Method for enhancing fruity aroma in black tea

Abstract

The present invention addresses the problem of providing: a method for producing black tea leaves that can be used, e.g., in the preparation of a black tea extract having enhanced fruity aroma; a black tea extract that is extracted from the black tea leaves; and products, including foods and beverages, that contain the black tea extract or the like.　The method for producing the black tea leaves comprises fermenting tea plant stems, preferably in the presence of one or more enzymes. Preferable examples of the one or more enzymes include pectinase and beta-glucosidase.

Description

Method for improving fruity aroma in black tea

[0001] The present invention relates to a method for producing black tea leaves that can be used for preparing a black tea extract with improved fruity aroma, a black tea extract extracted from the black tea leaves, food and beverages containing the black tea extract, etc.

[0002] Tea beverages have long been popular as favorite beverages and health beverages due to their unique aroma and refreshing flavor produced by bitterness and astringency. There are tea beverages prepared from various teas such as green tea, semi-fermented tea (oolong tea), fermented tea (black tea), etc., and in recent years, they are distributed as canned, PET bottle-packed, or paper-packed container beverages. Black tea beverages are one of the beverages particularly favored among tea beverages from the aspect of preference or health consciousness, due to the unique aroma of black tea and the taste with bitterness and astringency, and black tea beverages prepared with various flavor variations are provided as container-packed black tea beverages filled in cans, PET bottles, etc.

[0003] By the way, Patent Document 1 describes a method for producing a tea extract with enhanced aroma, characterized in that when treating tea leaves with tannase and / or after treatment, a glycoside-degrading enzyme is allowed to act on the tea leaves. On the other hand, Patent Document 2 describes a method for increasing the yield and tea solid solubility of black tea by enzyme treatment, characterized by including the following steps: 1) a step of wetting black tea leaves with an enzyme solution containing tannase and at least one cell wall-digesting enzyme; 2) a step of incubating the enzyme-wetted tea to cause partial digestion and fermentation of the tea leaves; 3) a step of neutralizing the tea with an edible base to a pH of about 4.75 to about 5.75; and 4) a step of inactivating the enzyme;

[0004] However, it has not been known that black tea leaves capable of obtaining a black tea extract with improved fruity aroma can be produced by fermenting the stems of Camellia sinensis.

[0005] Japanese Patent No. 4381263 Japanese Unexamined Patent Application Publication No. 60-105454

[0006] The object of the present invention is to provide a method for producing tea leaves that can be used to prepare tea extracts with enhanced fruity aroma, as well as tea extracts extracted from said tea leaves, and food and beverages containing said tea extracts.

[0007] In order to solve the above problems, the inventors of this invention diligently investigated various methods and discovered that using tea leaves fermented from the stems of the tea plant yields a tea extract with an improved fruity aroma, thus completing the present invention.

[0008] In other words, the present invention provides the following inventions: (1) A method for producing black tea leaves, comprising step A of fermenting the stems of the tea plant; (2) The method for producing black tea leaves according to (1), wherein an enzyme is added when fermenting the stems of the tea plant; (3) The method for producing black tea leaves according to (2), wherein the enzyme is one or more selected from the group consisting of pectinase, cellulase, hemicellulase, and β-glucosidase; (4) The method for producing black tea leaves according to any one of (1) to (3), wherein the stems of the tea plant are stems derived from fresh leaves cultivated in Japan; (5) The method for producing black tea leaves according to (4), wherein the variety of fresh leaves is one or more selected from the group consisting of Yabukita, Benifuki, Yutakamidori, and Kanayamidori; (6) A method for producing tea leaves according to any one of (1) to (5) above, wherein step A is a step of fermenting the stems and leaves of the tea plant together or separately, and before fermentation, the step of kneading the stems and leaves of the tea plant separately; (7) Tea leaves produced by the method according to any one of (1) to (6) above; (8) Tea leaves according to (7) above, containing 15% by mass or more of stems with respect to the total amount of tea leaves; (9) A method for producing a tea extract, comprising a step of contacting the tea leaves according to (7) or (8) above with a solvent for extraction; (10) A tea extract produced by the method according to (9) above; (11) Food and beverages containing the tea extract according to (10) above; (12) Food and beverages containing the tea leaves according to (7) or (8) above; (13) A method for improving the fruity aroma in a tea extract, comprising a step of contacting the tea leaves according to (7) or (8) above with a solvent for extraction;

[0009] According to the present invention, it is possible to provide a method for producing tea leaves that can be used to prepare tea extracts with enhanced fruity aroma, as well as tea extracts extracted from said tea leaves, and food and beverages containing said tea extracts, etc.

[0010] The present invention includes: [1] a method for producing tea leaves, comprising step A of fermenting the stems of the tea plant (hereinafter also referred to as "the method for producing tea leaves of the present invention"); [2] tea leaves produced by the method for producing tea leaves of the present invention (hereinafter also referred to as "the tea leaves of the present invention"); [3] a method for producing a tea extract, comprising a step of contacting the tea leaves of the present invention with a solvent for extraction (hereinafter also referred to as "the method for producing the tea extract of the present invention"); [4] a tea extract, comprising the method for producing the tea extract of the present invention (hereinafter also referred to as "the tea extract of the present invention"); [5] food and beverages, comprising the method for producing tea leaves of the present invention or the tea extract of the present invention (hereinafter also referred to as "the food and beverages of the present invention"); [6] a method for improving the fruity aroma in a tea extract, comprising a step of contacting the tea leaves of the present invention with a solvent for extraction (hereinafter also referred to as "the improvement method of the present invention"); and the like.

[0011] <Step A> The method for producing black tea leaves according to the present invention is not particularly limited as long as it includes step A, which involves fermenting the stems of the tea plant. Step A is not particularly limited as long as it involves fermenting the stems of the tea plant.

[0012] (Tea plant stems) Any tea plant stem can be used as long as it is harvested from the tea plant (scientific name: Camellia sinensis), regardless of its variety, origin, harvesting time, harvesting method, cultivation method, or size. However, stems that have been harvested, withered, and twisted from the tea plant are preferred. Preferred tea plant varieties include one or more selected from the group consisting of Yabukita, Benifuki, Yutakamidori, Kanayamidori, and Koshun. One or more selected from the group consisting of Yabukita, Benifuki, Yutakamidori, and Kanayamidori are preferred, one or more selected from the group consisting of Yabukita and Benifuki are preferred, and Benifuki is even more preferred.

[0013] The stems of the tea plant may be used alone, without the leaves, or they may be used in combination with the leaves. As for the tea leaves, any leaves picked from a tea plant can be used, regardless of variety, origin, picking time, picking method, cultivation method, or size, but leaves that have been picked, withered, and rolled are preferred. There are no particular limitations on the method of using both the stems and leaves of the tea plant (preferably a method that increases the proportion of tea plant stems), but examples include a method of separately picking, wilting, rolling and / or fermenting the stems and leaves of the tea plant and then mixing them (preferably mixing in a larger amount of stems), a method of picking, wilting, rolling and / or fermenting the stems and leaves of the tea plant without separating them and then removing some or all of the leaves, and a method of growing the tea plant stems longer than usual, for example, before picking, wilting and / or fermenting the stems and leaves. When using both the stems and leaves of the tea plant, there are no particular restrictions on their weight ratio. However, examples of lower limits for the dry weight of the stems relative to the total dry weight of the leaves and stems include 15% by mass or more, 20% by mass or more, 30% by mass or more, 40% by mass or more, 50% by mass or more, 60% by mass or more, and 70% by mass or more. There are no particular restrictions on the upper limit, but examples of upper limits include 100% by mass or less, 90% by mass or less, 80% by mass or less, and 70% by mass or less. Hereinafter, in this specification, the "stem" or "stem and leaves" of the tea plant will be collectively referred to as the stems, etc., of the tea plant.

[0014] The conditions and methods for the wilting process of the tea plant stems, etc. (i.e., the process of letting the harvested stems, etc. stand to reduce the moisture content within the stems, etc.) and the kneading process (i.e., the process of kneading while applying pressure) are not particularly limited as long as the effects of the present invention are obtained.

[0015] The wilting process is not particularly limited, but it includes a process of leaving the tea plant stems, etc., to stand for a certain period of time (for example, 8 to 20 hours) under conditions that reduce the moisture content, and preferably a process of applying hot air (for example, hot air at 40 to 50°C) to the tea plant stems, etc., using, for example, a hot air dryer, for a certain period of time (for example, 8 to 12 hours). The degree of moisture reduction in the tea plant stems, etc., due to the wilting process is such that the mass of the tea plant stems, etc., after wilting is, for example, 50 to 85% of the mass of the tea plant stems, etc., before wilting.

[0016] The kneading process is not particularly limited, and can include a process of kneading for a certain period of time using a kneading machine commonly used in the production of black tea and the like. The kneading time is not particularly limited as long as the effects of the present invention are obtained, but in the case of tea plant stems, from the viewpoint of obtaining more of the effects of the present invention, for example, 5 to 40 minutes, preferably 5 to 30 minutes, more preferably 5 to 20 minutes, 5 to 15 minutes, 7 to 20 minutes, or 7 to 15 minutes can be used. On the other hand, when tea plant leaves are used in combination, the kneading time for tea plant leaves can be, for example, 15 to 90 minutes, preferably 30 to 90 minutes, or 45 to 75 minutes. When tea plant stems and leaves are used in combination, it is preferable to separate the tea plant stems and leaves and knead each for a suitable time. That is, when tea plant stems and leaves are used in combination, step A is a step of fermenting the tea plant stems and leaves together or separately, and it is preferable that this step includes a step of kneading the tea plant stems and leaves separately before fermentation.

[0017] (Fermentation) The conditions for fermenting the stems of the tea plant can be appropriately set based on the fermentation conditions in known methods for producing black tea leaves, but the temperature conditions include, for example, 20 to 45°C, preferably 25 to 40°C, and more preferably 30 to 40°C. The fermentation time includes, for example, 10 minutes to 8 hours, preferably 20 minutes to 4 hours, more preferably 30 minutes to 2 hours, and even more preferably 1 to 2 hours. In terms of the relationship between temperature and fermentation time, it is desirable to adjust so that the fermentation time is shorter at high temperatures and longer at low temperatures. The fermentation process can be carried out using a fermenter for producing fermented tea, or by placing the tea leaves in a breathable container and letting them stand, or by continuously using a rolling machine or a net-type dryer. When using both the stems and leaves of the tea plant, they may be fermented separately or together.

[0018] From the viewpoint of obtaining more of the effects of the present invention, it is preferable to add enzymes when fermenting the tea plant stems, etc., in step A.

[0019] (Enzymes) In this specification, "enzymes" are not particularly limited as long as the effects of the present invention are obtained, and include one or more selected from the group consisting of pectinase, cellulase, hemicellulase, and β-glucosidase. From the viewpoint of obtaining more of the effects of the present invention, one or more selected from the group consisting of pectinase and β-glucosidase are preferred, and it is more preferable to use pectinase and β-glucosidase in combination.

[0020] Pectinase is an enzyme that hydrolyzes α-1,4 bonds in pectinic acid, pectin, pectic acid, etc. The pectinase used is not particularly limited as long as it possesses pectinase activity, and may originate from any organism. Furthermore, commercially available pectinase preparations can be used in this invention. Examples of commercially available pectinase preparations include sucrase® N, sucrase® A, sucrase® S (all manufactured by Mitsubishi Chemical Corporation), Pectinex Ultra® SP-L (manufactured by Novo Nordics A / S), Meiseraze® (manufactured by Meiji Seika Co., Ltd.), Ultrazyme® (manufactured by Novo Nordics A / S), and Neurase F® (manufactured by Amano Enzyme Co., Ltd.). These pectinases can be used individually or in combination.

[0021] Cellulase is an enzyme that hydrolyzes the glycosidic bonds of β-1,4-glucan (e.g., cellulose). The cellulase used is not particularly limited as long as it possesses cellulase activity, and may originate from any organism. Furthermore, commercially available cellulase preparations can be used in this invention. Examples of commercially available cellulase preparations include Sucrase® C (manufactured by Mitsubishi Chemical Corporation), Sumizyme AC (manufactured by Shin Nippon Chemical Industries, Ltd.), Sumizyme C (manufactured by Shin Nippon Chemical Industries, Ltd.), Cellulase A "Amano" 3 (manufactured by Amano Enzyme Co., Ltd.), and Cellulase A "Amano" 4 (manufactured by Amano Enzyme Co., Ltd.). These cellulases can be used individually or in combination.

[0022] Hemicellulase is an enzyme that hydrolyzes hemicellulose. The hemicellulase used is not particularly limited as long as it possesses hemicellulase activity, and may originate from any organism. Furthermore, commercially available hemicellulase preparations can be used in this invention. Examples of commercially available hemicellulase preparations include Sucrase® X (manufactured by Mitsubishi Chemical Corporation) and Hemicellulase "Amano" 90 (manufactured by Amano Enzyme Co., Ltd.). These hemicellulases can be used individually or in combination.

[0023] β-glucosidase is an enzyme that hydrolyzes one molecule of cellobiose into two molecules of glucose. The β-glucosidase used is not particularly limited as long as it possesses β-glucosidase activity, and may originate from any organism. Furthermore, commercially available β-glucosidase preparations can be used in this invention. Examples of commercially available β-glucosidase preparations include Sumizyme BGA (manufactured by Shin Nippon Chemical Industries, Ltd.) and Aromase H2 (manufactured by Amano Enzyme Co., Ltd.). These β-glucosidases can be used individually or in combination.

[0024] In the embodiment of enzyme addition, the amount of enzyme to be added is not particularly limited as long as the effects of the present invention are obtained, but for example, 0.05% by mass or more relative to the total mass of the tea plant stems, etc., and from the viewpoint of obtaining more of the effects of the present invention, preferably 0.1% by mass or more, 0.2% by mass or more, 0.3% by mass or more, 0.4% by mass or more, more preferably 0.5% by mass or more, 0.6% by mass or more, 0.7% by mass or more, 0.8% by mass or more, 0.9% by mass or more, even more preferably 1.0% by mass or more, 1.1% by mass or more, 1.2% by mass or more, 1.3% by mass or more, 1.4% by mass or more, 1.5% by mass or more, 1.6% by mass or more, 1.7% by mass or more, 1.8% by mass or more, 1.9% by mass or more, and more preferably 2.0% by mass or more. The upper limit is not particularly limited, for example, 10% by mass or less, 3% by mass or less. These lower and upper limits can be arbitrarily combined. When enzymes are used in combination, "amount of enzyme added" refers to the total amount of enzymes added, and "mass of enzyme" refers to the mass of the enzyme in its dry state. Furthermore, the above numerical range for the amount of enzyme added is particularly suitable when the enzyme is pectinase. In addition, there are no particular restrictions on the titer of these enzymes, but enzymes with titers of 1000 u / g or more, 2000 u / g or more, and 3000 u / g or more are preferred.

[0025] Another embodiment of the amount of enzyme to be added in the embodiment of enzyme addition is an enzyme activity of 20 u (units) or more per gram of tea plant stems etc. used. From the viewpoint of obtaining more of the effects of the present invention, for example, 30 u or more, 50 u or more, 75 u or more, 100 u or more, preferably 150 u or more, 300 u or more, 450 u or more, 600 u or more, more preferably 750 u or more, 900 u or more, 1050 u or more, 1200 u or more, 1350 u or more, even more preferably 1500 u or more, 1650 u or more, 1800 u or more, 1950 u or more, 2100 u or more, 2250 u or more, 2400 u or more, 2550 u or more, 2700 u or more, 2850 u or more, and more preferably 3000 u or more. There is no particular upper limit, for example, 30000 u or less, 10000 u or less, 5000 u or less. These lower and upper limits can be combined in any way. Furthermore, the above range of enzyme addition amounts is particularly suitable when the enzyme is pectinase. When the enzyme is cellulase or β-glucosidase, suitable enzyme titers to be used per gram of tea plant stems etc. are preferably 3u or more, 6u or more, 9u or more, 12u or more, more preferably 15u or more, 18u or more, 21u or more, 24u or more, 27u or more, even more preferably 30u or more, 33u or more, 36u or more, 39u or more, 42u or more, 45u or more, 48u or more, 51u or more, 54u or more, 57u or more, and more preferably 60u or more. The upper limit is not particularly limited and can be, for example, 600u or less, 200u or less, or 100u or less. These lower and upper limits can be combined in any way. Furthermore, when the enzyme is hemicellulase, suitable enzyme titers to be used per gram of tea plant stems etc. are preferably 25u or more, 50u or more, 75u or more, 100u or more, more preferably 125u or more, 150u or more, 175u or more, 200u or more, 225u or more, even more preferably 250u or more, 275u or more, 300u or more, 325u or more, 350u or more, 375u or more, 400u or more, 425u or more, 450u or more, 475u or more, and more preferably 500u or more. There are no particular restrictions on the upper limit, for example, 5000u or less, 1666u or less, and 833u or less.These lower and upper limits can be combined in any way.

[0026] (Optional Steps) The method for producing black tea leaves of the present invention may further include optional steps in addition to the fermentation step A described above. A preferred example of such optional step is "step B, in which the stems of the tea plant are dried after step A."

[0027] <Step B> The method for producing black tea leaves of the present invention does not necessarily have to include a step B after step A, in which the stems of the tea plant are dried, but it is preferable to include a step B. Known conditions can be used for drying. Examples of temperature conditions include 60 to 150°C, preferably 80 to 140°C, and more preferably 90 to 130°C. Examples of drying time include 10 minutes to 8 hours, preferably 20 minutes to 3 hours, and more preferably 30 to 90 minutes. Conventional known drying methods can be used, for example, a permeable dryer, a strip dryer, or a net dryer that supplies hot air indirectly or directly can be used. In addition, a vacuum dryer such as a freeze dryer may be used.

[0028] (Tea leaves) In this specification, "tea leaves" refers to tea made from the stems of the tea plant, etc., through a fermentation process. The tea leaves of the present invention are not particularly limited as long as they include the stems of tea leaves etc. produced by the tea leaf production method of the present invention, and may include (i) tea leaves that include the stems of tea leaves produced by the tea leaf production method of the present invention, but do not include the leaves of tea leaves (for example, consisting only of the stems of tea leaves produced by the tea leaf production method of the present invention), or (ii) tea leaves that include the stems of tea leaves produced by the tea leaf production method of the present invention and the leaves of tea leaves produced by a production method other than the tea leaf production method of the present invention (or consisting of the two), but (iii) tea leaves that include the stems of tea leaves produced by the tea leaf production method of the present invention and the leaves of tea leaves produced by the tea leaf production method of the present invention (or consisting of the two), or (i) tea leaves that include the stems of tea leaves produced by the tea leaf production method of the present invention, but do not include the leaves of tea leaves (for example, consisting only of the stems of tea leaves produced by the tea leaf production method of the present invention). A preferred embodiment of the tea leaves of the present invention is, from the viewpoint of obtaining a tea beverage with a more enhanced fruity aroma, tea leaves containing preferably 15% by mass or more, more preferably 20% by mass or more, and even more preferably 30% by mass or more, of the stems of tea leaves produced by the tea leaf production method of the present invention.

[0029] The uses of the tea leaves of the present invention are not particularly limited; they may be used to prepare tea extracts, or they may be used in food and beverages without extraction. When a tea extract is extracted from the tea leaves of the present invention, a tea extract with an enhanced fruity aroma can be obtained. The tea leaves of the present invention may also be packaged by filling them into a container.

[0030] <Method for producing the tea extract of the present invention, and the tea extract of the present invention> The method for producing the tea extract of the present invention is not particularly limited, as long as it includes a step of extracting the tea leaves of the present invention by contacting them with a solvent. The tea extract of the present invention has an improved fruity aroma.

[0031] In the extraction process, general extraction methods can be employed. For example, conventionally known extraction methods such as hot water extraction, steam distillation, liquefied carbon dioxide extraction, and alcohol extraction can be used. Furthermore, the type of extraction solvent used is not particularly limited, but when water is used as the extraction solvent, it is preferable to use deionized or distilled water. These are inexpensive, easy to prepare, and can be safely used in the extraction equipment. Other extraction solvents include ethanol and other hydrophilic organic solvents.

[0032] The extraction temperature is not particularly limited, but is preferably between 80°C and 100°C. Extraction within this temperature range yields relatively high extraction efficiency. The extraction time is also not particularly limited, but examples include 1 to 30 minutes, 3 to 30 minutes, etc.

[0033] The obtained black tea extract (e.g., black tea extract solution) may be filtered or centrifuged to separate impurities, or concentrated by drying or other treatments. The black tea extract can take various forms, including aqueous solutions, slurries, and solids. When using the black tea extract, it may be concentrated or diluted with water as needed. Furthermore, the black tea extract of this invention may be packaged by filling it into containers.

[0034] <Method for improving the present invention> The "method for improving the fruity aroma in black tea extract" of the present invention is not particularly limited as long as it includes a step of extracting by contacting the black tea leaves of the present invention with a solvent. The step of extracting by contacting the black tea leaves of the present invention with a solvent, and preferred embodiments thereof, are as described above in "Method for producing black tea extract of the present invention".

[0035] <Food and beverages of the present invention> The food and beverages of the present invention are not particularly limited as long as they contain "the black tea extract of the present invention" or "the black tea leaves of the present invention," but it is preferable that they contain "the black tea extract of the present invention." The food and beverages of the present invention are not particularly limited and may be beverages or foods other than beverages, but it is preferable that they be beverages.

[0036] Examples of the beverages mentioned above include tea beverages and non-tea beverages. Examples of tea beverages include black tea beverages and blended tea beverages, with black tea beverages being preferred. Examples of non-tea beverages include non-alcoholic beverages such as soft drinks (e.g., fruit juices, vegetable juices, sports drinks, isotonic drinks), coffee beverages, nutritional drinks, and beauty drinks, as well as alcoholic beverages such as beer, wine, sake, plum wine, sparkling wine, whiskey, brandy, shochu, rum, gin, and liqueurs.

[0037] Other food items besides the beverages mentioned above include, for example, confectionery (e.g., baked goods such as bread, cakes, cookies, and biscuits, chewing gum, chocolate, and candy), desserts (e.g., jelly, yogurt, and ice cream), ready-to-eat foods, and seasonings (e.g., sauces, soups, dressings, mayonnaise, and cream).

[0038] The form of the food or beverage of the present invention is not particularly limited and may be solid, powder, liquid, gel, slurry, or any other form that is easy to consume. Furthermore, the food or beverage of the present invention may be a food for specified health uses, a nutritional supplement, a functional food, etc., and examples include tablets, granules, lozenges, and candies (throat lozenges).

[0039] The content ratio of the black tea extract or the black tea leaves in the food and beverage of the present invention is not particularly limited, but examples of the content ratio of the black tea extract include 0.001 to 90% by weight, 0.001 to 80% by weight, 0.01 to 70% by weight, 0.1 to 60% by weight, and 0.5 to 50% by weight relative to the total amount of the food and beverage, and examples of the content ratio of the black tea leaves include 0.001 to 90% by weight, 0.001 to 80% by weight, 0.01 to 70% by weight, 0.1 to 60% by weight, and 0.5 to 50% by weight relative to the total amount of the food and beverage.

[0040] (Optional Components) The food and beverages of the present invention may further contain other ingredients and additives commonly used in general food and beverages as optional components. The amount of each component can be adjusted as appropriate depending on the desired effect. More specifically, optional components include various additives such as antioxidants, pH adjusters, flavorings, various esters, organic acids, organic acid salts, inorganic acids, inorganic acid salts, inorganic salts, colorants, emulsifiers, preservatives, seasonings, and quality stabilizers.

[0041] (Containers) The food and beverages of the present invention can be filled into containers to become packaged food and beverages (e.g., packaged beverages, packaged foods). Examples of containers include those known in the food and beverage industry (preferably sealed containers), which can be appropriately selected and used, and can be appropriately determined according to the distribution method and consumer needs. Specific examples include sealed containers made of glass, plastic (polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), etc.), paper, aluminum, steel, etc., or composite or laminated materials thereof. Transparent (including translucent) containers are particularly preferred. Transparent containers may be entirely transparent or partially transparent.

[0042] (Enhancement of Fruity Aroma) The black tea extract or black tea leaves of the present invention are black tea extracts or black tea leaves with enhanced fruity aroma. In this specification, "fruity aroma" means a fruity aroma (i.e., "fruit-like aroma"), and Muscat-like aroma and / or peach-like aroma are preferred.

[0043] In the present invention, the black tea extract with an improved "fruity aroma" refers to a black tea extract obtained by extracting from black tea leaves produced by fermenting only the leaves of Camellia sinensis var. sinensis (hereinafter also referred to as "control black tea extract 1") and having an improved fruity aroma; or a black tea extract obtained by extracting from black tea leaves produced by fermenting the stems of Camellia sinensis var. sinensis etc. without adding a predetermined amount of an enzyme (preferably, one or more enzymes selected from the group consisting of pectinase, cellulase, hemicellulase, and β-glucosidase, more preferably pectinase) (hereinafter also referred to as "control black tea extract 2") and having an improved fruity aroma. Further, in the present invention, the black tea leaves with an improved "fruity aroma" refer to black tea leaves having an improved fruity aroma as compared with (x) black tea leaves produced by fermenting only the leaves of Camellia sinensis var. sinensis (hereinafter also referred to as "control black tea leaves 1"); or (y) black tea leaves having an improved fruity aroma as compared with black tea leaves produced by fermenting the stems of Camellia sinensis var. sinensis etc. without adding a predetermined amount of an enzyme (preferably, one or more enzymes selected from the group consisting of pectinase, cellulase, hemicellulase, and β-glucosidase, more preferably pectinase) (hereinafter also referred to as "control black tea leaves 2").

[0044] Regarding the degree of the fruity aroma in a certain black tea extract or black tea leaves and how such a fruity aroma is compared with the control black tea extract or black tea leaves in the present invention (for example, whether the fruity aroma is improved, and to what extent it is improved), if it is a trained panel, it can be easily and clearly determined.

[0045] The present invention will be specifically described based on the following examples, but the present invention is not limited to these examples.

[0046] Test 1. [Effect of the tea leaf usage part on the fruity aroma of black tea beverages] In order to examine how the difference in the tea leaf usage part affects the fruity aroma of the obtained black tea beverages, the following test was conducted.

[0047] (1. Preparation of Sample Black Tea Beverages) 1 kg of fresh tea leaves of each variety that had been withered overnight was sorted into leaves and stems respectively. The leaves were kneaded for 1 hour and the stems were kneaded for 10 minutes. After each was fermented at 30°C for 1 hour, they were dried at 120°C for 40 minutes to obtain black tea leaves. 150 g of boiling water was added to 3 g of each of the obtained black tea leaves, extracted for 3 minutes, and then filtered to obtain each extract. These were used as the sample black tea beverages for Test Examples 1 to 10 (Table 1).

[0048] (2. Sensory Evaluation Test) Five trained professional panelists conducted a sensory evaluation test on the fruity aroma of each sample black tea beverage. Specifically, as the "fruity aroma", the muscat-like aroma and / or the peach-like aroma were evaluated. The fruity aroma was evaluated in 9 grades from 1.0 point to 5.0 point in 0.5-point increments based on the following [Evaluation Criteria]. The value obtained by rounding off the second decimal place of the average value of the evaluation scores of the five professional panelists was adopted as the sensory evaluation test result of that sample black tea beverage. The difference in each 0.5-point level from 1.0 point to 5.0 point was regarded as the same degree. Incidentally, in all the sample black tea beverages of Test Examples 1 to 10, the standard deviation of the evaluation scores of the fruity aroma was 0.5 or less.

[0049] [Evaluation Criteria] 5 points: The fruity aroma is strongly felt. 4 points: The fruity aroma is felt. 3 points: The fruity aroma is slightly felt. 2 points: The fruity aroma is faintly felt. 1 point: The fruity aroma is not particularly felt.

[0050] The sensory evaluation test results for the sample black tea beverages of Test Examples 1 to 10 are shown in Table 1.

[0051]

[0052] When using leaves from any of the tea varieties, the resulting sample tea beverages had little to no noticeable fruity aroma. However, when using stems from any of the varieties, the resulting sample tea beverages had a stronger fruity aroma compared to when using leaves. In particular, when using the stems of "Yabukita" and "Benifuki," the fruity aroma was more pronounced. In other words, the results in Table 1 indicate that using fermented tea stems can produce tea beverages with an enhanced fruity aroma. Furthermore, a similar trend of improved fruity aroma was observed not only in the sample tea beverages but also in the tea leaves themselves.

[0053] Experiment 2. [Effect of enzyme addition on the fruity aroma of black tea beverages] The following experiment was conducted to investigate how adding enzymes during the fermentation of tea leaf stems affects the fruity aroma of the resulting black tea beverage.

[0054] (1. Preparation of Sample Black Tea Beverages) 1 kg of "Yabukita" raw tea leaves, which had been withered overnight, were separated into leaves and stems. 100 g of the obtained stems were kneaded for 10 minutes, and 2% by mass of each enzyme was added to the stems, or left unadded, and mixed thoroughly to homogenize. Each was fermented at 30°C for 1 hour, then dried at 120°C for 40 minutes to obtain black tea leaves. 3 g of each obtained black tea leaf was mixed with 150 g of boiling water, extracted for 3 minutes, and then filtered to obtain each extract. These were used as sample black tea beverages for Test Examples 11-15 (Table 2). The enzymes used were cellulase (cellulase titer: 3000 u / g or higher), hemicellulase (hemicellulase titer: 25000 u / g or higher), pectinase (pectinase titer: 150000 u / g or higher), and β-glucosidase (β-glucosidase titer: 2000 u / g or higher).

[0055] (2. Sensory Evaluation Test) Using the sample black tea beverage from Test Example 11 as a control, five trained professional panelists conducted a sensory evaluation test on the fruity aroma of each sample black tea beverage. The fruity aroma was evaluated on a 9-point scale from 1.0 to 5.0 in 0.5-point increments, based on the following [Evaluation Criteria]. The average of the evaluation scores of the five professional panelists, rounded to the second decimal place, was adopted as the sensory evaluation test result for that sample black tea beverage. Note that the difference in degree between each 0.5 point from 1.0 to 5.0 was considered to be of a similar degree. Incidentally, the standard deviation of the evaluation scores for fruity aroma was 0.5 or less for all sample black tea beverages from Test Examples 11 to 15.

[0056] [Evaluation Criteria] 5 points: The fruity aroma is perceived to be very strong compared to the control (Test Example 11). 4 points: The fruity aroma is perceived to be very strong compared to the control (Test Example 11). 3 points: The fruity aroma is perceived to be about the same as the control (Test Example 11). 2 points: The fruity aroma is perceived to be weak compared to the control (Test Example 11). 1 point: The fruity aroma is perceived to be very weak compared to the control (Test Example 11).

[0057] Table 2 shows the results of the sensory evaluation tests for the sample black tea beverages in Test Examples 11-15.

[0058]

[0059] Regardless of whether cellulase, hemicellulase, pectinase, or β-glucosidase was added, the resulting black tea beverages exhibited a stronger fruity aroma compared to those without enzymes. In particular, the use of pectinase and β-glucosidase resulted in a very strong fruity aroma in the resulting black tea beverages. Thus, the results in Table 2 indicate that adding enzymes during the fermentation of tea leaf stems can produce black tea beverages with enhanced fruity aroma, and that pectinase and β-glucosidase are preferred enzymes for this purpose.

[0060] Test 3. [Effects of rolling time, enzyme addition rate, and / or fermentation temperature on the fruity aroma of black tea beverages] The following tests were conducted to investigate how differences in the rolling time of tea leaf stems, the enzyme addition rate, and / or fermentation temperature affect the fruity aroma of the resulting black tea beverages.

[0061] (1. Preparation of Sample Black Tea Beverages) 1 kg of "Benifuki" raw tea leaves, withered overnight, were separated into leaves and stems. 100 g of the obtained stems were kneaded for a predetermined time (10 minutes, 30 minutes, or 60 minutes), or not kneaded. Using the mass of these stems as 100% by mass, pectinase (pectinase titer: 150,000 u / g or higher) was added to the stems at a predetermined addition rate (0.1 to 2.0% by mass), or not added, and then thoroughly mixed to homogenize. Each was fermented at a predetermined temperature (15 to 60°C) for 1 hour, and then dried at 120°C for 40 minutes to obtain black tea leaves. 3 g of each obtained black tea leaf was mixed with 150 g of boiling water, extracted for 3 minutes, and then filtered to obtain each extract. These were used as sample black tea beverages for Test Examples 16 to 26 (Table 3).

[0062] (2. Sensory Evaluation Test) Using the sample tea beverage from Test Example 16 as a control, five trained professional panelists conducted a sensory evaluation test on the fruity aroma of each sample tea beverage. The fruity aroma was evaluated on a 9-point scale from 1.0 to 5.0 in 0.5-point increments, based on the following [Evaluation Criteria]. The average of the evaluation scores of the five professional panelists, rounded to the second decimal place, was adopted as the sensory evaluation test result for that sample tea beverage. Note that the difference in degree between each 0.5 point from 1.0 to 5.0 was considered to be of similar magnitude. Incidentally, the standard deviation of the evaluation scores for fruity aroma was 0.5 or less for all sample tea beverages from Test Examples 16 to 26.

[0063] [Evaluation Criteria] 5 points: The fruity aroma is perceived to be very strong compared to the control (Test Example 16). 4 points: The fruity aroma is perceived to be very strong compared to the control (Test Example 16). 3 points: The fruity aroma is perceived to be about the same as the control (Test Example 16). 2 points: The fruity aroma is perceived to be weak compared to the control (Test Example 16). 1 point: The fruity aroma is perceived to be very weak compared to the control (Test Example 16).

[0064] Table 3 shows the results of the sensory evaluation tests for the sample black tea beverages from Test Examples 16 to 26.

[0065]

[0066] In the sample black tea beverage of Test Example 20, where the tea leaf stems were kneaded for 10 minutes, the enzyme addition rate was 2.0%, and the fermentation temperature was 30°C, the fruity aroma was most strongly perceived. Furthermore, from the comparison of the results of each test example in Table 3, it was shown that in order to obtain a black tea beverage with an improved fruity aroma, the tea leaf stem kneading time should be 10 minutes or 30 minutes rather than 0 minutes or 60 minutes, the enzyme addition rate should be preferably 0.1 to 2.0%, more preferably 0.5 to 2.0%, and the fermentation temperature should be preferably 15 to 45°C, more preferably 15 to 30°C. It was also shown that a higher enzyme addition rate during the fermentation of the black tea leaves is preferable in order to obtain a black tea beverage with an improved fruity aroma.

[0067] Test 4. [Effects of production scale, fermentation time, drying temperature, and / or drying time on the fruity aroma of black tea beverages] The following tests were conducted to investigate how differences in production scale, fermentation time, drying temperature, and / or drying time affect the fruity aroma of the resulting black tea beverages.

[0068] (1. Preparation of Sample Black Tea Beverage) 25 kg of "Benifuki" raw tea leaves, which had been withered overnight, were separated into leaves and stems. 22.5 kg of the obtained leaves were kneaded for 1 hour, and 2.5 kg of stems were kneaded for 10 minutes. The mass of these stems was taken as 100% by mass, and either the mass of "pectinase (pectinase titer: 150,000 u / g or higher)" or "pectinase (pectinase titer: 150,000 u / g or higher) and β-glucosidase (β-glucosidase titer: 2,000 u / g or higher)" listed in Table 4 was added to the stems, or not added, and the mixture was thoroughly mixed to homogenize it. After fermenting each at 30°C for 2 hours, the mixture was dried at 100°C for 60 minutes to obtain black tea leaves. 3 g of each obtained black tea leaf was mixed with 150 g of boiling water, extracted for 3 minutes, and then filtered to obtain each extract. These were used as sample tea beverages for test examples 27-30 (Table 4).

[0069] (2. Sensory Evaluation Test) Five trained professional panelists conducted a sensory evaluation test on the fruity aroma of each sample black tea beverage. The fruity aroma was evaluated on a 9-point scale from 1.0 to 5.0 in 0.5-point increments, based on the following [Evaluation Criteria]. The average of the evaluation scores of the five professional panelists, rounded to two decimal places, was adopted as the sensory evaluation test result for that sample black tea beverage. Note that the difference in degree between each 0.5 point from 1.0 to 5.0 was considered to be of a similar magnitude. Incidentally, the standard deviation of the evaluation scores for fruity aroma was 0.5 or less for all sample black tea beverages in Test Examples 27 to 30.

[0070] [Evaluation Criteria] 5 points: The fruity aroma is perceived to be very strong compared to the control (Test Example 28). 4 points: The fruity aroma is perceived to be very strong compared to the control (Test Example 28). 3 points: The fruity aroma is perceived to be about the same as the control (Test Example 28). 2 points: The fruity aroma is perceived to be weak compared to the control (Test Example 28). 1 point: The fruity aroma is perceived to be very weak compared to the control (Test Example 28).

[0071] Table 4 shows the results of the sensory evaluation tests for the sample black tea beverages from Test Examples 27 to 30.

[0072]

[0073] The results in Table 4 show that even when tea leaves are obtained using different manufacturing scales, fermentation times, drying temperatures, and / or drying times than in Tests 1 and 2, the same trends as in Tests 1 and 2 are observed. In other words, in any case, using fermented tea leaf stems can produce a tea beverage with an enhanced fruity aroma, and adding pectinase during the fermentation of tea leaf stems can produce a tea beverage with an even more enhanced fruity aroma. Furthermore, using pectinase and β-glucosidase in combination can produce a tea beverage with an even more enhanced fruity aroma.

[0074] Test 5. [Effect of stem content in tea leaves on the fruity aroma of tea beverages] The following test was conducted to investigate how differences in stem content in tea leaves affect the fruity aroma of the resulting tea beverages.

[0075] (1. Preparation of Sample Black Tea Beverages) 20 g of tea leaves containing the black tea leaves obtained in Test Examples 27 and 29 of Test 4 (referred to as "Black Tea Leaf A (Leaves)" and "Black Tea Leaf B (Stems)," respectively) at the specified concentrations were added to 600 g of 85°C hot water, and the mixture was extracted for 5 minutes while stirring occasionally. The black tea leaves were separated into solid and liquid components using a strainer, and after cooling to 10°C, centrifugal separation was performed at 3000 rpm for 10 minutes. The mixture was then passed through the strainer again, and water was added to make a clear extract of 600 g. 0.4 g of ascorbic acid was added to 300 g of this extract, and the pH was adjusted to approximately 6.7 using sodium bicarbonate. The mixture was then diluted to 1000 g with water to prepare the blended solution. This blended solution was sterilized by the UHT method (equivalent to or better than 120°C for 4 minutes), and then filled into PET bottles to prepare the packaged black tea beverages. These were used as the sample black tea beverages for Test Examples 31 to 38 (Table 5). These samples were left at room temperature for one week before being subjected to sensory evaluation.

[0076] (2. Sensory Evaluation Test) Five trained professional panelists conducted a sensory evaluation test on the fruity aroma of each sample black tea beverage. The fruity aroma was evaluated on a 9-point scale from 1.0 to 5.0 in 0.5-point increments, based on the following [Evaluation Criteria]. The average of the evaluation scores of the five professional panelists, rounded to two decimal places, was adopted as the sensory evaluation test result for that sample black tea beverage. The difference between a score of 5 and a score of 4, and the difference between each 0.5-point increment from 1.0 to 5.0, were considered to be of similar magnitude. Incidentally, the standard deviation of the fruity aroma evaluation scores for all sample black tea beverages in Test Examples 31 to 38 was 0.5 or less.

[0077] [Evaluation Criteria] 5 points: A strong fruity aroma is detected. 4 points: A fruity aroma is detected. 3 points: A slight fruity aroma is detected. 2 points: A fruity aroma is detected very slightly. 1 point: No fruity aroma is detected at all.

[0078] Table 5 shows the results of the sensory evaluation tests for the sample black tea beverages from Test Examples 31 to 38.

[0079]

[0080] When tea leaves containing 15% or more by mass of tea leaf B (stem) were used, a fruity aroma was detected in the resulting sample tea beverage, and the fruity aroma became stronger as the percentage of stems increased. In other words, the results in Table 5 show that using tea leaves containing 15% or more by mass of stems yields a tea beverage with an improved fruity aroma, using tea leaves containing 20% ​​or more by mass of stems yields a tea beverage with an even more improved fruity aroma, using tea leaves containing 30% or more by mass of stems yields a tea beverage with an even more improved fruity aroma, using tea leaves containing 40% or more by mass of stems yields a tea beverage with an even more improved fruity aroma, and using tea leaves containing 70% or more by mass of stems yields a tea beverage with a particularly improved fruity aroma.

[0081] According to the present invention, it is possible to provide a method for producing tea leaves that can be used to prepare tea extracts with enhanced fruity aroma, as well as tea extracts extracted from said tea leaves, and food and beverages containing said tea extracts, etc.

Claims

1. A method for producing black tea leaves, comprising step A of fermenting the stems of the tea plant.

2. The method for producing black tea leaves according to claim 1, wherein an enzyme is added when fermenting the stems of the tea plant.

3. The method for producing black tea leaves according to claim 2, wherein the enzyme is one or more selected from the group consisting of pectinase, cellulase, hemicellulase, and β-glucosidase.

4. The method for producing tea leaves according to claim 1, wherein the stems of the tea plant are stems derived from fresh leaves cultivated in Japan.

5. The method for producing black tea leaves according to claim 4, wherein the variety of fresh leaves is one or more selected from the group consisting of Yabukita, Benifuki, Yutakamidori, and Kanayamidori.

6. The method for producing tea leaves according to claim 1, wherein step A is a step of fermenting the stems and leaves of the tea plant together or separately, and before fermentation, the step of kneading the stems and leaves of the tea plant separately.

7. Tea leaves produced by the manufacturing method described in any one of claims 1 to 6.

8. The tea leaves according to claim 7, which contain 15% by mass or more of stems relative to the total amount of tea leaves.

9. A method for producing a black tea extract, comprising the step of extracting the black tea leaves described in claim 7 by contacting them with a solvent.

10. Black tea extract produced by the manufacturing method described in claim 9.

11. A food or beverage comprising the black tea extract described in claim 10.

12. A food or beverage comprising the tea leaves described in claim 7.

13. A method for improving the fruity aroma in a black tea extract, comprising the step of extracting the black tea leaves described in claim 7 by contacting them with a solvent.

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