An oral gel preparation of jujube pulp polysaccharide for enhancing immunity, and its preparation method and application

Abstract

The present invention belongs to the extraction and application technology field of sour jujube polysaccharide, and in order to solve the problems existing in the extraction of sour jujube pulp polysaccharide at present, a sour jujube pulp polysaccharide oral gel for enhancing immunity and its preparation method and application are provided. Sour jujube is dried with hot air, crushed and sieved to obtain sour jujube fruit powder; after adding deionized water to sour jujube fruit powder, citric acid-sodium citrate buffer is used to adjust the pH value to 3-6, and a magnetic induction electric field device is used for extraction; papain removes protein in sour jujube pulp polysaccharide solution; polysaccharide solution is purified and concentrated by ultrafiltration membrane twice, freeze-dried, crushed and sieved to obtain sour jujube pulp polysaccharide powder; water, carrageenan, konjac gum, and flavoring agent are added to sour jujube pulp polysaccharide powder in proportion, and heated and sterilized at 50℃-80℃ to obtain sour jujube pulp polysaccharide gel. The use of food additives is reduced. The obtained gel has stable properties, is easy to carry, is convenient to eat, has the characteristics of comfortable taste, and is deeply loved by children.

Description

Technical Field

[0001] The invention belongs to the technical field of extraction and application of jujube polysaccharides, and particularly relates to an immunity-enhancing jujube pulp polysaccharide oral gel, a preparation method and application thereof. Background Art

[0002] Ziziphus jujuba ZiziphusjujubeMill.var.spinosa(Bunge)Hu exH.F.Chou ) is Rhamnaceae ( Rhammaceae )Ziziphus Ziziphus Mill. ) The dried mature fruit of the sour jujube. As a traditional Chinese medicine, the sour jujube was first recorded in the "Shennong Bencao Jing" and listed as a top-grade product. The sour jujube is widely distributed in northern areas such as Shanxi, Hebei, Henan, and Shandong. Modern research shows that the sour jujube contains a large amount of polysaccharides, alkaloids, flavonoids, triterpenes and their saponins, nucleosides and other chemical components, which have many nutritional values ​​and health benefits such as sedation and hypnosis, lowering blood sugar, protecting the cardiovascular system, anti-oxidation, enhancing human immunity, lowering blood pressure and preventing arteriosclerosis.

[0003] Polysaccharides are widely distributed in nature and have extremely important biological functions. Polysaccharides are closely related to the regulation of immune function. Many studies have shown that polysaccharides extracted from the pulp of sour jujube have anti-aging, immunomodulatory, and anti-myocardial ischemia effects. In recent years, a variety of technologies have been used to extract polysaccharides, such as alkaline extraction, microwave-assisted extraction, ultrasonic-assisted extraction, supercritical fluid extraction, and so on. These extraction technologies have their own advantages, but also have their own shortcomings. Alkaline extraction can increase the yield of polysaccharides, but it will make the extract have a strong alkaline taste and the solution is yellow, affecting the flavor and color of the finished product; microwave-assisted extraction is time-saving, efficient, energy-saving, and easy to operate, but microwaves are prone to local high temperatures, which will cause changes in the structure of polysaccharides; ultrasonic-assisted extraction has high extraction efficiency and short time, but it has the disadvantages of polluting the environment and a small effective range; supercritical fluid extraction requires complex equipment, high operating costs, and a limited extraction range.

[0004] The magnetic induction electric field extraction method is based on Ampere's law, which allows the charged solutes in the solution to migrate in a large-scale direction under the influence of the induced electric field, and the charged ions, particles and polar molecules in the solution reciprocate and rub, so that the polysaccharides are dissolved in large quantities. This extraction method has the advantages of increasing the yield of polysaccharides, shortening the extraction time and killing microorganisms in the solution. Common purification methods for polysaccharides include graded alcohol precipitation, gel column chromatography, cellulose column chromatography, ion exchange column chromatography and membrane separation. Membrane separation can be divided into microfiltration, ultrafiltration and nanofiltration, among which ultrafiltration uses pressure as the driving force to separate and purify polysaccharides of different molecular weights. Ultrafiltration has the characteristics of mild conditions, no phase change, low energy consumption, high purification efficiency and simple and easy equipment operation.

[0005] The sour jujube is a substance that is both a medicine and a food. The polysaccharides contained in the sour jujube have the effects of anti-oxidation and enhancing immunity. The traditional water extraction and alcohol extraction methods of sour jujube polysaccharides are time-consuming and inefficient. The present invention uses magnetic induction electric field technology to extract sour jujube pulp polysaccharides, significantly improving the polysaccharide yield and shortening the extraction time. The sour jujube polysaccharide solution is purified using ultrafiltration membrane technology. Compared with other purification technologies, it effectively reduces the use of organic solvents, facilitates concentration, shortens the purification time, and further obtains polysaccharides with higher purity.

[0006] Currently, polysaccharide preparations with immunity-enhancing effects on the market include: granules, tablets, capsules, oral liquids, injections, etc. Children are reluctant to swallow polysaccharide granules, tablets, and capsules, which makes medication difficult; polysaccharide injections may cause fear, resistance, and behavior in children; polysaccharide oral liquids are inconvenient to carry, which can easily lead to loss of oral liquids. Summary of the invention

[0007] In order to solve the existing problems in the extraction of jujube pulp polysaccharides, the present invention provides an oral gel of jujube pulp polysaccharides for enhancing immunity, and a preparation method and application thereof. The preparation method is short in time and simple in operation, and can improve the extraction rate of jujube pulp polysaccharides; the present invention also provides an application of the oral gel prepared from jujube pulp polysaccharides in the preparation of health foods or functional foods for enhancing immunity.

[0008] The invention is realized by the following technical scheme: a preparation method of an oral polysaccharide gel for enhancing immunity of jujube pulp, comprising the steps of drying jujube pulp with hot air, crushing and sieving to obtain jujube pulp powder; adding deionized water to the jujube pulp powder, adjusting the pH value to 3-6 with citric acid-sodium citrate buffer, and extracting the jujube pulp powder by using a magnetic induction electric field device; removing protein in the jujube pulp polysaccharide solution by using papain; purifying and concentrating the polysaccharide solution by ultrafiltration membrane twice, freeze-drying, crushing and sieving to obtain jujube pulp polysaccharide powder; adding water, carrageenan, konjac gum and flavoring agent to the jujube pulp polysaccharide powder in proportion, heating at 50-80°C, and sterilizing to obtain the jujube pulp polysaccharide gel.

[0009] The specific steps are as follows:

[0010] (1) Preparation of jujube fruit powder: Sort and clean the jujube fruits, separate the pulp from the core, place the pulp after core removal in a 60°C forced air drying oven, dry it with hot air for 26 h, grind it, and pass it through a 60-mesh sieve to obtain jujube powder;

[0011] (2) Extraction of polysaccharides by magnetic induction electric field: The jujube powder obtained in step 1) was added to deionized water at a solid-liquid ratio of 1:5-1:20 g / mL for magnetic induction electric field extraction. The magnetic induction electric field reaction frequency was 300 Hz-600 Hz, the excitation voltage was 700 V-1000 V, the extraction solution temperature was 50-80°C, the pH value was adjusted to 3-6 with citric acid-sodium citrate buffer, and the extraction time was 10-25 min.

[0012] (3) Obtaining a crude polysaccharide solution from the pulp of sour jujube: centrifuging the solution extracted by magnetic induction electric field in step 2) at 4000-5000 r / min for 15-20 min to obtain a crude polysaccharide solution from the pulp of sour jujube;

[0013] (4) Protein removal: Add papain to the crude polysaccharide solution of jujube pulp obtained in step 3) to prepare a solution with an enzyme mass fraction of 0.2%-0.5% and a pH value of 4-8, and perform enzymolysis in a water bath at 40-70°C for 0.5-2h. After the reaction is completed, inactivate in a boiling water bath for 5-15min, and remove the precipitate by centrifugation at 4000-5000 r / min for 10-15min to obtain a deproteinized jujube pulp polysaccharide solution; the protein removal rate is 86%, and the polysaccharide retention rate is 94%;

[0014] (5) Ultrafiltration to remove macromolecular impurities: The crude polysaccharide solution of jujube pulp obtained in step 4) is subjected to the first ultrafiltration, using a 0.02-0.05 μm ultrafiltration membrane at a pressure of 0.12-0.15 MPa. The initial temperature of the crude polysaccharide solution is adjusted to 25°C to 28°C to remove impurity molecules with a molecular weight of ≥500,000 Da;

[0015] (6) Secondary ultrafiltration to remove small molecules: The crude polysaccharide solution of the jujube pulp obtained in step 5) is subjected to a second ultrafiltration, using a 0.008-0.01 μm ultrafiltration membrane at a pressure of 0.1-0.2 MPa. The initial temperature of the crude polysaccharide solution is adjusted to 30-35°C to remove impurities with a molecular weight of ≤100,000 Da, thereby obtaining a jujube pulp polysaccharide solution with a molecular weight of 100,000 Da to 500,000 Da, and a polysaccharide concentration of 112 mg / mL to 165 mg / mL;

[0016] (7) Preparation of jujube pulp polysaccharide powder: freeze-dry the jujube pulp polysaccharide solution obtained in step 6, at -50°C to -60°C, pre-freeze for 8-10 hours, the cold trap temperature is -30°C to -50°C, the vacuum degree is 0.04-0.08 MPa, freeze for 25h-30h, then freeze-crush, and pass through a 60-100 mesh sieve to obtain jujube pulp polysaccharide powder;

[0017] (8) Preparation of gel: Add water to the jujube pulp polysaccharide powder obtained in step 7) at a solid-liquid ratio of 1:10 g / mL to 1:20 g / mL to prepare a polysaccharide solution;

[0018] Inulin, potassium chloride, citric acid, sodium citrate, potassium sorbate and distilled water are mixed in a mass ratio of 0.2-0.4: 0.01-0.02: 0.006-0.03: 0.004-0.02: 0.01-0.02: 3-15, and inulin, potassium chloride, citric acid, sodium citrate and potassium sorbate are added as flavoring agents to the polysaccharide solution to prepare a polysaccharide liquid;

[0019] The mass ratio of carrageenan, konjac gum and water is 0.06-0.16:0.06-0.16:1-3, and the mixture is heated to 60-100°C to dissolve, and stirred continuously to make it fully dispersed, absorb water, swell, and boil for 2-5 minutes to make it evenly dissolved, as a standby gelling agent;

[0020] The polysaccharide liquid and the standby gelling agent are mixed in a volume ratio of 1:3-1:5, during which the heating temperature is controlled at 50-80°C and the stirring is performed at 300-500r / min to obtain the jujube pulp polysaccharide gelling agent.

[0021] The specific method of freeze-crushing in step (7) is as follows: after freeze-drying the jujube pulp polysaccharide solution, freeze it at -50°C to -70°C for 10 min to 15 min, then use a freeze-crusher to grind it, and keep the grinding chamber temperature at -30°C to -60°C. After grinding, pass it through a 60-100 mesh sieve to obtain jujube pulp polysaccharide powder.

[0022] The prepared sour jujube pulp polysaccharide gel is heated and sterilized at 90-115° C. for 15-30 minutes until there are no large bubbles, and then filled into bagged gel when the temperature is naturally cooled to 60-80° C.

[0023] The invention also provides an oral gel preparation of polysaccharide from jujube pulp for enhancing immunity, which is prepared by the method.

[0024] The present invention also provides the use of the immunity-enhancing jujube pulp polysaccharide oral gel in the preparation of immunity-enhancing drugs.

[0025] In addition, the present invention also provides the use of the oral gel of jujube pulp polysaccharide for enhancing immunity in the preparation of health products or functional foods for enhancing immunity.

[0026] The jujube pulp polysaccharide powder and jujube pulp polysaccharide gel prepared by the present invention have the following advantages:

[0027] After the polysaccharide from the jujube pulp is extracted using the magnetic induction electric field method, papain is added to assist in removing excess protein, thereby increasing the polysaccharide extraction rate, speeding up the extraction, and significantly shortening the extraction time. The polysaccharide yield from the jujube pulp can reach 28.6%.

[0028] The polysaccharide solution is purified and concentrated by ultrafiltration membrane, and small molecular impurities, amino acids, etc. in the solution are removed at the same time. This method has the characteristics of no pollution, no use of organic solvents, rapid and accurate, high efficiency, simple and easy operation of equipment, etc. The purity of the obtained polysaccharide is as high as 86.5±0.02%.

[0029] The extracted jujube pulp polysaccharide solution is freeze-dried and dehydrated at low temperature, so that the physical, chemical and biological states of the polysaccharide itself remain basically unchanged, the nutrients and effective ingredients of the polysaccharide itself are retained to the maximum extent, and the biological activity of the jujube pulp polysaccharide is protected to the greatest extent.

[0030] The polysaccharide gel of the fruit pulp of sour jujube can significantly increase the thymus index, spleen index, phagocytic carbon clearance index of phagocytes, the number of lymphocytes in the blood, the number of white blood cells in the blood and the concentration of IFN-γ in the blood, indicating that the polysaccharide gel of the fruit pulp of sour jujube has the effect of enhancing immunity.

[0031] The invention extracts the polysaccharide components in the jujube pulp, so no sweeteners such as aspartame are added in the process of preparing the jujube pulp polysaccharide gel, thereby reducing the use of food additives. The jujube pulp polysaccharide gel has the characteristics of stable properties, easy to carry, convenient to eat, comfortable taste, and is deeply loved by children while ensuring the effect of enhancing immunity.

[0032] The present invention adopts low-temperature freeze drying technology to dry, and the polysaccharide solution is placed in a vacuum freeze dryer for pre-freezing for 8h to 10h, and the corresponding cold trap temperature and vacuum degree are set for freeze drying, and then crushed and sieved after drying to obtain the jujube pulp polysaccharide powder. Better protect the polysaccharide structure and better retain its immune-enhancing activity. The jujube pulp polysaccharide powder after extraction and purification is made into a polysaccharide solution, and a gelling agent, a flavoring agent and other additives are added. After mixing, heating, sterilization, filling and other steps, the jujube pulp polysaccharide is finally made into an oral gel, which has the characteristics of stable properties, comfortable taste, controllable quality, convenient carrying, and convenient eating. The present invention integrates the extraction and purification technology of magnetic induction electric field and ultrafiltration membrane synergy, greatly improves the extraction efficiency of jujube pulp polysaccharide, and makes the jujube pulp polysaccharide into a stable, controllable and convenient oral gel, which can further expand its application range and application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 is a protein standard curve graph;

[0034] Figure 2 This is a standard curve for glucose. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments; based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0036] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs, and the disclosure and materials cited therein are hereby incorporated by reference.

[0037] Technical equivalents to the specific embodiments described that are apparent to those skilled in the art using no more than routine experimentation are intended to be encompassed by this application.

[0038] The experimental methods in the following examples are all conventional methods unless otherwise specified. The instruments and equipment used in the following examples are all conventional laboratory instruments and equipment unless otherwise specified; the experimental materials used in the following examples are all purchased from conventional biochemical reagent stores unless otherwise specified.

[0039] Example 1: Single factor investigation of polysaccharide extraction process from jujube pulp

[0040] 1. Effect of different excitation voltages on the extraction rate of polysaccharides from jujube pulp

[0041] Weigh 10 g of jujube fruit powder, add deionized water at a solid-liquid ratio of 1:10 g / mL, adjust the pH value to 4, and set the temperature to 60 °C. During this period, a frequency of 400 Hz was applied, and different excitation voltages of 700 V, 800 V, 900 V, and 1000 V were treated for 15 min. After the time was reached, the hydrolyzate was taken out and centrifuged at 4000 r / min for 20 min to obtain the supernatant, and the polysaccharide content was determined. The results of the polysaccharide content determination are shown in Table 1.

[0042] Table 1 Different excitation voltages and polysaccharide content determination

[0043]

[0044] Taking into account the content of polysaccharides in jujube pulp under different excitation voltages, 800 V to 1000 V was selected as the optimal excitation voltage.

[0045] 2. Effect of different frequencies on the extraction rate of polysaccharides from sour jujube pulp

[0046] Weigh 10 g of jujube fruit powder, add deionized water at a solid-liquid ratio of 1:10 g / mL, adjust the pH value to 4, and keep the temperature at 60 °C. During this period, different frequencies of 300 Hz, 400 Hz, 500 Hz, and 600 Hz are applied, and the excitation voltage is 800 V for 15 min. After the time is up, the hydrolyzate is taken out and centrifuged at 4000 r / min for 20 min to obtain the supernatant, and the polysaccharide content is determined. The results of the polysaccharide content determination are shown in Table 2.

[0047] Table 2 Different frequencies and polysaccharide content determination

[0048]

[0049] Taking into account the content of polysaccharides in jujube pulp at different frequencies, 400 Hz to 600 Hz was selected as the optimal frequency.

[0050] 3. Effect of different pH values ​​on the extraction rate of polysaccharides from jujube pulp

[0051] Weigh 10 g of jujube fruit powder, add deionized water at a solid-liquid ratio of 1:10 g / mL, the temperature is 60 ℃, the pH value is adjusted to 3, 4, 5, 6, the excitation voltage is 800 V, the frequency is 400 Hz, and the treatment time is 15 min. After the hydrolyzate is taken out, centrifuge at 4000 r / min for 20 min to obtain the supernatant, and the polysaccharide content is determined. The results of the polysaccharide content determination are shown in Table 3.

[0052] Table 3 Different pH and polysaccharide content determination

[0053]

[0054] Taking into account the content of polysaccharides in jujube pulp at different pH values, pH 3-5 was selected as the optimal pH value.

[0055] 4. Effect of different temperatures on the extraction rate of polysaccharides from jujube pulp

[0056] Weigh 10 g of jujube fruit powder, add deionized water at a solid-liquid ratio of 1:10 g / mL, adjust the pH value to 4, apply different temperatures of 50 ℃, 60 ℃, 70 ℃, and 80 ℃, an excitation voltage of 800 V, and a frequency of 400 Hz for 15 min. After the time is up, the hydrolyzate is taken out and centrifuged at 4000 r / min for 20 min to obtain the supernatant, and the polysaccharide content is determined. The results of the polysaccharide content determination are shown in Table 4.

[0057] Table 4 Different temperatures and polysaccharide content determination

[0058]

[0059] Taking into account the content of polysaccharides in jujube pulp at different temperatures, 60 ℃ ~ 80 ℃ was selected as the optimal temperature.

[0060] 5. Effect of different time on the extraction rate of polysaccharides from sour jujube pulp

[0061] Weigh 10 g of jujube fruit powder, add deionized water at a solid-liquid ratio of 1:10 g / mL, adjust the pH value to 4, set the temperature to 60 ℃, the excitation voltage to 800 V, and the frequency to 400 Hz for different treatment times of 10 min, 15 min, 20 min, and 25 min. After the time is up, take out the hydrolyzate and centrifuge it at 4000 r / min for 20 min to obtain the supernatant, and determine the polysaccharide content. The results of the polysaccharide content determination are shown in Table 5.

[0062] Table 5 Determination of polysaccharide content at different times

[0063]

[0064] Taking into account the content of polysaccharides in jujube pulp at different times, 15 min to 25 min was selected as the optimal extraction time.

[0065] 6. Effect of different solid-liquid ratios on the extraction rate of polysaccharides from jujube pulp

[0066] Weigh 10 g of jujube fruit powder, add deionized water according to different solid-liquid ratios of 1:5 g / mL, 1:10 g / mL, 1:15 g / mL, and 1:20 g / mL, adjust the pH value to 4, set the temperature to 60 ℃, the excitation voltage to 800 V, and the frequency to 400 Hz for 15 min. After the treatment time is reached, the hydrolyzate is taken out and centrifuged at 4000 r / min for 20 min to obtain the supernatant, and the polysaccharide content is determined. The results of the polysaccharide content determination are shown in Table 6.

[0067] Table 6 Determination of polysaccharide content at different solid-liquid ratios

[0068]

[0069] Taking into account the content of polysaccharides in jujube pulp under different solid-liquid ratios, the optimal solid-liquid ratio was selected as 1:5 g / mL ~ 1:15 g / mL.

[0070] 7. Optimization of the extraction process of polysaccharides from jujube pulp by response surface methodology

[0071] The t-test of polysaccharide content under the above single factor conditions showed that the main effect factors affecting the polysaccharide content of jujube pulp were frequency, extraction temperature and pH value. According to the central composite design principle of Box-Behnken, a three-factor response surface design was designed using DesignExpert8.0.6 software, with frequency, extraction temperature and pH value as independent variables to further optimize the polysaccharide extraction process of jujube pulp.

[0072] In the Design expert software, the model was further analyzed for typicality, and the polysaccharide content of the jujube pulp was set to the maximum value. The software automatically predicted the optimal extraction conditions, predicting that the polysaccharide content extracted from the jujube pulp polysaccharide extraction process under these conditions was 165.35 mg / g. After comprehensive consideration, the frequency of 400 Hz to 600 Hz, the temperature of 60 ℃ to 80 ℃, and the pH of 3 to 5 were selected as the optimal extraction conditions.

[0073] Example 2: Single factor investigation of the preparation process of polysaccharide gel from jujube pulp

[0074] 1. Effect of carrageenan and konjac gum dosage on gelling property, fragility and elasticity of gelling agent: Carrageenan and konjac gum were pre-tested in different proportions, and the gelling property, fragility and elasticity of gelling agent were evaluated, and the results are shown in Table 7. According to the table, comprehensive consideration shows that the best effect is achieved when the ratio of carrageenan to konjac gum is 1:1.

[0075] Table 7 Effect of carrageenan and konjac gum dosage on finished products

[0076]

[0077] 2. Study on the effect of potassium chloride dosage on the gelling property and water precipitation of gelling agent: The dosage of potassium chloride has an effect on the mouthfeel, gel strength and water precipitation of gel after forming. Single factor study was carried out at different proportions, and the results are shown in Table 8. According to the table, when the dosage of potassium chloride is greater than 0.1%, the effect is better.

[0078] Table 8 Effect of potassium chloride dosage on finished products

[0079]

[0080] 3. Investigation of the effect of citric acid and sodium citrate dosage on gelling properties of gelling agent: Single factor investigation was carried out according to different proportions, and the results are shown in Table 9. According to the table, when the ratio of citric acid to sodium citrate is 3:1, the effect is better.

[0081] Table 9 Effect of citric acid and sodium citrate dosage on finished products

[0082]

[0083] 4. Investigation of the effect of temperature on the gelling property of gelling agent: The effect of different temperatures on the gelling degree is investigated, and the results are shown in Table 10. According to the results in the table, it can be seen that the effect is better when the temperature is above 50 ℃.

[0084] Table 10 Study on the effect of temperature on the gelling property of gelling agent

[0085]

[0086] Example 3: Determination of the clearance rate of polysaccharide protein in the pulp of wild jujube

[0087] The protein standard curve was determined by the Coomassie Brilliant Blue G-250 method. Accurately weigh 100 mg of Coomassie Brilliant Blue G250 and dissolve it in 50 mL of anhydrous ethanol, then add 100 mL of 85% phosphoric acid, dilute to 1000 mL with distilled water in a volumetric flask, filter, and store. Accurately measure 10.0 mg of bovine serum albumin and dilute to 100 mL with distilled water in a volumetric flask to obtain a bovine serum albumin mother solution with a concentration of 0.1 mg / mL. Accurately measure 0.0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, and 1.0 mL of 0.1 mg / mL bovine serum albumin solution and place them in stoppered test tubes, add distilled water to 1.0 mL, then add 4.0 mL of Coomassie Brilliant Blue reagent, mix well, and let stand for 5 min. Another 1.0 mL of distilled water was used as a blank control, and the absorbance was measured at 595 nm. The standard curve was drawn with protein concentration as the horizontal axis and absorbance as the vertical axis, and the linear regression equation was y=0.0069x+0.1434 (R 2 =0.9992), indicating a good linear relationship. Figure 1 .

[0088] The crude polysaccharide solution prepared under the extraction conditions of 400 Hz-600 Hz, 60 ℃-80 ℃ and pH 3-5 was placed in a clean container and papain was added to prepare a solution with a mass percentage of 0.3% enzyme and a pH value of 6. The solution was enzymatically hydrolyzed in a 60 ℃ water bath for 1.5 h, inactivated in a boiling water bath for 10 min after the reaction, and centrifuged at 4000 r / min for 10 min to remove the precipitate. The protein and polysaccharide solution was obtained, and the absorbance of protein and polysaccharide was measured at 595 nm. The protein clearance rate was calculated as follows: protein clearance rate = (protein content before protein removal - protein content after protein removal) / protein content before protein removal × 100%; the polysaccharide retention rate was calculated as follows: polysaccharide retention rate = the mass of polysaccharide in the sample after protein removal / the mass of polysaccharide in the sample before protein removal × 100%. After testing, the protein clearance rate of the polysaccharide solution of the jujube pulp was 86%, and the polysaccharide retention rate was 94%.

[0089] Example 4: Determination of the extraction rate of polysaccharides from the pulp of sour jujube: The extraction rate of polysaccharides from the pulp of sour jujube was determined by the phenol-sulfuric acid method. 10 mg of glucose reference substance was accurately weighed and fixed to volume in a 100 mL volumetric flask to obtain a glucose reference solution with a mass concentration of 0.1 mg / mL. 0, 0.2, 0.4, 0.6, 0.8 and 1.0 mL of glucose standard solution were respectively measured and placed in a stoppered graduated test tube, and then fixed to 10 mL with distilled water. Subsequently, 1 mL of 6% phenol solution and 5 mL of concentrated sulfuric acid solution were added, shaken and evenly mixed, and placed in a water bath at 60°C for 10 min. After taking out, it was cooled in a water bath for 5 min. The absorbance was measured at 490 nm. With the glucose content as the horizontal coordinate and the absorbance value as the vertical coordinate, the equation for the glucose standard curve was obtained as follows: y=0.0719x+0.0074(R 2 =0.9991) indicates a good linear relationship. Figure 2 .

[0090] Weigh 10 mg of the prepared jujube pulp polysaccharide powder and add deionized water to 25 mL. Accurately pipette 2 mL of the sample solution after volume adjustment, add 1 mL of 6% phenol and 5 mL of concentrated sulfuric acid solution, shake well and keep in a 60℃ water bath for 10 min, take out and cool in a water bath for 5 min. Use a UV-visible spectrophotometer to measure the absorbance of the polysaccharide solution at 490 nm, with distilled water as the blank control.

[0091] The extraction rate of jujube pulp polysaccharide is calculated as follows: extraction rate of jujube pulp polysaccharide % = (polysaccharide concentration × dilution multiple × volume) / mass of jujube pulp powder × 100%; the purity of jujube pulp polysaccharide is calculated as follows: purity of jujube pulp polysaccharide % = measured mass of jujube pulp polysaccharide / mass of jujube pulp polysaccharide test sample × 100%. The extraction rate of jujube pulp polysaccharide obtained by the method of the present invention is 28.6%, and the purity of jujube pulp polysaccharide is 86.5%.

[0092] Example 5: Comparison of different polysaccharide extraction methods

[0093] (1) Hot water extraction of polysaccharides from jujube pulp: Jujube pulp powder was used as the raw material for polysaccharide extraction. The extraction temperature was 85 °C, the solid-liquid ratio was 1:15, the extraction time was 2 h, and the number of extractions was 3 times. Under these conditions, the extraction rate of jujube pulp polysaccharides was 12.5%.

[0094] (2) Ultrasonic extraction of polysaccharides from jujube pulp: Jujube pulp powder was used as the raw material for polysaccharide extraction. The ultrasonic power was set to 400 W, the extraction temperature was 70 °C, the solid-liquid ratio was 1:15, the ultrasonic extraction time was 30 min, the extraction was repeated 3 times, and the polysaccharide extraction rate was 15.8%.

[0095] (3) Microwave extraction of polysaccharides from jujube pulp: Jujube pulp powder was used as the raw material for polysaccharide extraction. The solid-liquid ratio was 1:15, the microwave extraction temperature was 100 °C, the microwave power was 300 W, the extraction time was 5 min, and the extraction was repeated 3 times. The polysaccharide extraction rate was 17.3%.

[0096] (4) Ultrasonic-microwave synergistic extraction of polysaccharides from jujube pulp: Jujube pulp powder was used as the raw material for polysaccharide extraction. The solid-liquid ratio was 1:15, the extraction temperature was 80°C, and the ultrasonic extraction was performed at 400 W for 20 min. Then, the microwave extraction was performed at 100°C and 300 W for 8 min. The microwave-ultrasonic extraction method first performed microwave and then ultrasound. After three extractions, the polysaccharide extraction rate of this method was 19.6%.

[0097] (5) Magnetic induction electric field extraction of polysaccharides from jujube pulp: Jujube pulp powder was used as the raw material, with a solid-liquid ratio of 1:15, the pH value was adjusted to 3, the temperature was 60 °C, and an excitation voltage of 1000 V at a frequency of 400 Hz was applied for 15 min. During the reaction, the mixture was stirred for 10 s every 3 min. The extraction was performed 3 times, and the polysaccharide extraction rate was 28.6%.

[0098] The comparison results of different extraction methods are shown in Table 11. By comparing the methods of hot water extraction, ultrasonic extraction, microwave extraction, ultrasonic-microwave synergistic extraction and magnetic induction electric field extraction of jujube pulp polysaccharides, it can be seen that the method of extracting jujube pulp polysaccharides using magnetic induction electric field can greatly improve the yield of polysaccharides, and the extraction rate reaches 28.6%, indicating that the effect of extracting jujube pulp polysaccharides using magnetic induction electric field is better.

[0099] Table 11 Comparison of extraction rates of different extraction methods

[0100]

[0101] Example 6: The sour jujube fruit was sorted and cleaned, and the pulp was separated from the seed core. The pulp after the core was removed was placed in a 60°C blast drying oven, hot air dried for 26 h, crushed, and passed through a 60-mesh sieve to obtain sour jujube powder. Weigh 10 g of sour jujube fruit powder, add deionized water at a solid-liquid ratio of 1:15 g / mL, adjust the pH value to 3, and set the temperature to 60°C. During this period, an excitation voltage of 1000 V with a frequency of 400 Hz was applied for 15 min. Stirring was performed at intervals during the reaction, that is, stirring for 10 s every 3 min, and then centrifuged at 4000 r / min for 20 min to obtain a supernatant. The supernatant polysaccharide solution was placed in a clean container and papain was added to prepare a solution with an enzyme mass percentage of 0.3%, a pH value of 6, and enzymolysis was performed at 60°C water bath conditions for 1.5 h. After the reaction, the solution was inactivated in a boiling water bath for 10 min, and the precipitate was removed after centrifugation at 4000 r / min for 10 min to obtain a sour jujube pulp crude polysaccharide solution with protein removed. The protein clearance rate was 86%, and the polysaccharide retention rate was 94%. The crude polysaccharide solution of the sour jujube pulp was first filtered with a 0.03 μm ultrafiltration membrane at a pressure of 0.15 MPa and a temperature of 28 ℃ to obtain a filtrate with a molecular weight of less than 500,000 Da, and then filtered with a 0.01 μm ultrafiltration membrane at a pressure of 0.2 MPa and a temperature of 35 ℃ to obtain a polysaccharide solution with a molecular weight of 100,000 Da to 500,000 Da. The retentate was dried using a vacuum freeze dryer, -60 ℃, pre-frozen for 10 h, the cold trap temperature was -40 ℃, the vacuum degree was 0.08 MPa, and after freezing for 28 h, it was passed through an 80-mesh sieve to obtain the sour jujube pulp polysaccharide powder, with a polysaccharide yield of 28.6% and a purity of 86.5%.

[0102] Take 100 g of the prepared jujube pulp polysaccharide powder, 30 g of inulin, 10 g of carrageenan, 10 g of konjac gum, 2 g of potassium chloride, 0.9 g of citric acid, 0.3 g of sodium citrate, and 1 g of potassium sorbate, add 2500 mL of water to dissolve, mix evenly, heat at 80 ° C, sterilize at 115 ° C for 20 min, and fill to obtain the jujube pulp polysaccharide gel.

[0103] Example 7: The sour jujube fruit was sorted and cleaned, and the pulp was separated from the seed core. The pulp after the core was removed was placed in a 60 ℃ blast drying oven, hot air dried for 26 h, crushed, and passed through a 60-mesh sieve to obtain sour jujube pulp powder. Weigh 10 g of sour jujube fruit powder, add deionized water at a solid-liquid ratio of 1:15 g / mL, adjust the pH value to 7, and apply an excitation voltage of 300 Hz and 700 V at a temperature of 40 °C for 15 min. Stir at intervals during the reaction, that is, stir for 10 s every 3 min, then centrifuge at 4000 r / min for 20 min to obtain a supernatant. The supernatant polysaccharide solution was placed in a clean container and papain was added to prepare a solution with an enzyme content of 0.3%, a pH value of 6, and enzymolysis was performed at 60 ℃ water bath conditions for 1.5 h. After the reaction, it was inactivated in a boiling water bath for 10 min, and the precipitate was removed after centrifugation at 4000 r / min for 10 min to obtain a sour jujube pulp crude polysaccharide solution with protein removed. The protein clearance rate was 80%, and the polysaccharide retention rate was 84%. The crude polysaccharide solution of the sour jujube pulp was first filtered with a 0.03 μm ultrafiltration membrane, a pressure of 0.12 MPa, and a temperature of 28 ℃ to obtain a filtrate with a molecular weight of less than 500,000 Da, and then filtered through a 0.01 μm ultrafiltration membrane, a pressure of 0.1 MPa, and a temperature of 35 ℃ to obtain a polysaccharide solution with a molecular weight of 100,000 Da to 500,000 Da. The retentate was dried using a vacuum freeze dryer, -60 ℃, pre-frozen for 10 h, the cold trap temperature was -30 ℃, the vacuum degree was 0.04 MPa, and after freezing for 28 h, it was passed through a 60-mesh sieve to obtain the sour jujube pulp polysaccharide powder, with a polysaccharide yield of 18.4% and a purity of 57.5%.

[0104] Take 100 g of the prepared jujube pulp polysaccharide powder, 30 g of inulin, 10 g of carrageenan, 10 g of konjac gum, 2 g of potassium chloride, 0.9 g of citric acid, 0.3 g of sodium citrate, and 1 g of potassium sorbate, add 2500 mL of water to dissolve, mix evenly, heat at 80 ° C, sterilize at 115 ° C for 20 min, and fill to obtain the jujube pulp polysaccharide gel.

[0105] Example 8: The sour jujube fruit was sorted and cleaned, and the pulp was separated from the seed core. The pulp after de-core was placed in a 60 ℃ blast drying oven, hot air dried for 26 h, crushed, and passed through a 60-mesh sieve to obtain sour jujube powder. Weigh 10 g of sour jujube fruit powder, add deionized water at a solid-liquid ratio of 1:15 g / mL, adjust the pH value to 6, and the temperature to 70 °C. During the process, a frequency of 600 Hz and an excitation voltage of 1000 V were applied, and the treatment was carried out for 25 min. During the reaction, intermittent stirring was performed, that is, stirring for 10 s every 3 min, and then centrifuged at 4000 r / min for 20 min to obtain a supernatant. The supernatant polysaccharide solution was placed in a clean container and papain was added to prepare a solution with an enzyme content of 0.3%, a pH value of 6, and enzymatic hydrolysis was carried out at 60 ℃ water bath conditions for 1.5 h. After the reaction, the boiling water bath was inactivated for 10 min, and the precipitate was removed after centrifugation at 4000 r / min for 10 min to obtain a sour jujube pulp crude polysaccharide solution with protein removed. The protein clearance rate was 84% ​​and the polysaccharide retention rate was 90%. The crude polysaccharide solution of Jujube pulp was first filtered through a 0.03 μm ultrafiltration membrane, a pressure of 0.12 MPa, and a temperature of 25 °C to obtain a filtrate with a molecular weight of less than 500,000 Da, and then filtered through a 0.01 μm ultrafiltration membrane, a pressure of 0.2 MPa, and a temperature of 30 °C to obtain a polysaccharide solution with a molecular weight of 100,000 Da to 500,000 Da. The retentate was dried using a vacuum freeze dryer, -60 °C, pre-frozen for 8 h, the cold trap temperature was -50 °C, the vacuum degree was 0.07 MPa, and after freezing for 28 h, it was passed through a 70-mesh sieve to obtain Jujube polysaccharide powder, with a polysaccharide yield of 25.3% and a purity of 78.8%.

[0106] Take 100 g of the prepared jujube pulp polysaccharide powder, 30 g of inulin, 10 g of carrageenan, 10 g of konjac gum, 2 g of potassium chloride, 0.9 g of citric acid, 0.3 g of sodium citrate, and 1 g of potassium sorbate, add 2500 mL of water to dissolve, mix evenly, heat at 80 ° C, sterilize at 115 ° C for 20 min, and fill to obtain the jujube pulp polysaccharide gel.

[0107] Example 9: The sour jujube fruit was sorted and cleaned, and the pulp was separated from the seed core. The pulp after the core was removed was placed in a 60 ℃ blast drying oven, hot air dried for 26 h, crushed, and passed through a 60-mesh sieve to obtain sour jujube powder. Weigh 10 g of sour jujube fruit powder, add deionized water at a solid-liquid ratio of 1:15 g / mL, adjust the pH value to 4, and the temperature to 30 °C. During the process, an excitation voltage of 700 Hz and 800 V was applied for 20 min. Stir at intervals during the reaction, that is, stir for 10 s every 3 min, and then centrifuge at 4000 r / min for 20 min to obtain a supernatant. The supernatant polysaccharide solution was placed in a clean container and papain was added to prepare a solution with an enzyme content of 0.3%, a pH value of 6, and enzymolysis was performed at 60 ℃ water bath conditions for 1.5 h. After the reaction, it was inactivated in a boiling water bath for 10 min, and the precipitate was removed after centrifugation at 4000 r / min for 10 min to obtain a sour jujube pulp crude polysaccharide solution with protein removed. The protein clearance rate was 82%, and the polysaccharide retention rate was 86%. The crude polysaccharide solution of the fruit pulp of the sour jujube was first filtered through a 0.03 μm ultrafiltration membrane, a pressure of 0.15 MPa, and a temperature of 25 ℃ to obtain a filtrate with a molecular weight of less than 500,000 Da, and then filtered through a 0.01 μm ultrafiltration membrane, a pressure of 0.1 MPa, and a temperature of 30 ℃ to obtain a polysaccharide solution with a molecular weight of 100,000 Da to 500,000 Da. The retentate was dried using a vacuum freeze dryer, -50 ℃, pre-frozen for 8 h, the cold trap temperature was -40 ℃, the vacuum degree was 0.05 MPa, and after freezing for 28 h, it was passed through a 60-mesh sieve to obtain the sour jujube polysaccharide powder, with a polysaccharide yield of 21.5% and a purity of 69.2%.

[0108] Take 100 g of the prepared jujube pulp polysaccharide powder, 30 g of inulin, 10 g of carrageenan, 10 g of konjac gum, 2 g of potassium chloride, 0.9 g of citric acid, 0.3 g of sodium citrate, and 1 g of potassium sorbate, add 2500 mL of water to dissolve, mix evenly, heat at 80 ° C, sterilize at 115 ° C for 20 min, and fill to obtain the jujube pulp polysaccharide gel.

[0109] Example 10: Determination of the Immunity Enhancement Effect of Jujube Pulp Polysaccharide

[0110] 1. Determination of immune organ quality: 42 male mice were randomly divided into 7 groups, namely, model group, blank group, positive drug group and polysaccharide gel groups of Examples 6, 7, 8 and 9. Except for the blank group, the remaining groups of mice were intraperitoneally injected with cyclophosphamide at 0.005g / kg for 4 consecutive days. The mice gradually showed signs of low immunity such as weight loss, reduced activity, slow reaction, curled up arched back, and loose hair, indicating that the model was successfully replicated. According to 0.3 g / kg gavage, the positive drug group was given Zhenqi Fuzheng Granules, each gel group was given polysaccharide gel, and the blank group was given distilled water for 17 consecutive days. On the 21st day of administration, the mice were weighed and killed, the thymus and spleen were taken out and weighed, and the ratios of thymus / body weight and spleen / body weight were calculated. The results are shown in Table 12.

[0111] Table 12 Effects of jujube pulp polysaccharide gel on immune organ indices of mice (x±s, n=6)

[0112]

[0113] Note: Compared with the blank group, ## P<0.05; compared with the model group, ** P<0.05, * P<0.1

[0114] Compared with the model group, the blank group showed that the thymus index and spleen index of the model group were both reduced, which was statistically significant (P<0.05), and the model was established; compared with the model group, the polysaccharide gel group of Example 6-9 showed that the polysaccharide gel of jujube pulp had a certain promoting effect on the growth of the thymus and spleen of mice, and the thymus index and spleen index were increased (P<0.1); the thymus index and spleen index of mice in the polysaccharide gel group of Example 6 were close to those of the positive drug group, and the effect was the most significant, and the difference was statistically significant (P<0.05). Therefore, it is shown that the polysaccharide gel of jujube pulp can enhance the thymus and spleen function of mice and enhance the immunity of mice.

[0115] 2. Determination of phagocytic carbon clearance phagocytic index: 42 male mice were randomly divided into 7 groups, namely model group, blank group, positive drug group and polysaccharide gel group of Examples 6, 7, 8 and 9. Except for the blank group, mice in other groups were intraperitoneally injected with cyclophosphamide at 0.005 g / kg for 4 consecutive days. The mice gradually showed signs of low immunity such as weight loss, reduced activity, slow reaction, curled up arched back, and loose hair, indicating that the model was successfully replicated. 0.3 g / kg was gavaged orally for 17 consecutive days. On the 21st day of administration, the mice were weighed and anesthetized with urethane-normal saline solution. Each mouse was injected with Indian ink through the tail vein at a dose of 10 ml / kg. 20 μL of blood was collected from the posterior ocular venous plexus 5 min and 15 min after the injection of ink, and immediately added to 2 mL of 0.1% Na2CO3 solution. Na2CO3 solution was used as blank control, and the absorbance was measured at a wavelength of 600 nm. The mice were killed and the liver and spleen were separated and weighed. The phagocytic index a was used to represent the phagocytic capacity of mouse monocytes and macrophages. The results are shown in Table 13.

[0116] Table 13 Effects of jujube pulp polysaccharide gel on carbon clearance phagocytosis index of mouse phagocytes (x±s, n=6)

[0117]

[0118] Note: Compared with the blank group, ## P<0.05; compared with the model group, ** P<0.05, * P<0.1

[0119] Compared with the model group, the carbon clearance phagocytosis index a of the model group mice decreased in the blank group, which was statistically significant (P<0.05), and the model was established; compared with the model group mice in the polysaccharide gel groups of Examples 6-9, the carbon clearance phagocytosis index a values ​​of the sour jujube pulp polysaccharide gel group mice were all increased (P<0.1); the carbon clearance phagocytosis index a values ​​of the polysaccharide gel group mice in Example 6 and the positive drug group mice were relatively close, and the effect was the most significant, and the difference was statistically significant (P<0.05), indicating that the polysaccharide gel group in Example 6 had the best effect in enhancing immunity. In summary, the sour jujube pulp polysaccharide gel has the ability to enhance the body's immune organs, thereby enhancing the body's immunity.

[0120] 3. Blood routine test: 42 male mice were randomly divided into 7 groups, namely model group, blank group, positive drug group and polysaccharide gel group of Examples 6, 7, 8 and 9. Except for the blank group, the remaining groups of mice were intraperitoneally injected with cyclophosphamide at 0.005g / kg for 4 consecutive days. The mice gradually showed signs of low immunity such as weight loss, reduced activity, slow reaction, curled arched back, and loose hair, indicating that the model was successfully replicated. According to 0.3g / kg gavage, the positive drug group was given Zhenqi Fuzheng Granules, each gel group was given polysaccharide gel, and the blank group was given distilled water for 17 consecutive days. On the 21st day of administration, the mice were weighed and killed. Before being killed, 20μL of blood was collected from the tail vein, placed in diluent, and analyzed with a blood routine analyzer to determine the number of white blood cells and lymphocytes. The results are shown in Tables 14 and 15.

[0121] Table 14 Effect of jujube pulp polysaccharide gel on the number of white blood cells in mouse blood (x±s, n=6)

[0122]

[0123] Note: Compared with the blank group, ## P<0.05; compared with the model group, ** P<0.05, * P<0.1

[0124] Compared with the model group, the blank group had a decreased white blood cell count in the model group mice, which was statistically significant (P<0.05), and the model was established; compared with the model group mice, the white blood cell counts in the Axilla jujuba polysaccharide gel group mice in Examples 6-9 were increased (P<0.1); the white blood cell counts in the Axilla jujuba polysaccharide gel group mice and the positive drug group mice were close, with the most significant effect, and the difference was statistically significant (P<0.05), indicating that Axilla jujube polysaccharide gel can increase the number of white blood cells in the blood, thereby enhancing the body's immunity.

[0125] Table 15 Effect of Jujube Pulp Polysaccharide Gel on the Number of Lymphocytes in Mouse Blood (x±s, n=6)

[0126]

[0127] Note: Compared with the blank group, ## P<0.05; compared with the model group, ** P<0.05, * P<0.1

[0128] Compared with the model group, the number of lymphocytes in the blank group and the model group mice decreased, which was statistically significant (P<0.05), and the model was established; compared with the model group mice, the number of lymphocytes in the polysaccharide gel groups of Examples 6-9 was increased (P<0.1); the number of lymphocytes in the polysaccharide gel group of Example 6 and the positive drug group mice was close, and the effect was the most significant, and the difference was statistically significant (P<0.05), indicating that the polysaccharide gel of sour jujube pulp can increase the number of lymphocytes in the blood, thereby enhancing the body's immunity.

[0129] 4. Concentration of IFN-γ in blood: 42 male mice were randomly divided into 7 groups, namely, model group, blank group, positive drug group and polysaccharide gel group of Examples 6, 7, 8 and 9. Except for the blank group, the mice in the other groups were intraperitoneally injected with cyclophosphamide at 0.005 g / kg for 4 consecutive days. The mice gradually showed signs of low immunity such as weight loss, reduced activity, slow reaction, curled up arched back, and loose hair, indicating that the model was successfully replicated. According to 0.3 g / kg oral administration, the positive drug group was given Zhenqi Fuzheng Granules, each gel group was given polysaccharide gel, and the blank group was given distilled water for 17 consecutive days. The ocular venous blood of the mice was taken and centrifuged at 3000 r / min for 10 min to collect serum. The IFN-γ level in the serum was determined using the ELISA kit according to the instructions. The optical density value (OD) was determined using an enzyme marker (at a wavelength of 450 nm) within 15 minutes after the end, and its concentration was calculated. The results are shown in Table 16.

[0130] Table 16 Effect of jujube pulp polysaccharide gel on IFN-γ concentration in mouse blood (x±s, n=6)

[0131]

[0132] Note: Compared with the blank group, ## P<0.05; compared with the model group, ** P<0.05, * P<0.1

[0133] Compared with the model group, the blank group had a lower IFN-γ concentration in the blood of the model group mice, which was statistically significant (P<0.05), and the model was established; compared with the model group mice, the IFN-γ concentration in the blood of the mice in the polysaccharide gel groups of Examples 6-9 was increased in the jujube pulp polysaccharide gel group (P<0.1); the IFN-γ concentration in the blood of the mice in the polysaccharide gel group of Example 6 was close to that of the mice in the positive drug group, and the effect was the most significant, and the difference was statistically significant (P<0.05), indicating that the jujube pulp polysaccharide gel can increase the concentration of IFN-γ in the blood, thereby enhancing the body's immunity.

[0134] In summary, by adopting the method of the present invention, the purity of the polysaccharide obtained can reach 86.5±0.02%, and the jujube pulp polysaccharide gel can significantly improve the thymus index, spleen index, phagocytic carbon clearance phagocytosis index, the number of lymphocytes in the blood, the number of white blood cells in the blood and the concentration of IFN-γ in the blood, indicating that the jujube pulp polysaccharide gel has the effect of enhancing immunity.

[0135] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing an oral gel of jujube pulp polysaccharide for enhancing immunity, characterized in that: The method comprises the following steps: drying the sour jujube with hot air, crushing and sieving the sour jujube fruit powder; adding deionized water to the sour jujube fruit powder, adjusting the pH value to 3-6 with citric acid-sodium citrate buffer, and extracting the sour jujube fruit powder by using a magnetic induction electric field device; removing the protein in the sour jujube pulp polysaccharide solution by using papain; purifying and concentrating the polysaccharide solution by ultrafiltration membrane twice, freeze-drying, crushing and sieving the sour jujube pulp polysaccharide powder; adding water, carrageenan, konjac gum and flavoring agent to the sour jujube pulp polysaccharide powder in proportion, heating at 50℃-80℃ and sterilizing the sour jujube pulp polysaccharide gel; the specific steps are as follows: (1) Preparation of jujube fruit powder: Sort and clean the jujube fruits, separate the pulp from the core, place the pulp after core removal in a 60°C forced air drying oven, dry it with hot air for 26 h, grind it, and pass it through a 60-mesh sieve to obtain jujube powder; (2) Extraction of polysaccharides by magnetic induction electric field: the jujube powder obtained in step (1) is added to deionized water at a solid-liquid ratio of 1:5-1:20 g / mL for magnetic induction electric field extraction. The magnetic induction electric field reaction frequency is 300 Hz-600 Hz, the excitation voltage is 700 V-1000 V, the extraction solution temperature is 50-80°C, the pH value is adjusted to 3-6 with citric acid-sodium citrate buffer, and the extraction time is 10-25 min. (3) Obtaining a crude polysaccharide solution from the pulp of sour jujube: centrifuging the solution extracted by magnetic induction electric field in step (2) at 4000-5000 r / min for 15-20 min to obtain a crude polysaccharide solution from the pulp of sour jujube; (4) Protein removal: add papain to the crude polysaccharide solution of jujube pulp obtained in step (3) to prepare a solution with an enzyme mass fraction of 0.2%-0.5% and a pH value of 4-8, perform enzymolysis in a water bath at 40-70°C for 0.5-2h, inactivate in a boiling water bath for 5-15min after the reaction is completed, and remove the precipitate by centrifugation at 4000-5000 r / min for 10-15min to obtain a deproteinized jujube pulp polysaccharide solution; the protein removal rate is 86% and the polysaccharide retention rate is 94%; (5) Ultrafiltration to remove macromolecular impurities: The crude polysaccharide solution of jujube pulp obtained in step (4) is ultrafiltered for the first time, using a 0.02-0.05 μm ultrafiltration membrane for ultrafiltration at a pressure of 0.12-0.15 MPa, and the initial temperature of the crude polysaccharide solution is adjusted to 25°C to 28°C to remove impurity molecules with a molecular weight of ≥500,000 Da; (6) Secondary ultrafiltration to remove small molecules: The crude polysaccharide solution of jujube pulp obtained in step (5) is subjected to a second ultrafiltration, using an ultrafiltration membrane of 0.008-0.01 μm and a pressure of 0.1-0.2 MPa. The initial temperature of the crude polysaccharide solution is adjusted to 30-35° C. to remove impurities with a molecular weight of ≤100,000 Da, thereby obtaining a jujube pulp polysaccharide solution with a molecular weight of 100,000 Da to 500,000 Da; (7) Preparation of jujube pulp polysaccharide powder: freeze-dry the jujube pulp polysaccharide solution obtained in step (6) at -50°C to -60°C, pre-freeze for 8-10 hours, with a cold trap temperature of -30°C to -50°C and a vacuum degree of 0.04-0.08 MPa, freeze for 25-30 hours, grind, and pass through a 60-100 mesh sieve to obtain jujube pulp polysaccharide powder; (8) Preparation of gel: Add water to the jujube pulp polysaccharide powder obtained in step (7) at a solid-liquid ratio of 1:10 g / mL to 1:20 g / mL to prepare a polysaccharide solution; Inulin, potassium chloride, citric acid, sodium citrate, potassium sorbate and water are added as flavoring agents to a polysaccharide solution in a mass ratio of 0.2-0.4: 0.01-0.02: 0.006-0.03: 0.004-0.02: 0.01-0.02: 3-15 to prepare a polysaccharide liquid; wherein the mass ratio of citric acid to sodium citrate is 3:1; the amount of potassium chloride is greater than 0.1%; The mass ratio of carrageenan, konjac gum and water is 0.06-0.16:0.06-0.16:1-3, heated at 60-100°C to dissolve, and continued to stir to fully disperse, absorb water, swell, and boil for 2-5 minutes to make it evenly dissolved, as a standby gelling agent; wherein: the mass ratio of carrageenan to konjac gum is 1:1; The polysaccharide liquid and the standby gelling agent are mixed in a volume ratio of 1:3-1:5, during which the heating temperature is controlled at 50-80°C and the stirring is performed at 300-500r / min to obtain the jujube pulp polysaccharide gelling agent.

2. The method for preparing the oral gel of polysaccharide from jujube pulp for enhancing immunity according to claim 1, characterized in that: The specific method of pulverizing in step (7) is as follows: after freeze-drying the jujube pulp polysaccharide solution, freeze it at -50°C to -70°C for 10 min to 15 min, then use a freeze grinder to pulverize it, and keep the pulverizing chamber temperature at -30°C to -60°C. After pulverizing, pass it through a 60-100 mesh sieve to obtain jujube pulp polysaccharide powder.

3. The method for preparing the oral gel of polysaccharide from jujube pulp for enhancing immunity according to claim 1, characterized in that: The prepared sour jujube pulp polysaccharide gel is heated and sterilized at 90-115° C. for 15-30 minutes until there are no large bubbles, and then filled into bagged gel when the temperature is naturally cooled to 60-80° C.

4. An oral gel preparation of polysaccharide from jujube pulp for enhancing immunity prepared by the method according to any one of claims 1 to 3.

5. Use of the oral gel of polysaccharide from jujube pulp for enhancing immunity according to claim 4 in the preparation of drugs for enhancing immunity.

6. Use of the oral gel of jujube pulp polysaccharide for enhancing immunity according to claim 4 in the preparation of health products or functional foods for enhancing immunity.

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