A method of extracting plant salts from a halophyte

Abstract

This invention relates to a method for extracting plant salts from halophytes, belonging to the field of biomass resource recycling technology. The method includes five main steps: raw material pretreatment, salt extraction, ultrasonic-pressing combined desalination, filtration purification, and vacuum freeze-drying. Specifically, the salt extraction step employs a composite extraction system composed of a weakly alkaline ethanol aqueous solution, a choline-based eutectic solvent, and a combination of cellulase / pectinase / xylanase. Under gentle shaking conditions, the halophyte powder is synergistically extracted, significantly improving the dissolution rate of salts and flavor compounds. The ultrasonic-pressing combined treatment further breaks down plant tissues, enhancing the desalination effect. This invention features a simple process flow and high extraction efficiency. The resulting plant salt extract is a white or pale yellow loose porous solid, rich in minerals such as sodium and potassium, as well as various small-molecule amino acids, possessing good nutritional and flavor value, and is suitable as a natural seasoning or nutritional supplement.

Description

Technical Field

[0001] This invention belongs to the field of biomass resource recycling technology and relates to a method for extracting plant salts from halophytes. Background Technology

[0002] Halophytes, such as Suaeda salsa, Scutellaria barbata, Sea spinach, Salicornia glutinosa, Acer palmatum, Sea fennel, and Acer rubrum, are considered potential ideal raw materials for obtaining natural plant salts because they grow in harsh environments such as saline-alkali land and coastal zones. In order to adapt to high osmotic pressure stress, they actively accumulate a variety of inorganic salts (such as potassium, sodium, magnesium, and calcium ions), as well as unique organic flavor substances and trace elements in their tissues.

[0003] Existing technologies for extracting salts or active ingredients from plants mainly include water extraction, alcohol extraction, and conventional methods such as pressing and cooking. However, these methods have many limitations when applied to the extraction of halophytes: simple water extraction, while easy to operate, easily dissolves a large amount of water-soluble polysaccharides, proteins, and other impurities, leading to difficulties in subsequent separation and purification, and high temperatures may cause the loss of heat-sensitive flavor substances; conventional alcohol extraction has limited extraction efficiency for certain inorganic salts and does not strongly damage the plant cell wall structure, resulting in incomplete salt release. More importantly, existing technologies often overlook the physical barrier created by the tough cell wall structure of halophytes for the release of intracellular salts, leading to low extraction efficiency, low purity of the extract, and high energy consumption, making it difficult to achieve the green and efficient preparation of high-quality plant salts.

[0004] Therefore, developing an integrated extraction method that can gently and efficiently disrupt the cell structure of halophytes, selectively and maximally extract their intrinsic salts and flavor substances while preserving their natural active ingredients, and is applicable to a variety of common halophyte raw materials, is of great practical significance for promoting the industrial development of natural plant salts, enhancing the added value of saline-alkali land resources, and meeting the market demand for health foods. Summary of the Invention

[0005] The purpose of this invention is to provide a method for extracting plant salts from halophytes, which has the characteristic of high desalination rate.

[0006] The objective of this invention can be achieved through the following technical solutions: A method for extracting plant salts from halophytes, the specific process of which is as follows: S1: Raw material pretreatment Fresh halophytes were collected, roots and non-leaf parts were removed, and the plants were washed with deionized water to remove surface dust. They were then dried in a forced-air drying oven at 40-50℃ until constant weight. The dried halophyte leaves were crushed with a pulverizer and sieved to obtain halophyte powder. S2: Salt Extraction Add a 60-80% (v / mL) weakly alkaline ethanol aqueous solution to the halophyte powder obtained in S1 at a solid-liquid ratio of 1:5-8 (g / mL); then add 0.5-2.0 times the mass of the halophyte powder in a choline-based eutectic solvent; finally add a complex enzyme composed of cellulase, pectinase, and xylanase, the amount of which is 1-3% of the mass of the halophyte powder; and extract by shaking at 45-55℃ and 150-200 rpm for 60-90 min to obtain the halophyte extract. S3: Ultrasonic-pressing combined desalination The halophyte extract obtained in S2 was transferred to an ultrasonic treatment device and ultrasonically treated for 10-20 minutes at a power of 300-500W and a frequency of 28-40kHz. After ultrasonic treatment, the mixture was transferred to a pressing device and physically pressed at a pressure of 20-30MPa. All the filtrate obtained from the pressing was collected. S4: Filtration purification The filtrate obtained from S3 was initially filtered through double-layer filter paper, and then the filtrate was vacuum filtered through a microporous membrane of 0.22~0.45μm under a vacuum of 0.08~0.1MPa to obtain a clear salt extract. S5: Freeze-drying preparation of plant salt The clarified salt extract obtained in S4 was placed in a freeze-drying pan and pre-frozen at -40~-50℃ for 4~6h. Then the pre-frozen sample was transferred to a vacuum freeze dryer and freeze-dried for 24~48h under the conditions of cold trap temperature ≤-50℃ and vacuum degree ≤10Pa. After the sample was completely dried, the plant salt extract was obtained.

[0007] Furthermore, the halophytes in S1 include at least one of the following: *Salmonella spp.*, *Salmonella acutissima*, *Salmonella spp.*, *Quinomegia spp.*, *Salmonella palmatum*, *Suaeda salsa*, *Salmonella spp. ... and *Salmonella spp.*.

[0008] Furthermore, the particle size of the halophyte powder in S1 is 40-60 mesh.

[0009] Furthermore, the pH value of the weakly alkaline ethanol aqueous solution in S2 is 8-9.

[0010] Furthermore, the choline-based eutectic solvent in S2 is composed of choline chloride and urea in a molar ratio of 1:(1~2). The preparation method of the choline-based eutectic solvent is as follows: Choline chloride and urea were mixed at a molar ratio of 1:(1~2), placed in a sealed reaction vessel, heated at 70~90℃, and stirred at 300~500 rpm for 1~3h until the solid mixture was completely melted. After cooling to room temperature, the choline-based eutectic solvent was obtained.

[0011] Furthermore, the mass ratio of cellulase, pectinase, and xylanase in S2 is 1:1:1.

[0012] Furthermore, the plant salt extract obtained in S5 is a white or pale yellow loose porous solid.

[0013] This invention provides an innovative method for extracting plant salts from halophytes. This method combines the preparation process with the synergistic effect of multiple functional substances, achieving efficient, environmentally friendly and high-quality plant salt extraction.

[0014] The preparation method of this invention features tightly integrated steps, forming a highly efficient and scientific extraction system. In the raw material pretreatment stage, removing roots and non-leaf parts effectively reduces interference from non-target components, improving the purity of subsequent extractions. Washing with deionized water and drying to constant weight removes surface impurities and avoids the influence of moisture on the extraction process. The pulverizing and sieving steps ensure the uniformity of the raw materials, which is beneficial for the full release of components during subsequent extraction.

[0015] In the salt extraction stage, a weakly alkaline ethanol-water solution with a solid-liquid ratio of 1:5~8 was used as the extraction solvent. This ratio was optimized to ensure sufficient extraction capacity while avoiding solvent waste. Extraction was performed by shaking at 45~55℃ and 150~200 rpm. This combination of temperature and rotation speed promoted full contact between the extraction solvent and the raw material, accelerating the dissolution and release of salts. This temperature range neither damages the active ingredients in halophytes nor hinders extraction efficiency.

[0016] The combined ultrasonic-pressing desalination step is one of the innovations of this invention. Ultrasonic treatment utilizes the cavitation effect generated by high-frequency vibration to disrupt the structure of the cell walls of halophytes, making it easier to extract the salts from the cells. Simultaneously, ultrasonic treatment also promotes the uniform distribution of salts in the extract, improving the efficiency of subsequent pressing. The pressing process further squeezes out the salts from the extract using physical pressure, achieving effective salt separation. The combined use of ultrasound and pressing significantly improves the desalination effect and reduces salt loss.

[0017] The purification step, employing a combination of preliminary filtration with double-layer filter paper and vacuum filtration with a microporous membrane, effectively removes impurities and particles from the extract, yielding a clear salt extract. This step ensures the purity of the final product and improves the quality of the plant salt.

[0018] The freeze-drying process for preparing plant salt utilizes vacuum freeze-drying technology, where the clarified salt extract is pre-frozen at low temperature and then dried under vacuum conditions. This process avoids the destruction of active ingredients in plant salt by high temperatures, preserving the natural flavor and nutrients of the plant salt. At the same time, the freeze-drying process also causes the plant salt to form a loose and porous structure, improving its solubility and bioavailability.

[0019] In addition, the present invention incorporates a variety of functional substances during the extraction process, which play an important role in the extraction process.

[0020] A weakly alkaline aqueous ethanol solution is used as the extraction solvent because its weakly alkaline environment is conducive to the dissolution and release of salts. At the same time, as an organic solvent, ethanol can dissolve some fat-soluble components, improving the comprehensiveness of the extraction; in addition, ethanol also has a certain bactericidal effect, which helps to maintain the stability of the extract.

[0021] The addition of a choline-based eutectic solvent is another major innovation of this invention. This solvent consists of choline chloride and urea in a molar ratio of 1:1 to 2. Choline chloride, as a quaternary ammonium salt, exhibits good solubility and stability, while urea, as a polar solvent, enhances the solvent's ability to dissolve salts. The addition of this choline-based eutectic solvent significantly improves the solubility of salts in the extract, allowing for the extraction of more salts. Simultaneously, this solvent also exhibits selectivity, preferentially dissolving the target salts and reducing the extraction of non-target components.

[0022] The addition of a complex enzyme further improved extraction efficiency. This complex enzyme consists of cellulase, pectinase, and xylanase in a 1:1:1 mass ratio. Cellulase breaks down the cellulose components in the cell walls of halophytes, disrupting the cell structure and making it easier to extract intracellular salts. Pectinase breaks down the pectin components in the cell walls, further promoting salt release. Xylanase breaks down the xylan components in the cell walls, increasing the permeability of the extract. The synergistic effect of these three enzymes significantly accelerated the salt extraction process and improved extraction efficiency.

[0023] During the extraction process of this invention, a complex synergistic effect occurred among the added substances, which jointly promoted the extraction and purification of salt.

[0024] A favorable solvent system is formed between the weakly alkaline aqueous ethanol solution and the choline-based eutectic solvent. Ethanol, as an organic solvent, can dissolve some lipid-soluble components; while choline-based eutectic solvents have stronger polarity and solubility, enabling them to dissolve a greater amount of salt. The combined use of these two solvents expands the extraction range and improves extraction efficiency. Simultaneously, the weakly alkaline environment facilitates the dissolution and release of salts, further enhancing the extraction effect.

[0025] A synergistic effect also occurred between the complex enzyme and the solvent system. The complex enzyme disrupts cell structure by breaking down cell wall components, making it easier for the solvent to extract intracellular salts. Simultaneously, the enzymatic hydrolysis process generates a large amount of small molecules such as reducing sugars, which can act as solubilizers for the solvent, enhancing its solubility for salts. Furthermore, the enzymatic hydrolysis process releases intracellular enzyme-active substances, which may further promote the extraction and transformation of salts.

[0026] In the combined ultrasonic-pressing desalination process, the cavitation effect generated by ultrasonic treatment and the physical pressure generated by pressing work synergistically. The cavitation effect disrupts the cell wall structure and promotes the release of salt; while the physical pressure further squeezes out the released salt, achieving effective salt separation. The combination of the two significantly improves the desalination effect.

[0027] In summary, this invention achieves efficient, environmentally friendly, and high-quality extraction of plant salts from halophytes through a carefully designed preparation method and the synergistic effect of multiple functional substances. Detailed Implementation

[0028] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with embodiments, is provided below. Example 1:

[0029] A method for extracting plant salts from halophytes, the specific process of which is as follows: S1: Raw material pretreatment Fresh Suaeda salsa was collected, and the roots and non-leaf parts were removed. The leaves were washed with deionized water to remove surface dust, and then dried in a 40℃ forced-air drying oven to constant weight. The dried halophyte leaves were crushed with a pulverizer and sieved to obtain Suaeda salsa powder with a particle size of 40~60 mesh. S2: Salt Extraction Add a 70% (v / mL) weakly alkaline ethanol aqueous solution to the Suaeda salsa powder obtained in S1 at a solid-liquid ratio of 1:5 (g / mL). The pH of the weakly alkaline ethanol aqueous solution is 8. Then add a choline-based eutectic solvent with a mass ratio of 1.0 times that of the Suaeda salsa powder. Finally, add a complex enzyme composed of cellulase, pectinase, and xylanase in a mass ratio of 1:1:1. The amount of the complex enzyme added is 1.5% of the mass of the Suaeda salsa powder. Extract by shaking at 45℃ and 150 rpm for 60 min to obtain the halophyte extract. The choline-based eutectic solvent is composed of choline chloride and urea in a molar ratio of 1:1. The preparation method of the choline-based eutectic solvent is as follows. Choline chloride and urea were mixed at a molar ratio of 1:1 and placed in a sealed reaction vessel. The mixture was heated at 70°C and stirred at 300 rpm for 1 hour until the solid mixture was completely melted. After cooling to room temperature, the choline-based eutectic solvent was obtained.

[0030] S3: Ultrasonic-pressing combined desalination The halophyte extract obtained in S2 was transferred to an ultrasonic treatment device and ultrasonically treated for 10 minutes at a power of 300W and a frequency of 28kHz. After ultrasonic treatment, the mixture was transferred to a pressing device and physically pressed at a pressure of 20MPa. All the filtrate obtained from the pressing was collected. S4: Filtration purification The filtrate obtained from S3 was initially filtered through double-layer filter paper, and then the filtrate was vacuum filtered through a 0.45μm microporous membrane under a vacuum of 0.08MPa to obtain a clear salt extract. S5: Freeze-drying preparation of plant salt The clarified salt extract obtained in S4 was placed in a freeze-drying pan and pre-frozen at -40℃ for 6 hours. The pre-frozen sample was then transferred to a vacuum freeze dryer and freeze-dried for 24 hours under the conditions of cold trap temperature ≤ -50℃ and vacuum degree ≤ 10Pa. After the sample was completely dried, the plant salt extract was obtained. Example 2:

[0031] A method for extracting plant salts from halophytes, the specific process of which is as follows: S1: Raw material pretreatment Fresh Suaeda salsa was collected, and the roots and non-leaf parts were removed. The leaves were washed with deionized water to remove surface dust, and then dried in a 40℃ forced-air drying oven until constant weight. The dried halophyte leaves were crushed with a pulverizer and sieved to obtain Suaeda salsa powder with a particle size of 60 mesh. S2: Salt Extraction Add a 60% (v / mL) weakly alkaline ethanol aqueous solution to the Suaeda salsa powder obtained in S1 at a solid-liquid ratio of 1:8 (g / mL). The pH of the weakly alkaline ethanol aqueous solution is 8. Then add 0.5 times the mass of the Suaeda salsa powder in a choline-based eutectic solvent. Finally, add a complex enzyme composed of cellulase, pectinase, and xylanase in a mass ratio of 1:1:1. The amount of the complex enzyme added is 1% of the mass of the Suaeda salsa powder. Extract by shaking at 45℃ and 150 rpm for 60-90 min to obtain the halophyte extract. The choline-based eutectic solvent is composed of choline chloride and urea in a molar ratio of 1:1. The preparation method of the choline-based eutectic solvent is as follows. Choline chloride and urea were mixed at a molar ratio of 1:1 and placed in a sealed reaction vessel. The mixture was heated at 70°C and stirred at 300 rpm for 1 hour until the solid mixture was completely melted. After cooling to room temperature, the choline-based eutectic solvent was obtained.

[0032] S3: Ultrasonic-pressing combined desalination The halophyte extract obtained in S2 was transferred to an ultrasonic treatment device and ultrasonically treated for 10 minutes at a power of 300W and a frequency of 28kHz. After ultrasonic treatment, the mixture was transferred to a pressing device and physically pressed at a pressure of 20MPa. All the filtrate obtained from the pressing was collected. S4: Filtration purification The filtrate obtained from S3 was initially filtered through double-layer filter paper, and then the filtrate was vacuum filtered through a 0.22μm microporous membrane under a vacuum of 0.08MPa to obtain a clear salt extract. S5: Freeze-drying preparation of plant salt The clarified salt extract obtained in S4 was placed in a freeze-drying pan and pre-frozen at -40℃ for 4 hours. The pre-frozen sample was then transferred to a vacuum freeze dryer and freeze-dried for 24 hours under the conditions of cold trap temperature ≤ -50℃ and vacuum degree ≤ 10Pa. After the sample was completely dried, the plant salt extract was obtained. Example 3:

[0033] A method for extracting plant salts from halophytes, the specific process of which is as follows: S1: Raw material pretreatment Fresh Suaeda salsa was collected, and the roots and non-leaf parts were removed. The leaves were washed with deionized water to remove surface dust, and then dried in a 40℃ forced-air drying oven until constant weight. The dried halophyte leaves were crushed with a pulverizer and sieved to obtain Suaeda salsa powder with a particle size of 60 mesh. S2: Salt Extraction Add an 80% (v / mL) weakly alkaline ethanol aqueous solution to the Suaeda salsa powder obtained in S1 at a solid-liquid ratio of 1:8 (g / mL). The pH of the weakly alkaline ethanol aqueous solution is 9. Then add 2.0 times the mass of the Suaeda salsa powder in a choline-based eutectic solvent. Finally, add a complex enzyme composed of cellulase, pectinase, and xylanase in a mass ratio of 1:1:1. The amount of the complex enzyme added is 3% of the mass of the Suaeda salsa powder. Extract by shaking at 55℃ and 200 rpm for 90 min to obtain the halophyte extract. The choline-based eutectic solvent is composed of choline chloride and urea in a molar ratio of 1:2. The preparation method of the choline-based eutectic solvent is as follows. Choline chloride and urea were mixed at a molar ratio of 1:2 and placed in a sealed reaction vessel. The mixture was heated at 90°C and stirred at 500 rpm for 3 hours until the solid mixture was completely melted. After cooling to room temperature, the choline-based eutectic solvent was obtained.

[0034] S3: Ultrasonic-pressing combined desalination The halophyte extract obtained in S2 was transferred to an ultrasonic treatment device and ultrasonically treated for 20 minutes at a power of 500W and a frequency of 40kHz. After ultrasonic treatment, the mixture was transferred to a pressing device and physically pressed at a pressure of 30MPa. All the filtrate obtained from the pressing was collected. S4: Filtration purification The filtrate obtained from S3 was initially filtered through double-layer filter paper, and then the filtrate was vacuum filtered through a 0.45μm microporous membrane under a vacuum of 0.1MPa to obtain a clear salt extract. S5: Freeze-drying preparation of plant salt The clarified salt extract obtained in S4 was placed in a freeze-drying pan and pre-frozen at -50℃ for 6 hours. The pre-frozen sample was then transferred to a vacuum freeze dryer and freeze-dried for 48 hours under the conditions of cold trap temperature ≤ -50℃ and vacuum degree ≤ 10Pa. After the sample was completely dried, the plant salt extract was obtained.

[0035] Comparative Example 1 In this comparative example, no choline-based eutectic solvent was added in step S2, and the remaining steps were the same as in Example 1.

[0036] Comparative Example 2 In this comparative example, no complex enzyme was added in S2, and the remaining steps were the same as in Example 1.

[0037] The desalination rate and salt content of the examples and comparative examples were analyzed. The desalination rate test method is as follows: Samples of halophytes from the same batch were dried, ground into powder, and then extracted with deionized water at the same solid-liquid ratio. The initial salt content per unit mass (g / kg) was measured and calculated.

[0038] Desalination rate (%) = [(Initial salt content - Salt content of plant after pressing) / Initial salt content] × 100%

[0039] The experimental data are summarized in the table below.

[0040] Experimental data show that the process of this invention effectively improves the desalination rate, mineral content, and enrichment of flavor amino acids.

[0041] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method of extracting plant salts from a halophyte, characterized in that, The specific process of the method is as follows. S1: Raw material pretreatment Fresh halophytes were collected, roots and non-leaf parts were removed, and the plants were washed with deionized water to remove surface dust. They were then dried in a forced-air drying oven at 40-50℃ until constant weight. The dried halophyte leaves were crushed with a pulverizer and sieved to obtain halophyte powder. S2: Salt Extraction Add a 60-80% (v / mL) weakly alkaline ethanol aqueous solution to the halophyte powder obtained in S1 at a solid-liquid ratio of 1:5-8 (g / mL); then add 0.5-2.0 times the mass of the halophyte powder in a choline-based eutectic solvent; finally add a complex enzyme composed of cellulase, pectinase, and xylanase, the amount of which is 1-3% of the mass of the halophyte powder; and extract by shaking at 45-55℃ and 150-200 rpm for 60-90 min to obtain the halophyte extract. S3: Ultrasonic-pressing combined desalination The halophyte extract obtained in S2 was transferred to an ultrasonic treatment device and ultrasonically treated for 10-20 minutes at a power of 300-500W and a frequency of 28-40kHz. After ultrasonic treatment, the mixture was transferred to a pressing device and physically pressed at a pressure of 20-30MPa. All the filtrate obtained from the pressing was collected. S4: Filtration purification The filtrate obtained from S3 was initially filtered through double-layer filter paper, and then the filtrate was vacuum filtered through a microporous membrane of 0.22~0.45μm under a vacuum of 0.08~0.1MPa to obtain a clear salt extract. S5: Freeze-drying preparation of plant salt The clarified salt extract obtained in S4 was placed in a freeze-drying pan and pre-frozen at -40~-50℃ for 4~6h. Then the pre-frozen sample was transferred to a vacuum freeze dryer and freeze-dried for 24~48h under the conditions of cold trap temperature ≤-50℃ and vacuum degree ≤10Pa. After the sample was completely dried, the plant salt extract was obtained.

2. A method of extracting plant salt from a halophyte as claimed in claim 1, wherein, The halophytes in S1 include at least one of the following: *Salmonella spp.*, *Salmonella acutissima*, *Salmonella spp.*, *Quinomegia spp.*, *Salmonella palmatum*, *Suaeda salsa*, *Agropyron cristatum*, *Salmonella spp. ... and *Salmonella spp.*.

3. A method of extracting plant salt from a halophyte as claimed in claim 1, wherein, The particle size of the halophyte powder in S1 is 40-60 mesh.

4. The method for extracting plant salts from halophytes according to claim 1, characterized in that, The pH value of the weakly alkaline ethanol aqueous solution in S2 is 8-9.

5. The method for extracting plant salts from halophytes according to claim 1, characterized in that, The choline-based eutectic solvent in S2 is composed of choline chloride and urea in a molar ratio of 1:(1~2). The preparation method of the choline-based eutectic solvent is as follows. Choline chloride and urea were mixed at a molar ratio of 1:(1~2), placed in a sealed reaction vessel, heated at 70~90℃, and stirred at 300~500 rpm for 1~3h until the solid mixture was completely melted. After cooling to room temperature, the choline-based eutectic solvent was obtained.

6. The method for extracting plant salts from halophytes according to claim 1, characterized in that, The mass ratio of cellulase, pectinase and xylanase in S2 is 1:1:

1.

7. The method for extracting plant salts from halophytes according to claim 1, characterized in that, The plant salt extract obtained in step S5 is a white or pale yellow loose porous solid.

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