High-solubility asparagus powder rich in saponin and preparation method thereof

Abstract

The invention discloses high-solubility asparagus powder rich in saponin and a preparation method of the high-solubility asparagus powder, and belongs to the technical field of instant food. According to the invention, membrane filtration is coupled with freeze-drying and superfine grinding processes. Comprising the following steps: washing an asparagus raw material, pulping to obtain an asparagus leaching solution, and carrying out filter pressing through a 100-140-mesh sieve to obtain an asparagus press filtrate; performing ultrafiltration on the asparagus pressure filtrate to obtain asparagus ultrafiltrate, and combining pressure filtration and ultrafiltration residues; freeze-drying the asparagus ultrafiltrate, and controlling the moisture content of the product to be 10-15%; and carrying out superfine grinding on the freeze-dried sample to obtain the high-solubility asparagus powder rich in saponin. According to the method provided by the invention, the solubility of the asparagus powder and the yield of insoluble dietary fibers are improved while heat-sensitive components such as saponin in the asparagus powder are protected.

Description

Technical Field

[0001] The invention belongs to the technical field of instant foods, and particularly relates to highly soluble asparagus powder rich in saponins and a preparation method thereof. Background Art

[0002] Asparagus, scientifically known as Asparagus officinalis and also known as Gracilaria officinalis, is a perennial herbaceous plant of the genus Asparagus in the Liliaceae family. Its tender stems are rich in nutrients such as protein, carbohydrates, and vitamins, and possess high medicinal and edible value. Modern medical research indicates that asparagus saponins possess multiple benefits, including anti-cancer, antioxidant, immune-modulating, sleep-enhancing, and blood sugar-lowering properties. However, asparagus saponins are heat-sensitive, and high-temperature processing can easily degrade their active ingredients, thereby compromising their efficacy.

[0003] In the prior art, the preparation methods of asparagus powder mainly include vacuum freeze-drying process and traditional drying process. For example, “A Vacuum Freeze-Drying Process for Green Asparagus” (CN201610275254.3) uses vacuum freeze-drying technology. Although it can better retain the nutrients in asparagus, the process is time-consuming and cannot significantly improve the solubility of asparagus powder. On the other hand, “A Method for Making Asparagus Rice Cake” (CN202211017635.3) uses a traditional drying process. Although the processing time is short, high-temperature drying will destroy the heat-sensitive components in asparagus, resulting in a lower saponin content in the asparagus powder, poor solubility, and a low yield of insoluble dietary fiber.

[0004] Furthermore, existing technologies have low utilization rates for asparagus waste, failing to fully realize its economic value. Therefore, developing a preparation method that can effectively protect the heat-sensitive components in asparagus while increasing the solubility of asparagus powder and the yield of insoluble dietary fiber is of great practical significance. Summary of the Invention

[0005] The purpose of this section is to summarize some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the abstract and title of this application to avoid obscuring the purpose of this section, the abstract and the title of the invention, and such simplifications or omissions should not be used to limit the scope of the present invention.

[0006] In view of the above problems and / or the problems existing in the prior art, the present invention is proposed.

[0007] Therefore, the object of the present invention is to overcome the deficiencies in the prior art and provide a method for preparing a highly soluble asparagus powder rich in saponins.

[0008] In order to solve the above technical problems, the present invention provides the following technical solutions, including:

[0009] Wash the asparagus raw materials and beat them into a pulp to obtain an asparagus extract. Filter press through a sieve of 100 - 140 meshes to obtain an asparagus filter press filtrate;

[0010] Ultrafilter the asparagus filter press filtrate to obtain an asparagus ultrafiltrate, and combine the filter press residue and the ultrafiltration residue;

[0011] Freeze - dry the asparagus ultrafiltrate, and control the moisture content of the product to be 10% - 15%;

[0012] Ultra - micro - pulverize the freeze - dried sample to obtain a highly soluble asparagus powder rich in saponins;

[0013] Among them, the pressure parameter of the ultrafiltration is 0.2 - 0.4 MPa, and the flow rate is 1 - 3 m / s.

[0014] As a preferred scheme of the preparation method of the highly soluble asparagus powder rich in saponins of the present invention, wherein: the saponin content of the asparagus raw materials ≥ 7%.

[0015] As a preferred scheme of the preparation method of the highly soluble asparagus powder rich in saponins of the present invention, wherein: the asparagus raw materials include asparagus root waste.

[0016] As a preferred scheme of the preparation method of the highly soluble asparagus powder rich in saponins of the present invention, wherein: the temperature of the freeze - drying is - 60 - - 50 °C.

[0017] As a preferred scheme of the preparation method of the highly soluble asparagus powder rich in saponins of the present invention, wherein: the time of the freeze - drying is 6 - 8 h.

[0018] As a preferred scheme of the preparation method of the highly soluble asparagus powder rich in saponins of the present invention, wherein: the particle size of the ultra - micro - pulverization ≤ 40 μm.

[0019] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a highly soluble asparagus powder rich in saponins.

[0020] As a preferred scheme of the highly soluble asparagus powder rich in saponins of the present invention, wherein: the saponin content of the asparagus powder > 20%, and the dissolution precipitation rate is 0.

[0021] As a preferred scheme of the highly soluble asparagus powder rich in saponins of the present invention, wherein: the particle size of the asparagus powder ≤ 40 μm.

[0022] Advantages of the present invention:

[0023] (1) By the process of membrane filtration coupled with freeze - drying and ultra - micro - pulverization, while protecting the thermosensitive components such as saponins in the asparagus powder, the solubility of the asparagus powder and the yield of insoluble dietary fiber are significantly improved.

[0024] (2) The asparagus powder of the present invention has high solubility and an extremely low dissolution precipitation rate, almost zero. This indicates that the process of the present invention can effectively improve the solubility of asparagus powder, making it more suitable for use in granules.

[0025] (3) By optimizing the process parameters, the present invention significantly increases the yield of insoluble dietary fiber in asparagus powder, shortens the production time, and improves the production efficiency.

[0026] (4) The present invention uses the asparagus root waste in the canning production process as raw materials, and through a scientific processing technology, converts it into high-value-added asparagus powder. This not only improves the utilization rate of asparagus waste but also creates higher economic benefits for enterprises. Specific Embodiments

[0027] To make the above objects, features, and advantages of the present invention more obvious and understandable, the following describes the specific embodiments of the present invention in detail in conjunction with the embodiments of the specification.

[0028] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can also be implemented in other ways different from those described herein. Those skilled in the art can make similar extensions without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0029] Secondly, the so-called "one embodiment" or "embodiment" herein refers to specific features, structures, or characteristics that can be included in at least one implementation manner of the present invention. The "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor is it an individual or alternative embodiment that is mutually exclusive with other embodiments.

[0030] Unless otherwise specified, the raw materials used in the present invention are all commonly available in the market.

[0031] The materials prepared in the embodiments of the present invention are tested for performance according to the following methods:

[0032] Insoluble dietary fiber in residue (%) = dietary fiber content in the combined filter residue / dry weight of the filter residue.

[0033] Saponin content: Refer to the spectrophotometry method for detecting asparagus saponins in asparagus juice (powder) in DB 13 / T 2818-2018.

[0034] Dissolution precipitation rate (%) = weight of residue after powder dissolution / weight of powder.

[0035] Example 1

[0036] This example provides a method for preparing a high-solubility asparagus powder rich in saponins, specifically as follows:

[0037] Preparation of the extraction solution: Wash the asparagus root waste in the can production process and then make it into a pulp to obtain the asparagus extraction solution;

[0038] Pressure filtration: Pressurize and filter the extraction solution through a screen plate frame with 140 meshes to obtain the asparagus pressure filtrate;

[0039] Ultrafiltration: Carry out ultrafiltration on the asparagus pressure filtrate with a pressure parameter of 0.3 MPa and a flow rate of 1 m / s to obtain the asparagus ultrafiltrate, and combine the pressure filtration and ultrafiltration residues;

[0040] Freeze-drying: Freeze-dry the asparagus ultrafiltrate at -55 °C for 7 h;

[0041] Ultra-fine pulverization: Ultra-finely pulverize the freeze-dried sample and pass it through a 40-μm sieve to obtain the highly soluble asparagus powder rich in saponins.

[0042] Example 2

[0043] The difference between this example and Example 1 is that the pressure parameter of ultrafiltration is adjusted to 0.4 MPa, and the rest of the preparation processes are the same as those in Example 1 to obtain the asparagus powder.

[0044] Example 3

[0045] The difference between this example and Example 1 is that the pressure parameter of ultrafiltration is adjusted to 0.2 MPa, and the rest of the preparation processes are the same as those in Example 1 to obtain the asparagus powder.

[0046] Comparative Example 1

[0047] The difference between this comparative example and Example 1 is that the pressure parameter of ultrafiltration is adjusted to 0.1 MPa, and the rest of the preparation processes are the same as those in Example 1 to obtain the asparagus powder.

[0048] Perform performance tests on the asparagus powders obtained in the above examples and comparative examples, and the comparison results with Example 1 are shown in Table 1.

[0049] Table 1

[0050] Insoluble dietary fiber in residue (%) Saponin content (%) Dissolution and precipitation rate (%) Example 1 22.8 23.1 / Example 2 23.9 22.5 / Example 3 24.2 18.9 / Comparative Example 1 25.1 12.5 /

[0051] Note: " / " indicates almost not detected, close to 0.

[0052] ]As can be seen from the above table, adjusting the ultrafiltration pressure has a significant impact on the performance of asparagus powder. This is because the ultrafiltration pressure affects the molecular movement rate, and intense molecular collisions may cause the molecular structure of some active ingredients (such as saponins) to be damaged. Saponins are compounds with special physiological activities, and the glycosidic bonds and steroid or triterpenoid aglycone parts in their molecular structures are sensitive to pressure. Excessive pressure may lead to the cleavage of glycosidic bonds or the structural change of the aglycone part, thereby reducing their physiological activities. Excessive ultrafiltration pressure also causes some macromolecular impurities (such as some proteins, polysaccharides, etc.) to partially permeate. After the content of these macromolecular impurities increases in asparagus powder, they will interact with components such as saponins to form a complex network structure, hindering the contact between water molecules and saponin molecules, thereby reducing the solubility of asparagus powder. At too low a pressure, the ultrafiltration efficiency is low, and it is difficult to effectively separate the impurity components. These impurity components mixed in asparagus powder will also interfere with the interaction between components such as saponins and water molecules, reducing the solubility of asparagus powder. In addition, when the ultrafiltration time is extended at low pressure, the physical properties of some components may change, such as the change in crystallinity, further affecting the solubility of asparagus powder. According to the results of the above table, when the ultrafiltration pressure in the present invention is 0.3 MPa, the best technical effect can be obtained.

[0053] Example 4

[0054] The difference between this example and Example 1 is that the temperature of freeze-drying is adjusted to -75 °C, and the rest of the preparation processes are the same as those in Example 1, and asparagus powder is prepared.

[0055] Example 5

[0056] The difference between this example and Example 1 is that the temperature of freeze-drying is adjusted to -35 °C, and the rest of the preparation processes are the same as those in Example 1, and asparagus powder is prepared.

[0057] Comparative Example 2

[0058] The difference between this comparative example and Example 1 is that freeze-drying is adjusted to hot air drying, and the drying temperature is 90 °C, and the rest of the preparation processes are the same as those in Example 1, and asparagus powder is prepared.

[0059] Perform performance tests on the asparagus powder prepared in the above examples and comparative examples, and the comparison results with Example 1 are shown in Table 2.

[0060] Table 2

[0061] Insoluble dietary fiber in residue (%) Saponin content (%) Dissolution and precipitation rate (%) Example 1 24.8 23.1 / Example 4 24.8 21.1 / Example 5 24.8 15.4 / Comparative Example 2 24.8 4.6 /

[0062] Note: " / " indicates that it is almost not detected, close to 0.

[0063] As can be seen from the above table, adjusting the temperature of freeze-drying has a significant impact on the performance of asparagus powder. This is because temperature affects the stability of components such as saponins, leading to their degradation or structural changes, reducing biological activity; it also affects the formation and sublimation of ice crystals, resulting in an extended drying time or incomplete drying, affecting the pore structure and particle morphology of the dried asparagus powder, and affecting its solubility and storage stability. According to the results of the above table, when the temperature of freeze-drying in the present invention is -55°C, the best technical effect can be obtained.

[0064] Comparative Example 3

[0065] The difference between this comparative example and Example 1 is that after ultrafine grinding, it is sieved through a 0.1 mm sieve, and the rest of the preparation processes are the same as those in Example 1 to obtain asparagus powder.

[0066] Comparative Example 4

[0067] The difference between this comparative example and Example 1 is that freeze-drying is adjusted to spray drying, the inlet temperature is 170°C, the outlet temperature is 90°C, and the ratio of asparagus liquid to maltodextrin is 3:2. The rest of the preparation processes are the same as those in Example 1 to obtain asparagus powder.

[0068] Comparative Example 5

[0069] The difference between this comparative example and Example 1 is that the sieve in the pressure filtration process is adjusted to 400 mesh, and the rest of the preparation processes are the same as those in Example 1.

[0070] The overly dense sieve causes the filter cake to form quickly, making the filtrate unable to pass through the sieve, resulting in the failure of asparagus powder preparation.

[0071] Perform performance tests on the asparagus powder obtained from the above comparative examples, and the comparison results with Example 1 are shown in Table 3.

[0072] Table 3

[0073] Insoluble dietary fiber in residue (%) Saponin content (%) Dissolution and precipitation rate (%) Example 1 24.8 23.1 / Comparative Example 3 24.8 23.1 8.5 Comparative Example 4 / 5.1 /

[0074] Note: " / " indicates that it is almost not detected, close to 0.

[0075] In summary, the method provided by the present invention solves the problem of the yield of insoluble dietary fiber in the processing of asparagus waste. It solves the problems of low saponin content and low solubility of asparagus powder, and improves the utilization rate of asparagus waste. Through the process of membrane filtration coupled with freeze-drying and ultrafine grinding, while protecting heat-sensitive components such as saponins in asparagus powder, the solubility and the yield of insoluble dietary fiber of asparagus powder are significantly improved.

[0076] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered within the scope of the claims of the present invention.

Claims

1. A preparation method of a highly soluble asparagus powder rich in saponins, characterized in that: including Wash the asparagus raw materials and make them into a pulp to obtain an asparagus extract. Press-filter through a 100-140 mesh sieve to obtain an asparagus press filtrate; Ultrafilter the asparagus press filtrate to obtain an asparagus ultrafiltrate, and combine the press-filtered and ultrafiltered residues; Freeze-dry the asparagus ultrafiltrate, and control the moisture content of the product to be 10%-15%; Ultra-finely crush the freeze-dried sample to obtain a highly soluble asparagus powder rich in saponins; Among them, the pressure parameter of the ultrafiltration is 0.2-0.4 MPa, and the flow rate is 1-3 m / s.

2. The preparation method of the highly soluble asparagus powder rich in saponins according to claim 1, characterized in that: The saponin content of the asparagus raw materials is ≥7%.

3. The preparation method of the highly soluble asparagus powder rich in saponins according to claim 1, characterized in that: The asparagus raw materials include asparagus root scraps.

4. The preparation method of the highly soluble asparagus powder rich in saponins according to claim 1, characterized in that: The temperature of the freeze-drying is -75 to -35 °C.

5. The preparation method of the highly soluble asparagus powder rich in saponins according to claim 1, characterized in that: The time of the freeze-drying is 6-8 h.

6. The preparation method of the highly soluble asparagus powder rich in saponins according to claim 1, characterized in that: The particle size of the ultra-fine crushing is ≤40 μm.

7. A highly soluble asparagus powder rich in saponins prepared by the preparation method according to any one of claims 1-6.

8. The highly soluble asparagus powder rich in saponins according to claim 7, wherein: The saponin content of the asparagus powder is >20%, and the dissolution precipitation rate is 0.

9. The highly soluble asparagus powder rich in saponins according to claim 7 or 8, characterized in that: The particle size of the asparagus powder is ≤40 μm.