JP2007045798A - Method of extracting polyphenol and apparatus therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently extract a polyphenol especially tricaffeoylquinic acid from the stem and leaf part of a sweet potato. <P>SOLUTION: In the method of extracting the polyphenol, a solvent 4 most suitable to the stems and leaves A of a sweet potato is selected, and it is pressurized under high pressure of 2 MPa, heated at a temperature higher than the boiling point, that is, at 160°C, and brought into contact with the stems and leaves A of sweet potato set to an extraction apparatus main body 2 to react with them, and the poloyphenol 7 is extracted. The extracted polyphenol is recovered to a recovering device 10 after being cooled at a cooling device 8 in a state where the pressure is kept constant by a back pressure valve 9. The solvent 4 is a mixed solvent of water and ethanol, that is, a 70% ethanol solution. A substance high in accumulative yield of the polyphenol extracted by the 70% ethanol under the condition of 160°C is the tricaffeoylquinic acid. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a polyphenol extraction method and apparatus for extracting polyphenols useful for foods and pharmaceuticals from sweet potato foliage. More specifically, the present invention relates to a polyphenol extraction method and apparatus for efficiently extracting polyphenol by bringing a mixed solution of water and ethanol as a solvent into contact with sweet potato stems and leaves.

  Plants are rich in various useful components having physiologically active functions. Recent studies have revealed that, for example, sweet potatoes (hereinafter also referred to as sweet potatoes) contain a large amount of polyphenols having antioxidative activity and other functions as natural compounds. . It has been shown that tricaffeoylquinic acid has anti-HIV (AIDS virus) activity among polyphenols by suppressing active oxygen that causes aging of the body and carcinogenic substances.

Depending on the variety, the sweet potato leaf contains 4.5 g or more of total polyphenol per 100 g of dry matter. From this sweet potato leaf, it has been reported that caffeic acid derivatives and caffeic acid of chlorogenic acid, three kinds of dicaffeoylquinic acid, and tricaffeoylquinic acid can be obtained.
Polyphenols are generally resistant to bacteria, viruses, etc., and have antihypertensive action, antihyperglycemic action, blood cholesterol lowering action, and are attracting attention as effective substances for hypertension, diabetes, obesity, arteriosclerosis, etc. ing. Various extractions of these substances have been conventionally proposed. The extracted substance is generally extracted using water, hot water, or an aqueous alcohol solution as a raw material, and further, the extracted substance is concentrated and purified.

Examples of extraction techniques for polyphenols are shown in Patent Documents 1 and 2 as examples of the extraction technique. Patent Document 1 discloses a method of adding ascorbic acid, and Patent Document 2 discloses a method of immersing a plant in water or an alcohol extraction solvent for a predetermined time. Furthermore, Patent Document 3 discloses a technique for decomposing polyphenols from sweet potato leaves to produce caffeic acid.
JP 2002-97187 A JP-A-7-196645 JP 2004-350619 A

  In general, the conventional extraction method for extracting polyphenols from plant raw materials is a method of roasting in an open kettle or pan (ie, 100 ° C. or less), or batch extraction in a pressure-resistant container such as an autoclave. (For example, Japanese Patent No. 3212278). In contrast, the extraction method of the present invention is different from these conventional extraction methods.

  These polyphenols have different amounts of extraction depending on the solvent. Therefore, ideally, all the polyphenols contained in the sweet potato foliage should be able to be extracted efficiently in a short time. At present, the extraction is conducted on a trial basis by contacting only the most likely solvent with the target sweet potato foliage, but it is not efficient.

  As described above, sweet potato stems and leaves are rich in various useful substances. Therefore, if a variety of polyphenols contained in the same sweet potato foliage can be extracted at the same time and in a short time in a series of extraction processes, the extraction efficiency will be dramatically improved. The above-mentioned patent document is intended to effectively utilize sweet potato leaves and the like, and there is a technique for producing caffeic acid by acting a koji mold or an extract thereof on polyphenols mainly composed of extracted caffeic acid derivatives. Although proposed, it is not a technique of extraction itself. Moreover, it is not specified about tricaffeoylquinic acid.

  Therefore, it is known that sweet potato stems and leaves contain useful components such as polyphenol, particularly tricaffeoylquinic acid, which is effective for anti-HIV activity, as described above, but this is effectively extracted. Technology has not been established. Conventionally, it is a so-called batch extraction method carried out under normal pressure and at a temperature not higher than the boiling point of the extraction solvent. Therefore, it cannot be said that it is an efficient extraction method.

The present invention was developed in order to solve such a conventional problem, and achieves the following object.
The object of the present invention is to extract polyphenols from sweet potato stems and leaves, using an optimum solvent under high temperature and high pressure extraction conditions, and a polyphenol extraction technique that enables efficient extraction capable of performing a large amount of extraction in a short time and its In providing equipment.

  Hereinafter, the present invention takes the following means in order to achieve the object.

  The polyphenol extraction method of the present invention 1 is a method of extracting polyphenol from sweet potato stems and leaves, a solvent supplying step of taking out a previously prepared solvent, and raising the taken out solvent to a saturated vapor pressure or higher. A pressurizing step, a heating step of heating the extracted solvent, a supplying step of supplying the high pressure and heated solvent to the foliage, and a predetermined amount of the supplied solvent to the foliage at a predetermined pressure. And an extraction process for extracting the polyphenol by reacting by maintaining a predetermined temperature for a predetermined time, a cooling process for cooling the polyphenol extracted in the extraction process, and the cooled polyphenol above a certain pressure And a recovery step of holding and recovering.

  The polyphenol extraction method of the present invention 2 is characterized in that, in the polyphenol extraction method of the present invention 1, the polyphenol contains tricaffeoylquinic acid.

  The polyphenol extraction method of the present invention 3 is characterized in that, in the polyphenol extraction method of the present invention 1, the solvent is water or a mixed solvent of water and ethanol.

  The polyphenol extraction method of the present invention 4 is the polyphenol extraction method of the present invention 3, wherein the solvent is a mixed solution of water and ethanol, and the heating step is a step of setting the temperature of the solvent to 160 ± 10 ° C. In the high pressure step, the pressure of the solvent is set to be equal to or higher than the saturated vapor pressure of the ethanol at the predetermined temperature.

  The polyphenol extraction method of the present invention 5 is characterized in that, in the polyphenol extraction method of the present invention 4, the mixing ratio of the ethanol in the mixed solvent of water and ethanol is 70 ± 10%. However, polyphenols can be extracted in regions other than 70 ± 10%, but 10% before and after 70% has good extraction efficiency. In particular, about 70% can be extracted most efficiently.

  The polyphenol extraction method of the present invention 6 is the polyphenol extraction method of the present invention 1 to 5, wherein the time for extracting the polyphenol by bringing the solvent into contact with the foliage is increased by raising the solvent to a predetermined temperature. Is the time to complete. However, when the temperature rise time is early, that is, when the temperature gradient is large, it is necessary to perform the extraction operation for a while after the temperature rise is completed.

The polyphenol extraction apparatus according to the present invention 7 is a polyphenol extraction apparatus for extracting polyphenol from sweet potato stems and leaves, the solvent storage apparatus for storing the solvent, and the solvent taken out from the solvent storage apparatus at a high pressure. A supply device for supplying to the part, a heating device for heating the solvent taken out from the solvent storage device to supply to the foliage part, and the pressurized and heated solvent in contact with the foliage part for a predetermined time. An extraction device main body for reacting and extracting polyphenol; a reactor heating device provided in the extraction device main body for heating and maintaining the solvent and the foliage; a cooling device for cooling the extracted polyphenol; and the cooled A back pressure device that holds the polyphenol above a certain pressure and keeps it in the extraction device, and recovers the extracted polyphenol Consisting of a yield unit.
However, the extraction of the polyphenol of the present invention is not limited to this extraction apparatus, and the above-described extraction conditions are adjusted by filling the pressure vessel with the raw material and immersing the pressure vessel in the oil bath. That is, it may be a method that can be called a high-temperature and high-pressure batch system. The necessary pressure is a method of ensuring the necessary internal pressure by enclosing nitrogen gas in the pressure-resistant vessel at a pressure of 2 Mpa, for example.

  The polyphenol extraction device of the present invention 8 is the polyphenol extraction device of the present invention 7, wherein the high pressure by the pressure device is equal to or higher than a saturated vapor pressure of ethanol, and the heating temperature by the heating device is 160 ± 10 ° C. And the solvent is a mixed solvent of water and ethanol containing 70 ± 10% ethanol.

  The present invention is constituted by the above means. More specifically, for example, a percolator type pressure resistant container is used, and an extraction solvent optimal for polyphenol extraction in sweet potato stems and leaves charged in this container is obtained with a high pressure pump. By using a method of passing a liquid at a high pressure of 0.0 MPa, optimally, polyphenol can be extracted with a high yield in a temperature range equal to or higher than the boiling point of a preferable solvent of 160 ° C. The solvent is not only water, but also an organic solvent, and a solvent with pH and ionic strength adjusted to the optimum extraction conditions, especially a mixture of water and ethanol containing 70% ethanol, improving the yield of the target extract. it can.

  The polyphenol extraction method of the present invention is capable of supplying an optimum solvent prepared in advance, ie, a mixed solvent of water and ethanol, to sweet potato stems and leaves from sweet potato stems and leaves regardless of the variety. did. As a result, a large amount of polyphenols, especially tricaffeoylquinic acid, can be efficiently extracted from sweet potato stems and leaves in a short time under the optimum conditions.

  Hereinafter, specific modes of the present invention will be described as embodiments. In this embodiment, useful substances mainly used for foods and pharmaceuticals are extracted. Particularly, this is applied to sweet potato foliage (hereinafter referred to as “raw material”), and useful functionality having a bioactive function from this raw material. This is a technique for extracting a substance, that is, polyphenol, using an optimally prepared solvent. The raw material is mainly sweet potato stems and leaves.

  Tricaffeoylquinic acid is a type of polyphenol. This polyphenol is a general term for plant compounds having a plurality of phenolic hydroxyl groups in the same molecule, and is contained in most plants. It is a pigment with photosynthesis and a bitter component, and its structure has two or more OH groups. It has excellent antioxidant ability, suppresses blood pressure rise, suppresses blood sugar, and makes blood smooth. It is a substance.

  A caffeic acid derivative is a representative substance, but tricaffeoylquinic acid is also an effective substance, and has anti-HIV activity as described above, and is contained in a lot of sweet potato stems and leaves. ing. This polyphenol is also a substance that is attracting attention not only for pharmaceuticals but also for health foods because it is also contained in chocolate and cocoa.

  Next, a useful substance extraction technique according to the present embodiment will be described with reference to the drawings and tables. FIG. 1 is a schematic diagram of a polyphenol extraction apparatus 1 according to the present embodiment, schematically showing the apparatus. The extraction device main body 2 that forms the center of the configuration of the present invention is a reactor. The inside of the extraction device main body 2 is divided into spaces, and this space is filled with strips or finely ground sweet potato stems and leaves A. In the case of the present invention, sweet potato stems or leaves are targeted. Yes. The extraction apparatus main body 2 is charged with these raw materials, and is brought into contact with a heated and pressurized solvent to extract polyphenol.

  The configuration of the extraction technique relating to the present embodiment includes a solvent tank 3 that previously contains a solvent in addition to the extraction apparatus main body 2, a high-pressure pump 5 that takes out the solvent 4 in the solvent tank 3 and sends it out at a high pressure, and a pump. A heating device (heat exchanger) 6 for heating the solvent 4, the extraction device body 2 to which the solvent 4 heated by the heating device 6 is supplied, and the polyphenol 7 extracted by the extraction device body 2 A cooling device 8 for cooling, a back pressure valve 9 for maintaining the extracted polyphenol 7 in a high pressure state, a recovery device 10 for recovering the polyphenol 7 discharged through the back pressure valve 9, and the like.

  The extraction device body 2 is made of a stainless steel cylinder that houses the sweet potato stalks and leaves A that are fragmented therein, and has a structure in which porous filters 2b are arranged at both ends thereof. A reactor heating device 2a, which is an electric heater, is provided on the outer periphery in order to keep the extraction device main body 2 heated. Next, a technique for extracting the polyphenol 7 will be described in detail with reference to the drawings. As described above, the solvent 4 is supplied to the extraction apparatus main body 2, and water is usually used as the solvent 4. In the case of the present embodiment, in addition to water (distilled water), a harmless solvent useful for food, that is, a mixture of ethanol and water is targeted. As the solvent 4, this mixed solution of water and ethanol is used, and the liquid mixed at an optimal ratio is stored in advance in the dedicated solvent tank 3 as the solvent 4.

  The solvent 4 may be prepared by preparing a plurality of solvent tanks 3 in advance. Although not shown, this is a method in which a plurality of solvent tanks 3 that are optimal for the extraction raw material are individually prepared in advance and are selected by switching them with a switching device, and the selected optimal solvent is used. There is no limit to the number of individual solvents to be prepared. The solvent 4 can be used in addition to water, for example, an organic solvent, alcohol or a mixed solution thereof, a buffer solution, a pH adjusted solution, a solution in which salts are dissolved, etc. What is a thing is preferable.

  The solvent 4 taken out from the solvent tank 3 is brought to a high pressure by a high-pressure pump 5 and sent to a heating device 6. In the high-pressure pump 5, the solvent 4 is pressurized to a saturation vapor pressure or higher. In the case of this example, this pressure is 2 MPa, and good results are obtained. The reason for this is that the saturated vapor pressure of ethanol at 160 ° C. is 1.296 Mpa and the saturated vapor pressure of ethanol at 170 ° C. is 1.648 Mpa, so that the pressure slightly exceeding the saturated vapor pressure at these temperatures is 2 MPa. Is set. It was found that with a mixed solvent of water and ethanol 70%, the extraction temperature of polyphenol 7 from the stem and leaves of sweet potato was 160 ± 10 ° C., which was almost efficient. Therefore, considering the loss due to maintaining the liquid phase at 170 ° C., the maximum temperature of ethanol at this time, and increasing the energy cost due to unnecessary high pressure, about 2 Mpa is optimal in this embodiment. To be judged.

  The solvent 4 is increased in pressure in this way and guided to the heating device 6 to be heated. The heating device 6 is composed of a heating serpentine tube, and the heating serpentine tube is immersed in a solution such as a heated silicon oil tank or a salt bath. The solvent 4 is heated by heat exchange when passing through the heating serpentine tube. However, the heating device 6 is not limited to this configuration. The heating temperature of the solvent 4 varies depending on the raw material, but in the case of extraction with a mixed solvent of water and ethanol using the sweet potato foliage of the present embodiment as a raw material, the polyphenol is heated at a temperature of 160 ± 10 ° C. as described later. Good results in extraction.

The temperature of the solvent 4 is the most suitable temperature for extracting the polyphenol 7, but this heating temperature varies depending on the type of raw material, and is set so as to be the optimum condition for the raw material. The reason for pressurizing and heating in this way is to improve the yield of polyphenol 7 extraction from sweet potato foliage A. The solvent 4 is temperature-controlled by a temperature sensor such as a thermocouple (not shown) when supplied to the extraction apparatus main body 2.
By this temperature control, the reactor heating device 2a can set the solvent 4 to various temperatures in accordance with the raw materials, and can always maintain a constant temperature. In this way, the extraction temperature can be controlled. The lower limit is not lower than the freezing point of the solvent, but if the pressure resistance of the entire apparatus is increased, the high temperature side can be set even at a temperature higher than the critical point. The solvent 4 within the range of this condition is supplied to the extraction apparatus main body 2 through a pipe and brought into contact with the raw material A charged in the extraction apparatus main body 2 to extract the polyphenol 7. The extraction device body 2 is for extracting the polyphenol 7. The extraction device main body 2 is simply shown in the figure, but is simply a cylindrical body made of stainless steel and having a hollow inside.

  Stainless steel porous filters 2b are detachably fixed to both ends of the extraction device main body 2. This porous filter 2b has a large number of through holes in the range of 2 to 100 μm. The material of the porous filter 2b is stainless steel, but is not limited to stainless steel, and may be porous ceramic formed with a large number of pores communicating with each other. The optimum pore size of the porous ceramic is mainly determined by the particle size of the crushing raw material, but may be manufactured by selecting the particle size of the ceramic so that the most suitable pore is formed. Further, a supply port for supplying the solvent 4 and a discharge port for the extracted useful substance are provided at the upper and lower ends of the extraction apparatus main body 2. The raw materials charged in the extraction device main body 2 are stems and leaves of sweet potato, which are made into fine slices or powders, and are easily extracted.

  The polyphenol in the raw material flows out of the porous filter 2b, but since the raw material is held in the porous filter 2b, it does not flow out of the extraction device main body 2. A reactor heating device 2a is incorporated in the outer periphery of the extraction device main body 2, and holds the heated and heated solvent at a constant temperature. The reactor heating device 2a is an electric heater that heats the extraction device main body 2 from the outside in the present embodiment, but may be one that uses a heat exchanger for heating with a heat medium oil. The effective extraction time in the extraction device main body 2 is in the range of 5 to 60 minutes. This time range is the most suitable temperature range at which extraction is possible, but in practice, the optimal time is specified and set according to the type of raw material, extraction conditions, and the like.

  The polyphenol 7 extracted from the extraction device main body 2 is sent to the cooling device 8 as a solution or a suspension, and the polyphenol 7 is cooled to the boiling temperature or lower of the solvent under atmospheric pressure (in this embodiment, Room temperature). This cooling is for suppressing thermal decomposition and thermal denaturation of the polyphenol 7 and preventing boiling of the outflowing solvent. The cooled polyphenol 7 is finally maintained at a constant pressure by the back pressure valve 9, and is discharged to the outside through the back pressure valve 9 and collected in the collection tank 10.

  This back pressure valve 9 keeps the process of supplying the solvent 4 in a high pressure state, that is, the process after the high-pressure pump 5 until the end of cooling at a pressure equal to or higher than the saturated vapor pressure of the solvent 4 at the processing temperature. In order to keep the high-pressure pump 5, the heating device 6, the extraction device main body 2, and the cooling device 8 in a liquid phase. By maintaining the pressure, an extraction operation in a temperature region above the boiling point of the solvent 4 becomes possible. The extraction device 1 is also provided with a control device and switches for electrically controlling a temperature controller, a pressure controller and the like in the series of flows.

  As mentioned above, although embodiment of this invention was described, it cannot be overemphasized that this invention is not limited to this. Although this embodiment has been described mainly with respect to extraction of polyphenols from sweet potatoes, application to other applications is possible. Next, examples based on the present embodiment will be described.

Hereinafter, specific experimental examples will be described as examples. The purpose of this example is to confirm the conditions for efficiently extracting tricaffeoylquinic acid from the stem and leaves of sweet potato by applying an extraction method using a solvent at high temperature and high pressure. Comparison was made with a conventional batch-wise extraction method below the boiling point.
(sample)
The sample corresponding to the sweet potato foliage was obtained from the National Institute of Agricultural and Biological Sciences (Agricultural and Biological Species) after drying in the sweet potato (variety name: Koganen Cancer (Golden Senuki)) leaf part (water content 9.0) %) Was used.
(Extraction method)
Extraction was performed by applying the extraction apparatus shown in FIG. A sintered filter having a pore diameter of 20 μm is set in the solvent inflow portion and outflow portion of the reactor (extraction apparatus main body), and sweet potato foliage is charged therein. An oil bath filled with silicone oil was used as the heat exchanger, and a serpentine tube through which the extraction solvent flows was immersed in this. Although not shown, pressure gauges were respectively installed between the high-pressure pump 5 and the heat exchanger 6, the cooling device 8 and the back pressure valve 9 to measure the internal pressure. Moreover, the temperature in the extraction apparatus main body 2 was monitored by inserting a thermocouple thermometer in the upper part and the lower part of the reactor 2. The extraction device main body 2 can be used under pressure conditions up to 35 MPa with an internal volume of 20 mL.

About 0.5 g (wet base g) of sweet potato leaves cut into 3 mm square were charged into the extraction device main body 2 of this device, and the extraction device main body 2 was covered with a mantle heater. The liquid flow conditions were 2.0 MPa and 3.0 mL / min, and the temperature increase was started after the liquid flow started. In this example, the target temperatures after the temperature increase were set to 100 ° C., 120 ° C., and 160 ° C., and the extract was collected during the temperature increase and at intervals of 10 minutes after the temperature increase and used for the subsequent analysis. FIG. 2 schematically shows changes in extraction temperature and sampled fractions. At each temperature, the required time to reach the target temperature from room temperature was 20 minutes. In batch extraction, extraction was performed in an Erlenmeyer flask. Specifically, 0.5 g (wet base g) of a sample cut into a 3 mm square and 100 mL of a solvent were placed in a 300 mL Erlenmeyer flask, and shake extraction was performed at 75 ° C. for 1 hour. Extraction with 300 mL of solvent was performed for 3 hours for convenience, and the subsequent analysis was performed.
(analysis)
The polyphenols in the extract were quantified by high performance liquid chromatography (HPLC).

The analysis conditions are as follows.
Column: YMC-Pack ODS-AM
Eluent: 0.2% formic acid (solution A), 99.7% MeOH (solution B)
A: B = 98.2 → 55: 45 → 0: 100
Flow rate: 3.0mL / min
Sample loop: 20 μL
Clarent pump: JASCOPU-2089
Column heater: SugaiU-620TypeVP50
Column temperature: 40 ° C
Detector: HITACHI L-4000UV Detector (326 nm)
The amount of polyphenol in the extracted substance was fixed and quantified based on the retention time and peak area of the standard substance.
(result)
In FIG. 3, the solid content yield extracted using the flow-type reactor (extraction apparatus main body) was shown by the preparation amount (dry matter) reference | standard%. With the exception of 99% ethanol at 100 ° C and 120 ° C, each solvent (distilled water, 70% ethanol, 99% ethanol) has the highest amount of extraction in the temperature rising process under all extraction temperature conditions, and extraction after reaching the target temperature The amount was not so much. Therefore, it is determined that the maintenance time after reaching the target temperature is almost unnecessary. In addition, as shown in Table 1, the cumulative yield (up to 40 minutes) at this time was 70% ethanol and the amount extracted was large, and the cumulative yield at 160 ° C and 70% ethanol was the highest. It was. Next, the value with distilled water was large, and the value with 99% ethanol was the smallest.

  FIG. 4 shows a conventional example (batch type) extraction for comparison, and shows the extraction behavior when extraction is performed for 1 hour × 3 times in a batch type (75 ° C.). Even in the batch system, most of the soluble components were eluted during the first 1 hour (first time) extraction, and the extraction amount in the second and third extraction operations decreased. Moreover, the extraction time is required compared with the circulation type. As shown in Table 1, the cumulative extract amount in the batch type is close to the extraction amount at 100 ° C. in the flow type, and is smaller than the extraction amount under the temperature conditions of 120 ° C. and 160 ° C. 3 and 4 show the total amount of the extract extracted from the sweet potato leaves, that is, the percentage display on the basis of dryness by adding the amount of soluble matters including those other than polyphenols. Under the condition of 160 ° C., improvement in soluble matter yield is observed.

  Subsequently, the results of quantifying the polyphenols in the extract are shown in FIG. 5 (circulation type) and FIG. 6 (batch type). The yield of 4 types of polyphenols (3,5-diCQA 4,5-diCQA, 3,4-diCQA, 3,4,5-triCQA) that could be quantified by HPLC was shown in mg per 1 g of dried leaves. . As shown in FIG. 5, most of the polyphenols contained in the sweet potato leaves were extracted during the temperature rising process, and the extraction amount was a mixed solvent of 30% water and 70% ethanol (hereinafter also referred to as 70% ethanol). Sometimes the highest yield is found.

  The data shown in FIG. 5 and FIG. 6 indicate that four types (3,5-diCQA 4,5-diCQA, 3,4-diCQA, 3,4,5- The yield of triCQA) is compared per 1 g of charged dry leaves. It was revealed that polyphenols had the highest extraction efficiency under the solvent condition of 70% ethanol.

  FIG. 7 shows the relationship between the cumulative yield (mg) of quinic acids per 1 g of dried leaves and the extraction conditions. It can be seen that, under any extraction condition, the extraction amount is the highest and the content is high when a mixed solvent of 30% distilled water and 70% ethanol (hereinafter also referred to as 70% ethanol) is used as the extraction solvent. The results of FIGS. 3 to 7 are summarized in Table 2. Under any temperature condition, when 70% ethanol was used as the extraction solvent, the extraction amount was the largest and the content rate was high.

  As described above, among polyphenol extracts from sweet potato leaves, a particularly important one is 3,4,5-triCQA (3,4,5-tricaffeoylquinic acid). FIG. 8 shows the relationship between various extraction conditions and the amount of 3,4,5-triCQA in the extract. As shown in the figure, it can be seen that the amount of 3,4,5-triCQA, which is the target substance for extraction, is extracted in a particularly large amount under the conditions of 70% ethanol and 160 ° C. FIG. 9 is a diagram showing the relationship between the extraction temperature and the extraction amounts of various quinic acids. That is, “CA” is caffeic acid (also known as caffeic acid), “ChA” is chlorogenic acid, “4,5-diCQA” is 4,5-di-caffeoylquinic acid, “3,5-diCQA” Is 3,5-di-caffeoylquinic acid, “3,4-diCQA” is 3,4-di-caffeoylquinic acid, “3,4,5-triCQA” is 3,4,5- Tri-caffeoylquinic acid. It can be seen that the yield of 3,5-di-caffeoylquinic acid is large in any temperature range.

  The extraction amount was improved about 5 times compared with the 75 ° C. batch extraction amount using 70% ethanol, indicating the usefulness of this method. FIG. 8 shows the yield of the target substance 3,4,5-tricaffeoylquinic acid. As described above, under 70% ethanol and 160 ° C, the yield was five times that of the conventional method. Also, the extraction time was significantly shortened compared to the conventional method.

The extraction behavior of quinic acids under the optimum extraction solvent conditions (distilled water 30% and ethanol 70%) as clarified in Example 1 will be investigated, and 80 ° C. using a flow reactor. Extraction was performed at 120 ° C., 140 ° C., 160 ° C., and 180 ° C., and the relationship between the amount of quinic acids extracted and temperature conditions was examined.
(sample)
Same as Example 1.
(Extraction method)
Basically the same as in the first embodiment. About 0.5 g (wet base g) of sweet potato leaves cut into 3 mm square were charged into the reactor, and 70% ethanol was passed through under the requirements of 2.0 MPa and 3.0 mL / min. The temperature rise was started after the start of liquid flow, the temperature was raised to the target temperature (80 ° C., 120 ° C., 140 ° C., 160 ° C., 180 ° C.), and the liquid was further passed for 40 minutes to recover the extract. The extract was freeze-dried, and quinic acids contained in the dried product were analyzed by HPLC.
(analysis)
In addition to the quinic acids shown in Example 1, caffeic acid and chlorogenic acid were also analyzed.
(result)
FIG. 9 shows the relationship between the extracted components and the extraction temperature. As shown in the figure, the extraction using 70% ethanol yielded the highest yield at 160 ° C. It has also been found that the decrease in yield at 180 ° C. is due to thermal decomposition from the experimental results of examining the heat resistance. The target substance, tricaffeoylquinic acid, also had the highest yield at 160 ° C. From the above results, the optimum extraction condition for caffeoylquinic acid, especially tricaffeoylquinic acid, in sweet potato leaves was limited to 160 ° C.

FIG. 1 is a schematic diagram showing an extraction device for extracting polyphenols. FIG. 2 is a data diagram showing a temperature rising pattern and a sampling fraction under each temperature condition. FIG. 3 is a data diagram showing the total amount of extract in the flow reactor. FIG. 4 is a data diagram showing the total amount of extract by batch extraction at 75 ° C. FIG. 5 is a data diagram showing the amount of polyphenols extracted per circulation formula (per 1 g of dried leaves). FIG. 6 is a data diagram showing the amount of polyphenols extracted per batch (per 1 g of dried leaves). FIG. 7 is a data diagram showing the cumulative yield of caffeoylquinic acids under various extraction conditions. FIG. 8 is a data diagram showing the cumulative yield of tricaffeoylquinic acids under various extraction conditions. FIG. 9 is a diagram showing the relationship between the extraction temperature and the extraction amounts of various quinic acids.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Extraction device 2 ... Extraction device main body 3 ... Solvent tank 4 ... Solvent 5 ... High pressure pump 6 ... Heating device 7 ... Polyphenol 8 ... Cooling device 9 ... Back pressure valve 10 ... Recovery device

Claims (8)

A method for extracting polyphenols from the stems and leaves of sweet potato,
A solvent supply step of taking out the solvent prepared in advance;
A pressurizing step for bringing the extracted solvent to a pressure higher than a saturated vapor pressure;
A heating step of heating the extracted solvent;
Supplying the high pressure and heated solvent to the foliage part;
An extraction step of extracting the polyphenol by reacting the supplied solvent with a predetermined amount of the foliage part maintained at a predetermined pressure and a predetermined temperature for contact for a predetermined time;
A cooling step of cooling the polyphenol extracted in the extraction step;
A polyphenol extraction method comprising: a recovery step of recovering the cooled polyphenol by holding it at a predetermined pressure or higher. In the extraction method of the polyphenol of Claim 1,
The method for extracting polyphenol, wherein the polyphenol contains tricaffeoylquinic acid. In the extraction method of the polyphenol of Claim 1 or 2,
The polyphenol extraction method, wherein the solvent is water or a mixed solvent of water and ethanol. The polyphenol extraction method according to claim 3,
The solvent is a mixture of water and ethanol;
The heating step is a step of setting the temperature of the solvent to 160 ± 10 ° C.,
In the high pressure step, the pressure of the solvent is set to be equal to or higher than the saturated vapor pressure of the ethanol at the predetermined temperature. In the extraction method of the polyphenol of Claim 4,
The polyphenol extraction method, wherein the mixing ratio of the ethanol in the mixed solvent of water and ethanol is 70 ± 10%. In one selected by the polyphenol extraction method according to claim 1,
The time for extracting the polyphenol by bringing the solvent into contact with the foliage is a time required for raising the solvent to a predetermined temperature and completing the extraction. An apparatus for polyphenols that extracts polyphenols from the stems and leaves of sweet potato,
A solvent storage device for storing the solvent;
A supply device for supplying the solvent taken out from the solvent storage device to the foliage with a high pressure;
A heating device that heats the solvent taken out of the solvent storage device and supplies the solvent to the foliage part; and
An extraction apparatus main body for extracting the polyphenol by reacting the pressurized and heated solvent by contacting the foliage part for a predetermined time;
A reactor heating device that is provided in the extraction device body and that heats and maintains the solvent and the foliage part;
A cooling device for cooling the extracted polyphenol;
A back pressure device for holding the cooled polyphenol above a certain pressure and retaining it in the extraction device;
A polyphenol extraction device comprising: a recovery device for recovering the extracted polyphenol. In the polyphenol extraction device according to claim 7,
The high pressure by the pressure device is equal to or higher than the saturated vapor pressure of ethanol, the heating temperature by the heating device is 160 ± 10 ° C., and the solvent is a mixed solvent of water and ethanol containing 70 ± 10% ethanol. The polyphenol extraction apparatus characterized by the above-mentioned.

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