Black Leaf Tea Products

Abstract

The present invention relates to a black leaf tea product. More specifically, it is a black leaf tea product having altered aroma characteristics. The present invention provides a black leaf tea product containing methylbutanal compounds in the range of 4.5 to 10 mg / kg of tea leaves.

Description

[Technical Field]

[0001] The present invention relates to black leaf tea products, and more particularly to black leaf tea products with altered aroma characteristics. [Background technology]

[0002] Tea is one of the most popular beverages consumed worldwide. There are various types of tea available, such as black tea, green tea, and oolong tea. Of these, black tea is more popular. Black tea is generally prepared by a process that includes withering, maceration, fermentation, and roasting / drying. On the other hand, the green tea production process does not include fermentation. Therefore, the characteristic profile of green tea is different from that of black tea.

[0003] The sensory characteristics of tea are considered to be the most important factor in selecting a particular type of tea. Aroma is one such sensory characteristic that determines the quality and type of tea product. The sensory characteristics, including the aroma profile, of black tea are significantly different from those of green tea due to differences in the manufacturing process. Black tea is associated with a stronger aroma, such as floral notes and woody notes. On the other hand, green tea does not possess all of these black tea aromas.

[0004] Black and green teas with altered aroma profiles have been disclosed in the art.

[0005] US2007071870 (Unilever, 2007) discloses a process for producing black or green tea that imparts the floral aroma of oolong tea. The process utilizes tumbling to physically damage the leaves to induce the oolong aroma and does not involve the traditional sun-withering step.

[0006] CN107549344A (GUANGXI ZHAOPING TIANCHENG ECOLOGICAL AGRICULTURAL CO LTD, 2018) discloses a fragrant chestnut-flavored green tea and its preparation method, which belongs to the technical field of tea processing. The fragrant chestnut-flavored green tea is processed through processes such as withering, fixing, rolling, tea-roasting, intermediate rolling, sorting, and roasting. Tea leaves picked after mid-August are used as raw materials, maximizing the use of tea leaf resources and improving the utilization rate of autumn tea; the preparation method for the fragrant green tea is simple, with short processing times, simple operation, and easy to realize industrial production.

[0007] Floral and green aromas are very commonly found in tea products. However, tea products with aromas that provide malty / buttery notes have not been disclosed in the art. Furthermore, we have found that malty / buttery notes provide rich sensory characteristics to black tea products that are preferred by consumers. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] US2007071870 [Patent Document 2] CN107549344A Summary of the Invention [Problem to be solved by the invention]

[0009] Therefore, there is a need to provide a black tea product with an aroma that provides malty / buttery notes.

[0010] While addressing the above problem, the inventors surprisingly discovered that a particular group of compounds is responsible for imparting malty / buttery notes to tea products. Moreover, the inventors discovered that such malty / buttery notes are only perceptible when such compounds are available above certain levels in black tea products. [Means for solving the problem]

[0011] Therefore, in a first aspect of the present invention, there is provided a black leaf tea product containing a methylbutanal compound in the range of 4.5 to 10 mg / kg of tea leaves.

[0012] In a second aspect, the present invention provides a tea blend comprising 5 to 99% of the tea product of the first aspect.

[0013] These and other aspects, features, and advantages will become apparent to those skilled in the art upon reading the following detailed description. For the avoidance of doubt, any feature of one aspect of the present invention may be utilized in any other aspect of the present invention. The word "comprising" is intended to mean "including," but not necessarily "consisting of" or "consisting of." In other words, the listed steps or options need not be exhaustive. It should be noted that the examples set forth in the following description are intended to clarify the invention, but are not intended to limit the invention to those examples themselves. Similarly, all percentages are weight / weight percentages unless otherwise indicated. Except in the working and comparative examples, or unless otherwise clearly indicated, all numbers in this description indicating amounts of materials or reaction conditions, physical properties of materials, and / or use are to be understood as modified by the word "about." Numerical ranges expressed in the format "x to y" are to be understood to include x and y. When multiple preferred ranges for a particular feature are listed in the format "x to y," it is to be understood that all ranges combining the different endpoints are also contemplated. DETAILED DESCRIPTION OF THE INVENTION

[0014] For purposes of the present invention, "tea" preferably refers to material derived from Camellia sinensis var. sinensis and / or Camellia sinensis var. assamica. Material derived from Assam is particularly preferred due to the higher levels of active ingredients in tea than in the Chinese species.

[0015] For the purposes of the present invention, "leaf tea" means a tea product (i.e., "processed tea") that contains tea leaves and / or stems, preferably in uninfused form, and that has been dried to a moisture content of less than 30% by weight, typically in the range of 1-10% by weight.

[0016] "Fresh tea leaves" refers to tea leaves, buds and / or stems that have not been dried to a moisture content of less than 30% by mass and that typically have a moisture content in the range of 60 to 90%.

[0017] "Fermentation" refers to the oxidative and hydrolytic process that tea undergoes when certain endogenous enzymes and substrates are brought together, for example, by mechanically disrupting the cells by maceration of the leaves. During this process, the colorless catechins in the leaves are converted into a complex mixture of yellow and orange to dark brown polyphenolic substances.

[0018] "Black tea" refers to tea that has been substantially fermented. Black tea has different properties than green tea. Black tea is more astringent in taste and less bitter than green tea. The red color of black tea liquor is also significantly higher than that of green tea. Black tea also contains higher levels of theaflavins.

[0019] The present invention provides a black leaf tea product containing methylbutanal compounds in the range of 4.5 to 10 mg / kg of tea leaves, preferably 4.75 to 10 mg / kg of tea leaves, more preferably 5.0 to 8 mg / kg of tea leaves, and most preferably 5 to 7 mg / kg of tea leaves.

[0020] Preferred methylbutanal compounds include 2-methylbutanal and 3-methylbutanal. In the most preferred embodiment of the present invention, the methylbutanal compounds are 2-methylbutanal and 3-methylbutanal. The structures of 2-methylbutanal and 3-methylbutanal are represented below:

[0021] [ka]

[0022] The tea product of the present invention preferably further comprises 2-methylpropanal, which has the following structure:

[0023] [ka]

[0024] 2-Methylpropanal is present preferably in the range of 2 to 7 mg / kg of tea leaves, more preferably in the range of 2 to 6 mg / kg of tea leaves, and most preferably in the range of 2 to 5 mg / kg of tea leaves.

[0025] The tea products of the present invention also preferably contain phenylacetaldehyde, which has the following structure:

[0026] [ka]

[0027] The total amount of 2-methylbutanal, 3-methylbutanal and 2-methylpropanal is preferably in the range of 6.5 to 17 mg / kg of tea leaves, more preferably in the range of 6.5 to 12 mg / kg of tea leaves, and most preferably in the range of 7 to 12 mg / kg of tea leaves.

[0028] The tea product of the present invention is preferably a black tea product. The tea product is preferably obtained from the plant Camellia sinensis.

[0029] The tea products of the present invention can be prepared by adding the methylbutanal compound to the final leaf tea product in the desired ratio as disclosed above. The most preferred leaf tea product is a black leaf tea product.

[0030] Alternatively, the tea product of the present invention can be obtained by producing a black tea product comprising tea leaves having a conductivity of preferably greater than 100 μS, where the conductivity is measured by placing the leaves in water for about 10 minutes to 2 hours and measuring the conductivity of the resulting water. More preferably, the conductivity is greater than 150 μS, and most preferably greater than 200 μS. The tea leaves are preferably placed in water for about 15 minutes to 1 hour, and most preferably 30 minutes to 45 minutes.

[0031] Tea leaves that provide a conductivity higher than 100 μS as disclosed above are preferably obtained by keeping fresh tea leaves in a carbon dioxide rich environment with humidity above 90%, preferably above 95%, most preferably above 98%.

[0032] The tea leaves are then preferably subjected to a maceration process to produce dhool. This comminution process is preferably carried out by crushing, tearing and curling (known in the art of tea processing as CTC). One or more CTC steps may be carried out, in which the incubated leaves are broken down to release the enzymes present in the leaves.

[0033] Alternatively, the maceration process can be carried out by rolling the tea leaves in conventional rollers or by pulverising them in a mill, or a combination thereof. During these processes, precursors present in the tea leaves become accessible to enzymes.

[0034] The macerated leaves are then preferably fermented. This is a process in which the macerated tea leaves undergo biochemical changes in the presence of endogenous enzymes present in the tea leaves. This process results in the formation of the typical organoleptic characteristics of black leaf tea products. Fermentation is preferably carried out by holding the leaves at a temperature of 10°C to 60°C for 15 minutes to 5 hours. The fermentation temperature is preferably 25°C to 45°C, more preferably 25°C to 40°C. The fermentation time is preferably 30 minutes to 4 hours, more preferably 1 to 4 hours, and most preferably 1 to 3 hours.

[0035] After fermentation, the fermented dhool may preferably be dried. During the drying step, the dhool is dried to a moisture content preferably less than 10% by weight of the tea leaves, more preferably less than 5% by weight of the tea leaves, to obtain a black leaf tea product.

[0036] The drying step is preferably carried out by heat drying, freeze drying or vacuum drying.

[0037] Thermal drying is preferably carried out by contacting the leaves with air; the temperature of the air is preferably 80-160°C, more preferably 90-150°C, and most preferably 100-130°C. Thermal drying can be carried out in any conventional dryer. However, fluidized bed dryers or tray dryers are particularly preferred for thermal drying. The leaves may also be dried by vacuum drying. During vacuum drying, the tea leaves are preferably dried at a concentration of 66.7-6.67 x 10 4 Pa, more preferably 6.67 × 10 3 ~3.9×10 4 Pa, most preferably 1.3 x 10 4 ~2.67×10 4 The mixture is exposed to an absolute pressure of 100 Pa. Vacuum drying is preferably carried out at a temperature in the range of 20 to 70° C., more preferably 25 to 60° C., and most preferably 30 to 55° C. Vacuum drying may be carried out in any suitable vacuum dryer, preferably a rotary vacuum dryer.

[0038] The present invention also provides a tea blend comprising 5 to 99%, preferably 5 to 50% by mass of the tea product of the present invention.

[0039] The present invention is further demonstrated by the following examples, which are for illustrative purposes only and are not intended to limit the scope of the present invention in any way. [Example]

[0040] Preparation of different tea products: All experiments were conducted in Kenya using fresh tea leaves obtained from Kenyan tea plantations.

[0041] Example A Fresh tea leaves were harvested from tea plantations in Kenya. The moisture content of the tea product was approximately 78%. The tea leaves were withered at a temperature of 25°C for 72 hours. The tea leaves were then subjected to CTC (cut, tear, roll) four times to obtain macerated dhool. The macerated dhool was then fermented (exposed to air at 25°C) for 90 minutes, and then dried (at 140°C) to a moisture content of less than 5% by weight to obtain the black leaf tea product.

[0042] Example 1 Fresh tea leaves were harvested from tea plantations in Kenya. The moisture content of the tea product was approximately 78%. The tea leaves were placed in a carbon dioxide-rich environment (approximately 20% by volume) with 98% humidity at a temperature of 25°C for 24 hours until the conductivity reached 250 μS. The tea leaves were then subjected to CTC four times to obtain macerated dhool. The macerated dhool was then fermented (exposed to air at 25°C) for 90 minutes and then dried (at 140°C) to a moisture content of less than 5% by mass to obtain the black leaf tea product.

[0043] Example 2 Fresh tea leaves were harvested from tea plantations in Kenya. The moisture content of the tea product was approximately 78%. The tea leaves were placed in a carbon dioxide-rich environment (approximately 20% by volume) with 98% humidity at a temperature of 25°C for 72 hours until the conductivity reached 250 μS. The tea leaves were then subjected to CTC (cut, tear, roll) four times to obtain macerated dhool. The macerated dhool was then fermented (exposed to air at 25°C) for 90 minutes, and then dried (at 140°C) to a moisture content of less than 5% by mass to obtain the black leaf tea product.

[0044] The above tea products were analyzed for 2-methylbutanal (2MB), 3-methylbutanal (3MB) and 2-methylpropanal (2MP) using the following protocol:

[0045] First, 2 g of tea was brewed in 200 mL of boiling water for 2 minutes and strained to produce black tea infusion.

[0046] The aroma profile of the tea infusion was characterized using gas chromatography (GC) as follows: 4 mL of the infusion was placed in a capped GC vial. The sample was pre-incubated (10 min) and then held at 70°C for 20 min before measuring the aroma in the headspace using an SPME (solid phase microextraction) fiber. The conditions for aroma extraction by gas chromatography and SPME are as follows:

[0047] GC-MS conditions: Volatile compounds from tea samples were analyzed using a gas chromatograph equipped with an MS detector (Agilent 7890B). A CP-Wax 52 CB (30 m x 0.25 mm, 0.15 μm film thickness) column was used for the analysis. The injector was operated in a splitless configuration with a constant flow rate of 1.0 mL / min using helium as the carrier gas. The injector was maintained at 230 °C. The oven ramp was as follows: initial temperature 45 °C held for 3 min, followed by a ramp to 180 °C at 5 °C / min and held for 0 min, and finally a ramp to 230 °C at 10 °C / min and held for 10 min.

[0048] SPME conditions: Analysis of volatile compounds released from tea samples was performed using SPME. More specifically, a 2 cm stable flexible fiber coated with 50 / 30 μm poly(divinylbenzene) (DVB) / carboxene (CAR) / poly(dimethylsiloxane) (PDMS) (Supelco, Bellefonte, PA) was used in an automated SPME system (Combi PAL system).

[0049] Equipment specifications and experimental conditions: SPME fiber: Gray fiber (PDMS / DVB / CAR) Pre-incubation time: 10:00 min Incubation temperature: 70℃ Needle Penetration: 12mm Fiber Penetration: 20mm Extraction time: 20:00 minutes Detachable: GC injector port 1 Infusion time: 5:00 minutes Fiber conditioning time: 15 minutes GC execution time: 40 minutes Cooling time: 10 minutes Fiber temperature control: 230℃ MS conditions: Tuning type: EI Synchronous EMV:1073 MS source: 230℃ Scan range: 50 to 500 (mass) Gain factor:1

[0050] Peak areas were calculated for individual volatile compounds from the GC chromatograms. Standard concentration curves were constructed for each volatile. These standard curves were used to convert peak areas to concentrations of each volatile.

[0051] The results are summarized below:

[0052] [Table 1]

[0053] Tasting of the tea products of this invention The tea products were also tasted by a panel of trained tea tasters. First, discrimination tests were performed separately between Example A and Example 1, and then between Example A and Example 2 to test whether the tasters could pick out any differences between the sample sets. In both cases, the tasters were able to pick out the products of Examples 1 and 2 as different from Example A.

[0054] In the next study, a descriptive analysis was carried out to obtain a description of the product in terms of sensory properties. - For Sample A, the main descriptors were woody, fresh green and black tea aromas. - In both samples 1 and 2, the main descriptors were caramel and malt-like with fairly low intensity of fresh green and black tea aromas.

[0055] From the above examples it is clear that the tea products within the scope of the present invention (Examples 1 and 2) have enhanced malty aromatic notes compared to the control tea product (Example A).

Claims

1. A black leaf tea product containing methylbutanal compounds in the range of 4.5 to 10 mg / kg of tea leaves, the methylbutanal compounds include 2-methylbutanal and 3-methylbutanal; The black leaf tea product further contains 2-methylpropanal, 2-methylpropanal ranges from 2 to 7 mg / kg tea leaves, The total amount of 2-methylbutanal, 3-methylbutanal and 2-methylpropanal is in the range of 6.5 to 17 mg / kg of tea leaves. tea products.

2. 2. The tea product of claim 1, wherein the methylbutanal compounds are 2-methylbutanal and 3-methylbutanal.

3. 3. The tea product of claim 1 or 2, further comprising phenylacetaldehyde.

4. 4. The tea product of any one of claims 1 to 3, wherein the black leaf tea product is obtained from the plant Camellia sinensis.

5. 5. A tea blend comprising 5 to 99% of the tea product of any one of claims 1 to 4.

6. 6. A tea blend according to claim 5, comprising 5 to 50% of the tea product according to any one of claims 1 to 4.

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