Method for extracellular preparation of rice bran protein-emblic leafflower fruit polysaccharide covalent graft

Abstract

The invention discloses a method for extracellular preparation of a rice bran protein-emblic leafflower fruit polysaccharide covalent graft, and relates to the technical field of biology. The method comprises the following steps: mixing fresh phyllanthus emblica fruits, rice bran protein and water, carrying out extraction treatment by adopting a flash extractor under the ultrasonic-assisted action, then filtering to obtain filtrate, concentrating the filtrate to obtain a concentrated solution, then carrying out alcohol precipitation treatment to obtain a precipitate, and drying the precipitate to obtain the phyllanthus emblica extract. And freezing and drying to obtain the rice bran protein-emblic leafflower fruit polysaccharide covalent graft. According to the method, the one-step efficient extraction of the emblic leafflower fruit polysaccharide is realized by combining the maximum rotating speed shearing of the flash extractor and the ultrasonic-assisted effect, and the rice bran protein-emblic leafflower fruit polysaccharide covalent graft is formed while the polysaccharide is extracted by controlling the Maillard reaction conditions, so that the yield and the purity of the graft product are remarkably improved, and the cost is reduced. And the stability of the product structure and the maximization of the functionality are ensured.

Description

Technical Field

[0001] The invention relates to the field of biotechnology, in particular to a method for preparing a rice bran protein-emblica polysaccharide covalent grafted product outside a cell. Background Art

[0002] Phyllanthus emblica polysaccharide (PEP) is a natural polysaccharide extracted from Phyllanthus emblica. Polysaccharide is a macromolecular polymer formed by connecting multiple monosaccharide molecules through glycosidic bonds. Rice bran protein (RBP) is a high-quality plant protein with good solubility and foaming properties. Rice bran protein can also be used as a food additive to improve the texture and taste of food. The present invention intends to combine the two through covalent grafting technology to develop a new type of food additive, which can improve the texture of food and increase the water retention and nutritional value of the product.

[0003] In the preparation of protein and polysaccharide polymers, there are chemical reagent cross-linking method, enzyme cross-linking method and Maillard reaction method. The chemical reagent cross-linking method has the advantages of fast reaction and high cross-linking efficiency. However, the cross-linking reagent itself has certain chemical toxicity and will produce irritation reaction to the human body. In addition, the chemical reagent cross-linking method is limited to the types of sugars. Sugars without free amino groups cannot form covalent cross-links with proteins. Enzyme cross-linking method is green and non-toxic, and has strong reaction targeting. However, its reaction efficiency is low, the cost is high, and it is highly restrictive to the substrate. Many sugars without phenolic acid structure and amino group cannot be prepared into covalent complexes with proteins by enzyme cross-linking. Summary of the invention

[0004] The purpose of the present invention is to provide a method for preparing rice bran protein-emblica polysaccharide covalent grafts outside the cell to solve the problems existing in the above-mentioned prior art. The method realizes the one-step efficient extraction of emblica polysaccharides by combining the maximum speed shearing of the flash extractor and the ultrasonic auxiliary effect, and forms rice bran protein-emblica polysaccharide covalent grafts (RBP-PEP) while extracting polysaccharides by controlling the Maillard reaction conditions. The method can make the polysaccharides in the emblica cell dissolve quickly, realize the high-efficiency covalent grafting between rice bran protein and emblica polysaccharides, not only significantly improve the yield and purity of the grafted product, but also ensure the stability of the product structure and the maximization of functionality.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] The present invention provides a method for preparing a rice bran protein-emblica polysaccharide covalent grafted product outside a cell, comprising the following steps:

[0007] After mixing fresh emblica fruit, rice bran protein and water, they are extracted by a flash extractor under the assistance of ultrasound, and then filtered to obtain a filtrate. The filtrate is concentrated to obtain a concentrated solution, and then an alcohol precipitation treatment is performed to obtain a precipitate. After freeze-drying, the rice bran protein-emblica polysaccharide covalent graft is obtained.

[0008] Furthermore, the ratio of the total mass of the fresh fruit of Emblica emblica and the rice bran protein to the mass of the water is 1:35.

[0009] Furthermore, the pH of the reaction system consisting of the fresh fruit of Emblica officinalis, the rice bran protein and the water is 6.5.

[0010] Furthermore, the concentration process is to concentrate the filtrate to 1 / 4-1 / 5 of the original volume.

[0011] Furthermore, the alcohol precipitation treatment is to add ethanol into the concentrated solution so that its volume fraction is 90%.

[0012] Furthermore, the mass ratio of the fresh fruit of Emblica emblica to the rice bran protein is 1:5; and / or

[0013] The ultrasonic power of the ultrasonic auxiliary effect is 640W; and / or

[0014] The extraction temperature of the extraction process is 70°C; and / or

[0015] The extraction time of the extraction process is 200 s.

[0016] The present invention also provides a rice bran protein-emblica polysaccharide covalent grafted product prepared according to the above method.

[0017] The invention also provides application of the rice bran protein-emblica polysaccharide covalent grafted product in preparing food additives.

[0018] The invention also provides a food additive, comprising the rice bran protein-emblica polysaccharide covalent grafted product.

[0019] The present invention also provides application of the above-mentioned food additive in preparing food.

[0020] The present invention discloses the following technical effects:

[0021] The present invention develops a method for preparing rice bran protein-emblica polysaccharide covalent grafts outside the cell, and realizes efficient extraction of emblica polysaccharide in one step by combining the maximum speed shearing of the flash extractor and the ultrasonic auxiliary effect, and forms rice bran protein-emblica polysaccharide covalent grafts (RBP-PEP) while extracting polysaccharide by controlling the Maillard reaction conditions, which is an innovation compared with the traditional extraction and grafting method requiring multiple steps. The method can make the polysaccharide in the emblica cell dissolve quickly, realize the high-efficiency covalent grafting between rice bran protein and emblica polysaccharide, not only significantly improve the yield and purity of the grafted product, but also ensure the stability of the product structure and the maximization of functionality.

[0022] In the method of the present invention, the mechanical shear force and cavitation effect generated by the ultrasonic-assisted flash extractor can destroy the plant cell wall, enhance the combination of polysaccharides and proteins, and improve the grafting efficiency; the high-frequency vibration of the ultrasonic wave promotes the penetration of the solvent and the dissolution of the polysaccharide, and achieves a rapid balance of the concentration of the emblica polysaccharide in the solution. The sufficient addition of rice bran protein forms a graft with an extracellular osmotic pressure higher than that inside the cell, which promotes the precipitation of the emblica polysaccharide inside the cell, and helps to quickly prepare the rice bran protein-emblica polysaccharide covalent graft outside the cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0024] Figure 1 It is a statistical diagram of the grafting degree of covalently grafted rice bran protein-emblica polysaccharide under different mass ratios of fresh emblica fruit and rice bran protein;

[0025] Figure 2 It is a statistical diagram of the grafting degree of rice bran protein-emblica polysaccharide covalent graft under different ultrasonic power conditions;

[0026] Figure 3 It is a statistical diagram of the grafting degree of rice bran protein-emblica polysaccharide covalent grafted products under different extraction temperature conditions;

[0027] Figure 4 It is a statistical diagram of the grafting degree of rice bran protein-emblica polysaccharide covalent grafted products under different extraction time conditions;

[0028] Figure 5 The schematic diagram is a principle diagram of the one-step extracellular extraction of rice bran protein-emblica polysaccharide covalent grafts of the present invention. DETAILED DESCRIPTION

[0029] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0030] It should be understood that the terms described in the present invention are only for describing a particular embodiment and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0031] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0032] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary only.

[0033] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0034] Example 1

[0035] 1. Methods

[0036] 1. One-step extracellular extraction of rice bran protein-emblica polysaccharide covalent grafted product (RBP-PEP)

[0037] Fresh Phyllanthus emblica was chopped and shelled, and a sufficient amount of rice bran protein was added, and deionized water (mass ratio of material to liquid was 1:35) was added, and the pH was adjusted to 6.5. The extract was extracted for a certain period of time in a flash extractor at a speed of 28,000 rpm and with the assistance of ultrasound. The waste residue was filtered out, centrifuged, and the supernatant was collected. The volume of the original solution was 1 / 4-1 / 5, and ethanol was added and adjusted to a final concentration of 90% (volume fraction). The extract was stored at 4°C overnight, centrifuged at 4000rpm for 15min, and the precipitate was collected, freeze-dried, and the extraction rate was weighed. The grafting degree was determined using the physical mixture of Phyllanthus emblica polysaccharide and rice bran protein (RBP / PEP) as a control.

[0038] Single factor experiment: A single factor experiment was used to evaluate the effects of the ratio of emblica fruit puree to rice bran protein, ultrasonic power, extraction temperature and extraction time on the grafting degree GD (%). The single factor experiment was set up as follows: the mass ratio of emblica fresh fruit to rice bran protein (10:1, 5:1, 1:1, 1:5, 1:10); ultrasonic power (480, 560, 640, 720, 800W); extraction temperature (50℃, 60℃, 70℃, 80℃, 90℃); extraction time (50, 100, 150, 200, 250s), as shown in Table 1, where A represents the mass ratio of emblica fresh fruit to rice bran protein, B represents ultrasonic power, C represents extraction temperature, and D represents extraction time.

[0039] Table 1 Extraction parameters of single factor experiment

[0040]

[0041]

[0042] 2. Determination of grafting degree

[0043] Determination of protein-polysaccharide grafting degree: Prepare 0.1% (w / v) 2,4,6-trinitrobenzenesulfonic acid (TNBS) working solution, prepare it before use, and avoid light. Take 3mL 10% (w / v) sodium dodecyl sulfate (SDS) in a test tube, and add 0.3mL sample to the test tube. Add 1.5mL 0.1% (w / v) TNBS and 3mL 0.1mol Na2SO3, mix the solutions evenly, and incubate in a 50℃ water bath in the dark for 1h. After the reaction is completed, let it stand at room temperature in the dark for 15min, set the wavelength to 420nm with an ultraviolet spectrophotometer, and determine its absorbance value. Deionized water is used instead of the sample as a blank control, and the grafting degree GD (%) is calculated as follows:

[0044] DG(%)=(A0-At) / A0×100%;

[0045] Where A0 is the absorbance of the RBP / PEP physical mixture; At is the absorbance of the RBP-PEP graft.

[0046] 2. Results

[0047] like Figure 1 As shown in the figure, with the increase of rice bran protein addition, the grafting degree of RBP-PEP gradually increased, and when the ratio of fresh fruit of emblica to rice bran protein (A) was 1:5 (g / g), the grafting degree GD reached the highest value (8.57%). Ultrasonic cavitation requires negative pressure to overcome the natural viscosity of the liquid in the thin region of the wave function. More solvent reduces the viscosity of the medium and the mass transfer resistance of the active substances dissolved in the solvent, thereby increasing the concentration gradient. The higher concentration gradient facilitates the site binding of emblica polysaccharides and rice bran protein, which improves the grafting efficiency and thus increases the grafting degree of RBP-PEP. Subsequently, when the ratio of fresh fruit of emblica to rice bran protein (A) was 1:10 (g / g), the grafting degree decreased. This phenomenon can be explained as follows: (1) The increase of solvent reduces the probability that the blade of the flash extractor contacts and shears the raw material, thereby reducing the grafting degree of protein and polysaccharide; (2) Excessive addition of rice bran protein makes the concentration and purification process more complicated, resulting in the loss of the target product.

[0048] Figure 2 It was shown that ultrasonic power had a significant effect on the grafting degree of RBP-PEP. In the range of 480-640W, the grafting degree of RBP-PEP increased significantly, reaching a maximum value (8.60%) at an ultrasonic power of 640W, and then the grafting degree decreased. This can be attributed to the physical cavitation effect and the mechanical effect generated by ultrasound, which destroyed the cell wall of Phyllanthus emblica, thereby enhancing the contact between rice bran protein and intracellular polysaccharides and promoting the formation of grafts through dynamic molecular penetration. However, too high ultrasonic power may lead to the degradation of the graft.

[0049] Next, the present invention observed that as the extraction temperature increased from 50°C to 70°C, the grafting degree of RBP-PEP increased significantly ( Figure 3 ). Increasing the extraction temperature can increase the diffusion rate and dissolution rate of polysaccharides in liquids, as well as promote the Maillard reaction. However, when the extraction temperature exceeds 70°C, there is no significant difference in the PEP yield with the change in temperature (P>0.05). Significance analysis shows that the optimal extraction temperature is 70°C. Appropriate extraction temperature can prevent energy waste and achieve a higher polysaccharide extraction rate. In addition, the wet heat Maillard reaction forms a covalent bond between the amino group at the end of the protein residue and the carbonyl group of the carbohydrate (monosaccharide, oligosaccharide or polysaccharide). Too high an extraction temperature will produce thermal processing hazards.

[0050] from Figure 4It can be observed that as the extraction time increases from 50 seconds to 250 seconds, the grafting degree of RBP-PEP increases significantly, reaching a maximum value (8.57%) at an extraction time of 200 seconds, and then the change is no longer significant. The cavitation effect generated by the flash extractor and ultrasound causes more damage to the plant tissue, resulting in a higher grafting degree of RBP-PEP.

[0051] From the above, it can be seen that the optimal process conditions for preparing RBP-PEP grafts by extracellular one-step ultrasonic-assisted flash extraction are: the ratio of fresh fruit of Phyllanthus emblica to rice bran protein is 1:5 (g / g), the ultrasonic power is 640W, the extraction temperature is 70℃, the extraction time is 200s, and the corresponding RBP-PEP grafting degree is 8.60±0.31%. There is no significant difference with the single factor experiment (P>0.05). The yield of RBP-PEP grafts prepared by extracellular one-step ultrasonic-assisted flash extraction is higher than that by hot water extraction and enzyme-ultrasonic extraction. Ultrasonic-assisted flash extraction to achieve the preparation of RBP-PEP grafts is based on the ultra-high-speed rotation of the specially designed head of the flash extractor and the secondary effect it produces, as well as the cavitation effect and solubilization mechanism of ultrasound ( Figure 5 ).

[0052] The flash extractor operates at maximum speed, generating significant mechanical shear forces during the initial extraction, instantly breaking the plant tissue into smaller particles and providing a larger mass transfer area. At the same time, ultrasound can also destroy the plant cell wall within seconds. Subsequently, the mass transfer barrier of the emblica cell wall can be more strongly destroyed. At the same time, the resonance and cavitation generated by ultrasound promote the penetration of the solvent into the cells, initiating the contact and dissolution of PEP. Afterwards, due to the rotation of the blade, a negative pressure vacuum zone is formed between the inner and outer edges, resulting in ultra-dynamic molecular penetration, which accelerates the desorption and dissolution kinetics of PEP from the emblica matrix under negative pressure and strong stirring. Once the PEP are released from the plant cell wall, they are quickly carried away and penetrate into the external solvent. It is worth noting that ultrasound helps this process through vibration, which not only promotes the release of polysaccharides from the cells, but also helps the polysaccharides to be more evenly dispersed in the solvent. The strong stirring and violent vibration generated by the friction and collision between the extraction liquid and the emblica particles driven by the flash extractor also help the dispersion. Finally, under the high-frequency vibration of ultrasound, the rapid expansion and collapse of a large number of tiny bubbles produced temporary high temperature, high pressure and micro-vortex in the solution, which accelerated the dissolution of polysaccharides, causing the PEP concentration in the solution to quickly reach equilibrium. In addition, the addition ratio of rice bran protein in the extraction system is high. In the solution system, while the polysaccharide of Phyllanthus emblica is extracted, through specific reaction conditions, the polysaccharide of Phyllanthus emblica forms a graft with rice bran protein outside the cell, and the concentration difference of the polysaccharide inside and outside the cell is formed. The concentration difference of rice bran protein inside and outside the cell of Phyllanthus emblica is formed, which promotes the precipitation of the polysaccharide inside the cell, and helps to quickly prepare the rice bran protein-polysaccharide graft outside the cell.

[0053] Example 2

[0054] The RBP-PEP graft used in this example was prepared according to the optimal process conditions of Example 1.

[0055] 1. Determination of the thermomechanical properties of dough

[0056] Different concentrations of RBP-PEP grafts and RBP / PEP physical mixtures were added to flour according to the flour ratio, and the samples were mixed experimentally determined using Mixolab to explore the effects of the two different types of additives on the dough during mixing and baking. The results are shown in Table 2.

[0057] The thermomechanical properties of the agglomeration of wheat mixed flour with different additions of RBP-PEP grafts were determined using a Mixolab2 mixing tester. The "Chopinp+" standard protocol mode was selected: the dough mass was set to 50g, the target consistency (C1) was 1.1Nm (±0.05Nm), the dough speed was maintained at 80r / min, the temperature in the first stage was 30℃, and the temperature was kept for 8min. In the second stage, the temperature was increased to 90℃ at a rate of 4℃ / min and kept at 90℃ for 7min. In the third stage, the temperature was reduced to 50℃ at a rate of 4℃ / min and kept at 50℃ for 5min. Wheat flour without addition and RBP / PEP physical mixture were selected as the control group.

[0058] Table 2 Effects of different RBP-PEP grafts and RBP / PEP mixtures on the thermomechanical properties of dough

[0059]

[0060] Note: Different superscript letters in the same column indicate significant differences (P<0.05).

[0061] There was a significant difference in the water absorption rate of the mixed flour dough between the control group and the added mixture (P<0.05). The addition of RBP-PEP grafts increased the water absorption rate of the dough, and it increased with the increase in the amount of addition. This is explained by the fact that PEP is a hydrophilic polysaccharide. After combining with RBP, it can produce a strong hydration effect and increase the water absorption rate of the mixed flour dough. The increase in the water absorption rate of the dough can not only maintain the moisture of the dough and reduce the cracking phenomenon caused by insufficient moisture, but also help to improve the yield of noodle products.

[0062] The longer the dough formation time, the longer it takes for the dough to absorb water and form from powdery state. As can be seen from Table 2, the addition of RBP-PEP grafts and RBP / PEP physical mixtures delayed the formation of dough, and the grafts had a greater impact on the dough. This may be because they compete with gluten protein for water absorption during dough mixing, interfering with the development of the gluten protein network, resulting in a longer dough formation time.

[0063] The longer the stability time, the more resistant it is to mechanical shear or kneading, indicating that the dough has good stability and strong processing resistance. As can be seen from Table 2, the addition of RBP-PEP grafts and RBP / PEP physical mixtures prolongs the stability time of the dough, and the effect of the grafts is better, indicating that adding a certain amount of grafts can improve the processing resistance of the dough. The C1-C2 value represents the degree of weakening of gluten protein. The weakening degree reflects the strength of the gluten structure. A small weakening degree indicates that the gluten strength in the dough is strong. As can be observed from the above table, the addition of RBP-PEP grafts and RBP / PEP physical mixtures both show higher dough stability times and lower C1-C2 values ​​than the control samples, and the effect of the grafts is more obvious. This shows that the addition of RBP-PEP grafts improves the stability and gluten strength of the dough.

[0064] Under heating conditions, C4 / C3 represents the cooking stability of the dough, and the C5-C4 value represents the degree of starch retrogradation, which can be used to determine the effect of additives on the gelatinization properties of dough starch. As shown in Table 2, the addition of RBP-PEP grafts showed a greater improvement in the dough cooking stability C4 / C3 than the control sample and the addition of RBP / PEP physical mixture. The C5-C4 value represents the degree of starch retrogradation, which is related to the recrystallization characteristics of starch. Compared with the control group, the addition of RBP-PEP grafts and RBP / PEP physical mixtures reduced the C5-C4 value of the dough, and the addition of grafts had a greater effect on the C5-C4 value, which was stronger than the direct addition of the mixture, and decreased with the increase in the amount of addition. Grafts have the effect of inhibiting dough aging and starch retrogradation, thereby extending the shelf life of the product.

[0065] 2. Texture characteristics analysis

[0066] The sweet dough is made using the following recipe: Sweet dough recipe: 1000g high-gluten flour, 20g yeast, 10g salt, 100g white sugar, 495g water, 100g margarine, 20g whole milk powder, and 80g whole egg liquid.

[0067] Different amounts of RBP-PEP grafts were mixed into flour according to the flour addition ratio, and sweet dough was made according to the above formula. No-addition wheat flour and RBP / PEP physical mixture were selected as the control group. The dough was made by direct method. All raw materials except butter were placed in a dough mixer. First, they were stirred at low speed for 3 minutes until the dough was basically formed, then stirred at high speed for 4 minutes until the gluten network was fully formed, and then butter was added. The butter was stirred at low speed for 3 minutes to mix the butter and dough evenly, and then stirred at high speed for 4 minutes until the butter was fully mixed with the dough and the gluten was fully formed. Then, it was left to stand and relax at 25°C for 10 minutes, and the dough was divided into 50g and rolled and shaped. After primary fermentation, scheduling, and secondary fermentation, it was baked at 180°C for 25 minutes to prepare the finished sweet bread.

[0068] The sweet bread was cooled to room temperature, and the texture characteristics of the samples were measured using a texture analyzer to study the effects of different additives on the dough hardness, elasticity, adhesiveness and recovery parameters. The results are shown in Table 3. A P / 100 probe was used for two consecutive compression tests. The pre-test speed was 1.0 mm / s, the test speed was 1.0 mm / s, the post-test speed was 3.0 mm / s, the compression ratio was 50%, the trigger force was 5 g, and the interval between the two compressions was 5 s.

[0069] Table 3 Analysis of the structural properties of sweet bread with different RBP-PEP grafts and RBP / PEP mixtures

[0070]

[0071] As shown in Table 3, with the gradual increase in the amount of RBP-PEP graft added, the hardness of the sweet bread was significantly less than that of the bread without RBP / PEP addition and the bread with RBP / PEP mixture. The elasticity gradually increased with the addition of RBP-PEP graft, and the resilience and elasticity had the same trend of change. Among them, there were significant differences between the barbecued pork buns treated by different freezing methods (P<0.05), which showed that RBP-PEP graft had an improvement effect on the organizational structure of the dough, which may affect the components and binding methods such as gluten protein and starch, so that the elasticity and resilience were significantly improved, and stronger than the mixture. Adhesion is a property unique to semi-solid samples. There are differences in the adhesiveness shown between the groups, which shows that different additives will change the characteristics of sweet dough to varying degrees. In short, RBP-PEP graft can improve the taste of sweet bread, making it softer and more elastic, and the improvement effect increases with the increase of the amount added.

[0072] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for preparing rice bran protein-emblica polysaccharide covalent grafts outside the cell, characterized in that: The following steps are involved: After mixing fresh emblica fruit, rice bran protein and water, they are extracted by a flash extractor under the assistance of ultrasound, and then filtered to obtain a filtrate. The filtrate is concentrated to obtain a concentrated solution, and then an alcohol precipitation treatment is performed to obtain a precipitate. After freeze-drying, the rice bran protein-emblica polysaccharide covalent graft is obtained.

2. The method according to claim 1, characterized in that The ratio of the total mass of the fresh fruit of Emblica officinalis and the rice bran protein to the mass of the water is 1:

35.

3. The method according to claim 1, characterized in that The pH of the reaction system consisting of the fresh fruit of Emblica officinalis, the rice bran protein and the water is 6.

5.

4. The method according to claim 1, characterized in that: The concentration treatment is to concentrate the filtrate to 1 / 4-1 / 5 of the original volume.

5. The method according to claim 1, characterized in that The alcohol precipitation treatment is to add ethanol into the concentrated solution so that its volume fraction is 90%.

6. The method according to claim 1, characterized in that The mass ratio of the fresh fruit of Emblica officinalis to the rice bran protein is 1:5; and / or The ultrasonic power of the ultrasonic auxiliary effect is 640W; and / or The extraction temperature of the extraction process is 70°C; and / or The extraction time of the extraction process is 200 s.

7. A rice bran protein-emblica polysaccharide covalent grafted product prepared according to the method according to any one of claims 1 to 6.

8. Use of the rice bran protein-emblica polysaccharide covalent grafted product as claimed in claim 7 in the preparation of food additives.

9. A food additive, characterized in that: It includes the rice bran protein-emblica polysaccharide covalent grafted product as described in claim 7.

10. Use of the food additive according to claim 9 in preparing food.

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