JPH0134974B2 - - 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, in the present invention, an extraction solution containing extract components from plants is adjusted to a predetermined pH such that the added metal salt produces a hardly soluble metal hydroxide, and then the metal salt is added to the extraction solution. A step of generating a sparingly soluble metal hydroxide in a solution, followed by electrolysis using a metal in which the metal hydroxide is sparingly soluble in a solution containing the above-mentioned added metal salt as an electrode to produce the above-mentioned extracted solution. By performing a process to generate poorly soluble metal hydroxide in
This is a method for extracting and purifying plant components, characterized in that impurities in the extraction solution are removed by the adsorption action of the hardly soluble metal hydroxide. 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, as a method for producing an adsorbent in a plant extract solution, a metal salt is added to the solution and the produced metal hydroxide is used as an adsorbent. It consists of a method in which the metal hydroxide to be produced is made conductive and the metal is used as an electrode, and the metal hydroxide is produced by electrolysis and used as an adsorbent. In the present invention, when adding a metal salt to the extraction solution and using the generated metal hydroxide as an adsorbent, add the metal salt to the plant extraction solution and make sure that the generated hydroxide exists stably. 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 that a clean extract can be obtained by filtering this later. Metal salts added to the plant extraction solution include aluminum salts such as aluminum sulfate and sodium aluminate, magnesium salts such as magnesium chloride, calcium salts such as calcium chloride, ferrous chloride, ferric chloride, and ferrous sulfate. Metal salts that produce hydroxides that are sparingly soluble in water, such as iron salts such as iron and ferric sulfate, 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. Moreover, among aluminum salts, sodium aluminate is advantageous because it can reduce the concentration of by-product salts. In addition, the by-produced salt can also be made into sodium chloride, so it does not pose a problem even if the extracted and purified product is for food use, and is also easy to remove using an ion exchange resin. Furthermore, the amount of metal salt added to the plant extract solution should be such that the amount of by-product salt is 1 to 2 g per 1 part of the plant extract solution, and sufficient conductivity for electrolysis can be obtained. In order to save power in the electrolytic process and to reduce the load of the ion exchange resin treatment carried out after the electrolytic process, it is advantageous to set the amount between 1 and 10 g/g/. 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. In the present invention, as a method for producing an adsorbent in a conductive plant extract solution by electrolysis, a metal selected from aluminum, iron, magnesium, zinc, etc. is used as an electrode, and the metal is absorbed by electrolysis. hydroxide is formed in the conductive extraction solution. 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 involves adding a metal salt, and then adding a metal such as aluminum or iron to the negative electrode and an insoluble electrode such as carbon to the positive electrode in the extracted solution, which is adjusted to a state where it can be electrolyzed by the by-produced salt. Alternatively, if the same metal is used for both the positive and negative electrodes and a voltage higher than the electrolytic voltage is applied and a current is passed, metal ions are eluted in proportion to the amount of current, and metal hydroxide 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 centrifugal separator or the like improves the separation efficiency and provides an extremely transparent extraction solution. In the present invention, the adsorbent is produced by adding a metal salt to the plant extract and neutralizing it with an acid or alkali (hereinafter referred to as the neutralization method). The purpose of this method is to remove impurities, and at the same time, make the extract conductive by the salt produced as a by-product, and use this conductivity to remove the remaining impurities by electrolysis. In other words, when attempting to perform sufficient treatment using only the neutralization method, the salt concentration in the extract increases, which has the disadvantage of shortening the life of the ion exchange resin for desalting treatment. If this is done, the salt concentration will be just the amount necessary to provide conductivity, and the processing costs will be limited to consumption of the aluminum plate and electrical power. Therefore, the concentration of the salt by-produced by adding a metal salt to the plant extract solution and neutralizing it is the salt concentration (1 to 10 g /
), and if this solution is purified by electrolytic treatment, the disadvantage of shortening the life of the ion exchange resin can be overcome.
In addition, since the electrolysis method is performed after the neutralization method, it has become an effective means of reducing power consumption. In a method that uses an electrolysis method after this neutralization method (hereinafter referred to as a combination method), the metal of the metal salt used in the neutralization method and the metal of the electrode used during electrolysis do not necessarily have to match. Calcium chloride is used to neutralize with an alkali to generate calcium hydroxide in the extract, and the by-produced salt provides conductivity.
It is also possible to electrolytically treat an aluminum electrode plate. Alternatively, the same metal may be selected. For example, by adding sodium aluminate and neutralizing with hydrochloric acid, aluminum hydroxide is generated, and if the conductivity of the by-product salt is electrolyzed using an aluminum electrode plate, the same adsorbent will be generated in the extract. This is preferable because the processing rate becomes high. Also, the solubility of aluminum hydroxide is much lower than that of other metal hydroxides, making it an optimal adsorbent. The present invention is characterized in that the adsorbent produced in the target plant extract 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. This is thought to be due to the fact that hydroxide has extremely high adsorption activity, so the amount of adsorption becomes large. In addition, when processing by electrolytic method, impurities are adsorbed to the generated metal hydroxide, grow large, and at the same time float up due to the generated gas, causing a separation effect.
The target extract is extremely clean. 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, although the mechanism by which impurities in the plant extract solution are removed has not yet been studied in detail, the plant extract solution contains an extremely large amount of borifenols such as tannins, in addition to the target active ingredients.
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 borifenols 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 perform wastewater treatment again, and the extraction and purification process can be shortened, making it a method with great economic merit. The method of the present invention is characterized in that, because purification can be controlled, extraction and purification of plants, which was difficult to achieve continuously in the past, can be easily carried out continuously. The present invention will be explained below with reference to Examples and Comparative Examples. It should be noted 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 30 kg of water was added to 2 kg of coarsely ground raw material, which was made by passing dry Stevia leaves through a pulverizer and passing through a 10 mmφ filter, and the mixture was heated to 80 ml.
Extraction was performed with stirring at ℃ for 30 minutes. After extraction, 26 kg of a dark brown extract was obtained by centrifugation. Main extract 5Kg
22.5g of sodium aluminate was added to the solution, and while stirring, hydrochloric acid was added to adjust the pH to 7. by centrifugation
4.5 kg of treatment liquid was obtained (Example-1-1). Add 10g of salt to the other 5kg and mix in 8 electrolytic baths 24×18×
Using 2 cm of aluminum as both positive and negative electrodes, electrolytic treatment was performed at 10 V5A for 2 hours using an electrolytic method with 10 second switching, and after electrolysis, 4.6 kg of treated solution was obtained by centrifugation (Example-1-2). Furthermore, 14 g of sodium aluminate was added to 5 kg of the extract, and the pH was adjusted to 7 with hydrochloric acid. This solution was subjected to electrolytic treatment for 50 minutes at 10V5A in the electrolytic cell, and after the treatment, 4.5 kg of treated solution was obtained by centrifugation (Example-1-3). The results for each treatment solution are summarized in (Table 1).

[Table] Example 2 Stevia extract 1 obtained by the same method as Example 1
2.83g of sodium aluminate, 11.5g of aluminum sulfate 18hydrate, aluminum chloride hexahydrate,
8.33 g was added and the pH was adjusted to 7 with hydrochloric acid and sodium hydroxide, respectively, to produce 3.45×10 ⁻² nole/aluminum hydroxide in the solution. Furthermore, an aluminum electrode plate of 13 x 17 x 0.1 cm was used in these solutions.
After electrolytic treatment at 10V-1.5A for 30 minutes, a transparent slightly colored liquid was obtained by centrifugation. Table 2 shows the total solid content, sweet component concentration, color removal rate, and salt concentration of the extract at the time when aluminum hydroxide was generated by metal salt addition and neutralization, and after electrolytic treatment. This result shows that the concentration of salt remaining in the treatment solution after electrolysis is low in the case of sodium aluminate.

[Table] Expressed as the rate of decrease in the absorbance of the treated solution with respect to the degree of absorption.

Claims (1)

[Scope of Claims] 1. After adjusting an extraction solution containing extracted components from plants to a predetermined pH such that the added metal salt produces a hardly soluble metal hydroxide, the metal salt is added to the extraction solution. , producing a sparingly soluble metal hydroxide in the extraction solution, then electrolyzing the metal hydroxide using a metal as an electrode in which the metal hydroxide is sparingly soluble in the solution containing the added metal salt; A plant ingredient characterized in that impurities in the extract solution are removed by the adsorption action of the sparingly soluble metal hydroxide by performing a step of generating a sparingly soluble metal hydroxide in the extract solution. extraction and purification method. 2. The extraction and purification method according to claim 1, in which an aluminum salt is used as the metal salt added to the plant extraction solution. 3. The extraction and purification method according to claims 1 and 2, wherein aluminum is used as an electrode when producing an adsorbent by an electrolytic method.