Method for obtaining non-epi catechin and non-epi catechin obtained using the same

Abstract

To provide a method of preparing a non-epimeric catechin, and a non-epimeric catechin prepared thereby.SOLUTION: A method of preparing a non-epimeric catechin comprises: putting green tea leaves into a vessel; and, after closing the vessel, increasing the temperature of air in the vessel while circulating the air, and leaving the green tea leaves for 5-30 minutes at a temperature of at least 160°C. Also provided is a non-epimeric catechin prepared by the preparation method.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a method for obtaining non-epi catechin and non-epi catechin obtained using the same.

Background Art

[0002] There are roughly eight types of components in tea catechins existing in nature. The tea catechin content is 10% - 15% of the total dry weight of green tea leaves, and among them, epigallocatechin gallate (EGCG) occupies 50% - 60%. Gallocatechin gallate (GCG) is a catechin with a low content of only 0.8% - 1.5% of the catechin content existing in green tea as the 2-carbon isomer of epigallocatechin gallate.

[0003] Typical catechins present in green tea are epicatechin [(-)EC], epigallocatechin [(-)EGC], epicatechin gallate [(-)ECG], and epigallocatechin gallate [(-)EGCG]. From the antioxidant effects of green tea reported so far, the reduction of cholesterol absorption, the suppression of the increase in triglycerides, antiviral, antitumor, anticancer, skin beautification, obesity suppression, mutagenicity suppression effects, etc. are represented by the activities of these catechins. Recently, during the pasteurization process for making green tea beverages, it was confirmed that these catechins are respectively converted into their isomers, non-epicatechins, namely catechin [(-)C], gallocatechin [(-)GC], catechin gallate [(-)CG], and gallocatechin gallate [(-)GCG]. Also, when green tea leaves are leached in hot water, it was confirmed that the epicatechins in the green tea leaves are converted into catechin epimers, which are non-epicatechins. The antioxidant efficacy of these isomers exhibits effects equal to those of their respective isomers (Xu J.Z. et al., British Journal of Nutrition, 91, 873-881, 2004; Unno T. et al., J. Sci. Food Agric., 80, 601-606, 2000). The cholesterol absorption-reducing effect is more excellent in catechin gallate and gallocatechin gallate than their isomers (Ikeda I. et al., J. Agric. Food Chem., 51, 7303-7307, 2003). The anti-allergy efficacy is also more excellent in gallocatechin gallate, which is an isomer of epigallocatechin gallate (Nagai H. et al., J. Sci. Food Agric., 85, 1606-1612, 2005). Gallocatechin gallate activates the peroxisome proliferator-activated receptor (PPAR)-alpha subtype and promotes the expression of filaggrin, a skin moisturizing factor, thereby exhibiting excellent skin dryness prevention and skin moisturizing effects (Korean Patent Application No. 2005-0086821).In addition, the non-epi catechins present in green tea for drinking not only stabilize the epi-catechins but also have an even better effect on taste. Thus, with the industrial utility potential of non-epi catechins such as gallocatechin gallate becoming clear, attempts are being made to utilize them. However, their content in green tea is extremely low, and until now, high temperature and pH adjustment have been required for the conversion of catechins to epimers. It is impossible to extract, separate, and purify non-epi catechins such as gallocatechin gallate from green tea leaves and mass-produce them.

[0004] More specifically, to extract non-epi catechins from green tea leaves, three main methods have been used to date: (i) a method of promoting the thermal isomerization of epi-catechins such as epigallocatechin gallate by adjusting the pH or temperature in an aqueous solution; (ii) a method of promoting the thermal isomerization reaction of epi-catechins such as epigallocatechin gallate by adjusting the pH or temperature during the heat sterilization process in the production of green tea beverages; and (iii) a method of promoting the thermal isomerization reaction of epi-catechins such as epigallocatechin gallate by heat-treating green tea leaves or green tea beverages under high-pressure conditions using an autoclave.

[0005] However, with such methods, the conversion rate (isomerization rate) of epi-catechins to non-epi catechins is extremely low, and the purity of the obtained non-epi catechins is not high. This is presumably because the non-epi catechins are not extracted from green tea leaves without pretreatment, but rather the green tea leaves are heated with an organic solvent or the pH is adjusted, resulting in low purity. However, no method is known for obtaining non-epi catechins with a high yield and purity from green tea leaves without pretreatment, and even if it were possible, only extremely small amounts could be obtained at the laboratory level.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Non-Patent Documents

[0007] [Non-Patent Document 1] Xu J.Z. et al., British Journal of Nutrition, 91, 873-881, 2004 [Non-Patent Document 2] Unno T. et al., J. Sci. Food Agric., 80, 601-606, 2000 [Non-Patent Document 3] Ikeda I. et al., J. Agric. Food Chem., 51, 7303-7307, 2003 [Non-Patent Document 4] Nagai H. et al., J. Sci. Food Agric., 85, 1606-1612, 2005 [Summary of the Invention] [Problems to be Solved by the Invention]

[0008] One embodiment provides a method for very easily converting the epi-catechins in green tea leaves into non-epi-catechins with a high yield and high content.

[0009] Another embodiment provides non-epi-catechins obtained by using the above method. [Means for Solving the Problems]

[0010] According to one embodiment, there is provided a method for obtaining non-epi-catechins, including the steps of putting green tea leaves into a container, sealing the container, circulating the air in the container to increase the temperature of the air, and leaving the green tea leaves at a temperature of 160°C or higher for 5 to 30 minutes.

[0011] The container may be a non-oil fryer.

[0012] The step of leaving the green tea leaves may be carried out at a temperature of 160°C to 200°C.

[0013] The step of leaving the green tea leaves can be a step carried out at a temperature of 180°C.

[0014] The step of leaving the green tea leaves can be a step carried out for 5 to 10 minutes.

[0015] The step of putting green tea leaves into the container may include the step of putting green tea leaves into the container and spraying water on the green tea leaves.

[0016] The green tea leaves may have a weight that is 4 to 6 times the weight of the water to be sprayed.

[0017] After the step of leaving the green tea leaves, the method may further include the step of taking out the green tea leaves from the container and refluxing with alcohol.

[0018] The alcohol is ethanol, and the step of refluxing with ethanol can be a step carried out at 50°C to 70°C for 30 minutes to 2 hours.

[0019] After the step of refluxing with alcohol, the method may further include the steps of filtration and distillation.

[0020] The non-epicatechin may include gallocatechin, catechin, gallocatechin gallate, and catechin gallate.

[0021] Another embodiment provides non-epicatechin obtained by the above-mentioned obtaining method. Another embodiment also provides a green tea extract containing non-epicatechin obtained by the above-mentioned obtaining method.

Advantages of the Invention

[0022] According to one embodiment, non-epicatechin can be easily obtained from green tea leaves with a high yield and a high content.

Modes for Carrying Out the Invention

[0023] Hereinafter, embodiments of the present invention will be described in detail so that those having ordinary knowledge in the technical field to which the present invention pertains can easily implement it. However, the present invention can be embodied in various different forms and is not limited to the embodiments described herein.

[0024] In this specification, when a part such as a layer, film, region, plate, etc. is "on" another part, this includes not only the case where it is "directly on" another part but also the case where there are other parts in between. Conversely, when a part is "directly on" another part, it means that there are no other parts in between.

[0025] Unless otherwise defined in this specification, "combination" means mixing or copolymerization. Also, "copolymerization" means block copolymerization or random copolymerization, and "copolymer" means block copolymer or random copolymer.

[0026] Unless otherwise defined in this specification, the eight catechins are composed of four epi-catechins and four non-epi-catechins. The four epi-catechins mean epigallocatechin, epicatechin, epigallocatechin gallate, and epicatechin gallate, and the other four non-epi-catechins that make up the eight catechins mean gallocatechin, catechin, gallocatechin gallate, and catechin gallate.

[0027] Hereinafter, a method for obtaining non-epi-catechins according to an embodiment will be described. A method for obtaining non-epi-catechins according to an embodiment includes the steps of putting green tea leaves in a container, and after sealing the container, circulating the air in the container to increase the temperature of the air, and leaving the green tea leaves at a temperature of 160°C or higher for 5 to 30 minutes.

[0028] According to one embodiment, after putting green tea leaves without any pretreatment into a container, through a very simple process of leaving the green tea leaves for a certain period of time only at the temperature raised by air circulation immediately without any separate organic solvent or the like, the epi-catechins in the green tea leaves can be converted into non-epi-catechins, and the conversion efficiency and purity are also very high.

[0029] This is to heat-treat green tea leaves without using any organic solvent or the like and without pretreatment for a certain period of time. Also, instead of using a conventional heat source for the heat treatment, air is circulated at high speed to increase the temperature of the air, and the green tea leaves are heat-treated only with the heated air. By suppressing chemical changes such as oxidative polymerization, hydrolysis, and reverse isomerization rate reaction of non-epi-catechins, the residual rate of non-epi-catechins increases, and it is considered that the conversion efficiency and purity of non-epi-catechins increase.

[0030] The temperature of the air raised by the air circulation must be 160°C or higher. Only when the temperature range is 160°C or higher, the conversion efficiency of epi-catechins to non-epi-catechins becomes high.

[0031] Also, the green tea leaves must be left for 5 to 30 minutes at the temperature of 160°C or higher. Only when the leaving time of the green tea leaves is within the time range, the conversion efficiency of epi-catechins to non-epi-catechins becomes high.

[0032] For example, the container can be a no-oil fryer, and the no-oil fryer can include not only a household no-oil fryer but also a no-oil fryer used in a factory or the like for mass production. Generally, a no-oil fryer circulates the air inside the no-oil fryer at high speed to raise the temperature, and cooks the food inside the no-oil fryer with the raised temperature. It is possible to fry food without oil, and the cooking process is not as complicated as that of an oven. Therefore, the cases where no-oil fryers are used for food cooking are increasing. According to one embodiment, by using a general no-oil fryer used for food cooking, the epicatechins in green tea leaves can be easily converted into non-epicatechins very simply (by only using the method of using a general no-oil fryer). This is much easier than the conventional method of converting epicatechins into non-epicatechins, and has excellent conversion efficiency. Since a principle completely different from the conventional method is used, the method for obtaining non-epicatechins according to one embodiment has a significant difference from the conventional method of converting epicatechins into non-epicatechins in terms of composition and effect. On the other hand, the air circulation speed in a generally used no-oil fryer is 600 m / min to 2000 m / min. Therefore, the air circulation speed during air circulation in the container according to one embodiment can also be 600 m / min to 2000 m / min. In order to maintain the temperature of the air in the container at 160°C or higher, it is necessary to have an air circulation speed within the above range. Therefore, it is preferable to use a commercial no-oil fryer as the container in the method for obtaining non-epicatechins according to one embodiment, and since it is only necessary to use a commercial no-oil fryer, it is very easy to use. Furthermore, a low pressure can be maintained only when the air circulation speed during air circulation in the container is within the above range. For example, when the air circulation speed exceeds 2000 m / min, the temperature inside the container also increases, but thereby the pressure inside the container increases. Although the conversion efficiency of epicatechins into non-epicatechins may be excellent, it will result in the destruction of the entire catechins and a decrease in the total amount of catechins.As will be described later, even if the conversion efficiency of epicatechin to non-epicatechin is high, when the total amount of catechins decreases, it becomes difficult to achieve the antioxidant effect and the excellent sensory improvement effect such as in food for the converted non-epicatechin. That is, the method for obtaining non-epicatechin according to one embodiment relates to a method that can prevent the decrease in the total amount of catechins and at the same time increase the conversion efficiency of epicatechin to non-epicatechin.

[0033] For example, the step of leaving the green tea leaves can be carried out at a temperature of 160°C to 200°C. For example, the step of leaving the green tea leaves can be carried out at a temperature of 160°C or higher, for example 165°C or higher, for example 170°C or higher, for example 175°C or higher, and can also be carried out at a temperature of 200°C or lower, for example 195°C or lower, for example 190°C or lower, for example 185°C or lower.

[0034] For example, the step of leaving the green tea leaves can be carried out at a temperature of 180°C.

[0035] For example, the step of leaving the green tea leaves can be a step of carrying out for 5 minutes to 30 minutes. For example, the step of leaving the green tea leaves can be carried out for 5 minutes or more, for example 6 minutes or more, for example 7 minutes or more, and can also be carried out for 30 minutes or less, for example 25 minutes or less, for example 20 minutes or less, for example 15 minutes or less, for example 10 minutes or less, for example 9 minutes or less, for example 8 minutes or less, for example 7 minutes or less.

[0036] For example, the step of leaving the green tea leaves can be a step of carrying out for 5 minutes to 10 minutes, for example 5 minutes to 7 minutes.

[0037] For example, the method for obtaining non-epicatechin according to one embodiment may include a step of putting green tea leaves into a container, a step of circulating the air in the container after sealing the container to increase the temperature of the air, and a step of leaving the green tea leaves at a temperature of 160°C to 200°C, for example 180°C, for 5 minutes to 30 minutes, for example 5 minutes to 7 minutes.

[0038] For example, the step of putting green tea leaves into the container may include the step of putting green tea leaves into the container and spraying water on the green tea leaves. In this case, the green tea leaves may have a weight that is 4 to 6 times the weight of the water being sprayed. If there is no water or if the amount of water used is excessively small, the temperature may rise due to the high-speed circulation of air in the container, and there is a risk that the green tea leaves may be partially burned. If the amount of water used is excessively large, the green tea leaves may not be dried despite the temperature being raised by the high-speed circulation of air in the container.

[0039] For example, the method for obtaining non-epicatechins according to one embodiment may further include, after the step of leaving the green tea leaves, the step of taking out the green tea leaves from the container and refluxing them with alcohol.

[0040] For example, the alcohol may be ethanol.

[0041] Also, the step of refluxing with ethanol may be a step of performing the reflux at 50°C to 70°C for 30 minutes to 2 hours.

[0042] For example, the method for obtaining non-epicatechins according to one embodiment may further include, after the step of refluxing with alcohol, the steps of filtration and distillation.

[0043] The steps of filtration and distillation may be steps of lowering the temperature of the green tea leaf sample refluxed with ethanol to room temperature (20°C to 25°C) and then distilling it, for example, by vacuum distillation, and finally obtaining a green tea extract in powder form through these steps.

[0044] The finally obtained green tea extract in powder form contains all 8 catechin components (4 epi-catechins and 4 non-epi-catechins), and the 8 catechin components can be contained in an amount of 20% by weight or more based on the total amount (100% by weight) of the dried green tea extract. At the same time, the total amount of 4 non-epi-catechin components among the 8 catechin components can be 5% to 10% by weight, for example, 6% to 10% by weight. For example, when the 8 catechin components are less than 20% by weight based on the total amount (100% by weight) of the dried green tea extract, even if the conversion rate of epi-catechin to non-epi-catechin is high, it is difficult for the non-epi-catechin to exhibit effects such as further improving the antioxidant efficacy and the taste of green tea-containing foods such as green tea beverages.

[0045] Another embodiment provides a non-epi-catechin obtained by the method for obtaining the non-epi-catechin.

[0046] Still another embodiment provides a dried green tea extract (in powder form) obtained by the method for obtaining the non-epi-catechin. The dried green tea extract may contain the 8 catechin components (4 epi-catechins and 4 non-epi-catechins).

Examples

[0047] Hereinafter, the content of the present invention will be described more specifically with reference to Examples and Comparative Examples. These Examples are presented for understanding the content of the present invention, and the scope of the rights of the present invention is not limited to these Examples and Test Examples. Modifications, substitutions, insertions, etc. that are commonly known in the art can be made, and these are also included in the scope of the present invention.

[0048] (Example) [Conversion of epi-catechins present in green tea leaves to non-epi-catechins] 100 g of green tea (Camellia sinensis, Jeju Osulloc Farm) was placed in a no-oil fryer (Lotte 3.5L digital no-oil fryer, LSF804), and 20 ml of water was sprayed using a sprayer. Then, the reaction (standing) was carried out under the conditions shown in Table 1 below. After that, 1000 ml of 50% ethanol was added to the sample taken out from the no-oil fryer, and the mixture was refluxed and stirred at 60°C for 1 hour. The temperature of the sample was lowered to room temperature, and the solution obtained by filtration was distilled under reduced pressure to obtain a dark brown powder of green tea extract (GreenEpimer) (yield 23%). The contents of epimeric catechins and non-epimeric catechins in the green tea extracts obtained by reacting under various conditions were measured using the apparatus shown in Table 2 below, and the results are shown in Table 1 below. As a reference, green tea leaves were extracted immediately at a temperature of 60°C without reacting in the no-oil fryer.

[0049]

Table 1

[0050]

Table 2

[0051] From Table 1 above, it can be seen that when green tea leaves are subjected to high-speed air circulation treatment at a specific temperature (especially 180°C) for a specific time (especially 7 minutes), epimeric catechins are effectively converted into non-epimeric catechins. Here, the effective non-epimeric catechins are assumed to contain 20% by weight or more of the contents of 8 kinds of catechins based on the total powder amount (100% by weight) of the finally obtained green tea leaves.

[0052] As described above, the preferred embodiments of the present invention have been described in detail. However, the scope of the rights of the present invention is not limited thereto, and various modifications and improvements by those skilled in the art using the basic concept of the present invention defined in the following claims also belong to the scope of the rights of the present invention.

Claims

1. A step of putting green tea leaves into a container, after sealing the container, circulating the air inside the container to raise the temperature of the air, and leaving the green tea leaves at a temperature of 160°C or higher for 5 to 30 minutes, comprising, The step of putting green tea leaves into the container includes a step of putting green tea leaves into the container and spraying water on the green tea leaves, a method for obtaining non-epicatechins.

2. The container is a non-oil fryer, the method for obtaining non-epicatechins according to Claim 1.

3. The step of leaving the green tea leaves is a step carried out at a temperature of 160°C to 200°C, the method for obtaining non-epicatechins according to Claim 1.

4. The step of leaving the green tea leaves is a step carried out at a temperature of 180°C, the method for obtaining non-epicatechins according to Claim 3.

5. The step of leaving the green tea leaves is a step carried out for 5 to 10 minutes, the method for obtaining non-epicatechins according to Claim 1.

6. The green tea leaves have a weight that is 4 to 6 times the weight of the water being sprayed, the method for obtaining non-epicatechins according to Claim 1.

7. After the step of leaving the green tea leaves, further comprising a step of taking out the green tea leaves from the container and refluxing with alcohol, the method for obtaining non-epicatechins according to Claim 1.

8. The alcohol is ethanol, The step of refluxing with ethanol is a step carried out at 50°C to 70°C for 30 minutes to 2 hours, the method for obtaining non-epicatechins according to Claim 7.

9. After the step of refluxing with alcohol, further comprising a step of filtering and distilling, the method for obtaining non-epicatechins according to Claim 7.

10. The non-epicatechins include gallocatechin, catechin, gallocatechin gallate and catechin gallate, the method for obtaining non-epicatechins according to Claim 1.

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