Manufacturing method and processing method of tea leaf product for cold brew tea beverage

Abstract

To provide a tea leaf product for cold brew using non-pulverized tea leaves which is excellent in component extraction efficiency.SOLUTION: The present invention is a method for manufacturing a tea leave product for cold brew tea beverage. The manufacturing method includes: an immersion process of immersing water into non-pulverized and non-extracted dry fear leaves; and a Freeze drying process of freeze drying tea leaves after the immersion process.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for manufacturing and processing a tea leaf product for a cold-brewed tea beverage.

Background Art

[0002] A tea beverage is an extract obtained from tea leaves using water (H2O) or the like. As the water used for extraction, hot water (for example, water at 80°C or higher) or warm water (for example, water at 50 to 70°C) is usually used. In recent years, however, extraction using water at a lower temperature has also become widespread. Such extraction using water at a lower temperature is known as "cold-brewing" or the like.

[0003] On the other hand, in cold-brewing, the efficiency of extracting components from tea leaves is low, and it takes a long time for extraction (for example, several hours or more). Therefore, various tea leaf products for achieving cold-brewing in a short time have been proposed. Examples of such tea leaf products include those in which a pulverized product of tea leaves is formed and a cold-brewed tea beverage can be obtained simply by pouring water (for example, Patent Documents 1 and 2).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] Here, the conventional tea leaf product for cold-brewing as described above is one in which water is poured into a formed product of a pulverized tea leaf and it is directly consumed as a tea beverage. That is, the conventional tea leaf product for cold-brewing aims to allow ingestion of all components contained in the tea leaves. However, the inventors have found that since tea leaves also contain components that exhibit off-flavors, astringency, etc., tea beverages obtained from conventional tea leaf products for infusion may be inferior in palatability.

[0006] Therefore, the inventors aimed to develop a tea leaf product for infusion that is excellent in the efficiency of extracting components from tea leaves without pulverizing the tea leaves.

[0007] The present invention has been made in view of the above circumstances, and an object thereof is to provide a tea leaf product for infusion that uses unfragmented tea leaves and is excellent in component extraction efficiency.

Means for Solving the Problems

[0008] As a result of investigations by the inventors, it has been found that in the method for producing a tea leaf product for infusion, the above problems can be solved by immersing predetermined dried tea leaves in water and then freeze-drying them, and the present invention has been completed. More specifically, the present invention provides the following.

[0009] (1) A method for producing a tea leaf product for an infusion tea beverage, wherein the production method includes an immersion step of immersing unfragmented and unextracted dried tea leaves in water, and a freeze-drying step of freeze-drying the tea leaves after the immersion step. Production method.

[0010] (2) The production method according to (1), wherein the immersion time of the dried tea leaves in the immersion step is 20 minutes or less.

[0011] (3) The production method according to (1), wherein the temperature of the water in the immersion step is 20°C or less.

[0012] (4) A processing method for a tea leaf product for an infusion tea beverage, wherein the processing method includes an immersion step of immersing unfragmented and unextracted dried tea leaves in water, and a freeze-drying step of freeze-drying the tea leaves after the immersion step. Processing method.

Advantages of the Invention

[0013] According to the present invention, there is provided a tea leaf product for water extraction that uses uncrushed tea leaves and has excellent component extraction efficiency.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Modes for Carrying Out the Invention

[0015] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited thereto.

[0016] <Manufacturing Method of Tea Leaf Product for Cold Brew Tea Beverage> The manufacturing method of the tea leaf product for cold brew tea beverage according to the present invention (hereinafter, also referred to as "the manufacturing method of the present invention") includes all of the following steps in one aspect. · Soaking step of soaking water into uncrushed and unextracted dry tea leaves. · Freeze-drying step of freeze-drying the tea leaves after the soaking step.

[0017] A tea beverage is a tea leaf extract obtained by extracting various components contained in tea leaves with water (H2O) or the like. Here, regarding the water used for extraction, it is known that the components extracted from tea leaves differ depending on the temperature of the water. Generally, the higher the temperature of the water, the more efficiently the components contained in the tea leaves can be extracted in a short time. For example, when extraction is performed with water at a high temperature, caffeine and epigallocatechin gallate, which is an astringency component, are eluted, and a tea beverage with a strong astringency can be obtained. On the other hand, when extraction (water extraction) is performed with water at a lower temperature (for example, 25°C or lower), a tea beverage with a strong umami taste can be obtained, in which theanine and epigallocatechin are eluted while the elution of caffeine and epigallocatechin gallate is suppressed. However, to obtain a tea beverage using water at a low temperature, extraction for a long time (for example, several hours or more) is required, and the component extraction efficiency is extremely low.

[0018] Therefore, as a result of intensive studies by the present inventors, it has been found that by processing tea leaves by the above-described steps, a tea leaf product with extremely good component extraction efficiency can be obtained even with extraction using water at a low temperature.

[0019] Hereinafter, the production method of the present invention will be described in detail.

[0020] (1) Definition The terms used in the present invention include the following meanings.

[0021] In the present invention, "water extraction (of tea leaves)" includes extraction with water at a lower temperature than hot water (for example, water at 80°C or higher) or warm water (for example, water at 50 to 70°C). For example, the temperature of the water used for water extraction is preferably 25°C or lower, more preferably 0°C or higher and 20°C or lower, and even more preferably 4°C or higher and 10°C or lower. Hereinafter, the water within this temperature range may be referred to as "water for water extraction" in order to distinguish it from hot water and warm water.

[0022] In the present invention, the "tea leaf product for water-extracted tea beverage" or "tea leaf product for water extraction" includes any form of tea leaf product to be subjected to water extraction. In one aspect of the present invention, the form of the tea leaf product is a freeze-dried product (freeze-dried product).

[0023] In the present invention, the "water-extracted tea beverage" is a tea leaf extract obtained by pouring water for water extraction into a tea leaf product for water extraction. However, the present invention does not exclude a usage mode in which a tea leaf product obtained from the production method of the present invention is extracted using hot water or warm water instead of water for water extraction.

[0024] In the present invention, the "component extraction efficiency" can be represented by, for example, the amount of specific components (such as theanine and epigallocatechin) eluted from tea leaves when the extraction conditions are the same in the extraction from tea leaves using water or the like. When different tea products are extracted under the same extraction conditions, it can be said that the higher the amount of specific components eluted from the tea leaves, the higher the component extraction efficiency for that component.

[0025] In the present invention, "excellent in (component extraction efficiency from tea leaves)" includes, for example, that when the extraction conditions are the same, a larger amount of specific components elute from the tea leaves in a shorter time.

[0026] (2) Immersion step In the immersion step, water is permeated into the uncrushed and unextracted dry tea leaves.

[0027] (2-1) Uncrushed and unextracted dry tea leaves In the production method of the present invention, the uncrushed and unextracted dry tea leaves are raw materials for tea products for obtaining brewed tea beverages. The dry tea leaves may be used alone or in combination of two or more.

[0028] (2-1-1) Dry tea leaves In the present invention, the "dry tea leaves" include those obtained by drying any plant part (leaves or stems) that is a raw material for tea beverages.

[0029] The water content of the dry tea leaves is not particularly limited, but is preferably 12% by mass or less, more preferably 5% by mass or less, based on the dry tea leaves.

[0030] The type of plant from which the dry tea leaves are derived is not particularly limited, and examples include Camellia sinensis, Camellia taliensis, Camellia irrawadiensis, etc.

[0031] The drying method of the tea leaves is not particularly limited and is appropriately selected according to the type of tea beverage to be obtained and the like. For example, the manufacturing method of sencha (including rough rolling, rolling, medium rolling, fine rolling, etc.), the manufacturing method of pan-fired tea (including rolling, water drying, tightening frying, etc.), and any drying method adopted in the manufacturing methods of white tea, oolong tea (oolong tea, baozhong tea, etc.), and black tea (including withering, etc.) can be mentioned.

[0032] The type of dried tea leaves is not particularly limited, and for example, any of unfermented tea, slightly fermented tea, semi-fermented tea, fermented tea, post-fermented tea, etc. may be used. Examples of unfermented tea include green tea (sencha, gyokuro, kabusecha, bancha, tamaryokucha, matcha, houjicha, etc.). Examples of slightly fermented tea include baihao yinzhen, white peony, etc. Examples of semi-fermented tea include baozhong tea, oolong tea, etc. Examples of fermented tea include black tea, etc. Examples of post-fermented tea include pu-erh tea, etc.

[0033] The dried tea leaves may be not only the tea leaves dried by the manufacturer of the tea product itself, but also commercially available dried tea leaves.

[0034] In one aspect of the present invention, the dried tea leaves are preferably unfermented tea, more preferably green tea.

[0035] (2-1-2) Uncrushed dried tea leaves In the present invention, the "uncrushed dried tea leaves" include dried tea leaves that have not been subjected to pulverization treatment, grinding treatment, etc. Therefore, powdered tea (tea leaves ground into powder) is excluded as uncrushed dried tea leaves. However, in the present invention, in a mode where tea leaf powder (for example, powdered tea (powder generated during the manufacturing process of sencha), etc.) is mixed in the dried tea leaves within a range that does not inhibit the effects of the present invention, it is not excluded.

[0036] As the unground dried tea leaves, not only those maintaining the leaf shape, but also cut ones and those obtained by the CTC method are included. The "CTC method" includes a manufacturing method in which each process of "Crush (crush)", "Tear (tear)", and "Curl (roll into granules)" is applied to the dried tea leaves. These dried tea leaves are preferable from the viewpoint of enabling efficient immersion described later.

[0037] The length of the cut dried tea leaves or the dried tea leaves obtained by the CTC method is not particularly limited, but is usually 0.5 mm or more.

[0038] Whether the dried tea leaves are unground dried tea leaves can be determined, for example, by using a sieve. For example, dried tea leaves with a mesh size defined in ASTM E11 of preferably 35 or more (opening size 500 μm or less), more preferably 40 or more (opening size 425 μm or less) can be preferably used as unground dried tea leaves.

[0039] (2-1-3) Unextracted dried tea leaves In the present invention, the "unextracted dried tea leaves" include dried tea leaves that have not undergone an extraction process with water or the like. Therefore, tea husks (the remaining residue after extraction from tea leaves) are excluded as unextracted dried tea leaves.

[0040] (2-2) Immersion in water In the immersion step, the unground and unextracted dried tea leaves are immersed in water. The present inventors have found an unexpected finding that after performing this immersion and then freeze-drying the tea leaves (described later), a tea leaf product in which components contained in the tea leaves can be easily extracted can be obtained even with water at a low temperature.

[0041] The various conditions for immersing the dried tea leaves in water are not particularly limited as long as the entire dried tea leaves can be sufficiently immersed in water. However, long-term immersion is preferably avoided because it causes excessive outflow of components in the dried tea leaves.

[0042] The immersion process may be continuous or intermittent throughout. The immersion conditions (such as temperature) in the immersion process may be constant or may change during the process.

[0043] The water for immersing the dried tea leaves is not particularly limited as long as it is a liquid containing water, and may be a liquid consisting only of water (H2O), or may be a liquid containing components other than water together with water (H2O). In the latter case, as components other than water, components and amounts that can be blended in tea beverages can be appropriately selected within a range that does not inhibit the effects of the present invention. Examples of such components include antioxidant substances (such as ascorbic acid).

[0044] The amount of water for immersing the dried tea leaves is not particularly limited as long as the entire dried tea leaves can be immersed. From the viewpoint of easily preventing excessive outflow of components, the upper limit of the amount of water for immersing the dried tea leaves is preferably 8 times or less, more preferably 6 times or less, still more preferably 5 times or less, based on the dry mass of the dried tea leaves. From the viewpoint of facilitating sufficient immersion, the lower limit of the amount of water for immersing the dried tea leaves is preferably 1 time or more, more preferably 2 times or more, based on the dry mass of the dried tea leaves.

[0045] From the viewpoint of suppressing the outflow of components from the dried tea leaves, it is preferable that the temperature of the water for immersing the dried tea leaves is not too high. From the viewpoint of easily preventing excessive outflow of components, the upper limit of the temperature of the water for immersing the dried tea leaves is preferably 20°C or less, more preferably 15°C or less, still more preferably 10°C or less, and even more preferably 5°C or less. From the viewpoint of facilitating sufficient water absorption, the lower limit of the temperature of the water for immersing the dried tea leaves is preferably -4°C or more, more preferably 1°C or more, still more preferably 4°C or more.

[0046] The upper limit of the immersion time of the dried tea leaves in water is not particularly limited, but from the viewpoint of easily preventing excessive outflow of components, it is preferably 24 hours or less, more preferably 1 hour or less, still more preferably 20 minutes or less, and even more preferably 15 minutes or less. The lower limit of the immersion time of the dried tea leaves in water is not particularly limited, but from the viewpoint of facilitating sufficient immersion, it is preferably 1 minute or more, more preferably 10 minutes or more.

[0047] The means for immersing the dried tea leaves in water is not particularly limited as long as the dried tea leaves and water can come into contact with each other. For example, the following methods can be mentioned. It is preferable to carry out any of these methods in a low-temperature environment (for example, an environment of 4°C or lower such as inside a refrigerator). · Put the dried tea leaves together with water in an arbitrary container (such as a resin container), and carry out static absorption or shaking (vibration) absorption. · Immerse the dried tea leaves in water using a decompression machine, a pressurization machine, or the like. · Spray water onto the dried tea leaves using a coating machine or the like.

[0048] (3) Freeze-drying step In the freeze-drying step, the tea leaves after the immersion is completed are freeze-dried.

[0049] In the freeze-drying step, any conditions that can be adopted in the freeze-drying of food and drink can be adopted, and usually, the following steps are included. · Freeze the tea leaves after the immersion is completed. · Dry the frozen tea leaves while maintaining the frozen state. Regarding the above steps, it is preferable that the immersion step and the freezing of the tea leaves are continuous (no other steps are included between the two steps). Also, from the viewpoint of easily suppressing the deterioration of the quality of the obtained tea product, it is preferable to carry out freezing promptly (for example, within 1 hour) after the completion of the immersion step. However, once the tea leaves are frozen, they may be directly subjected to drying as they are after freezing, or they may be stored in a refrigerator or the like until they are subjected to drying.

[0050] The freezing conditions of the tea leaves after the immersion is completed are not particularly limited. The freezing temperature is usually -30°C or higher and -1°C or lower.

[0051] The drying conditions of the frozen tea leaves can be appropriately set according to the mass of the tea leaves and the degree of vacuum, and are not particularly limited. The trap cooling temperature is usually -45°C or lower. The ultimate vacuum is usually 10 Pa or lower.

[0052] In the freeze-drying process, any device known as a freeze dryer (such as a flask type, dry chamber type, etc.) can be used.

[0053] (4) Tea leaf products The freeze-dried tea leaves obtained after the freeze-drying process correspond to the tea leaf products for the cold-brewed tea beverage in the present invention.

[0054] The obtained tea leaf products may be directly used for extraction or the like to prepare a tea beverage, or may be appropriately packaged and stored.

[0055] The obtained tea leaf products may be appropriately processed and prepared, for example, in the following forms. · Loose tea leaf products in a container · Tea bag products · Cup products in which the tea leaf products are fixed inside together with a filter or the like · Tea leaf products for tea dispensers

[0056] (5) Preparation examples of tea beverages From the tea leaf products obtained by the production method of the present invention, a tea beverage can be prepared by any extraction method known as a method for producing a tea beverage. However, since the tea leaf products obtained by the production method of the present invention are particularly suitable for the preparation of cold-brewed tea beverages, preferred preparation examples will be described below.

[0057] The method for preparing a tea beverage from tea leaf products is not particularly limited, and any method of bringing the tea leaf products into contact with water can be adopted. However, in order to obtain a cold-brewed tea beverage, it is preferable to use the water for cold-brewing (described above) as the water brought into contact with the tea leaf products.

[0058] According to the present invention, since the component extraction efficiency is excellent as described above, a sencha beverage can be obtained in a short time. For example, according to the present invention, a sencha beverage can be obtained with an extraction time of preferably 20 minutes or less, more preferably 15 minutes or less, still more preferably 10 minutes or less, and even more preferably 5 minutes or less. When using a conventional tea product, it took several hours to obtain a sencha beverage (for example, refer to the comparative example described later). Therefore, the present invention has an important technical significance in that it significantly shortens the extraction time of the sencha and increases the component extraction efficiency.

[0059] As described above, by using water at a low temperature and performing extraction in a short time, a sencha beverage with a strong umami flavor in which theanine and epigallocatechin are eluted while suppressing the elution of caffeine and epigallocatechin gallate can be obtained.

[0060] <Processing method of tea product for sencha beverage> As described above, according to the present invention, a tea product for sencha with excellent component extraction efficiency can be obtained. Therefore, the present invention also includes a processing method of a tea product for a sencha beverage including the following steps in one aspect thereof. · An immersion step of immersing water in uncrushed and unextracted dried tea leaves. · A freeze-drying step of freeze-drying the tea leaves after the immersion step.

Example

[0061] Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

[0062] <Manufacture of tea product> Tea leaves were processed by the following method to produce a tea product.

[0063] (1) Preparation of dried tea leaves As the dried tea leaves, commercially available sencha produced from the leaves (new shoots) of Camellia sinensis was used. This tea leaf is a so-called green tea (unfermented tea) and corresponds to "undamaged and unextracted dried tea leaves".

[0064] (2) Immersion process The dried tea leaves were immersed in water placed in a rectangular parallelepiped container so that the whole was immersed. As for the water, water five times the amount of the dried tea leaves (about 4°C) was used. Next, the dried tea leaves in the container were put into a refrigerator (about 4°C) and left standing for about 15 minutes to allow the tea leaves to fully absorb water.

[0065] (3) Freeze-drying process After completion of the immersion process, the container was quickly taken out of the refrigerator, frozen in a refrigerator (about -20°C), and then put into a freeze-dryer (flask type) and dried under vacuum conditions. The conditions for freeze-drying were set at a trap cooling temperature of -50°C or lower, a degree of vacuum of 30 Pa or lower, and 24 hours.

[0066] (4) Obtaining tea leaf products After completion of the freeze-drying process, tea leaf products (freeze-dried products) were obtained. These were subjected to the following extraction test.

[0067] <Extraction test> The obtained tea leaf products were subjected to the following tests to evaluate the component extraction efficiency.

[0068] (1) Preparation of samples · Example: Tea leaf products (freeze-dried products) obtained in the above "<Manufacture of tea leaf products>" · Comparative example: Dried tea leaves obtained in "(1) Preparation of dried tea leaves" in the above "<Manufacture of tea leaf products>" (corresponding to ordinary green tea)

[0069] (2) Extraction treatment Each sample was put into water (about 10°C) placed in a container so that the whole was immersed. Next, the container was put into a refrigerator (about 4°C), and at each time point from 3 minutes after the input to 24 hours later, a solution sample (drained tea beverage) was collected while avoiding the tea leaves.

[0070] (3) Component analysis The contents (component elution rates) of epigallocatechin (EGC), epigallocatechin gallate (EGCG), caffeine, and theanine contained in each solution sample were analyzed using high-performance liquid chromatography. The details of the analysis conditions are as follows.

[0071] (3-1) Analysis conditions for EGC, EGCG, and caffeine · Instrument: "Shimadzu LC-20AD system", Shimadzu Corporation · Guard column: "Security Guard Cartridge C18" (i.d. 4*3 mm), Phenomenex · Column: "Wakopak Navi C18-5" (5 μm, i.d. 4.6*150 mm), Fujifilm Wako Pure Chemical Corporation · Eluent: (Mobile phase A) DW: acetonitrile: phosphoric acid = 400:10:1 by volume (Mobile phase B) Methanol: mobile phase A = 1:2 by volume · Detector: "SPD-40V" (242 nm, EGC; 272 nm, EGCG, caffeine), Shimadzu Corporation · Flow rate: 1 mL / min · Column temperature: 40 °C · Injection volume: 20 μL · Gradient: Refer to the following table.

[0072]

Table 1

[0073] (3-2) Analysis conditions for theanine · Instrument: o-phthalaldehyde automatic pre-column derivatization method using "Shimadzu LC-20AD, SIL-40C system" (Shimadzu Corporation) · Guard column: "Security Guard Cartridge C18" (i.d. 4*3 mm), Phenomenex · Column: "Inertsil ODS-4 C18" (3μm, i.d. 4.6 * 150mm), GL Sciences Inc. · Eluent: (Mobile phase A) 20 mM potassium phosphate buffer (pH 6.4) (Mobile phase B) DW: Acetonitrile: Methanol at a volume ratio of 15:45:40 · Detector: "RF-20Axs" (excitation wavelength 350 nm, fluorescence wavelength 450 nm), Shimadzu Corporation · Flow rate: 0.8 mL / min · Column temperature: 40 °C · Injection volume: 1 μL · Internal standard substance: Glycylglycine · Gradient: Refer to the following table.

[0074]

Table 2

[0075] (3-3) Results The analysis results are shown in Figure 1. Figure 1 is the analysis result of the eluted components from the tea leaf product of the example. Figure 2 is the analysis result of the eluted components from the dried tea leaf of the comparative example.

[0076] Each result is expressed as the relationship between the elution time (elapsed time from the sample injection time) and the elution rate of each component. Also, the component elution rate is shown as a relative value when the component amount when the tea leaves of the "comparative example" were extracted with hot water at 80 °C for 2 minutes was set as "100%".

[0077] As shown in Figure 1, according to the tea leaf product obtained by the production method of the present invention, even in the case of extraction in a refrigerator, an extract (tea beverage) in which epigallocatechin and theanine were sufficiently eluted was obtained in a short time of 5 minutes or less. This result shows that in the tea leaf product obtained by the production method of the present invention, the component extraction efficiency from tea leaves is extremely excellent.

[0078] In contrast, as shown in Fig. 2(A), in the case of the dried tea leaves of the comparative example (ordinary green tea), it took a very long time for the components to elute during extraction in the refrigerator, and it took nearly half a day to reach the same elution rate level as the tea leaf product obtained by the production method of the present invention. Regarding the dried tea leaves of the comparative example, extraction was also carried out at room temperature (about 26°C) instead of in the refrigerator (Fig. 2(B)), but still it took a long time for the components to elute, and it took nearly 1 hour to reach the same elution rate level as the tea leaf product obtained by the production method of the present invention.

[0079] From the above, it was found that according to the tea leaf product obtained by the production method of the present invention, even in the case of extraction with water (about 4°C), the extraction time can be significantly shortened, and efficient component extraction can be realized.

Claims

1. A method for manufacturing a tea leaf product for a cold-brewed tea beverage, wherein the manufacturing method comprises: a soaking step of soaking water in uncrushed and unextracted dried tea leaves; a freeze-drying step of freeze-drying the tea leaves after the soaking step. The manufacturing method.

2. The manufacturing method according to claim 1, wherein the soaking time of the dried tea leaves in the soaking step is 20 minutes or less.

3. The manufacturing method according to claim 1, wherein the temperature of the water in the soaking step is 20°C or less.

4. A processing method for a tea leaf product for a cold-brewed tea beverage, wherein the processing method comprises: a soaking step of soaking water in uncrushed and unextracted dried tea leaves; a freeze-drying step of freeze-drying the tea leaves after the soaking step. The processing method.

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