effect is far inferior to Example 1. Comparative Example 2 has high hardness but low cohesiveness, and its bolus integrity and smoothness are both weaker than Example 1. Comparative Example 3 has excessively high adhesion; it sticks to the side of the spoon when tilted and cannot maintain its shape after being pressed with a fork, failing to meet the IDDSI 4 standard requirements and posing a swallowing safety hazard.

[0095] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of the claims of this patent application.

Claims

1. An oat protein composite hydrogel ink suitable for use by a dysphagia sufferer, characterised in that, It is made from the following raw materials in weight percentage: 19.0~21.0% oat protein isolate-inulin Maillard reaction covalent complex, 0.7~0.9% κ-carrageenan and 0.6~0.8% xanthan gum, with the balance being purified water; the oat protein isolate-inulin Maillard reaction covalent complex is prepared by reacting oat protein isolate with inulin via a solid-phase dry heat Maillard reaction.

2. The oat protein composite hydrogel ink suitable for use by dysphagic individuals according to claim 1, characterized in that, During the solid-phase dry heat Maillard reaction, the mass ratio of oat protein isolate to inulin is 1:(2~2.5), and the purity of inulin is above 90%. The inulin is food-grade low-polymerization inulin or fructooligosaccharide-type inulin with an average degree of polymerization of DP 2~20.

3. The oat protein composite hydrogel ink suitable for use by dysphagic individuals according to claim 2, characterized in that, The solid-phase dry thermal Maillard reaction was carried out at a temperature of 50–60°C, a relative humidity of 75%–82%, and a reaction time of 24–48 h.

4. The oat protein composite hydrogel ink suitable for use by dysphagic individuals according to claim 2 or 3, characterized in that, The oat protein isolate-inulin Maillard reaction covalent complex is prepared by mixing oat protein isolate, inulin and deionized water to prepare a mixed solution with a total solids content of 10-15%, adjusting the pH to 7.5-8.5, freeze-drying and then performing a solid-phase dry heat Maillard reaction.

5. A process for the preparation of an oat protein composite hydrogel ink suitable for use by dysphagic individuals, characterised in that, The method includes the following steps: mixing the oat protein isolate-inulin Maillard reaction covalent complex according to any one of claims 1-4 in the following weight percentages: 19.0~21.0% oat protein isolate-inulin Maillard reaction covalent complex, 0.7~0.9% κ-carrageenan and 0.6~0.8% xanthan gum, with the balance being purified water, and then sequentially subjecting the mixture to hydration, degassing, heat treatment and cooling to obtain the composite hydrogel ink.

6. The method for preparing oat protein composite hydrogel ink suitable for patients with swallowing disorders according to claim 5, characterized in that, The hydration process involves first pre-dry mixing oat protein isolate-inulin Maillard reaction covalent complex, κ-carrageenan, and xanthan gum to obtain a mixed powder. Then, the mixed powder is mixed with purified water at 70-80°C and stirred at a high speed of 4000-6000 rpm for 2-3 minutes.

7. The method for preparing oat protein composite hydrogel ink suitable for patients with swallowing disorders according to claim 5 or 6, characterized in that, The degassing is centrifugal degassing or vacuum degassing; the heat treatment is heating in a water bath at 87~93°C for 10~13 min; the cooling is rapid cooling in an ice-water bath; after cooling, there is also an equilibration treatment, which is refrigerating at 4°C overnight and equilibrating at room temperature for 30~35 min before 3D printing.

8. A 3D-printed hydrogel suitable for people with swallowing disorders, characterized in that, The oat protein composite hydrogel ink prepared by the method described in any one of claims 1-4 or the method described in any one of claims 5-7 is 3D printed; the hydrogel has a cohesiveness of 0.6~1.0 and an adhesion of 0.4~0.5 mJ.

9. The 3D-printed hydrogel for individuals with swallowing disorders according to claim 8, characterized in that, The 3D printing conditions are as follows: injection barrel temperature is 25–30°C; nozzle diameter is 0.6–1.0 mm; layer height is 0.5–0.8 mm; and printing speed is 10–20 mm / s.

10. The application of a 3D-printed hydrogel suitable for patients with swallowing disorders in personalized 3D-printed swallowing diets for patients with swallowing disorders, characterized in that, The 3D-printed hydrogel is the 3D-printed hydrogel suitable for people with swallowing disorders as described in claim 8 or 9.

Images