JPH0134973B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for extracting and purifying sweet ingredients such as stevia, sweet tea, and licorice, as well as active ingredients in other plants. Conventionally, in order to extract and purify active ingredients from plants such as stevia, calcium carbonate, calcium hydroxide, etc. are adsorbed onto an extract using water, an organic solvent, or a mixture of water and a water-soluble organic solvent. Purification is performed by adding agents to remove impurities, or by further treatment with ion exchange resins or adsorption resins, but these methods shorten the life of the resin because they do not remove impurities sufficiently, or require regeneration treatment. It has the disadvantage of requiring a large number of repetitions. Particularly in removing pigment components, etc., each method has its own limited ability, so at present they are used in combination, but even when used in combination, a satisfactory treatment effect is not necessarily obtained.
Furthermore, after extraction and purification using this method, wastewater with a high BOD and COD load is generated, so it is necessary to perform color removal treatment using activated carbon, etc. and activated sludge treatment, which requires the use of treatment equipment, etc. Equipment costs and running costs account for a large proportion of the extraction and refining costs economically. In addition, in conventional extraction and purification methods, the processing method is complicated and many batch systems are used, making continuous processing difficult. Therefore, the present inventor investigated an excellent impurity removal method that eliminates the drawbacks of these conventional techniques, and completed the present invention. That is, the present invention is a method for extracting and purifying plant components, which is characterized by removing impurities using aluminum or iron hydroxide produced in an extraction solution containing extracted components from plants as an adsorbent. The plants according to the present invention are preferably plants containing sweet components such as stevia, sweet tea, licorice, and sugar cane, and in particular, stevia containing steviosides. In addition, other plants containing active ingredients other than sweet ingredients are also effective. In the extraction and purification method according to the present invention, plants are first extracted using an extraction solvent in a conventional manner. Water is preferably used as the solvent for extracting the active ingredients of plants, but water-soluble organic solvents, mixtures of water-soluble organic solvents and water, and water-insoluble organic solvents can also be used. However, when extraction is performed using a water-insoluble solvent, it is necessary to concentrate the extracted solution to dryness and redissolve it in water, a water-soluble organic solvent, or a mixture of a water-soluble organic solvent and water. In the present invention, the method for producing an adsorbent in a plant extract solution includes a method in which a metal salt is added to the solution and the produced metal hydroxide is used as an adsorbent; There is a method in which a metal hydroxide is used as an electrode and a metal hydroxide is generated by electrolysis. In the method of the present invention, a metal salt is added to an extraction solution and the generated metal hydroxide is used as an adsorbent. Adjust the pH range using acids such as hydrochloric acid and sulfuric acid, or bases such as sodium hydroxide and potassium hydroxide. At this time, the hydroxide generated in the extraction solution adsorbs impurities in the extraction solution and precipitates, so by filtering this, a clean extract can be obtained. Metal salts added to the plant extraction solution include aluminum salts such as aluminum sulfate and sodium aluminate, iron salts such as ferrous chloride, ferric chloride, ferrous sulfate, and ferric sulfate. On the other hand, metal salts that produce poorly soluble hydroxides are used. The selection of these salts can be made by considering the adsorption performance of metal hydroxides in the target plant extract solution, the properties of the components to be purified, the purpose of use, and even safety. Aluminum salts are excellent in terms of adsorption performance, safety, etc. When using aluminum sulfate as the metal salt, for example, PH with sodium hydroxide or potassium hydroxide, and when using sodium aluminate as the metal salt, PH with hydrochloric acid, etc.
When the value is adjusted to around 7, aluminum hydroxide is generated, which adsorbs impurities in the extraction solution and precipitates them. When the method of the present invention is carried out using an electrolytic method, it is necessary that the extraction solution is conductive, and if it is not conductive, it may be made conductive by adding an electrolyte or replaced with a conductive solvent. is necessary. Even if the material is electrically conductive, if the electrical conductivity is low, it is preferable to add an electrolyte to increase the electrical conductivity because this will increase the electrolytic efficiency. In the present invention, various electrolytes that increase conductivity can be used as the electrolyte to be added to the plant extract solution, and the electrolyte is selected depending on the properties of the extracted components and the purpose of use of the extracted purified product. The electrolyte used at this time is preferably an alkali metal salt or an alkaline earth metal salt.
Particularly when extracting and purifying steviosides from stevia, sodium chloride is preferred. This means that even if sodium chloride remains in the purified product, it will not interfere with the intended use, and if further purification is required, salts can be easily removed using an ion exchange resin. It's for a reason. The amount of electrolyte added to the extraction solution is sufficient to provide the necessary conductivity for the electrode metal used to be electrolyzed, and it is not necessary to use a large amount.
For example, in the case of a strong electrolyte such as sodium chloride, 1 to
Approximately 2 g/g is sufficient to fulfill its role. In the present invention, as a method for producing an adsorbent in a plant extract solution, there is a method in which aluminum or iron is used as an electrode and a hydroxide of the metal is produced in a conductive extract solution by electrolysis. preferable. It is preferable to use the above metals as electrodes because the metal hydroxides produced are poorly soluble hydroxides and have excellent adsorption ability. In particular, aluminum has a particularly good adsorption ability for the aluminum hydroxide produced. It is extremely superior because it can be electrolyzed near neutrality. The electrolysis method is to use a metal such as aluminum or iron as a negative electrode and an insoluble electrode such as carbon as a positive electrode in an extraction solution adjusted to a state capable of electrolysis, or to use the same metal for both positive and negative electrodes and set the electrolytic voltage. If the above voltage is applied and current is passed, metal ions will be eluted in proportion to the amount of current, and metal hydroxides can be generated in the solution. Furthermore, when the same metal is used for both the positive and negative electrodes, PR electrolysis can prevent the formation of an anodic oxide film and increase the electrolytic efficiency. The metal hydroxide produced in this way adsorbs impurities, and since these impurities float to the surface in the form of bubbles due to the gas generated by electrolysis, they can be easily removed. Furthermore, separation using a centrifuge or the like improves the separation efficiency and provides an extremely transparent extraction solution. The plant extract solution obtained as described above has a pH of
is 8 to 9, the target component can be obtained by neutralizing with hydrochloric acid, acetic acid, etc. and then concentrating to dryness. If further purification is required, salts and slightly remaining pigments can be removed from the treated solution using an ion exchange resin, adsorption resin, activated carbon, etc., making purification extremely easy. Note that when the adsorbed particles adsorbing impurities are small, it is possible and effective to expand the particles and promote precipitation by adjusting the pH using an acid or base after electrolysis. The present invention is characterized in that the adsorbent produced in the target plant extract solution works extremely effectively. In other words, the method of the present invention works more effectively than a method using a powdered compound such as a commercially available metal hydroxide. Because hydroxide has extremely high adsorption activity,
This seems to be due to an increase in the amount of adsorption.
In addition, when processing by electrolysis, impurities are adsorbed to the metal hydroxide produced, grow large, and at the same time float to the surface by the generated gas, causing a separation effect and making the target extract extremely clean. I have to. In the present invention, if the plant extract solution is treated,
It is characterized in that most impurities are removed and the target components remain in the processing solution without being removed.
In addition, other components in the treatment solution include a small amount of remaining pigment components and salts, but even when this is further treated with an ion exchange resin or adsorption resin, most of the impurities are removed. Therefore, the load on the resin is small, reducing deterioration and wear and tear. In the present invention, the mechanism by which impurities are removed from the plant extract solution has not yet been studied in detail, but in addition to the target active ingredients, the plant extract solution contains a large number of polyphenols such as tannins,
Components such as protein and chlorophyll are extracted and included at the same time. In particular, tannins are difficult substances that give the extract a dark brown color and are associated with the plant refining process, but in the present invention, the adsorbent produced in the extract solution works effectively to adsorb and remove tannins. It is estimated to be. In other words, the ultraviolet absorption spectrum of the solution fully treated with the present invention includes:
This is also supported by the disappearance of absorption derived from polyphenols and proteins. In the present invention, impurities contained in the plant extract are removed by an adsorbent produced in the solution, and in the case of electrolytic treatment, impurities can be separated by flotation separation, and these are Furthermore, it can be solidified and removed by separation by centrifugation, filter press, etc., and is also characterized by the ability to extract and purify the active components of plants and treat wastewater at the same time. Therefore, there is no need to treat wastewater again, and the extraction and purification process can be shortened, making it a method with great economic merit. The method of the present invention, particularly the electrolytic treatment method, allows for control of purification, and is therefore characterized in that it can be easily made continuous for extraction and purification of plants, which has conventionally been difficult to do continuously. The present invention will be explained below with reference to Examples and Comparative Examples. Note that the examples are for the purpose of deepening the understanding of the present invention, and the present invention is not limited to these examples in any way. Example 1 400 g of dried Stevia leaves were extracted with 10 parts of water at 80°C for 30 minutes and centrifuged to obtain a dark brown extract of about 9 parts. 1 g of NaCl was added to 0.5 of this extract, and electrolysis was carried out for 10, 30, and 60 minutes using 13 x 7 cm aluminum plates as positive and negative electrodes with a distance of 5 cm between the electrodes and a current of 2 A. The blackish brown impurities were removed by electrolysis. It was adsorbed to the aluminum hydroxide produced and floated to the surface by the generated gas. When the solid content was separated using paper, a treated solution was obtained which was significantly decolored compared to the original extract. Colored components derived from impurities in this treatment solution were measured using ultraviolet spectroscopy, and sweet components of steviosides were quantified using a thin layer chromatography automatic detector (Yatron Corporation, Iatroskyan TFG-10). Furthermore, the total solid concentration was determined by the dry weight method, and the results are shown in Table 1. As can be seen from the results in Table 1, the decolorization rate is extremely high according to the electrolytic treatment method of the present invention, and the concentration of steviosides, which are the target components, in the treatment solution is almost the same as before treatment. Furthermore, thin-layer chromatography revealed that there was no chemical change in sweet components due to electrolysis. However, the color removal rate was determined by measuring the absorbance at 32.5 nm of a solution diluted to 1/100, and expressed as the rate of decrease in the absorbance of the treated solution relative to the absorbance of the original extract. That is, color removal rate (%) = absorbance of extract - absorbance of treated solution/absorbance of extract x 100. Example 2 450 ml each of the treatment liquid obtained in Example 1 was added to 50 ml of ion exchange resin Amberlite 1R-120H and 1RA-
The remaining salts were removed by passing through a 20 mmφ, 200 ml column packed with 100 ml of 410 mixed resin. The total solid concentration, color removal rate, and sweet component concentration of the flow-through liquid were determined in the same manner as in Example 1, and the results are shown in Table 1. Example 3 For the Stevia extract obtained under the same conditions as Example 1, using aluminum and iron for both the positive and negative electrodes,
Using NaCl, NH ₄ Cl Na ₂ CO ₃ as the electrolyte, PR electrolysis was performed at 1.5 A for 30 minutes at 10 second intervals at a concentration of 2 g/min, and the color removal rate of the treatment solution was measured. The results are shown in Table 2, and show that aluminum is particularly good as an electrode, and NaCl is optimal as an electrolyte. Example 4 Stevia extract obtained under the same conditions as Example 1
In contrast, Al ₂ (SO ₄ ) ₃ 18aq,
NaAlO ₂ , FeCl ₃ ° 6H ₂ O and as a comparison MgCl ₂ °
Add 6H ₂ O, CaCl ₂゜ 2H ₂ O, respectively,
For NaAlO ₂ , 6N hydrochloric acid was used, and for the others, 6N sodium hydroxide was used to adjust the pH to the specified value while stirring, and after 1 hour, the hydroxide that had adsorbed impurities was separated, and the color removal rate of the resulting treatment solution was determined. The results are shown in Table 3 along with Comparative Example 1. Furthermore, the prescribed PH is
Al(OH) ₃ is 7, Mg(OH) ₂ is 10, Ca(OH) ₂ is
11.5, Fe(OH) ₃ is 11.5. Comparative Example 1 For each of the same extracts as in Example 4, Al(OH) ₃ , Mg(OH) ₂ , and Ca(OH) ₂ were added 10 times as much as the hydroxide produced in Example 4 using commercially available reagents. The solution was added in portions and stirred, separated after 1 hour, and the color removal rate of the solution was measured. Example 5 1 kg of dried Stevia leaves was extracted using 25% water at 80°C for 30 minutes and centrifuged to obtain an extract liquid of about 20%. Add 24 g of NaCl to 10 of this extract,
In an electrolytic tank, using 24 x 18 cm aluminum plates as both positive and negative electrodes, 5A, 7
The time-treated liquid is centrifuged, and this liquid is used with ion exchange resins Amberlite 1R120H1 and 1RA-
As a result of passing through a mixed resin column of 410, 2 at SV2 and concentrating the flow through to dryness, a slightly yellow Stevioside
34g of the same substance was obtained. The recovery rate of sweet components was 85% for the extract used. Example 6 48 g of NaAlO ₂ for 10 of the extract obtained in Example 5
was added with stirring, the pH was adjusted to 7 with about 48 ml of concentrated hydrochloric acid, and after standing overnight, it was separated to obtain a treated solution of about 8 ml. This liquid was treated with the same ion exchange resin column as in Example 5 and concentrated to dryness, resulting in approximately 32 g of pale yellow slavioside powder. The recovery rate was 80%.

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[Table] Example 7 100 g of dried licorice root was soaked in 0.7 g of water at 50° C. for 24 hours to obtain a brown extract. This extract 0.5
1 g of NaCl was added to the solution, electrolysis was carried out for 30 minutes at a current of 1.5 A with a distance of 5 cm between the electrodes using 13 x 7 cm aluminum plates as both positive and negative electrodes, and the solid content was separated using paper to obtain a transparent treatment liquid. Furthermore, this liquid is added to the ion exchange resin.
After passing through a mixed resin column containing 50 ml of 1R-120H, 100 ml of 1R-410, and concentrating to 50 ml, a syrup was obtained. There was almost no loss of the sweet component glycyrrhizin, and there was no chemical change in the component. Example 8 300 g of dried leaves of sweet tea were soaked in 1.5 g of water at 50° C. for 24 hours to obtain a dark brown extract. Using 0.5 of this extract, electrolysis was carried out for 45 minutes under the same conditions as in Example 7, and a clear slightly yellow treated solution was obtained. Additionally, 18aq5g of Al ₂ (SO ₄ ) ₂ was added to 0.5 of the other extract and neutralized with 6N sodium hydroxide to adsorb impurities to the resulting aluminum hydroxide, which was separated to form a slightly yellow, transparent treated solution. I got it. The color removal rate is 98.3% for the former and 98.3% for the latter.
98.1%, and in both cases there was almost no loss of the sweet component phyllodulcin, and there was no chemical change in the components. Example 9 After extracting 200 g of Sencha with hot water (1.5 g) while stirring for 1 hour, a brown extract (1.3 g) was obtained. Add 2 g of NaCl to this solution, use 13 x 14 cm aluminum plates for both positive and negative electrodes, with a distance of 5 cm between the electrodes, and a current of 3.5 A.
After performing PR electrolysis for ±10 seconds for 45 minutes, it was separated to obtain a transparent treatment solution 1.2. When 0.4 g of chloroform was added to this treated solution for extraction and distillation to precipitate crystals, 3.5 g of white powdered caffeine was obtained.

[Brief explanation of drawings]

Figure 1 shows 2g of salt per 500ml of Stevia extract.
Added, 130×70cm aluminum electrode, 1.5A,
1.65A/dm ² , color removal rate by PR electrolysis method and
Shows the color removal rate using iron electrode, 1.5A, 1.65A/dm ² PR electrolysis method. In addition, when an iron electrode is used, the color removal rate with electrolysis time of 30 minutes and the color removal rate of the superfluid with the pH adjusted to 2 are shown. FIG. 2 shows the color removal rate when a metal salt is added to the Stevia extract to generate hydroxide in the solution. FIG. 3 shows the color removal rate when a commercially available reagent is used for the Stevia extract.

Claims (1)

[Scope of Claims] 1. A method for extracting and purifying plant components, characterized in that impurities are removed using aluminum or iron hydroxide produced in an extraction solution containing extracted components from plants as an adsorbent. 2. The method for extracting and purifying plant components according to claim 1, wherein aluminum or iron hydroxide is produced by an electrolytic method using the metal as an electrode. 3. The method for extracting and purifying plant components according to claim 1, wherein the hydroxide of aluminum or iron is produced by adding a metal salt of the metal to an extraction solution.