JP2018027898A - Oolong tea extract and production method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an oolong tea extract which is excellent in lipase inhibitory activity, includes less dregs and is light-colored, and a production method thereof.SOLUTION: The oolong tea extract is provided that is obtained by using oolong tea leaves as raw material, water as an extraction solvent, and subjecting the oolong tea leaves to subcritical treatment at pressure equal to or higher than saturation vapor pressure at a temperature of 160-210°C. A production method of the oolong tea extract is also provided.SELECTED DRAWING: None

Description

  The present invention relates to an oolong tea extract and a method for producing the same.

  It is known that the extract of oolong tea leaves contains polymerized polyphenol and has lipase inhibitory activity. Conventionally, oolong tea extract is generally produced by aqueous extraction such as hot water.

  Patent Document 1 describes an oolong tea extract containing more polymerized catechins than non-polymerized catechins, but does not describe extraction methods other than hot water extraction.

JP 2012-97085 A

  The hot water extract is dark brown in color, has a lot of starch, has a bad appearance, and has no problems other than oolong tea. In particular, when water is extracted from oolong tea, a floc, suspended or cloudy suspension / precipitate, so-called starch, is generated. While this starch has a bitter taste and impairs its taste characteristics, it may be mistaken for mold, and it is fatal for general tea-based beverages including oolong tea sealed in transparent containers such as PET bottles. . Therefore, starch control is an important quality control item in terms of commercial value in terms of its visual characteristics, but in the past, special solid-liquid separation processes such as centrifugation, ultrafiltration, and microfiltration are required, and cooling precipitation In some cases, complicated temperature profile control such as a process is required.

  An object of the present invention is to provide a oolong tea extract having excellent lipase inhibitory activity, low starch and light color, and a method for producing the same.

  The present invention relates to an oolong tea extract obtained by subcritical treatment using oolong tea leaves as a raw material and water as an extraction solvent at a temperature of 160 to 210 ° C. and a pressure equal to or higher than a saturated vapor pressure.

  When the solid concentration is adjusted to 2.5 mg / ml, the absorbance at 530 nm is preferably 0.30 or less, and the absorbance at 660 nm is preferably 0.10 or less.

  The present invention also relates to a method for producing a oolong tea extract comprising an extraction step in which oolong tea leaves are used as a raw material and water is used as an extraction solvent at a temperature of 160 to 210 ° C. and a pressure equal to or higher than a saturated vapor pressure.

  The treatment time for the subcritical treatment is preferably 10 to 60 minutes.

  The oolong tea extract of the present invention and the oolong tea extract obtained by the method for producing the oolong tea extract of the present invention are oolong tea extracts having excellent lipase inhibitory activity, low starch and light color.

It is a graph which shows the result of a lipase inhibitory activity test. It is a graph which shows the measurement result (color) of the light absorbency in 530 nm. It is a graph which shows the measurement result (starch) of the light absorbency in 660 nm.

  The oolong tea extract of the present invention is a oolong tea extract obtained by subcritical processing.

Raw material The oolong tea leaf used as the raw material of the oolong tea extract of the present invention is not particularly limited, and those generally marketed as oolong tea can be used. In addition, the oolong tea leaf raw material may include not only leaves but also stems.

Production Method The oolong tea extract of the present invention is a oolong tea extract obtained by subcritical treatment using water as an extraction solvent. As an example of a method for producing an oolong tea extract, an extraction process in which subcritical processing is performed using water, and a solid-liquid separation process in which an extract is obtained by separating an extract from a raw material residue will be described.

Extraction Step The extraction step is a step of obtaining an extraction processed product by extracting the oolong tea leaf raw material, and in this specification refers to an extraction step by subcritical processing. As the extraction solvent used for extraction, water is most preferably used from the viewpoint of extraction efficiency of water-soluble components and safety. Since the subcritical treatment is excellent in terms of a short time and a high extraction rate, an oolong tea extract containing a large amount of polymerized polyphenol having a lipase inhibitory activity can be obtained efficiently from a small amount of raw materials.

  The subcritical treatment is a process in which a subcritical fluid as an extraction solvent brought into a subcritical state under the conditions of a predetermined temperature and pressure is brought into contact with a raw material to be extracted (in the present invention, oolong tea leaves) from the extracted raw material. The component is extracted. For example, when water is raised to a pressure of 22.12 MPa and a temperature of 374.15 ° C., it shows a state where it is neither liquid nor gas. This point is called the critical point of water, and hot water at a temperature and pressure lower than the critical point is called subcritical water. This subcritical water has an excellent component extraction action and hydrolysis action due to a decrease in dielectric constant and an improvement in ionic product.

  When water is used as the extraction solvent used for the subcritical treatment, it can be used in a liquid state or a gas state as long as the water treatment is performed at a high temperature. That is, water vapor may be supplied to the subcritical processing tank, water may be supplied, or both of them may be supplied. The temperature of water or water vapor is desirably 100 ° C. or higher, and the desired reaction field is more likely to proceed in the liquid state than in the gas. The use of water in the state is preferred. More specifically, the extract obtained by putting the raw material and water as the extraction solvent in a pressure vessel such as metal or ceramics, sealing it, and making contact with each other for a certain period of time in a subcritical state of water. Can be a subcritical processed product.

  The extraction solvent used for the subcritical treatment includes, for example, ethylene, ethane, propane, carbon dioxide, methanol, ethanol and mixtures thereof in addition to water. Among these, it is most preferable to use water from the viewpoint of safety. Next, processing conditions when the extraction solvent is water will be described.

  The subcritical treatment temperature is preferably between 160 and 210 ° C, more preferably between 180 and 200 ° C for the reason of increasing the extraction rate. When the temperature of subcritical processing is less than 160 ° C., the effect of reducing starch and color tends to deteriorate. Moreover, when the temperature of subcritical processing exceeds 210 degreeC, lipase inhibitory activity falls.

  The subcritical processing pressure is preferably carried out at a saturated vapor pressure or higher at each temperature. The saturated vapor pressure at each temperature can be determined by referring to the Japan Society of Mechanical Engineers steam table (1968). For example, 160 ° C .: 0.62 MPa (6.30 at), 170 ° C .: 0.79 MPa (8.08 at), 180 ° C .: 1.00 MPa (10. 22 at), 190 ° C .: 1.25 MPa (12.80 at), 200 ° C .: 1.55 MPa (15.68 at), 210 ° C .: 1.90 MPa (19.45 at). By setting this pressure, it becomes easy to efficiently obtain a polymerized polyphenol. In addition, although the upper limit of the pressure of a subcritical process is not specifically defined, it is preferable to suppress to around 20-30 MPa on the specification of a high voltage | pressure apparatus.

  The subcritical processing time is preferably 5 to 150 minutes, more preferably 5 to 60 minutes. By making it into the range of this processing time, it becomes easy to obtain the functional component of oolong tea efficiently. If the subcritical processing time is less than 5 minutes, the resulting extract tends to be insufficient. Moreover, when subcritical processing time exceeds 150 minutes, it will decompose excessively and there exists a tendency for lipase inhibitory activity to fall.

  That is, as extraction conditions by subcritical processing of oolong tea leaves when the extraction solvent is water, the processing temperature is 160 to 210 ° C., the processing pressure is equal to or higher than the saturated vapor pressure of each temperature, and the processing time is 5 to 150 minutes. It is preferable. By performing under these conditions, it is possible to extract a oolong tea extract having excellent lipase inhibitory activity, low starch, and light color.

Solid-liquid separation step The solid-liquid separation step is a step of separating the subcritical processed product into oolong tea extract and raw material residue (solid material). Specific solid-liquid separation processes include filtration using filter paper, centrifugation, decantation, screw press, roller press, rotary drum screen, belt screen, vibrating screen, multi-plate vibrating filter, vacuum dehydration, pressure dehydration, Belt press, centrifugal concentration dehydration, multiple disk dehydration and the like can be mentioned. Among these, filtration is preferable because the operation is simple and the separation efficiency is excellent.

  Furthermore, in order to efficiently precipitate substances that cause starch, it is preferable to perform a freeze-thaw step in which the subcritical processing solution separated from the raw material residue is once frozen and then thawed. The temperature to freeze is not specifically limited, A general freezer can be used.

  When starch is precipitated as a result of the freeze-thaw step, it is preferable to perform a solid-liquid separation step for the purpose of removing the starch by a solid-liquid separation step. The above-mentioned method is mentioned as the said solid-liquid separation process. Among these, filtration is preferable because the operation is simple and the separation efficiency is excellent.

  The oolong tea extract obtained by the solid-liquid separation step can be used as it is or in a concentrated state. Moreover, it can also be made to dry according to a usage method. A solid oolong tea extract is obtained by drying the extract. As a drying method, a general drying method can be used. Naturally, it is allowed to stand naturally, heat transfer drying such as box drying or spray drying which is a heating system, internal heat drying such as microwave drying, non-heating system Freeze drying, vacuum drying, suction drying, pressure drying, ultrasonic drying, and the like are possible. Of course, it is acceptable to dry using a general and simple oven and thermostat. Moreover, you may perform the decoloring using adsorption agents, such as activated carbon and an ion exchange resin, before a drying process suitably.

  Extraction with organic solvents (alcohols, ketones, acetones, etc.) is performed on the extract that has undergone the solid-liquid separation process and drying process in order to selectively obtain components with higher functionality (lipase inhibitory activity). Good. Of these, ethanol is preferred because it has little effect on the human body and is easy to use in foods and cosmetics.

Oolong tea extract The oolong tea extract of the present invention is characterized by excellent lipase inhibitory activity, low starch and light color.

  The lipase inhibitory activity of the oolong tea extract can be measured by a commercially available lipase inhibitory activity measurement kit such as Lipase Kit S manufactured by DS Pharma.

  The amount of starch in the oolong tea extract is based on the absorbance at 530 nm when the solid content concentration of the oolong tea extract is adjusted to 2.5 mg / ml. The absorbance at 530 nm is preferably 0.30 or less, and more preferably 0.25 or less. Moreover, it shows that there is little starch, so that the said light absorbency is low, and a minimum is not specifically limited.

  The color of the oolong tea extract is based on the absorbance at 660 nm when the solid content concentration of the oolong tea extract is adjusted to 2.5 mg / ml. The absorbance at 660 nm is preferably 0.10 or less, and more preferably 0.08 or less. Further, the lower the absorbance, the lighter the color, and the lower limit is not particularly limited.

  The oolong tea extract of the present invention is characterized by excellent lipase inhibitory activity, low starch and light color, so it can be used as it is, or it can be suitably used for foods such as health foods and supplements, cosmetics, etc. be able to.

  The present invention will be described based on examples, but the present invention is not limited to the examples.

<Preparation of oolong tea extract>
The preparation process of the oolong tea extract of an Example and a comparative example is demonstrated.

Example 1 (subcritical treatment 175 ° C., 10 minutes)
40 g of commercially available oolong tea leaf powder and 300 g of distilled water were placed in a pressure-resistant container having a volume of 2 l, and subcritical processing was performed at a processing temperature of 175 ° C., a processing pressure of 0.9 MPa, and a processing time of 10 minutes. After the subcritical treatment is completed, the processed product (subcritical residue + subcritical treatment liquid) in the treatment can is collected in a 1 l container and suction filtered through a cellulose filter paper (pore size: 7 μm, 5A manufactured by Advantec). (Subcritical extract) was obtained. The obtained subcritical extract was frozen at −25 ° C. and then thawed at room temperature. Then, the precipitated starch in the subcritical extract was removed by suction filtration with a cellulose filter paper (pore size: 1 μm, 5C manufactured by Advantec). The solid content concentration of the obtained subcritical processing solution was measured to prepare a subcritical processing solution having a solid content concentration of 2.5 mg / ml.

Example 2 (Subcritical treatment 175 ° C., 30 minutes)
Except that the subcritical treatment time was 30 minutes, the subcritical treatment and solid-liquid separation steps (including freeze-thawing and starch removal) were performed in the same manner as in Example 1 to obtain a powdery subcritical extract.

Example 3 (Subcritical treatment 195 ° C., 5 minutes)
Subcritical processing, solid-liquid separation process (including freeze-thawing and starch removal) as in Example 1, except that the subcritical processing temperature was 195 ° C., the processing pressure was 1.6 MPa, and the subcritical processing time was 5 minutes. And a subcritical processing solution was prepared.

Example 4 (subcritical treatment 195 ° C., 10 minutes)
Subcritical processing, solid-liquid separation process (including freeze-thawing and starch removal) as in Example 1, except that the subcritical processing temperature was 195 ° C., the processing pressure was 1.6 MPa, and the subcritical processing time was 10 minutes. And a subcritical processing solution was prepared.

Example 5 (subcritical treatment 195 ° C., 20 minutes)
Subcritical processing, solid-liquid separation process (including freeze-thawing and starch removal) as in Example 1, except that the subcritical processing temperature was 195 ° C., the processing pressure was 1.6 MPa, and the subcritical processing time was 20 minutes. And a subcritical processing solution was prepared.

Example 6 (Subcritical treatment 195 ° C., 30 minutes)
Subcritical processing, solid-liquid separation process (including freeze-thawing and starch removal) as in Example 1, except that the subcritical processing temperature was 195 ° C., the processing pressure was 1.6 MPa, and the subcritical processing time was 30 minutes. And a subcritical processing solution was prepared.

Comparative Example 1 (hot water treatment)
In a 1000 ml beaker, 20 g of commercially available oolong tea leaf powder and 500 g of distilled water were added, and hydrothermal treatment was performed at a treatment temperature of 95 ° C. under atmospheric pressure for a treatment time of 30 minutes to obtain a hydrothermal treatment product.
The hydrothermally treated product was subjected to suction filtration with a cellulose filter paper (pore diameter: 7 μm, manufactured by Advantec) to obtain a filtrate (hot water extract). The obtained hot water extract was frozen at −25 ° C. and then thawed at room temperature. The hot water extract was suction filtered with cellulose filter paper (pore size: 1 μm, 5C manufactured by Advantec). The solid content concentration of the obtained hot water extract was measured and the solid content concentration was adjusted to 2.5 mg / ml to obtain a hot water extract.

Comparative Example 2 (subcritical treatment at 155 ° C., 10 minutes)
Subcritical processing, solid-liquid separation process (including freeze-thawing and starch removal) as in Example 1 except that the subcritical processing temperature was 155 ° C., the processing pressure was 0.5 MPa, and the subcritical processing time was 10 minutes. And a subcritical processing solution was prepared.

Solid content concentration measurement The subcritical processing solution and the hot water extract were quantified and dried in an oven at 105 ° C. (STERILIZER SI401 made by YAMATO), and the mass of the obtained solid matter was measured with the subcritical processing solution and the hot water extraction solution. Measured by dividing by quantity.

<Evaluation>
The subcritical treatment liquid and hot water extract prepared in each example and comparative example were evaluated in the following tests.

Lipase inhibitory activity 25 μl of each subcritical extract or hot water extract (sample solution), 85 μl of the color reagent supplied with the lipase kit S (manufactured by DS Pharma), 10 μl of substrate solution and enzyme solution (0.1 mg / ml pig) 10 μl of pancreatic lipase (Sigma Aldrich) /0.1 M citrate buffer) was mixed and reacted at 30 ° C. for 30 minutes. Thereafter, 170 μl of stop solution attached to the lipase kit S was added to the reaction solution to stop the reaction, the absorbance at a wavelength of 413 nm was measured, the lipase inhibition rate (%) was calculated from the following formula, and the lipase activity was 50%. The sample concentration to inhibit (IC50 value) was calculated. A blank using distilled water instead of the sample solution was used.
Lipase inhibitory activity (%) = 1− (absorbance after enzyme reaction of sample solution−absorbance of sample solution before enzyme reaction) / (absorbance after enzyme reaction of blank−absorbance of blank before enzyme reaction) × 100

Measurement of Starch and Color The absorbance at 530 nm and the absorbance at 660 nm of each subcritical processed product and hot water extract were measured with a spectrophotometer (U-5100 manufactured by Hitachi, Ltd.). Absorbance at 530 nm was used as an index for the amount of starch, and absorbance at 660 nm was used as an index for color.

Polymerized polyphenol concentration The polymerized polyphenol concentration of each subcritical processed product and hot water extract was measured by high performance liquid chromatography (HPLC) under the following conditions.
Measuring device: LC-2010HT manufactured by Shimadzu Corporation
Column: TSKGEL ODS-80TS QA manufactured by Tosoh Corporation
Mobile phase A: 0.05% (w / v) TFA-containing acetonitrile / water = 10/90
Mobile phase B: 0.05% (w / v) TFA-containing acetonitrile / water = 80/20
0min-5min; A: B = 100: 0
5min-11min; A: B = 100: 0 → 92: 8
11min-21min; A: B = 92: 8 → 90: 10
21min-22min; A: B = 90: 10 → 0: 100
22min-30min; A: B = 0: 100
30min-31min; A: B = 0: 100 → 100: 0
Column temperature: 40 ° C
Detection wavelength: 280 nm
Introduction amount: 10 μl
Flow rate: 1.0 ml / min
Analysis time: 30 min

  From the results shown in Table 1, it can be seen that the oolong tea extract obtained by the predetermined subcritical treatment is excellent in lipase inhibitory activity, has less starch, and is light in color.

Claims (5)

An oolong tea extract obtained by subcritical treatment using oolong tea leaves as a raw material and water as an extraction solvent at a temperature of 160 to 210 ° C. and a pressure equal to or higher than a saturated vapor pressure. When adjusting the solid content concentration to 2.5 mg / ml,
The absorbance at 530 nm is 0.30 or less,
The oolong tea extract according to claim 1, which has an absorbance at 660 nm of 0.10 or less. The oolong tea extract according to claim 1 or 2, wherein a treatment time of the subcritical treatment is 5 to 60 minutes. A method for producing an oolong tea extract comprising an extraction step using oolong tea leaves as a raw material and using water as an extraction solvent at a temperature of 160 to 210 ° C. and a pressure equal to or higher than a saturated vapor pressure. The manufacturing method according to claim 4, wherein a processing time of the subcritical processing is 5 to 60 minutes.

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