A method for drying Astragalus extract

Abstract

This invention relates to the field of Astragalus processing technology and discloses a method for drying Astragalus extract. The method involves adding a drying dispersant to the Astragalus extract and then spray drying it. The drying dispersant is β-cyclodextrin or the residue after Astragalus extraction. In this invention, spray drying is used to dry the Astragalus aqueous extract, and a dispersant (β-cyclodextrin or residue) is added to the system to be dried. Practical verification shows that the inlet air temperature can be controlled at around 130℃, which improves drying efficiency. Furthermore, the yield after drying, based on the calculated solids content, can reach over 95%.

Description

Technical Field

[0001] This invention relates to the field of Astragalus processing technology, specifically to a method for drying Astragalus extract. Background Technology

[0002] Astragalus is the root of Astragalus memeranaceus (Fisch.) Bge. Var. mongholicus (Bge.) Hsiao or Astragalus membranaceus (Fisch.) Bge., belonging to the genus Astragalus of the legume family. It has the effects of strengthening the spleen and replenishing the middle jiao, raising yang and lifting prolapse, benefiting wei qi and consolidating the exterior, promoting diuresis, and promoting tissue regeneration and detoxification. It is one of the commonly used Chinese medicinal materials.

[0003] Longxi is one of the authentic producing areas of Astragalus membranaceus in my country. As early as the Northern and Southern Dynasties, the great pharmacologist Tao Hongjing wrote in his "Collected Annotations on the Materia Medica" that "Astragalus membranaceus comes first from Longxi, with a yellowish-white color and a sweet taste, which is still rare today." This shows that Longxi was already a major producer of Astragalus membranaceus before the Northern and Southern Dynasties. The Tang Dynasty's "Treatise on the Nature of Medicinal Herbs" records, "For deficiency and coldness, use Longxi Astragalus membranaceus." The Song Dynasty's "Taiping Yulan" records, "The Qin Prefecture Records say that Astragalus membranaceus comes from Xiangwu County in Longxi (Xiangwu County in Longxi is the present-day Longxi County)." Today, Astragalus membranaceus is a major local medicinal herb from Longxi, sold throughout the country, and a "flagship" product in the Chinese medicinal herb industry. In 2001, Longxi was named "Hometown of Astragalus membranaceus in China" by the Chinese Society of Agricultural Sciences. In 2003, "Longxi Astragalus membranaceus" obtained the State Administration for Quality Supervision, Inspection and Quarantine's registration certification for geographical indication. In 2016, "Longxi Astragalus" was recognized as a "Geographical Indication Protected Product" by the Ministry of Agriculture, and the State Administration for Quality Supervision, Inspection and Quarantine named Longxi County a "National Famous Brand Demonstration Zone for the Chinese Medicinal Herbs (Astragalus and Codonopsis) Industry." In 2017, the "Longxi Astragalus" geographical indication certification trademark was recognized as a "China Famous Trademark" by the State Administration for Industry and Commerce, further proving that Longxi is rightfully known as the "Hometown of Astragalus in China." In 2019, "Longxi Astragalus" was recognized as a "Gansu Flavor" regional public brand of agricultural products by the Gansu Provincial Department of Agriculture and Rural Affairs. In 2021, "Longxi Astragalus" was included in the third batch of "National Famous, Special, High-Quality and New Agricultural Products" by the Ministry of Agriculture and Rural Affairs. Currently, the planting area of ​​Longxi Astragalus is stable at around 100,000 mu annually, with an annual output of 15 million kilograms, accounting for more than 70% of the national total output, making it the largest Astragalus medicinal herb source base in China.

[0004] In the processing of Astragalus membranaceus, the target components are usually extracted, dried, and powdered for later use. However, current drying methods for Astragalus membranaceus extract present the following problems: Astragalus membranaceus extract contains a large amount of polysaccharides, and traditional drying methods often result in a solidified layer forming after surface drying, causing internal moisture to remain trapped due to shrinkage. If the drying temperature is increased, exceeding 60°C will trigger the Maillard reaction, causing the product to darken in color and affecting its sensory quality. Summary of the Invention

[0005] The present invention aims to provide a drying method for Astragalus membranaceus extract, in order to solve the problems of high difficulty and unsatisfactory drying effect in the existing technology.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: a drying method for Astragalus extract, wherein a drying dispersant is added to the Astragalus extract and then spray-dried, wherein the drying dispersant is β-cyclodextrin or the residue after Astragalus extraction.

[0007] Preferably, as an improvement, a method for drying Astragalus extract includes the following steps:

[0008] Step 1: Concentrate the Astragalus extract to obtain a concentrated solution;

[0009] Step 2: Add a drying and dispersing agent to the concentrate, stir evenly, and then spray dry. The drying and dispersing agent is β-cyclodextrin or the residue after astragalus extraction.

[0010] Preferably, as an improvement, in step two, the drying dispersant is β-cyclodextrin, the amount of β-cyclodextrin added is 0-20% of the mass of the concentrate, and the particle size of β-cyclodextrin is 100 mesh.

[0011] Preferably, as an improvement, in step two, the drying dispersant is the residue after Astragalus membranaceus extraction, and the amount of residue added is 5-15% of the mass of the concentrate. The residue is dried, pulverized, and then passed through an 80-mesh sieve.

[0012] Preferably, as an improvement, the spray drying conditions are: inlet air temperature 130-135℃ and outlet air temperature 65-75℃.

[0013] Preferably, as an improvement, the spray drying conditions are: inlet air temperature 135℃ and outlet air temperature 70-75℃.

[0014] Preferably, as an improvement, the spray drying conditions are: inlet air temperature 130℃ and outlet air temperature 65-70℃.

[0015] The principle and beneficial effects of this technical solution are as follows: The product of Astragalus membranaceus extraction—the extract—contains a large amount of polysaccharides, making subsequent drying extremely difficult. Traditional drying methods often result in a solidified layer forming after surface drying, leading to shrinkage and preventing the internal moisture from drying out. Increasing the drying temperature above 60℃ will cause the Maillard reaction, darkening the product color. Spray drying results in wall adhesion, leading to low product yield. Freeze drying is time-consuming and costly, unsuitable for industrial application. This technical solution uses spray drying for the Astragalus membranaceus water extract, adding a dispersant (β-cyclodextrin / residue) to the drying system. Optimizing the drying temperature is a major challenge. Higher inlet air temperatures facilitate drying, but also increase outlet air temperatures, leading to higher energy consumption. Conversely, insufficient inlet air temperatures result in inadequate heat to completely evaporate the moisture, causing excessive moisture content, wall adhesion, and clumping. Practical verification shows that the inlet air temperature can be controlled at around 130℃, which can improve drying efficiency. After drying, the yield can reach more than 95% by measuring the solid content.

[0016] Astragalus extract (water extraction, enzymatic hydrolysis) mainly consists of polysaccharides, with a content between 20-40%. Polysaccharides melt when heated, so the conventional spray drying temperature is generally 190-200℃. Such temperatures easily cause the polysaccharides to melt, producing viscosity and leading to wall adhesion and clumping. Adding a dispersant can effectively solve this problem. This method experiments on the effects of different dispersants on spray drying, and the selection of the residue after astragalus extraction as the drying dispersant is a highlight of this invention. By adding 5-15% (based on the weight of the concentrated liquid) of the residue, not only can the wall adhesion problem be solved, but the inlet air temperature of the spray dryer can also be reduced, thus reducing energy consumption. It also increases the flowability of the material, making it easier to collect. Detailed Implementation

[0017] The following detailed description provides further details on specific embodiments, but the embodiments of the present invention are not limited thereto. Unless otherwise specified, the technical means used in the following embodiments are conventional means well known to those skilled in the art; the experimental methods used are all conventional methods; and the materials and reagents used are all commercially available.

[0018] Example 1

[0019] A method for drying Astragalus membranaceus extract, comprising the following steps:

[0020] Step 1: Concentrate the Astragalus extract to obtain a concentrated solution. The concentration conditions are: temperature 70℃, pressure -0.06-0.08 MPa, and the concentration endpoint is a solid content ≥30%.

[0021] Step 2: Drying. The extract concentrate is dried using the following method: Add 10% of the residue after enzymatic hydrolysis and centrifugation (the residue is dried and pulverized to 80 mesh, based on the weight of the concentrate) to the concentrate, mix and stir evenly, and then spray dry. The spray drying conditions are: inlet air temperature 130℃, outlet air temperature 65-70℃, and feed rate 15ml / min.

[0022] The residue after enzymatic hydrolysis and centrifugation of the sieve residue refers to the residue obtained after pulverizing Astragalus membranaceus and passing it through a 60-mesh sieve during the preparation of Astragalus membranaceus extract. The sieve residue is then subjected to gel milling, enzymatic hydrolysis using cellulase, and centrifugation. The resulting liquid and residue are the supernatant obtained after centrifugation.

[0023] Experimental Example 1: The Effect of Dispersant Addition Amount on Spray Drying Efficiency

[0024] Experimental methods:

[0025] Step 1: Concentrate the Astragalus extract to obtain a concentrated solution. The concentration conditions are: temperature 70℃, pressure -0.06-0.08 MPa, and the concentration endpoint is a solid content ≥30%.

[0026] Step two: Add different doses of dispersant to the concentrate and dry it according to the following methods. The specific processing methods are as follows:

[0027] ① The concentrate is directly spray-dried. The spray-drying conditions are: inlet air temperature 195℃, outlet air temperature 90-95℃, and feed rate 15ml / min.

[0028] ② The concentrate is directly spray-dried. The spray-drying conditions are: inlet air temperature 140℃, outlet air temperature 70-75℃, and feed rate 15ml / min.

[0029] ③ Add 5% β-cyclodextrin (by mass of concentrate) to the concentrate, stir well, and then spray dry. The spray drying conditions are: inlet air temperature 135℃, outlet air temperature 70-75℃, and feed rate 15ml / min.

[0030] ④ Add 10% β-cyclodextrin (by mass of concentrate) to the concentrate, stir well, and then spray dry. The spray drying conditions are: inlet air temperature 135℃, outlet air temperature 70-75℃, and feed rate 15ml / min.

[0031] ⑤ Add 15% β-cyclodextrin (by mass of concentrate) to the concentrate, stir well, and then spray dry. The spray drying conditions are: inlet air temperature 135℃, outlet air temperature 67-72℃, and feed rate 15ml / min.

[0032] ⑥ Add 20% β-cyclodextrin (by mass of concentrate) to the concentrate, stir well, and then spray dry. The spray drying conditions are: inlet air temperature 135℃, outlet air temperature 65-70℃, and feed rate 15ml / min.

[0033] Note: The fineness of β-cyclodextrin is 80 mesh.

[0034] The experimental results are shown in Table 1:

[0035] Table 1

[0036]

[0037] Note: Moisture content was tested according to GB 5009.3-2016.

[0038] Solid content was determined using a rapid moisture analyzer.

[0039] Yield = [(Product mass - β-cyclodextrin addition) / Solid content of concentrate] * 100%

[0040] Experiment Example 2: Effect of different dispersants on spray drying at the same dosage

[0041] Experimental method: Step 1: Concentrate the Astragalus extract to obtain a concentrated solution. The concentration conditions are: temperature 70℃, pressure -0.06-0.08 MPa, and the concentration endpoint is a solid content ≥30%.

[0042] Step 2: Drying. The extract concentrate with 10% of different dispersants added is dried using the following method:

[0043] ⑦ Add 10% β-cyclodextrin (by mass of concentrate) to the concentrate, stir well, and then spray dry. The spray drying conditions are: inlet air temperature 135℃, outlet air temperature 70-75℃, and feed rate 15ml / min.

[0044] ⑧ Add 10% maltodextrin (by weight of concentrate) to the concentrate, stir well, and then spray dry. The spray drying conditions are: inlet air temperature 140℃, outlet air temperature 72-77℃, and feed rate 15ml / min.

[0045] ⑨ Add 10% soluble starch (by weight of concentrate) to the concentrate, stir well, and then spray dry. The spray drying conditions are: inlet air temperature 145℃, outlet air temperature 75-80℃, and feed rate 15ml / min.

[0046] ⑩ Add 10% polydextrose (by weight of concentrate) to the concentrate, stir well, and then spray dry. The spray drying conditions are: inlet air temperature 140℃, outlet air temperature 72-77℃, and feed rate 15ml / min.

[0047] Add 10% of the residue from enzymatic hydrolysis and centrifugation (the residue is dried and pulverized to 80 mesh, based on the weight of the concentrate) to the concentrate, mix thoroughly, and spray dry. The spray drying conditions are: inlet air temperature 130℃, outlet air temperature 65-70℃, and feed rate 15ml / min.

[0048] Table 2

[0049]

[0050]

[0051] Note:

[0052] Yield = [(Product mass - Dispersant addition amount) / Solid content of concentrate] * 100%

[0053] The experimental results are shown in Table 2. As can be seen from the data in Table 2, the addition of 10% β-cyclodextrin or the residue after enzymatic hydrolysis and centrifugation of the sieve residue in this application can ensure a moisture content of approximately 4% after drying, with a yield of approximately 95%. Furthermore, the material is dry and has good flowability. While using maltodextrin or soluble starch as a dispersant can achieve material drying, the material flowability is poor, and the moisture content is relatively high. Using polydextrose as a dispersant leads to severe wall adhesion.

[0054] Experimental Example 3: Product yield, purity, wall adhesion, and sensory quality after drying (yield is expressed as solids content).

[0055] Experimental Methods: A comparative experiment was conducted on the concentrated liquid obtained in Example 1 using different drying methods. The specific treatment methods and results are shown in Table 3. It is evident that the spray drying method (with dispersant) presented in this technical solution demonstrates superior performance in product state, yield, and product moisture content. While freeze-drying produces a better product state, its high cost makes industrial application difficult. In the spray drying (with dispersant) treatment, the use of β-cyclodextrin or the residue after enzymatic hydrolysis and centrifugation of the sieve residue as the dispersant resulted in similar drying outcomes.

[0056] Table 3

[0057]

[0058]

[0059] The above descriptions are merely embodiments of the present invention, and common knowledge such as specific technical solutions and / or characteristics are not described in detail here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the technical solutions of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A method for drying processing of Astragalus extract, characterized in that: After adding a drying dispersant to the Astragalus extract, spray drying is performed. The drying dispersant is the residue after Astragalus extraction, and the amount of residue added is 5-15% of the mass of the concentrate. The spray drying conditions are: inlet air temperature 130-135℃ and outlet air temperature 65-75℃. ​ 2. The method of drying the extract of Astragalus membranaceus according to claim 1, characterized in that, Includes the following steps: Step 1: Concentrate the Astragalus extract to obtain a concentrated solution; Step 2: Add a drying and dispersing agent to the concentrate, stir evenly, and then spray dry. The drying and dispersing agent is the residue after Astragalus extraction.

3. The method of claim 2, wherein the method is characterized by: In step two, the drying dispersant is the residue after Astragalus membranaceus extraction. The residue is dried, pulverized, and then passed through an 80-mesh sieve.

4. The method of claim 3, wherein the drying is performed at a temperature of 40-60°C for 1-3 days. The spray drying conditions are: inlet air temperature 130℃, outlet air temperature 65-70℃.

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