Polymerization-resisting and dissolution-promoting method of hot-dried RG-I pectin

Abstract

The invention discloses a polymerization-resisting and dissolution-promoting method of hot-dried RG-I pectin, and belongs to the technical field of biology. The polymerization-resisting and dissolution-promoting method of the hot-dried RG-I pectin comprises the following steps: (1) mixing pericarp powder and an acid solution, carrying out acid extraction, and centrifuging to obtain supernate; adjusting the pH value of the obtained supernatant to 5-7, then carrying out alcohol precipitation, and filtering to obtain a precipitate; and (2) mixing the precipitate obtained in the step (1) with a displacer for replacement for multiple times, and then filtering and drying with hot air to obtain the RG-I pectin. According to the method, residual water in RG-I pectin is fully replaced to increase the free volume of pectin molecules, the process of affinity aggregation of adjacent pectin molecular chains dragged by dissipation of water molecules is inhibited, the aggregation phenomenon among the pectin molecules in the drying process is remarkably reduced, the solubility of the pectin is greatly improved, and the stability of the pectin is improved. Therefore, the application effect of the method in various fields is improved.

Description

Technical Field

[0001] The invention belongs to the field of biotechnology, and in particular relates to an anti-aggregation and dissolution-promoting method for heat-dried RG-I pectin. Background Art

[0002] RG-I pectin is an important component of plant cell walls and is found in large quantities in fruit and vegetable processing waste. RG-I pectin has many functional properties that are superior to traditional pectin, such as immunomodulation, anti-inflammatory and cancer prevention. It can also be used as a gel, thickener and heavy metal ion adsorbent, and has shown great application potential in food, pharmaceuticals and cosmetics.

[0003] Industrially, the preparation process of RG-I pectin usually includes extraction, filtration, pH adjustment, alcohol precipitation and drying. Among them, the drying method includes freeze-drying and thermal drying. Although the RG-I pectin after freeze-drying has a relatively acceptable solubility, the high cost and complexity of the preparation process are generally difficult to accept in food processing, and thermal drying is more widely used in pectin drying due to its low cost and high production efficiency. However, thermal drying often leads to poor solubility of RG-I pectin, which seriously affects its subsequent processing and use. Therefore, how to improve the solubility of RG-I pectin is a technical problem that needs to be solved urgently in the process of preparing RG-I pectin.

[0004] At present, existing research mainly modifies the traditional pectin structure by substitution, derivatization, cross-linking and other methods, thereby enhancing the functional properties of pectin such as dissolution during application. For example, patent CN116462858A discloses that pectin and amino acids form conjugates to make it have better thermal reversibility and also increase the water solubility of pectin. However, on the one hand, the scheme causes the sample to undergo structural transformation due to the introduction of amino acid groups. On the other hand, the method relies on double-link pH regulation and calcium ions, and the process is relatively complex, which also limits its production in low-calcium or calcium-free environments. In addition, there are also methods that combine redox systems with grafting modification. For example, patent CN114716579A discloses that pectin is grafted and modified using coumaric acid. The resulting pectin graft copolymer has good solubility and high antioxidant activity. However, this method also introduces phenolic acid groups into the pectin molecules due to grafting copolymerization, which changes the molecular structure of pectin. In addition, there are also technologies for producing probiotic-coated pectin by enzymatic viscosity reduction and composite granulation, such as patent CN114634655A, which prepares pectin with low viscosity, good solubility, and superior coating performance. However, the enzymatic hydrolysis process is a degradation process. The smaller the molecular weight of pectin, the better the solubility. However, the change in structure will also reduce the viscosity and other thickening properties. In addition, the amount of enzyme used in the process is large, and the production cost is high. The above processes basically change the structure of pectin, and the object of the volume-enhancing modification is traditional pectin. Even if the same preparation process is used, its solubility will be better than RG-I pectin.

[0005] Therefore, there is an urgent need for a dissolution-promoting method that can not only improve the solubility of RG-I pectin, but also retain the original function of RG-I pectin to the greatest extent, while achieving no chemical residue, no by-product generation, and economic and environmental protection requirements. Summary of the invention

[0006] In order to solve the above technical problems, the present invention proposes a method for preventing aggregation and promoting dissolution of heat-dried RG-I pectin.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] The present invention provides a method for resisting polymerization and promoting dissolution of heat-dried RG-I pectin, comprising the following steps:

[0009] (1) mixing the peel powder and the acid solution for acid extraction, and obtaining a supernatant after centrifugation; adjusting the pH of the obtained supernatant to 5-7, and then performing alcohol precipitation, and filtering to obtain a precipitate;

[0010] (2) The precipitate obtained in step (1) is mixed with a displacing agent for displacement, and then filtered and dried with hot air to obtain RG-I pectin.

[0011] Preferably, in step (1), the solid-liquid ratio of the peel powder to the acid solution is 1:(10-20) (w / v); the acid solution is a hydrochloric acid solution; and the pH of the acid solution is 1-3.

[0012] Preferably, in step (1), the acid extraction is carried out at a temperature of 20 to 60° C. and for a time of 0.5 to 2 h.

[0013] Preferably, in step (1), the reagent used for the alcohol precipitation is anhydrous ethanol; the volume ratio of the anhydrous ethanol to the supernatant is 2:1; and the alcohol precipitation time is 5 hours.

[0014] Preferably, in step (2), the displacing agent is selected from ethanol and isopropanol.

[0015] Preferably, in step (2), the volume of the displacing agent is 50 to 100 times the mass of the precipitate.

[0016] Preferably, in step (2), the replacement is specifically as follows: the precipitate obtained in step (1) is mixed with the replacement agent and then replaced for 5 minutes, filtered and then the replacement agent is added for the next replacement.

[0017] Preferably, in step (2), when the replacement agent is ethanol, the number of replacements is 3 to 4 times.

[0018] Preferably, in step (2), when the displacing agent is isopropanol, the number of displacements is 2 to 3 times.

[0019] Preferably, in step (2), the hot air drying temperature is 60° C. and the time is 2 h.

[0020] Compared with the prior art, the present invention has the following advantages and technical effects:

[0021] (1) The present invention fully replaces the residual water in RG-I pectin to increase the free volume of pectin molecules, inhibits the affinity aggregation process of adjacent pectin molecular chains pulled by the escape of water molecules, significantly reduces the aggregation phenomenon between pectin molecules during the drying process, greatly improves the solubility of pectin, and thus enhances its application effect in various fields.

[0022] (2) The method provided by the present invention does not change the basic structure of RG-I pectin, and can improve the solubility of RG-I pectin while retaining its original functionality, such as gelling and thickening, to the greatest extent, thereby meeting a wider range of application requirements.

[0023] (3) The present invention uses food-grade organic solvents as replacement agents for replacement. During the thermal drying process, the organic solvents are volatile, leave no residue, and do not produce harmful by-products, thereby ensuring the safety and environmental friendliness of the product throughout the entire process and meeting the requirements of modern production for green and sustainable production.

[0024] (4) The process of the present invention is simple and can be easily integrated into an existing production line. It can realize large-scale production at low cost and high efficiency and has good industrialization prospects.

[0025] (5) The method of the present invention is not only applicable to the processing of RG-I pectin, but can also be extended to the processing technology of other similar polysaccharides. It has good adaptability and promotion potential and can meet the needs of different fields for polysaccharide solubility. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0027] Figure 1 It is a microscopic dissolution process diagram of RG-I pectin obtained in Example 1 and Comparative Examples 1 to 3;

[0028] Figure 2 It is a microscopic dissolution process diagram of RG-I pectin obtained in Examples 2 to 3 and Comparative Examples 3 to 4. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0031] The embodiment of the present invention provides a method for preventing aggregation and promoting dissolution of heat-dried RG-I pectin, comprising the following steps:

[0032] (1) mixing the peel powder and the acid solution for acid extraction, and obtaining a supernatant after centrifugation; adjusting the pH of the obtained supernatant to 5-7, and then performing alcohol precipitation, and filtering to obtain a precipitate;

[0033] (2) The precipitate obtained in step (1) is mixed with a displacing agent for displacement, and then filtered and hot-air dried to obtain RG-I pectin.

[0034] At present, the reason for the poor solubility of heat-dried RG-I pectin is still unclear. The inventors speculate that it is related to the aggregation of pectin hydrophilic chains induced by water molecules during the heat drying process. Therefore, the inventors tried to replace the residual water in RG-I pectin to increase the free volume of pectin molecules and inhibit the affinity aggregation process of adjacent pectin molecular chains pulled by the escape of water molecules, so as to achieve the effect of improving the solubility after drying.

[0035] In a preferred embodiment, in step (1), the peel powder includes citrus peel powder.

[0036] In a preferred embodiment, in step (1), the method for preparing the peel powder comprises the following steps: drying the peel at 50-60° C. and crushing the peel to obtain the peel powder.

[0037] In a preferred embodiment, in step (1), the solid-liquid ratio of the peel powder to the acid solution is 1:(10-20) (w / v), that is, (10-20) mL of acid solution is used for every 1 g of peel powder; further preferably, it is 1:(15-20) (w / v). In a further preferred embodiment, the solid-liquid ratio of the peel powder to the acid solution is 1:20 (g / mL).

[0038] In a preferred embodiment, in step (1), the acid solution is a hydrochloric acid solution; the pH of the acid solution is 1 to 3, more preferably 1 to 2.

[0039] In a preferred embodiment, in step (1), the temperature of the acid extraction is 20 to 60° C., more preferably 20 to 40° C.; the time of the acid extraction is 0.5 to 2 h, more preferably 0.5 to 1 h.

[0040] In a preferred embodiment, in step (1), the pH of the obtained supernatant is adjusted to 5-7, more preferably 5.

[0041] In a preferred embodiment, in step (1), the reagent used for the alcohol precipitation is anhydrous ethanol; the volume ratio of the anhydrous ethanol to the supernatant is 2:1; and the alcohol precipitation time is 5 hours.

[0042] In a preferred embodiment, in step (2), the displacing agent is selected from one of ethanol and isopropanol. The present invention uses a food-grade organic solvent as a displacing agent for displacement, which is volatile and has no residue during the thermal drying process, and does not produce harmful by-products, thereby ensuring the safety and environmental protection of the product in the entire process.

[0043] In a preferred embodiment, in step (2), the volume amount of the displacer is 50 to 100 times the mass of the precipitate. The amount of the displacer in the present invention will affect the solubility of RG-I pectin. Too little displacer cannot fully displace the water in RG-I pectin. Too much displacer will waste reagents and will not improve the solubility of pectin.

[0044] In a preferred embodiment, in step (2), the replacement is specifically: mixing the precipitate and the replacement agent and replacing them for 5 minutes, filtering and then adding the replacement agent for the next replacement.

[0045] In a preferred embodiment, in step (2), when the displacing agent is ethanol, the number of times of the displacement is 3 to 4 times; when the displacing agent is isopropanol, the number of times of the displacement is 2 to 3 times. Too few times of displacement cannot fully replace the water in the RG-I pectin, affecting the solubility of the RG-I pectin.

[0046] In a preferred embodiment, in step (2), the hot air drying temperature is 60° C. and the time is 2 hours.

[0047] Unless otherwise specified, the raw materials in the examples of the present invention were purchased from commercial sources.

[0048] Example 1

[0049] A method for preventing aggregation and promoting dissolution of heat-dried RG-I pectin, comprising the following specific steps:

[0050] (1) drying citrus peel at 50° C. and crushing to obtain citrus peel powder; mixing the citrus peel powder with a hydrochloric acid solution of pH=1 at a solid-liquid ratio of 1:20 (g / mL), extracting at 40° C. for 1 hour, centrifuging, collecting the supernatant and adjusting the pH of the supernatant to 5, then adding anhydrous ethanol to the supernatant at a volume ratio of 2:1, standing for 5 hours, filtering with a filter cloth, and obtaining a precipitate;

[0051] (2) The precipitate obtained in step (1) is mixed with ethanol and replaced for 5 minutes. After filtering, ethanol is added for the next replacement. A total of 3 replacements are performed. The volume of ethanol used in each replacement is 100 times the mass of the precipitate. The residual water is continuously replaced by ethanol. After the replacement is completed, the mixture is filtered and then hot-air dried at 60° C. for 2 hours to obtain RG-I pectin.

[0052] The solubility of the RG-I pectin obtained in Example 1 was measured to be 79.67%. The bulk density of the RG-I pectin obtained in Example 1 was measured by a powder determination method to be 0.658 g / cm 3 .

[0053] Comparative Example 1

[0054] A method for preventing aggregation and promoting dissolution of heat-dried RG-I pectin, comprising the following specific steps:

[0055] (1) drying citrus peel at 50° C. and crushing to obtain citrus peel powder; mixing the citrus peel powder with a hydrochloric acid solution of pH=1 at a solid-liquid ratio of 1:20 (g / mL), extracting at 40° C. for 1 hour, centrifuging, collecting the supernatant and adjusting the pH of the supernatant to 5, then adding anhydrous ethanol to the supernatant at a volume ratio of 2:1, standing for 5 hours, filtering with a filter cloth, and obtaining a precipitate;

[0056] (2) The precipitate obtained in step (1) is mixed with ethanol and replaced for 5 minutes. After filtering, ethanol is added again for the next replacement. A total of 2 replacements are performed. The volume of ethanol used in each replacement is 100 times the mass of the precipitate. The residual water is continuously replaced by ethanol. After the replacement is completed, it is filtered and then hot-air dried at 60° C. for 2 hours to obtain RG-I pectin.

[0057] The solubility of the RG-I pectin obtained in Comparative Example 1 was measured to be 68.92%. The bulk density of the RG-I pectin obtained in Comparative Example 1 was measured by a powder determination method to be 0.708 g / cm 3 .

[0058] Comparative Example 2

[0059] A method for preparing heat-dried RG-I pectin, the specific steps are as follows:

[0060] (1) drying citrus peel at 50° C. and crushing to obtain citrus peel powder; mixing the citrus peel powder with a hydrochloric acid solution of pH=1 at a solid-liquid ratio of 1:20 (g / mL), extracting at 40° C. for 1 hour, centrifuging, collecting the supernatant and adjusting the pH of the supernatant to 5, then adding anhydrous ethanol to the supernatant at a volume ratio of 2:1, standing for 5 hours, filtering with a filter cloth, and obtaining a precipitate;

[0061] (2) The precipitate obtained in step (1) was mixed with ethanol for replacement for 5 minutes, wherein the volume of ethanol used was 100 times the mass of the precipitate, and the residual water was continuously replaced by ethanol. After the replacement, the mixture was filtered and then hot-air dried at 60° C. for 2 hours to obtain RG-I pectin.

[0062] The solubility of the RG-I pectin obtained in Comparative Example 2 was measured to be 49.06%. The bulk density of the RG-I pectin obtained in Comparative Example 2 was measured by the powder determination method to be 0.714 g / cm 3 .

[0063] Comparative Example 3

[0064] A method for preparing heat-dried RG-I pectin, the specific steps are as follows:

[0065] (1) drying citrus peel at 50° C. and crushing to obtain citrus peel powder; mixing the citrus peel powder with a hydrochloric acid solution of pH=1 at a solid-liquid ratio of 1:20 (g / mL), extracting at 40° C. for 1 hour, centrifuging, collecting the supernatant and adjusting the pH of the supernatant to 5, then adding anhydrous ethanol to the supernatant at a volume ratio of 2:1, standing for 5 hours, filtering with a filter cloth, and obtaining a precipitate;

[0066] (2) The precipitate obtained in step (1) is dried by hot air at 60° C. for 2 h to obtain RG-I pectin.

[0067] The solubility of the RG-I pectin obtained in Comparative Example 3 was measured to be 23.91%. The bulk density of the RG-I pectin obtained in Comparative Example 3 was measured by powder determination method to be 0.767 g / cm 3 .

[0068] Test Example 1: Take a small amount of the RG-I pectin powder obtained in Example 1 and Comparative Examples 1 to 3, place it on a glass slide, then add a drop of distilled water, and observe the dissolution process of the pectin under an inverted microscope. The results are shown in Figure 1 .

[0069] Figure 1 The microscopic dissolution process diagram of RG-I pectin obtained in Example 1 and Comparative Examples 1 to 3. In the figure, the white area represents the aqueous solution, and the black area represents the pectin powder. As time goes by, when the pectin continues to diffuse and dissolve in the water, the black area of ​​the pectin will decrease. Figure 1It can be seen that the RG-I pectin prepared in Example 1 dissolves the fastest, indicating that it has a higher solubility rate. The dissolution rate of the RG-I pectin prepared in Comparative Example 2 is slower, and even after 480s, most of the pectin is still not dissolved, indicating that there are still more insoluble parts. It can be seen that the RG-I pectin prepared by the anti-aggregation dissolution-promoting method provided by the present invention has better solubility.

[0070] The residual water content was indirectly tested by HPLC, and the final residual water content of the RG-I pectin prepared in Example 1 was 0.45%, the residual water contents of the RG-I pectins prepared in Comparative Examples 1 and 2 were 3.30% and 3.68%, respectively, and the residual water content of the RG-I pectin prepared in Comparative Example 3 was 31.97%. It can be seen that as more residual water is replaced, the solubility of the RG-I pectin is better.

[0071] Example 2

[0072] A method for preventing aggregation and promoting dissolution of heat-dried RG-I pectin, comprising the following specific steps:

[0073] (1) drying citrus peel at 50° C. and crushing to obtain citrus peel powder; mixing the citrus peel powder with a hydrochloric acid solution of pH=1 at a solid-liquid ratio of 1:20 (g / mL), extracting at 40° C. for 1 hour, centrifuging, collecting the supernatant and adjusting the pH of the supernatant to 5, then adding anhydrous ethanol to the supernatant at a volume ratio of 2:1, standing for 5 hours, filtering with a filter cloth, and obtaining a precipitate;

[0074] (2) The precipitate obtained in step (1) was mixed with isopropanol for replacement for 5 minutes, and isopropanol was added again after filtration for the next replacement. A total of 3 replacements were performed, and the volume of isopropanol used for each replacement was 100 times the mass of the precipitate. The residual water was continuously replaced by isopropanol. After the replacement was completed, the mixture was filtered and then hot-air dried at 60° C. for 2 hours to obtain RG-I pectin.

[0075] The solubility of the RG-I pectin obtained in Example 2 was measured to be 77.85%. The bulk density of the RG-I pectin obtained in Example 2 was measured by powder determination method to be 0.543 g / cm 3 .

[0076] Example 3

[0077] A method for preparing heat-dried RG-I pectin, the specific steps are as follows:

[0078] (1) drying citrus peel at 50° C. and crushing to obtain citrus peel powder; mixing the citrus peel powder with a hydrochloric acid solution of pH=1 at a solid-liquid ratio of 1:20 (g / mL), extracting at 40° C. for 1 hour, centrifuging, collecting the supernatant and adjusting the pH of the supernatant to 5, then adding anhydrous ethanol to the supernatant at a volume ratio of 2:1, standing for 5 hours, filtering with a filter cloth, and obtaining a precipitate;

[0079] (2) The precipitate obtained in step (1) is mixed with isopropanol for replacement for 5 minutes, and isopropanol is added again after filtration for the next replacement. A total of 2 replacements are performed, and the volume of isopropanol used for each replacement is 100 times the mass of the precipitate. The residual water is continuously replaced by isopropanol. After the replacement is completed, the mixture is filtered and then hot-air dried at 60° C. for 2 hours to obtain RG-I pectin.

[0080] The solubility of the RG-I pectin obtained in Example 3 was measured to be 75.40%. The bulk density of the RG-I pectin obtained in Example 3 was measured by powder determination method to be 0.615 g / cm 3 .

[0081] Comparative Example 4

[0082] A method for preparing heat-dried RG-I pectin, the specific steps are as follows:

[0083] (1) drying citrus peel at 50° C. and crushing to obtain citrus peel powder; mixing the citrus peel powder with a hydrochloric acid solution of pH=1 at a solid-liquid ratio of 1:20 (g / mL), extracting at 40° C. for 1 hour, centrifuging, collecting the supernatant and adjusting the pH of the supernatant to 5, then adding anhydrous ethanol to the supernatant at a volume ratio of 2:1, standing for 5 hours, filtering with a filter cloth, and obtaining a precipitate;

[0084] (2) The precipitate obtained in step (1) was mixed with isopropanol for replacement for 5 minutes, wherein the volume of isopropanol used was 100 times the mass of the precipitate, and the residual water was continuously replaced by isopropanol. After the replacement, the mixture was filtered and then hot-air dried at 60° C. for 2 hours to obtain RG-I pectin.

[0085] The solubility of the RG-I pectin obtained in Comparative Example 4 was measured to be 64.47%, and the bulk density of the RG-I pectin obtained in Comparative Example 4 was measured by powder determination method to be 0.642 g / cm 3 .

[0086] Test Example 2: Take a small amount of RG-I pectin powder obtained in Examples 2 to 3 and Comparative Examples 3 to 4, place it on a glass slide, then add a drop of distilled water, and observe the dissolution process of pectin under an inverted microscope. The results are shown in Figure 2 .

[0087] Figure 2The microscopic dissolution process diagram of RG-I pectin obtained in Examples 2-3 and Comparative Examples 3-4. In the figure, the white area represents the aqueous solution, and the black area represents the pectin powder. As time goes by, when the pectin continues to diffuse and dissolve in the water, the black area of ​​the pectin will decrease. Figure 2 It can be seen that the RG-I pectin prepared in Example 2 dissolves the fastest, indicating that it has a higher solubility rate. The dissolution rate of the RG-I pectin prepared in Comparative Example 3 is slower, and even after 480s, most of the pectin is still undissolved, indicating that there are still more black areas. It can be seen that the RG-I pectin prepared by the anti-aggregation dissolution-promoting method provided by the present invention has better solubility.

[0088] The residual water content was indirectly tested by HPLC, and the final residual water contents of the RG-I pectins prepared in Example 2 and Example 3 were measured to be 0.44% and 1.50%, respectively. The residual water content of the RG-I pectin prepared in Comparative Example 4 was 6.23%, and the residual water content of the RG-I pectin prepared in Comparative Example 3 was 31.97%. It can be seen that as more residual water is replaced, the solubility of the RG-I pectin is better.

[0089] Comparative Example 5

[0090] A method for preparing heat-dried RG-I pectin, the specific steps are as follows:

[0091] (1) drying citrus peel at 50° C. and crushing to obtain citrus peel powder; mixing the citrus peel powder with a hydrochloric acid solution of pH=1 at a solid-liquid ratio of 1:20 (g / mL), extracting at 40° C. for 1 hour, centrifuging, collecting the supernatant and adjusting the pH of the supernatant to 5, then adding anhydrous ethanol to the supernatant at a volume ratio of 2:1, standing for 5 hours, filtering with a filter cloth, and obtaining a precipitate;

[0092] (2) The precipitate obtained in step (1) was mixed with acetone for replacement for 5 minutes, and acetone was added again after filtering for the next replacement. A total of 3 replacements were performed, and the volume of acetone used for each replacement was 100 times the mass of the precipitate. The residual water was continuously replaced by acetone, filtered, and hot-air dried at 60° C. for 2 hours to obtain RG-I pectin.

[0093] The solubility rate of the RG-I pectin obtained in Comparative Example 5 was measured to be 57.74%.

[0094] The above are only preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for preventing aggregation and promoting dissolution of heat-dried RG-I pectin, characterized in that: The following steps are involved: (1) mixing the peel powder and the acid solution for acid extraction, and obtaining a supernatant after centrifugation; adjusting the pH of the obtained supernatant to 5-7, and then performing alcohol precipitation, and filtering to obtain a precipitate; (2) The precipitate obtained in step (1) is mixed with a displacing agent for displacement, and then filtered and hot-air dried to obtain RG-I pectin.

2. The method for preventing aggregation and promoting dissolution of heat-dried RG-I pectin according to claim 1, characterized in that: In step (1), the solid-liquid ratio of the peel powder to the acid solution is 1:(10-20) (w / v); the acid solution is a hydrochloric acid solution; and the pH of the acid solution is 1-3.

3. The anti-aggregation and dissolution-promoting method of heat-dried RG-I pectin according to claim 1, characterized in that: In step (1), the acid extraction is carried out at a temperature of 20 to 60° C. and for a time of 0.5 to 2 h.

4. The anti-aggregation and dissolution-promoting method of heat-dried RG-I pectin according to claim 1, characterized in that: In step (1), the reagent used for the alcohol precipitation is anhydrous ethanol, and the volume ratio of the anhydrous ethanol to the supernatant is 2:1; and the alcohol precipitation time is 5 hours.

5. The method for preventing aggregation and promoting dissolution of heat-dried RG-I pectin according to claim 1, characterized in that: In step (2), the displacing agent is selected from ethanol and isopropanol.

6. The method for preventing aggregation and promoting dissolution of heat-dried RG-I pectin according to claim 1, characterized in that: In step (2), the volume of the displacing agent is 50 to 100 times the mass of the precipitate.

7. The method for preventing aggregation and promoting dissolution of heat-dried RG-I pectin according to claim 1, characterized in that: In step (2), the replacement is specifically as follows: the precipitate obtained in step (1) is mixed with the replacement agent and then replaced for 5 minutes, filtered and then the replacement agent is added for the next replacement.

8. The method for preventing aggregation and promoting dissolution of heat-dried RG-I pectin according to claim 5, characterized in that: In step (2), when the replacement agent is ethanol, the number of replacements is 3 to 4 times.

9. The method for preventing aggregation and promoting dissolution of heat-dried RG-I pectin according to claim 5, characterized in that: In step (2), when the displacing agent is isopropanol, the number of times of the displacement is 2 to 3 times.

10. The method for preventing aggregation and promoting dissolution of heat-dried RG-I pectin according to claim 1, characterized in that: In step (2), the hot air drying temperature is 60° C. and the time is 2 h.

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