METHOD AND PRODUCT FOR PREPARING EASY-TO-SWALLOW FOOD BY REGULATING PROTEIN ELECTROSTATIC INTERACTION
Patent Information
- Application Number
- NL4000259
- Authority / Receiving Office
- NL · NL
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2025-07-17
- Filing Date
- 2025-10-17
- Publication Date
- 2026-07-02
- Estimated Expiration
- 2045-10-16
Smart Images
Figure 00000000_0000_ABST
Abstract
Description
TECHNICAL FIELD The invention relates to the field of food technology, in particular to a . BACKGROUND Easy-to-swallow food refers to a type of food specially designed to meet the dietary needs of people with reduced chewing and / or swallowing functions (such as the elderly, post-operative rehabilitation patients) by improving the physical properties of food (such as texture, consistency, particle size). Its forms range from solid to liquid, which are specifically divided into six categories, corresponding to 6 grades in texture classification. Dysphagia is a common problem caused by various diseases or aging, and patients often need to use modified easy-to- swallow food to assist in eating. At present, most commercially available gel-like dysphagia foods rely on thermally induced gel systems, which have unstable texture and are difficult to balance swallowing safety and nutrient retention. Black rice anthocyanin (BRA) is a natural water-soluble functional pigment with antioxidant, anti-inflammatory and neuroprotective effects, but its stability in the gastrointestinal environment is poor. In addition, gels prepared by a single protein or polysaccharide system cannot meet the texture adjustment requirements of the IDDSI standard (such as Levels 3-5) for patients with dysphagia, so there is an urgent need to develop a new type of composite gel system with a charge-regulated stable structure. Egg white protein (EWP) is a natural protein that can be thermally induced to gel. If it is subjected to charge regulation modification (such as phosphorylation, succinylation), its negative charge density can be significantly increased, thereby regulating its conformational behaviour, interaction and network assembly characteristics in the composite gel system. The existing technologies have the following defects: (1) Most commercially available dysphagia foods rely on thermally induced gel systems, which have unstable texture and are difficult to balance swallowing safety (IDDSI standard) and nutrient retention. (2) A single protein / polysaccharide gel cannot meet the IDDSI Level 5 texture requirements, and the bioavailability of active ingredients such as black rice anthocyanin (BRA) is low. Therefore, to solve the above technical problems, it is necessary to develop a . SUMMARY The purpose of the invention is to provide a . By enhancing the negative charge density of egg white protein (EWP) through charge regulation modification (such as phosphorylation, succinylation), it can dominate the electrostatic cross-linking of the gel network and achieve precise texture control. To achieve the above purpose, the invention adopts the following technical schemes: In the first aspect of the invention, a are provided, and the method includes: homogenizing black rice paste to form a colloidal matrix; and adding modified egg white protein with a mass concentration of 5%-10% to the colloidal matrix, mixing uniformly, then performing thermal induction to form a gel, and cooling for shaping to obtain a composite gel product (BRP), so that the product achieves a precisely controllable IDDSI Level 5 texture grade. Further, the modified egg white protein (MEWP) is modified by phosphorylation combined with succinylation, and the grafting rate of negative charge groups of the modified egg white protein is 15% - 30%. Further, the phosphorylation combined with succinylation modification uses sodium tripolyphosphate and succinic anhydride to react at pH 7 and a temperature of 65°C for 4 - 12 hours. As a specific implementation mode, sodium tripolyphosphate and succinic anhydride are used as modifiers to react with egg white protein at pH 7 and a temperature of 65°C for 4 - 12 hours, where the mass ratio of sodium tripolyphosphate, succinic anhydride and egg white protein is 2 : 1 : 7. Further, the conditions of the thermal induction include: a temperature of 85°C i 2°C and a time of 10 - 30 minutes. In the second aspect of the invention, a product prepared by the above method is provided. Further, when the concentration of the modified protein is 5%-10%, it passes the IDDSI Level 5 test: after pressing with a fork, broken particles remain in the gaps, and all slide off when the spoon is tilted. One or more technical solutions in the embodiments of the invention have at least the following technical effects or advantages: 1. The provided by the invention introduce controllable negative charge density through charge-regulated modified egg white protein (phosphorylation / succinylation); it combines black rice protein and polysaccharides to construct an electrostatic cross-linked network, realizing a composite gel (BRP) with IDDSI Level 5, enzyme hydrolysis resistance and high nutrient retention. 2. The invention accurately controls the ionic bond cross-linking density by regulating the concentration of modified protein (5%-10%), realizing: (1) achieving IDDSI Level 5 (fine filling type) by regulating protein electrostatic interaction: when the concentration of modified protein is 5% - 10%, more than 50% of broken particles remain after pressing with a fork, and all slide off when the spoon is tilted (see Fig. 5); accurately regulating IDDSI Level 5 through negative charge density to reduce the risk of aspiration; the electrostatic cross-linked network improves the resistance to salivary enzyme hydrolysis (structural integrity > 90%). (2) improving swallowing safety anti-aspiration performance: the electrostatic cross-linked network significantly enhances cohesion, enabling the gel to maintain integrity during oral processing (structural integrity after simulated salivary enzyme hydrolysis > 92%, while that of the control group < 10%), see Fig. 3 for the comparison of microstructures. (3) enhancing nutritional functions efficient embedding of black rice anthocyanins: the negative charge network forms a dense microenvironment (reduced porosity in Fig. 2), increasing the retention rate of black rice anthocyanins from 22.3% (control group) to 58.7% (an absolute increase of 36.4 percentage points). 3. The invention realizes a new gel construction strategy for regulating protein conformation and force structure by introducing different degrees of negative charge density; it forms a network structure with the synergistic cross-linking of electrostatic interaction + hydrophobic interaction + disulfide bonds, significantly improving the stability, mechanical strength and enzyme hydrolysis resistance of the gel; through the adjustment of the concentration of different modified egg white proteins, it can accurately control the texture of IDDSI standard Level 5 dysphagia food, which has important clinical nutritional value. BRIEF DESCRIPTION OF THE FIGURES To explain the technical solutions in the embodiments of the invention more clearly, the following will briefly introduce the drawings needed in the description of the embodiments. Obviously, the drawings in the following description are some embodiments of the invention. For those of ordinary skill in the art, other drawings can also be obtained according to these drawings without creative work. Fig. 1 is a graph showing the change of the proportion of molecular forces under different modification concentrations. Fig. 2 is the microstructure of anthocyanin-double protein composite gels with different concentrations of modified egg white protein added. Fig. 3 is the microstructure of anthocyanin-double protein composite gels with different concentrations of modified egg white protein added after simulated oral processing, where SBRP represents the black rice anthocyanin protein gel after saliva treatment. Fig. 4 are the results of the IDDSI texture classification test of samples with different concentrations (0%-7.5%) of modified egg white protein added. Fig. 5 are the results of the IDDSI texture classification test of samples with different concentrations (10%) of modified egg white protein added. Fig. 6 shows the ATR infrared spectra of samples with different EWP addition amounts; (A) is BRP before saliva treatment, and (B) is SBRP after saliva treatment. Fig. 7 shows the apparent viscosity curves of samples with different EWP addition amounts; (A) is BRP before saliva treatment, and (B) is SBRP after saliva treatment. Fig. 8 shows the amplitude sweep curves of samples with different EWP addition amounts; (A) is BRP before saliva treatment, and (B) is SBRP after saliva treatment. Fig. 9 shows the frequency sweep curves of samples with different EWP addition amounts; (A) represents the changes of G' and G" of BRP with angular frequency before saliva treatment; (B) represents the changes of G' and G" of SBRP with angular frequency after saliva treatment; (C) represents the change of tanö of BRP with angular frequency before saliva treatment; (D) represents the change of tanô of SBRP with angular frequency after saliva treatment. DESCRIPTION OF THE INVENTION The invention will be specifically explained below in combination with specific implementation modes and embodiments, and the advantages and various effects of the invention will be more clearly presented. Those skilled in the art should understand that these specific implementation modes and embodiments are used to explain the invention, not to limit the invention. Throughout the specification, unless otherwise specified, the terms used shall be understood as the meanings commonly used in the field. Therefore, unless otherwise defined, all technical and scientific terms used in the invention have the same meanings as those understood by those of ordinary skill in the art to which the invention belongs. If there is a conflict, the specification shall prevail. Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the invention can be purchased from the market or prepared by existing methods. The following will explain in detail a traditional Chinese medicine preparation for preventing and treating fish trichodinosis in the application with examples, comparative examples and experimental data. Embodiment 1: A 1. Preparation of black rice paste: taking 100 g of black rice (containing natural black rice anthocyanins), crushing and sieving through a 100-mesh sieve; adding deionized water to adjust the solid content to 20%, and gelatinizing at 90°C for 30 minutes; treating with a homogenizer (50 MPa, 2 times) to obtain a colloidal matrix. The black rice paste contains black rice anthocyanins. 2. Preparation of modified protein Phosphorylation combined with succinylation modification: using sodium tripolyphosphate, succinic anhydride and egg white protein to react at pH 7 and a temperature of 65°C for 8 hours. The mass ratio of sodium tripolyphosphate, succinic anhydride and egg white protein is 2:1:7. 3. Adding modified egg white protein with a mass concentration of 5% to the colloidal matrix, mixing uniformly, then performing thermal induction to form a gel, and cooling for shaping to obtain a composite gel product. Embodiment 2 In this embodiment, modified egg white protein (MEWP) with a mass concentration of 7.5% is added, and other steps are the same as those in Embodiment 1. Embodiment 3 In this embodiment, modified egg white protein (MEWP) with a mass concentration of 10% is added, and other steps are the same as those in Embodiment 1. Comparative Example 1 This comparative example only contains the natural components of black rice paste, without adding modified egg white protein (MEWP), and other steps are the same as those in Embodiment 1. Comparative Example 2 In this comparative example, modified egg white protein (MEWP) with a mass concentration of 2.5% is added, and other steps are the same as those in Embodiment 1. Experimental Example 1: Composition of Molecular Forces 1. The soluble proteins treated with different reagents are used to determine the change trend and relative proportion of various intermolecular forces in the composite gel systems of each example and comparative example, and the results are shown in Fig. 1. Fig. 1 shows the change trend and relative proportion of various intermolecular forces in the composite gel system under different negative charge density regulation conditions (by adjusting the addition amount of modified egg white protein). It can be seen from Fig. 1 that with the increase of the concentration of modified egg white protein, the content of disulfide bonds in the gel increases most obviously (from 8% to 13%), but the proportion decreases (from 80% to 65%), indicating that although the covalent cross-linking is enhanced, the dominant force of the structure is gradually changed from disulfide bonds to ionic bonds; the content of ionic bonds increases significantly (from 0.2% to 3.5%, and the proportion increases to 18%), indicating that the negative charge-mediated electrostatic cross- linked network is formed; the contents of hydrophobic interaction and hydrogen bonds increase slightly, but their relative proportions basically remain unchanged. The experimental results show that with the enhancement of the grafting degree of negative charge groups, the main intermolecular forces (disulfide bonds, ionic bonds, hydrophobic interactions, hydrogen bonds) in the gel all increase to different degrees. Among them, the content of disulfide bonds increases most obviously, from the initial about 8 mg / mL to 13 mg / mL, which is attributed to the formation of more covalent bonds by the sulfhydryl groups in the egg white protein under heat treatment. At the same time, the content of ionic bonds increases from 0.2 mg / mL to 3.5 mg / mL, and its proportion increases significantly, from the initial about 2% to 18%, indicating that charge regulation significantly enhances the electrostatic interaction between protein chains, providing important support for the establishment of the gel network structure. In contrast, the contents of hydrophobic interaction and hydrogen bonds also increase, but their proportions in the total forces basically remain stable, maintaining at about 13% and 4% respectively. It should be noted that although the absolute value of disulfide bond content increases significantly, its relative proportion in the total force decreases from about 80% to 65%, indicating that in the negative charge-dominated system, the electrostatically driven ionic bonds gradually become one of the dominant forces. In conclusion, negative charge regulation not only promotes the formation of cross-linked structures between proteins, but also significantly changes the chemical force composition of the gel. Among them, ionic bonds, disulfide bonds and hydrophobic interactions are the main contributing forces to maintain the gel stability, and the contribution importance of ionic bonds increases with the enhancement of the modification degree. 2. Phosphorylation combined with succinylation modification The negative charge density on the surface of egg white protein is determined under the conditions of Comparative Example 1 (without modification), single modification and Embodiment 1 of the invention (5% combined modification), as shown in the following table. Table 1 white protein (measured at pH 7.0) It can be seen from Table 1 that the surface negative charge density of egg white protein is significantly increased by introducing phosphorylation-succinylation combined modification. In Embodiment 1, the modified protein (MEWP) forms a composite cross-linked structure dominated by electrostatic attraction and supported by disulfide bonds and hydrophobic interactions in the black rice paste matrix. With the increase of the concentration of modified protein, the content of disulfide bonds in the gel increases from 8 mg / mL to 13 mg / mL, but the relative proportion decreases from 80% to 65%, while the content of ionic bonds increases from 0.2 mg / mL to 3.5 mg / mL, and the proportion increases to 18%, indicating that electrostatic interaction gradually becomes the dominant force for structure construction. Experimental Example 2: Performance Comparison Experiment The hardness, adhesiveness, resilience, cohesion, elasticity, gumminess and chewiness of the composite gel products obtained in Embodiments 1-3 and Comparative Examples 1-2 are determined. In addition, the composite gel products obtained in Embodiments 1-3 and Comparative Examples 1-2 are subjected to incubating artificial saliva at 37°C for 10 minutes using a constant temperature water bath to simulate the oral environment temperature; the BRP gel samples are prepared into cylinders with a diameter of 3 cm and a height of 10 mm; before the test, saliva accounting for 20% of the sample volume is added to the upper and lower parts of the sample respectively; after adding saliva, the samples are incubated at 37°C for 1 minute using a constant temperature water bath to simulate the short-term interaction between the samples and saliva in the oral environment, forming the protein gel samples (SBRP-0%, SBRP- 2.5%, SBRP-5%, SBRP-7.5%, SBRP-10%) after saliva treatment as shown in Fig. 3. Then, the hardness, adhesiveness, resilience, cohesion, elasticity, gumminess and chewiness are determined, and the results are shown in table 2. From these results, it can be seen that: After saliva treatment in the oral cavity: (1) Hardness decrease: for BRP-10%, the hardness decreases from 850.65 9 to 787.41 9. Saliva hydrolysis and wetting lead to softer texture, but the decrease range is limited due to the high integrity of the electrostatic cross-linked network. (2) Chewiness decrease: for BRP-10%, the chewiness decreases from 579.41 to 546.74. The electrostatic / covalent cross-linking enhances the structure recovery force, and good shear resistance is still maintained even if it is partially damaged. (3) Little change in cohesion: the cohesion of BRP-5% is 0.56 before and after treatment. The electrostatic repulsion of proteins forms a dense structure, preventing saliva from dispersing the gel microstructure. (4) Little change in gumminess: the gumminess changes from 422.28 to 367.29, indicating that the adhesive force is mainly derived from the network structure dominated by the surface charge of proteins, and residual adsorption is still maintained after damage. (5) In the simulated saliva treatment experiment, the hardness, chewiness and gumminess of the gel decreased slightly after treatment, but the change range is significantly lower than that of the group without modified protein added. The chewiness of BRP-10% decreased from 579.41 to 546.74, and the change is relatively slow, indicating that the structural network formed under electrostatic driving has strong stability and resistance to saliva degradation. This structural feature is particularly critical for patients with dysphagia, as it can maintain the gel structure from collapsing during oral shearing and wetting, reducing the risk of aspiration. Table 2 U) 8 ê 8 5 à ? ä = <> Ë: $ ë Ë .s Ë'äïgëeä Group I 5 & o . a 5 < u----- Comparative Example1 BRP-0% 61.35 -53.70 _m 97.38 55.10 53.66 Comparative Example2 BRP-2.5% 85.35 -139.64 10.14 89.05 46.20 41.15 Embodiment1 BRP-5% 243.90 -116.88 16.77 90.58 130.72 118.46 Embodiment2 BRP-7.5% 660.21 -114.72 28.12 91.18 422.28 387.60 Embodiment3 BRP-10% 850.65 -41.44 35.88 87.19 621.18 579.41 Comparative Example 1 + SBRP-0% 35.64 -30.86 4.60 0.76 95.64 27.21 26.02 saliva treatment Comparative Example 2 + SBRP- 64.93 -67.26 12.00 0.50 84.69 32.44 27.53 saliva treatment 2.5% Embodiment 1 + saliva SBRP-5% 217.58 -55.48 15.06 0.56 85.12 114.75 83.050 treatment Embodiment 2 + saliva SBRP- 555.49 -39.46 27.40 0.56 82.45 367.29 303.24 treatment 7.5% Embodiment 3 + saliva BRP-10% 787.41 -23.39 34.94 78.75 594.67 546.74 treatment Experimental Example 3: Gel IDDSI Texture Classification Test According to the International Dysphagia Diet Standardization Initiative (IDDSI), which is also a widely recognized standard, the initiative divides the food for people with dysphagia into eight levels (0 to 7). Table 3 shows the International Dysphagia Diet Classification. Levels 3 to 7 are semi-solid or solid foods, which are evaluated by spoon tilting or fork pressure tests. From Level 3 to 7, the food texture gradually changes from viscous (no need for chewing) to semi-solid or solid (needing chewing for swallowing). The pressure exerted by the human tongue during swallowing can be as high as about 17 kPa, which is equivalent to the pressure applied when testing foods of Levels 3 to 7. Table 3 International Dysphagia Diet Classification Test Level Judgment Standard Characteristics Examples Method Fork, Ability to maintain _ _ _ 3 Flowable and thick Thick yogurt, rice paste spoon shape Fork, Ability to maintain Carrot puree, avocado puree or 4 Viscous spoon shape potato puree Minced meat, minced fish, fruit Fork, Ability to maintain Soft and moist without liquid 5 puree, soft bread, cooked carrot spoon shape on the surface _ diced During the breaking process, Fork, Ability to the food is moist and soft, Tender cooked meat, cooked fish, 6 spoon, decompose into _ _ _ _ _ _ _ With no flowable thin l|qU|d b0iled or steamed vegetables chopsticks small pieces around or on the surface 7 - - Hard, naturally soft or fluffy Various foods with normal texture To determine the feasibility of each group of samples as dysphagia food, the fork pressure test, dining car drop test and spoon tilting test are carried out according to the International Dysphagia Food Standard (referred to as IDDSI) formulated by the International Dysphagia Food Standard Action Committee. By regulating the introduction degree of negative charge groups in egg white protein, the performance of the composite system in the IDDSI (International Dysphagia Diet Standard) test is significantly improved, which is manifested in the systematic regulation of cohesion, adhesiveness and fluidity. 2. IDDSI Swallowing Safety Test Table 4 Spoon Tilting Test Group Fork Pressure Test Result IDDSI Level Result Comparative Completely broken and scattered, Flowing quickly Level 3 Example 1 passing through the fork gaps without residue (moderately thick) _ _ _ _ _ Adhering to the Comparative Small broken particles remaining in Level 4 _ _ _ spoon surface _ _ Example 2 the gaps, no whitening of nails _ _ (highly thick) Without flowmg More than 50% of broken particles All sliding off without Level 5 Embodiment1 _ _ _ _ _ _ _ remaining, tight structure reSIdue (fine filling type) Embodiment 2 More than 50% of broken particles All sliding off without ___ remaining, slightly higher hardness slowly, no residue (fine filling type) It can be seen from Table 4 and Figs. 4 - 5 that: In Comparative Example 1, BRP-0% (without modified egg white protein added): the sample has a loose structure and insufficient cohesion, which is easy to break and scatter when pressed with a fork, and cannot maintain its shape in the drop test, with strong fluidity. It is determined as IDDSI Level 3 (moderately thick), with a certain risk of aspiration. In Comparative Example 2, BRP-2.5%: after adding an appropriate amount of charge- modified egg white protein, the sample structure is enhanced, which can maintain a piled shape on the spoon surface, with reduced fluidity and good performance in the drop test. It is determined as IDDSI Level 4 (highly thick), suitable for people with dysphagia who need moderate support. In Embodiment 1, BRP-5%: the sample shows higher cohesion and good shape retention, which can not only adhere to the spoon surface, but also slide down smoothly under appropriate external force, meeting the requirements of IDDSI Level 5 (fine filling type), and is an ideal state of dysphagia food. In Embodiment 2, BRP-7.5%: more than 50% of broken particles remain, with a tight structure, meeting the requirements of IDDSI Level 5 (fine filling type), and is an ideal state of dysphagia food. In Embodiment 3, BRP-10%: after further improving the charge regulation level, the sample maintains the structural characteristics of the fine filling type, while the hardness increases, and has strong self-sustaining shape ability. However, if the intake is too large, it may cause swallowing discomfort or obstruction risk. It is still determined as IDDSI Level 5 (fine filling type), suitable for consumption under the condition of controlled dosage. In conclusion, negative charge regulation, as a structural modification method, can realize the precise regulation of the consistency level of dysphagia food, and while meeting the food rheological properties, it effectively reduces the risk of aspiration and improves swallowing safety and palatability. 3. Comparison of functional characteristics is shown in Table 5. Table 5 Resistance to salivary enzyme Retention rate of black rice Risk of swallowing aspiration High risk Very low risk 4. From the perspective of texture classification, the concentration of 5%-10% all belongs to Level 5, and a further analysis is made in combination with the texture data: Table 6 A (D O) w a 9 : $ ä 3 3 ë 8 g 8 Ê E % $ % 6 ;;, % & ä £ 8 8 a = 5 w % 8 I (D < Stable Moderate hardness, 243.90 130.72 118.46 -116.88 Embodiment BRP- (90.58 decreased > > > > 1 5% > adhesiveness, good 217.58 114.75 83.05 -55.48 85.12) structural stability Slightly hard, relatively 660.21 422.28 387.60 91.18 -114.72 Embodiment BRP- high gumminess, still > > > > > 2 7.5% tight structure after 555.49 367.29 303.24 82.45 -39.46 saliva treatment Too hard, too strong 850.65 621.18 579.41 -41.44 Embodiment BRP- Significant adhesiveness, reducing > > > > 3 10% decrease sliding property and 787.41 594.67 546.74 -23.39 palatability It can be seen from Table 6 that: Optimal addition amount: 5% modified protein, IDDSI Level 5, suitable for patients with severe dysphagia, Embodiemnt 1 is the best example; Balanced texture: moderate hardness (<300 g), chewiness within the safe swallowing range, and gumminess suitable for sliding; Stable performance after saliva treatment, indicating that the gel structure has good stability under electrostatic cross-linking; In terms of electrostatic regulation mechanism: at 5%, the ratio of ionic bonds to disulfide bonds is balanced, which synergistically maintains a good composite network structure without excessive rigidity; Best palatability, minimum risk of aspiration, and friendly to oral processing. Through the swallowing level test and texture parameter analysis, it is found that when the addition amount of modified egg white protein is 5%, the prepared composite gel can reach Level 5 "fine filling type" in the IDDSI classification standard, showing good swallowability and structural stability. Compared with the low-concentration group, the gel hardness, elasticity and adhesiveness of this group are all in the appropriate range, and the structural damage is small after saliva treatment, which is suitable for oral processing of patients with dysphagia. Although the protein addition higher than 7.5% can enhance the colloidal network, the hardness and gumminess increase significantly, with the risk of choking. Therefore, 5% is the optimal addition amount under charge regulation, and the composite electrostatic network structure formed by it has significant advantages in improving swallowing safety, oral sliding property and storage stability. Charge regulation mainly enhances the electrostatic attraction between proteins (the ionic bond content increases to 3.5 mg / mL, and the proportion increases to 18%), strengthens the network structure of the gel, thereby improving its formability, resistance to saliva damage, shape retention and oral sliding property. Compared with the network mainly supported by covalent bonds and disulfide bonds, electrostatic regulation endows the gel with more flexible and palatable characteristics. It can be seen from the above that the method of the application can greatly improve the retention rate of black rice anthocyanins, and the prepared product realizes precise control of the IDDSI Level 5 texture, which is suitable for patients with dysphagia caused by stroke, Alzheimer's disease, etc., and has both high safety and nutritional functions. Experimental Example 4: Comparison Before and After Saliva Treatment (l) Molecular Structure Regulation Mechanism Revealed by Functional Group Changes 1. Displacement of OH / NH peak positions (about 32703300 cm"): Phenomenon: with the increase of the concentration of modified protein, the peak position of OH / NH stretching vibration shifts slightly to the blue, from 3305.7 cm1 to 3282.3 cm'1. It shows that the hydrogen bond network is broken or reconstructed, and new hydrogen bond arrangements are formed between proteins; the hydrogen bond interaction between modified protein molecules is enhanced, which is conducive to the densification of the gel structure and the improvement of network stability. 2. Enhancement of Amide l & ll regions and stable peak positions: Amide l (about 1653 cm'1) and Amide ll (about 1533 cm4) are the characteristic peaks of the secondary structure of proteins. In the modified group, there is no obvious displacement of these peaks in terms of wave number, but the intensity is increased, especially at the protein concentration of 5%-10%. It indicates that after the introduction of negative charges, the conformational stability of the protein is enhanced (the proportion of ß-sheet is increased), which can induce more regular aggregation and directional binding, supporting the construction of a stable network. 3. Enhancement of characteristic peaks of phosphate / ester bonds at about 1010950 cm'1: This is the absorption peak of new functional groups generated by phosphorylation (P=O, POC) and succinylation modification. The higher the modification concentration, the more obvious the characteristic peak (such as 995.7 cm'1 > 1016.8 cm'1), indicating that the modified groups are fully introduced. These groups enhance the negative charge density, which is conducive to the formation of an electrostatic repulsion-entanglement network and drives the formation of a stable gel between molecules. (ll) Mechanism of Enhanced lntermolecular Forces 1. Electrostatic interaction: After modification, the surface Zeta potential decreases significantly (-29.6 mV), indicating that the protein forms a stronger electrostatic repulsion network. lt promotes the uniform dispersion of proteins, avoids aggregation and precipitation, and is conducive to the formation of a uniform colloidal system. 2. Rearrangement of hydrogen bonds and hydrophobic interactions: The changes in the OH / NH region and CH peaks indicate that under thermal induction, the protein forms a structure with a hydrophobic cross-linked core and a hydrogen bond network shell. The modified protein provides more functional groups involved in the interaction, which is conducive to the multi-point and multi-dimensional network construction and improves cohesion. 3. Synergy of covalent and non-covalent cross-linking mechanisms: The phosphate / succinyl groups introduced by modification enhance the electrostatic cross- linking with anthocyanins / proteins in the black rice paste. A three-way cross-linked structure of "protein-anthocyanin-protein" is formed, which enhances the mechanical strength and enzyme hydrolysis resistance of the gel. Table 7 Modification _ Spectral Support Technical Advantage Mechanism Formation of electrostatic cross- _ Increased negative potential + _ _ _ _ Charge denSIty linked network, realizmg pre0ise enhanced characteristic peaks (1014- regulation regulation of IDDSI levels (Levels 4 1016 cm") 5) Hydrogen Dense gel structure, maintaining Blue shift of OH / NH region + bond / conformational _ integrity in the oral cavity (resistance enhancement of Amide l / ll stability to salivary enzyme hydrolysis) Enhanced cohesion and structural Cross-linking Enhanced characteristic peaks + strength, improving anthocyanin enhancement increased ßsheet structure embedding efficiency The FTIR spectra of A and B in Fig. 6 clearly characterize the change trend and characteristic peak enhancement of protein functional groups (OH / NH, Amide l / ll, P=O) with the increase of the concentration of modified egg white protein (2.5% > 10%). Combined with the Zeta potential test data (-10.8 mV > -29.6 mV), it is proved that the phosphorylation- succinylation combined modification significantly increases the negative charge density of the protein, thereby driving the formation of a stronger electrostatic network structure. By regulating the hydrogen bonds, hydrophobic interactions and electrostatic repulsion between proteins, precise control of the IDDSI level and significant improvement of the gel structure stability are realized. (III) Rheological Property Analysis By regulating the addition amount (5%10%) of phosphorylated-succinylated modified egg white protein (MEWP), the invention forms a composite protein-polysaccharide network in the black rice matrix, realizing the enhancement of rheological properties, the improvement of structural stability and the improvement of swallowing safety. 1. Viscosity determination As shown in Fig. 7 (A), before saliva treatment, the apparent viscosity of samples with different MEWP addition amounts decreases with the increase of shear rate, showing shear thinning behavior and presenting the characteristics of typical pseudoplastic fluids. It indicates that when the sample is subjected to shear force, the internal gel structure is destroyed, the relative interaction between molecules is weakened, and the apparent viscosity decreases, which meets the requirements of dysphagia food for "palatability" and "low swallowing resistance". The viscosity of the group without modified protein added (BRP-0%) at low shear rate is 325 Pa-s, while that of the group with 10% modified protein added (BRP-10%) increases to 40675 Pa-s, with an increase of more than 125 times. It indicates that the negatively charged enhanced protein and black rice polysaccharide undergo charge complementarity, hydrophobic cross-linking and multi-point coupling of entanglement structures, significantly enhancing the structural viscosity and shear resistance of the gel. After saliva treatment, the viscosity of SBRP-0% is extremely low (from 325 to 106 Pa-s), while the high-protein addition group (SBRP-10%) still maintains high viscosity (from 40675 to 7465 Pa-s), indicating that the cross-linked network under high negative charge density has stronger resistance to enzyme hydrolysis. It supports the functional goals of improving swallowing safety and prolonging the structure retention time in the oral cavity. As shown in Fig. 8 (A), before saliva treatment, the shear stress of black rice gels with different MEWP addition amounts increases with the increase of shear strain, and under the same shear strain, the shear stress of black rice gels increases with the increase of MEWP addition amount. Under the same shear strain, the BRO-0% sample without MEWP added has the lowest shear force, which is 0 - 162 Pa, and shows a gentle linear response in the low shear strain range of 0% 20%, which indicates that its internal gel network structure is a weak network structure dominated by polysaccharides, with a relatively fragile gel structure and poor resistance to shear deformation. In the samples with MEWP addition amount of 2.5% 10%, with the increase of MEWP addition amount, the shear stress increases significantly, and the shear strain of BRP-10% even reaches 4637 Pa under the condition of 100% shear strain, which is much higher than that of BRO-0% without MEWP added. This indicates that the protein in MEWP forms a denser composite network structure with black rice polysaccharides through hydrophobic interaction and electrostatic complementation, which enhances the stability of the black rice gel structure, makes the gel structure tougher and improves the resistance to shear deformation. At the same time, the linear viscoelastic region (LVR) of BRP samples with low MEWP addition amount is wider, the LVR of BRO-0% is 0% 40% strain, and the LVR of samples with high MEWP addition amount becomes narrower, the LVR of BRO-10% is 0% 20% strain, which indicates that the black rice gel with high EWP addition amount is more sensitive to shear, but the gel structure strength is higher. As shown in Fig. 8 (B), after saliva treatment, the change trend of the shear stress of black rice gels with different MEWP addition amounts is generally similar to that before saliva treatment, but the overall shear stress value is significantly lower than that before saliva treatment. Under the condition of 100% shear strain, the shear stress of BRO-0% decreases from 162 Pa to 60 Pa of SBRO-0%, and the shear stress of BRO-10% decreases from 4637 Pa to 279 Pa of SBRO-0%, which indicates that the salivary enzyme in saliva destroys the formed protein-polysaccharide composite gel structure and reduces the ability of the sample to resist shear deformation. However, the black rice gel with high MEWP addition amount still maintains a certain gel structure, maintaining a certain rheological property of the sample, which can resist shear deformation to a certain extent, help maintain the structural stability of the gel sample during the simulated oral digestion process, prolong the stable time of the food bolus in the oral cavity, and reduce the risk of aspiration. 2. Storage modulus (G') refers to the energy required for a substance to recover after undergoing sinusoidal deformation in one vibration cycle, which can be used to characterize the elastic characteristics of the substance; loss modulus (G") refers to the energy lost or consumed by a substance after undergoing sinusoidal deformation in one vibration cycle, which can be used to characterize the viscous characteristics of the substance. When studying the rheological properties of an object, storage modulus and loss modulus are the most critical parameter indicators. Loss factor (tanô) is the ratio of loss modulus G" to storage modulus G', and with the increase of tanô value, the substance shows more obvious viscous characteristics. Figs. 9 (A) and (C) are graphs showing the changes of storage modulus G', loss modulus G" and loss factor tanô of samples (BRP) before saliva treatment and samples (SBRP) after saliva treatment with angular frequency. Before saliva treatment, the G' and G" values of BRP samples with different MEWP addition amounts all increase with the increase of angular frequency, and G' is greater than G". It indicates that the sample is a gel dynamic rheological system, the sample forms a weak gel, and the viscoelasticity of the sample shows frequency dependence. With the increase of MEWP addition amount from 0% to 10%, the storage modulus G' ofthe sample increases significantly, from 100 Pa to 15000 Pa at low frequency of 0.1 rad / s, which indicates that the elasticity of the sample increases, the cross-linked network between protein and black rice polysaccharide in MEWP is enhanced, and a more stable gel structure is formed. In the BRP-7.5% and BRP-10% groups with high MEWP addition amount, the 6' curve becomes relatively flat, which indicates that the frequency dependence of the sample becomes low, and a more uniform and tough three-dimensional network structure is formed inside the gel, which maintains relatively stable under different shear rates and has stronger resistance to oral shear, and has a more suitable swallowing taste. The loss modulus G" of the sample also increases with the increase of MEWP addition amount, but it is always lower than the storage modulus G', which indicates that the rheological behavior of the BRP sample is dominated by elastic behavior. At high frequency of 100 rad / s, G" tends to be the same with the increase of MEWP addition amount, which is related to the dynamic cross-linking response of the protein in the sample. The loss factor tanô decreases with the increase of MEWP addition amount, and tanô is less than 1. The tanô value of BRP-0% is the highest, and the tanô value of BRP-10% is the lowest, which indicates that the elasticity of the sample increases and the viscosity decreases with the increase of MEWP addition amount. As shown in Figs. 9 (B) and (D), after saliva treatment, the storage modulus G' of all samples decreases significantly, especially the samples with low MEWP addition amount. The G' of SBRP-0% decreases to 10 Pa at 0.1 rad / s. Although the samples with high MEWP addition amount all decrease, they still retain high G', and the G' of SBRP-10% still reaches 5000 Pa at 0.1 rad / s, which indicates that the salivary enzyme in saliva destroys the gel structure in the sample, but with the increase of MEWP addition amount, the gel structure in the sample is retained more and is more stable, which improves the resistance of the gel to saliva decomposition. At the same time, after saliva treatment, the G" of the SBRP-0% sample without MEWP added is greater than G', which indicates that the viscosity of the sample increases significantly, which will affect the swallowing safety. Compared with before saliva treatment, the tanô value after saliva treatment also increases significantly, and the tanö of SBRP-0% is even greater than 1, which further indicates that the cross-linked network structure inside the gel is hydrolyzed by salivary enzymes, leading to increased viscosity and decreased elasticity. The results show that the addition of modified MEWP can improve the rheological properties of the black rice / egg white protein gel system and improve the swallowing safety. In conclusion, frequency scanning: the elastic modulus is significantly increased, forming a high-strength and low-loss swallowing colloid. (1) Enhancement of storage modulus G', elastic structure construction: G' increases from 100 Pa to 15000 Pa at low frequency of 0.1 rad / s (from BRP-0% to BRP-10%), indicating that a large number of electrostatic-hydrophobic-hydrogen bond multi-networks are formed between protein and polysaccharide. After a significant decrease in G', SBRP-10% still maintains a storage modulus of 5000 Pa, while SBRP-0% only has 10 Pa, indicating that the high MEWP group significantly improves the resistance to salivary enzyme hydrolysis and structure retention. (2) Decreased frequency dependence, more uniform structure: the G' curve of the high MEWP group tends to be flat, showing better frequency independence, indicating that a stable and dense three-dimensional gel network is formed, enhancing chewing tolerance and structure retention. (3) Decreased tanö, showing more "elasticity-dominated" characteristics: the tanö value of BRP-10% is the lowest (far < 1), indicating that the internal molecular chain cross-linking density is higher and the structure is more regular, and the taste is more elastic and not easy to fluidize, which is conducive to controlling aspiration. After saliva treatment, the tanô of SBRP-0% is > 1 (viscosity-dominated), while the tanô of SBRP-10% is < 1 (elasticity-dominated), indicating that the addition of charge-regulated protein can effectively avoid the aspiration risk caused by structural collapse during swallowing. In conclusion, based on the above shear rheological behavior, amplitude response and frequency scanning results, by regulating the negative charge density and addition amount (5%- 10%) of modified egg white protein, the invention can construct a three-dimensional composite network structure centered on the electrostatic complementary cross-linking of protein- polysaccharide-anthocyanin, endowing the product with excellent structural stability, resistance to salivary enzyme hydrolysis and rheological viscoelastic properties, so that it maintains integrity during oral chewing and swallowing, meets the IDDSI Level 5 easy-to-swallow food standard, and significantly improves swallowing safety and nutritional effectiveness. Finally, it should also be noted that the terms "including", "comprising" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or equipment including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or elements inherent to such process, method, article or equipment. Although the preferred embodiments of the invention have been described, those skilled in the art can make additional changes and modifications to these embodiments once they learn the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the invention. Obviously, those skilled in the art can make various changes and modifications to the invention without departing from the spirit and scope of the invention. In this way, if these modifications and variations of the invention fall within the scope of the claims of the invention and their equivalent technologies, the invention is also intended to include these changes and variations.
Claims
1. A method for preparing easy-to-swallow food by electrostatic to regulate the interaction of proteins, comprising: the homogenization of black rice paste to form a colloidal matrix; and the addition of modified egg protein to the colloidal matrix with a mass concentration of 5% - 10%, mixing evenly, then performing thermal induction to form a gel, and cooling before molding to obtain a composite gel product, where the product has a precisely adjustable lDDSI texture degree with a value of 5 reaches.
2. The method under claim 1, whereby the modified egg protein is modified by phosphorylation in combination with succinylation, and the inoculation rate of negative charge groups of the modified egg protein amount to 15% - 30%.
3. The method according to claim 1, whereby in the combined phosphorylation succinylation modification makes use of sodium tripolyphosphate and succinic anhydride to react for 4 - 12 hours at a pH of 7 and a temperature of 65 °C.
4. The method according to claim 1, whereby the conditions of thermal induction include a temperature of 85 °C and a time of 30 minutes.
5. A product prepared according to the method according to any of the claims 1 - 4.
6. Application of the product pursuant to claim 5 as an aid in dysphagia in patients with a stroke or Alzheimer's disease. Fig. 1