Manufacturing method and processing method of tea leaf product for cold-extracted tea beverage

Abstract

The present invention addresses the problem of providing a tea leaf product for cold extraction, which uses unpulverized tea leaves and has excellent component extraction efficiency. The present invention provides a method for producing a tea leaf product for a cold-extracted tea beverage, the method comprising an impregnation step for impregnating dry tea leaves, which are not crushed and not extracted, in water, and a freeze-drying step for freeze-drying the tea leaves after the impregnation step.

Description

Technical Field

[0001] The invention relates to a manufacturing method and a processing method of a tea product for cold-brew tea beverage. Background Art

[0002] Tea beverages are extracts obtained from tea leaves using water (H2O) or the like.

[0003] The water used for extraction is usually hot water (e.g., water at 80°C or higher) and / or warm water (e.g., water at 50°C to 70°C), but extraction using lower temperature water has become popular in recent years. This extraction using lower temperature water is known as "cold extraction."

[0004] On the other hand, cold brewing has a low efficiency in extracting components from tea leaves and requires a long time (eg, several hours or more) for extraction.

[0005] Therefore, various tea products have been proposed for achieving cold brewing in a short time. Examples of such tea products include tea products that mold ground tea leaves and produce cold brew tea beverages simply by adding water (e.g., Patent Documents 1 and 2).

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Laid-Open No. 06-217695

[0009] Patent Document 2: Japanese Patent Application Laid-Open No. 01-108939 Summary of the Invention

[0010] Technical problem to be solved by the invention

[0011] Here, the conventional cold brew tea product as described above is a product in which water is added to a molded product of ground tea leaves and the resulting product is drunk directly as a tea beverage. In other words, the conventional cold brew tea product is a product that ingests all the ingredients contained in the tea leaves.

[0012] However, the inventors of the present invention have discovered that tea beverages obtained from conventional cold brew tea products may have poor palatability because tea leaves also contain components that impart off-flavors and astringency.

[0013] Therefore, the inventors of the present invention aimed to develop a tea product for cold brewing that is excellent in efficiency in extracting components from tea leaves even without crushing the tea leaves.

[0014] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a tea product for cold brewing that uses unground tea leaves and has excellent component extraction efficiency.

[0015] Solutions to Problems

[0016] The inventors of the present invention have discovered that, in a method for producing a cold brew tea product, the above-mentioned problems can be solved by immersing predetermined dried tea leaves in water and then freeze-drying them, thereby completing the present invention. More specifically, the present invention provides the following.

[0017] (1) A method for producing a tea product for a cold brew tea beverage, characterized in that:

[0018] The manufacturing method comprises:

[0019] a soaking step of soaking un-crushed and un-extracted dried tea leaves in water; and

[0020] A freeze drying step is performed to freeze dry the tea leaves after the immersion step.

[0021] (2) The production method according to (1), wherein the immersion time of the dried tea leaves in the immersion step is 24 hours or less.

[0022] (3) The production method according to (1), wherein the temperature of the water in the immersion step is 20° C. or lower.

[0023] (4) A method for processing tea products for cold brew tea beverages, characterized in that:

[0024] The processing method comprises:

[0025] a soaking step of soaking un-crushed and un-extracted dried tea leaves in water; and

[0026] A freeze drying step is performed to freeze dry the tea leaves after the immersion step.

[0027] Effects of the Invention

[0028] According to the present invention, a tea product for cold brew is provided which uses unground tea leaves and has excellent component extraction efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a graph showing the analysis results of eluted components from tea products of Examples.

[0030] Figure 2 This is a graph showing the analysis results of eluted components from tea products of comparative examples. DETAILED DESCRIPTION

[0031] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited thereto.

[0032] <Method for producing tea products for cold brew tea beverages>

[0033] The method for producing a tea product for a cold brew tea beverage of the present invention (hereinafter also referred to as "the production method of the present invention") includes all the following steps in one embodiment.

[0034] A soaking step in which un-crushed and un-extracted dry tea leaves are soaked in water.

[0035] A freeze-drying step of freeze-drying the tea leaves after the immersion step.

[0036] Tea beverages are tea extracts obtained by extracting various components contained in tea leaves with water (H2O) or the like.

[0037] Here, it is known that different components are extracted from tea leaves depending on the temperature of the water used for extraction.

[0038] Generally speaking, the higher the water temperature, the faster and more efficiently the components contained in tea leaves can be extracted. For example, if high-temperature water is used for extraction, caffeine and epigallocatechin gallate, an astringent component, will be dissolved, resulting in a tea beverage with a strong astringency.

[0039] On the other hand, when extraction is performed with water at a relatively low temperature (e.g., 25°C or lower) (cold extraction), the dissolution of caffeine and epigallocatechin gallate is suppressed, while theanine and epigallocatechin dissolve, resulting in a tea beverage with a strong taste.

[0040] However, in order to obtain a tea beverage using low-temperature water, a long extraction period (eg, several hours or more) is required, which significantly reduces the efficiency of component extraction.

[0041] Therefore, the inventors of the present invention conducted intensive research and found that by processing tea leaves using the above-mentioned process, even if low-temperature water is used for extraction, a tea product with very high efficiency in extracting components from tea leaves can be obtained.

[0042] Hereinafter, the production method of the present invention will be described in detail.

[0043] (1) Definition

[0044] The terms used in the present invention include the following meanings.

[0045] In the present invention, "cold extraction (of tea leaves)" includes extraction with water having a temperature lower than hot water (eg, water at 80°C or higher) or warm water (eg, water at 50°C to 70°C).

[0046] For example, the temperature of water used for cold 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, water within this temperature range may be referred to as "cold extraction water" to distinguish it from hot water or warm water.

[0047] In the present invention, "tea products for cold brew tea beverages" or "tea products for cold brew" include tea products in any form for cold brew. In one embodiment of the present invention, the tea product is in the form of a freeze-dried product (freeze-dried product).

[0048] In the present invention, the "cold brew tea beverage" is a tea extract obtained by injecting cold brew water into a tea product for cold brew.

[0049] However, the present invention does not exclude the use of hot water or warm water instead of cold extraction water to extract the tea product obtained by the manufacturing method of the present invention.

[0050] In the present invention, "component extraction efficiency" can be expressed by the amount of a specific component (eg, theanine or epigallocatechin) dissolved from tea leaves when extracted from tea leaves using water or the like under the same extraction conditions.

[0051] When different tea products are extracted under the same extraction conditions, the greater the amount of a specific component dissolved from the tea leaves, the higher the component extraction efficiency can be said to be.

[0052] In the present invention, “excellent efficiency in extracting components (from tea leaves)” includes, for example, eluting more specific components from tea leaves in a shorter time under the same extraction conditions.

[0053] (2) Impregnation process

[0054] In the steeping process, un-crushed and un-extracted dry tea leaves are steeped in water.

[0055] (2-1) Uncrushed and unextracted dried tea leaves

[0056] In the production method of the present invention, the un-crushed and un-extracted dry tea leaves are the raw materials for obtaining tea products for cold-brew tea beverages.

[0057] The dried tea leaves may be used alone or in combination of two or more.

[0058] (2-1-1) Drying tea leaves

[0059] In the present invention, "dried tea leaves" include dried tea leaves of any plant part (leaves or stems) that is a raw material for tea beverages.

[0060] The moisture content of the dried tea leaves is not particularly limited, but is preferably 12% by mass or less, and more preferably 5% by mass or less, based on the dry tea leaves.

[0061] The type of plant from which the dried tea leaves are derived is not particularly limited, and examples thereof include Camellia sinensis, Camellia taliensis, and Camellia irrawadiensis.

[0062] The method for drying tea leaves is not particularly limited and can be appropriately selected depending on the type of tea beverage desired. For example, any drying method used in the production of sencha (including rough rolling, twisting, medium rolling, and fine rolling), the production of pan-fried tea (including twisting, water drying, and stir-frying), and the production of white tea, green tea (such as oolong tea and baozhong tea), and black tea (including withering) can be cited.

[0063] The type of dried tea leaves is not particularly limited, and may be, for example, any of non-fermented tea, slightly fermented tea, semi-fermented tea, fermented tea, and post-fermented tea.

[0064] Examples of unfermented tea include green tea (such as sencha, gyokuro, kancha, bancha, gamryocha, tencha, matcha, and hojicha).

[0065] Examples of slightly fermented tea include Silver Needle Baihao and White Peony.

[0066] Examples of semi-fermented tea include Baozhong tea and Oolong tea.

[0067] Examples of fermented tea include black tea.

[0068] Examples of post-fermented tea include Pu'er tea.

[0069] The dried tea leaves may be not only tea leaves dried by the manufacturer of the tea product but also commercially available dried tea leaves.

[0070] In one embodiment of the present invention, the dried tea leaves are preferably unfermented tea, more preferably green tea.

[0071] (2-1-2) Uncrushed dried tea leaves

[0072] In the present invention, "unground dry tea leaves" include dry tea leaves that have not been subjected to a powdering process or a grinding process.

[0073] Therefore, powdered tea (tea obtained by grinding dry tea leaves into powder) is excluded as unground dry tea leaves. However, the present invention does not exclude the possibility of mixing dry tea leaves with powdered tea leaves (for example, powdered tea (powdered tea produced during the production of sencha)) within a range that does not hinder the effects of the present invention.

[0074] Uncrushed dry tea leaves include not only tea leaves that have retained their leaf shape, but also cut tea leaves, tea leaves granulated by rolling or bagging, and tea leaves produced by the CTC method. The term "CTC method" encompasses methods in which dry tea leaves are subjected to various treatments, including "crushing," "tearing," and "curling."

[0075] These dried tea leaves are preferred from the viewpoint of enabling efficient impregnation described below.

[0076] The length of the cut dried tea leaves or dried tea leaves obtained by the CTC production method is not particularly limited, but is usually 0.5 mm or longer.

[0077] Whether the dried tea leaves are un-crushed can be determined by, for example, using a sieve. For example, dried tea leaves having a mesh size of preferably 35 or greater (mesh opening 500 μm or less), and more preferably 40 or greater (mesh opening 425 μm or less) as specified in ASTM E11 can be preferably used as the un-crushed dried tea leaves.

[0078] (2-1-3) Unextracted dried tea leaves

[0079] In the present invention, "unextracted dried tea leaves" include dried tea leaves that have not been subjected to an extraction step using water or the like.

[0080] Therefore, tea husks (residues produced after extraction from tea leaves) are excluded as unextracted dried tea leaves.

[0081] (2-2) Immersion in water

[0082] In the steeping process, un-crushed and un-extracted dry tea leaves are steeped in water.

[0083] The inventors of the present invention unexpectedly discovered that by freeze-drying the tea leaves after the immersion (described later), a tea product from which components contained in the tea leaves can be easily extracted can be obtained even with water at low temperatures.

[0084] The conditions for immersing the dried tea leaves in water are not particularly limited as long as the entire dried tea leaves can be fully immersed in water. However, prolonged immersion may cause excessive loss of components in the dried tea leaves, so prolonged immersion is preferably avoided.

[0085] The immersion step may be continuous or intermittent throughout, and the immersion conditions (temperature, etc.) during the immersion step may be constant or may be changed during the immersion step.

[0086] The water used to dry the tea leaves is not particularly limited as long as it is a liquid containing water. It may be a liquid consisting solely of water (H 2 O) or a liquid containing water (H 2 O) and components other than water.

[0087] In the latter case, as ingredients other than water, the ingredients and amounts that can be incorporated into the tea beverage can be appropriately selected within the scope that does not hinder the effects of the present invention. Examples of such ingredients include antioxidants (such as ascorbic acid).

[0088] In a preferred embodiment of the present invention, the water used in the immersion step does not contain substances that decompose or deteriorate the components contained in the dried tea leaves. For example, the water used in the immersion step preferably does not contain enzymes.

[0089] The amount of water used to immerse the dried tea leaves is not particularly limited as long as the entire dried tea leaves are immersed.

[0090] From the viewpoint of easily preventing excessive outflow of components, the upper limit of the amount of water used to immerse the dry tea leaves is preferably 8 times or less, more preferably 6 times or less, and even more preferably 5 times or less, based on the dry mass of the dry tea leaves.

[0091] From the viewpoint of facilitating sufficient immersion, the lower limit of the amount of water in which the dry tea leaves are immersed is preferably 1 time or more, more preferably 2 times or more, based on the dry mass of the dry tea leaves.

[0092] From the viewpoint of suppressing outflow of components from the dry tea leaves, the temperature of the water in which the dry tea leaves are immersed is preferably not too high.

[0093] From the viewpoint of easily preventing excessive outflow of components, the upper limit of the temperature of the water in which the dried tea leaves are immersed is preferably 20°C or lower, more preferably 15°C or lower, further preferably 10°C or lower, and even more preferably 5°C or lower.

[0094] From the viewpoint of facilitating sufficient water absorption, the lower limit of the temperature of the water in which the dried tea leaves are immersed is preferably -4°C or higher, more preferably 1°C or higher, and even more preferably 4°C or higher.

[0095] 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, preferably 12 hours or less, preferably 5 hours or less, more preferably 1 hour or less, more preferably 40 minutes or less, more preferably 30 minutes or less, further preferably 20 minutes or less, and further preferably 15 minutes or less.

[0096] The lower limit of the immersion time of the dried tea leaves in water is not particularly limited, but is preferably 1 minute or longer, more preferably 10 minutes or longer, from the viewpoint of facilitating sufficient immersion.

[0097] The method for immersing the dried tea leaves in water is not particularly limited as long as the dried tea leaves are in contact with water, and examples thereof include the following methods. All methods are preferably performed in a low temperature environment (e.g., in a refrigerator at 4°C or below).

[0098] Place the dried tea leaves and water in any container (resin container, etc.) and allow to absorb by standing or vibrating.

[0099] Using a decompression machine or a press machine, immerse the dried tea leaves in water.

[0100] Spray water onto the dried tea leaves using a coating machine or the like.

[0101] (3) Freeze-drying process

[0102] In the freeze-drying step, the soaked tea leaves are freeze-dried (lyophilized).

[0103] The freeze-drying step can employ any conditions that can be employed for freeze-drying of food and beverages, but generally includes the following steps.

[0104] Freeze the infused tea leaves.

[0105] The frozen tea leaves are dried while maintaining the frozen state.

[0106] For the above-mentioned process, preferably the freezing of the tea leaves is carried out continuously with the immersion process (excluding other processes between the two processes). In addition, from the viewpoint of easily suppressing the quality reduction of the obtained tea product, it is preferred to freeze quickly (for example, within 1 hour) after the immersion process is completed.

[0107] However, the temporarily frozen tea leaves may be dried directly after freezing, or may be stored in a refrigerator or the like until they are dried.

[0108] The freezing conditions of the tea leaves after the soaking are not particularly limited.

[0109] The freezing temperature is usually -30°C or higher and -1°C or lower.

[0110] The drying conditions for the frozen tea leaves can be appropriately set according to the quality of the tea leaves and the degree of vacuum, and are not particularly limited.

[0111] The capture cooling temperature is usually below -45°C.

[0112] The vacuum degree reached is usually below 10Pa.

[0113] In the freeze-drying step, any device known as a freeze-dryer (flask type, drying chamber type, etc.) can be used.

[0114] (4) Tea products

[0115] The freeze-dried tea leaves obtained after the freeze-drying step are equivalent to the tea products used for the cold-brew tea beverage in the present invention.

[0116] The obtained tea product can be directly used for extraction or the like to prepare a tea beverage, or can be appropriately packaged and stored.

[0117] The obtained tea product can be processed appropriately, for example, prepared into the following forms.

[0118] Leaf tea products in containers

[0119] Tea bag products

[0120] ·Cup products with tea products and filter devices fixed inside

[0121] Tea products for tea machines

[0122] (5) Preparation Example of Tea Beverage

[0123] Tea beverages can be prepared from the tea product obtained by the production method of the present invention by any extraction method known as a method for producing tea beverages.

[0124] However, the tea product obtained by the production method of the present invention is particularly suitable for the preparation of cold-brew tea beverages, so a preferred preparation example is described below.

[0125] The method for preparing a tea beverage from a tea product is not particularly limited, and any method that brings the tea product into contact with water can be employed.

[0126] However, in order to obtain a cold brew tea beverage, it is preferable that the water that comes into contact with the tea product is the cold brew water (described above).

[0127] According to the present invention, as described above, due to the excellent component extraction efficiency, a cold-brew tea beverage can be obtained in a short time. For example, according to the present invention, a cold-brew tea beverage can be obtained with an extraction time of preferably 20 minutes or less, more preferably 15 minutes or less, even more preferably 10 minutes or less, and even more preferably 5 minutes or less.

[0128] When conventional tea products are used, several hours of extraction time is required to obtain a cold brew tea beverage (for example, see the comparative example described below).

[0129] Therefore, the present invention has important technical significance in significantly shortening the extraction time of cold extraction and improving the efficiency of component extraction.

[0130] As described above, by performing extraction in a short time using low-temperature water, the elution of caffeine and epigallocatechin gallate is suppressed, while theanine and epigallocatechin are eluted, resulting in a cold brew tea beverage with a strong taste.

[0131] <Processing method of tea products for cold brew tea beverages>

[0132] As described above, according to the present invention, a tea product for cold brewing having excellent component extraction efficiency can be obtained.

[0133] Therefore, one aspect of the present invention also includes a method for processing tea products for cold-brew tea beverages, which includes the following steps.

[0134] The steeping process involves steeping un-crushed and unextracted dry tea leaves in water.

[0135] A freeze-drying step of freeze-drying the tea leaves after the immersion step.

[0136] Example

[0137] Hereinafter, the present invention will be described in further detail with reference to Examples, but the present invention is not limited to these Examples.

[0138] <Manufacturing of tea products>

[0139] The following method is used to process tea leaves and make tea products.

[0140] (1) Preparation of dried tea leaves

[0141] As the dried tea leaves, commercially available sencha produced from leaves (new shoots) of the tea plant (scientific name: Camellia sinensis) was used.

[0142] The tea leaves are so-called green tea (unfermented tea), which corresponds to "un-crushed and unextracted dried tea leaves".

[0143] (2) Impregnation process

[0144] The dried tea leaves were immersed in water added to a rectangular container until the entire container was submerged. The amount of water used was five times the amount of the dried tea leaves (at about 4°C).

[0145] Next, place the dried tea leaves together with the container in a refrigerator (about 4°C) and let it stand for about 15 minutes to allow the tea leaves to fully absorb water.

[0146] (3) Freeze-drying process

[0147] After the impregnation step, the container was quickly taken out of the refrigerator, frozen in a refrigerator (about -20°C), and then placed in a freeze dryer (flask type) and dried under vacuum conditions.

[0148] The freeze-drying conditions were set as a collection cooling temperature of -50°C or lower, a vacuum degree of 30 Pa or lower, and 24 hours.

[0149] (4) Acquisition of tea products

[0150] After the freeze-drying step, a tea product (freeze-dried product) was obtained and subjected to the following extraction test.

[0151] Extraction test

[0152] The obtained tea product was subjected to the following test to evaluate the component extraction efficiency.

[0153] (1) Sample preparation

[0154] Example: Tea product (freeze-dried product) obtained in the above-mentioned "<Manufacturing of tea product>"

[0155] Comparative Example: Dried tea leaves obtained in "(1) Preparation of dried tea leaves" in "<Manufacturing of tea products>" (equivalent to ordinary green tea)

[0156] (2) Extraction processing

[0157] Each sample was placed in water (about 10° C.) in a container so that the entire sample was immersed.

[0158] Then, the container was placed in a refrigerator (about 4° C.), and the tea leaf recovery solution sample (cold brew tea beverage) was removed at various time points from 3 minutes to 24 hours after the addition.

[0159] (3) Component analysis

[0160] The content (component dissolution rate) of epigallocatechin (EGC), epigallocatechin gallate (EGCG), caffeine, and theanine in each solution sample was analyzed using high performance liquid chromatography. Details of the analysis conditions are as follows.

[0161] (3-1) Analysis conditions for EGC, EGCG, and caffeine

[0162] Device: "Shimadzu LC-20AD system", Shimadzu Corporation

[0163] Guard column: "Security Guard Cartridge C18" (id4*3mm), Phenomenex

[0164] Column: "Wakopak Navi C18-5" (5μm, ID4.6*150mm), Fujifilm Wako Pure Chemical Industries, Ltd.

[0165] Eluent:

[0166] (Mobile phase A) DW: acetonitrile: phosphoric acid in a volume ratio of 400:10:1

[0167] (Mobile phase B) Methanol: Mobile phase A by volume ratio of 1:2

[0168] Detector: "SPD-40V" (242nm, EGC; 272nm, EGCG, caffeine), Shimadzu Corporation

[0169] Flow rate: 1 mL / min

[0170] Column temperature: 40°C

[0171] Injection volume: 20 μL

[0172] Gradient: Refer to the table below.

[0173] Table 1

[0174]

[0175] (3-2) Analysis conditions for theanine

[0176] · Apparatus: Automated pre-column derivatization of o-phthalaldehyde using Shimadzu LC-20AD and SIL-40C systems (Shimadzu Corporation)

[0177] Guard column: "Security Guard Cartridge C18" (id4*3mm), Phenomenex

[0178] ·Column: "Inertsil ODS-4C18" (3μm, id4.6*150mm), GL Sciences Co., Ltd.

[0179] Eluent:

[0180] (Mobile phase A) 20 mM potassium phosphate buffer (pH 6.4)

[0181] (Mobile phase B) DW: acetonitrile: methanol (volume ratio: 15:45:40)

[0182] Detector: "RF-20Axs" (excitation wavelength 350 nm, fluorescence wavelength 450 nm), Shimadzu Corporation

[0183] Flow rate: 0.8 mL / min

[0184] Column temperature: 40°C

[0185] Injection volume: 1 μL

[0186] Internal standard substance: Glycine

[0187] Gradient: Refer to the table below.

[0188] Table 2

[0189]

[0190] (3-3) Results

[0191] The analysis results are as follows Figure 1 shown.

[0192] Figure 1 These are the analysis results of the eluted components from the tea products of the Examples. Figure 2 These are the analysis results of eluted components from dried tea leaves of Comparative Examples.

[0193] The results are presented as the relationship between the dissolution time (elapsed time from sample injection) and the dissolution rate of each component. The component dissolution rate is expressed as a relative value, with the amount of the component in the tea leaves of the "Comparative Example" extracted in 80°C hot water for 2 minutes being set as "100%."

[0194] like Figure 1 As shown, according to the tea product obtained by the production method of the present invention, even if the extraction is carried out in a refrigerator, an extract (tea beverage) in which epigallocatechin and theanine are sufficiently dissolved can be obtained in a short time of 5 minutes or less.

[0195] This result shows that the tea product obtained by the production method of the present invention has a very excellent efficiency in extracting components from tea leaves.

[0196] In contrast, Figure 2 As shown in (A), the dried tea leaves of the comparative example (normal green tea) took a very long time to dissolve the components during extraction in a refrigerator, and it took nearly half a day to reach the same level of dissolution rate as the tea product obtained by the production method of the present invention.

[0197] It should be noted that, for the dried tea leaves of the comparative example, extraction was also performed at room temperature (about 26°C) instead of in a refrigerator ( Figure 2 (B)), but the dissolution of the components still takes time, and it takes nearly 1 hour to reach the same level of dissolution rate as the tea product obtained by the production method of the present invention.

[0198] In summary, the tea product obtained by the production method of the present invention can significantly shorten the extraction time even when extracted with water (about 4° C.), thereby achieving efficient component extraction.

Claims

1. A method for producing a tea product for cold brew tea beverage, characterized in that: The manufacturing method comprises: a soaking step of soaking un-crushed and un-extracted dried tea leaves in water; and A freeze drying step is performed to freeze dry the tea leaves after the immersion step.

2. The manufacturing method according to claim 1, wherein The immersion time of the dried tea leaves in the immersion step is 24 hours or less.

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

4. A method for processing tea products for cold brew tea beverages, characterized in that: The processing method comprises: a soaking step of soaking un-crushed and un-extracted dried tea leaves in water; and A freeze drying step is performed to freeze dry the tea leaves after the immersion step.

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