Drying method for raw material tea of Tuo tea

Abstract

The invention relates to the technical field of Tuo tea preparation, in particular to a drying method of Tuo tea raw material tea. The drying method of the raw material tea of the Tuo tea comprises the following steps: sequentially performing spreading, fixation, alcoholization, rolling and drying treatment on fresh leaves of summer and autumn tea to obtain the raw material tea of the Tuo tea, the drying treatment comprises the steps of firstly drying at 60 DEG C to be 50-70% dry, and then drying in the sun. The method disclosed by the invention is beneficial to improving the comprehensive quality of the summer and autumn Tuo tea raw material tea, and the summer and autumn Tuo tea raw material tea is green and moist in appearance color, greener in soup color, fragrant in fragrance, mellow in taste, fresh, high in delicate flavor strength and reduced in bitterness, and can improve the utilization rate of the Chongqing local summer and autumn tea fresh leaf raw material. The Tuo tea prepared by the method disclosed by the invention is high in tea polyphenol content, amino acid content, water extract content and chlorophyll content and low in ester catechin content.

Description

Technical Field

[0001] The invention relates to the technical field of Tuo tea preparation, in particular to a method for drying raw material tea of ​​Tuo tea. Background Art

[0002] Tuocha is mainly produced in Chongqing and Yunnan. Traditional Chongqing Tuocha uses spring Yunnan large-leaf green tea as the main raw material, with a small amount of roasted green tea and fried green tea, and then goes through refined blending, weighing, steaming, pressing, drying and other processes. The utilization rate of summer and autumn tea fresh leaves is low, and there is a high dependence on foreign raw materials. The raw tea processing technology lacks standards, resulting in poor product stability, lack of distinctive features, and declining market competitiveness. Drying is an important part of raw tea processing. At present, the common methods of drying raw tea used in Tuocha production include drying, sun drying, frying, and a combination of sun drying and baking. Among them, drying and sun drying are more commonly used, and a combination of sun drying and baking is also gradually being used, but it mostly remains at the empirical level. The raw tea for Tuo tea tastes bitter in summer and autumn, which seriously affects its quality. The appropriate drying process has not yet been formed. In addition, Chongqing is hot and humid in summer and autumn. How to combine sun-drying and oven-drying to improve the drying process of raw tea, facilitate production control, improve production efficiency, and effectively reduce its bitterness is crucial to improving the quality of Tuo tea in summer and autumn and improving its economic benefits. Summary of the invention

[0003] In order to better utilize the local summer and autumn tea fresh leaf raw materials in Chongqing and reduce the bitterness of summer and autumn Tuo tea, the present invention provides a method for drying Tuo tea raw material tea with reduced bitterness.

[0004] To achieve the above object, the present invention provides the following solutions:

[0005] The present invention provides a method for drying raw material tea of ​​Tuocha, comprising the following steps:

[0006] The fresh summer and autumn tea leaves are sequentially spread, withered, aged, rolled and dried to obtain Tuo tea raw material tea;

[0007] The drying process is to first bake at 60° C. until 50% to 70% dry, and then dry in the sun.

[0008] The present invention discloses the following technical effects:

[0009] The method of the invention is beneficial to improving the comprehensive quality of summer and autumn Tuo tea raw material tea, with green and moist appearance, greener soup color, fresh aroma, mellow and fresh taste, high umami intensity and reduced bitterness, and can improve the utilization rate of Chongqing local summer and autumn tea fresh leaf raw materials.

[0010] The Tuo tea prepared by the method of the invention has high contents of tea polyphenols, amino acids, water extracts and chlorophyll, and low content of ester-type catechins. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0012] Figure 1 The taste attributes of tea samples with different drying methods in Example 1 of the present invention. DETAILED DESCRIPTION

[0013] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0014] It should be understood that the terms described in the present invention are only for describing a particular embodiment and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0015] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0016] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to the skilled artisan. The present invention description and examples are exemplary only.

[0017] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0018] The present invention provides a method for drying raw material tea of ​​Tuocha, comprising the following steps:

[0019] The fresh summer and autumn tea leaves are sequentially spread, withered, aged, rolled and dried to obtain Tuo tea raw material tea;

[0020] The drying process is to first bake at 60° C. until 50% to 70% dry, and then dry in the sun.

[0021] In a preferred embodiment of the present invention, the drying process is first drying at 60° C. until 70% dry, and then drying in the sun.

[0022] In a preferred embodiment of the present invention, the spreading thickness is 8 to 10 cm; and the spreading time is 2 hours.

[0023] In a preferred embodiment of the present invention, the fixing is performed by hot air.

[0024] In a preferred embodiment of the present invention, the air inlet temperature of the killing process is 90° C. and the time is 7 to 9 minutes.

[0025] In a preferred embodiment of the present invention, the alcoholization specifically comprises reducing the leaf temperature of the leaves to be withered to below 40°C, piling them to a thickness of 50 cm, and alcoholization for 1 hour.

[0026] In a preferred embodiment of the present invention, the kneading parameters are set as: 25kg / barrel, 50r / min, and light kneading for 20min.

[0027] The present invention also provides a Tuocha raw material tea prepared by utilizing the above Tuocha raw material tea drying method.

[0028] The technical solutions described in the present invention, unless otherwise specified, are all conventional solutions in the art, and the reagents or raw materials used, unless otherwise specified, are purchased from commercial channels or have been disclosed.

[0029] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0030] Example 1

[0031] 1 Materials and methods

[0032] 1.1 Materials and Equipment

[0033] Fresh leaves: The test raw materials were fresh leaves of Fuding Dabai (Camellia sinensis cv.'Fuding-dabaicha') with 1 bud and 2 leaves picked in August 2024, collected from the experimental tea garden of the Tea Research Institute of Chongqing Academy of Agricultural Sciences (29°75′N, 105°71′E, 440m above sea level).

[0034] Reagents: Methanol, acetic acid, gallic acid, caffeine, and catechin standards (C, EC, EGCG, GCG, EGC, ECG, and GC) were of chromatographic grade and purchased from Sigma. Sodium carbonate, Folin phenol reagent, potassium dihydrogen phosphate, sodium hydrogen phosphate, ninhydrin hydrate, stannous chloride, sulfuric acid, anthrone, ethanol, acetone, and aluminum chloride were of analytical grade and purchased from Guizhou Platinum Strontium Titanium Chemical Products Co., Ltd.

[0035] Equipment: spreading trough; 6CRSF-100 hot air fixing machine (Shanfeng Tea Machinery Co., Ltd., Mingshan District, Ya'an City); 6CR-55 rolling machine (Shanfeng Tea Machinery Co., Ltd., Mingshan District, Ya'an City); JY-6CHZ-7B tea roasting machine (Fujian Jiayou Tea Machinery Intelligent Technology Co., Ltd.); HB43-S moisture meter (Mettler-Toledo International Co., Ltd.); TU1901 UV-visible spectrophotometer (Beijing Puxi General Instrument Co., Ltd.); electronic tongue (SmarTongue, Switzerland); 1200HPLC (Agilent Technologies (China) Co., Ltd.).

[0036] 1.2 Test methods

[0037] Technological process: fresh leaves - spreading - withering - aging - rolling - drying.

[0038] The processing parameters are shown in Table 1, and the drying method is shown in Table 2.

[0039] Table 1 Processing parameters of raw materials of Tuocha

[0040] Process Process parameters Spread Use indoor spreading trough, thickness 8-10cm, time 2h Finish Use hot air to kill the green, the air inlet is 90℃, the time is 7min46s Aging The temperature of the dead leaves dropped to below 40℃, piled to 50cm thick, and aged for 1h Rolling Use 6CR-55 rolling machine, 25kg / barrel, 50r / min, light rolling for 20min

[0041] Table 2 Drying treatment of raw tea materials

[0042]

[0043]

[0044] 1.3 Detection Method

[0045] 1.3.1 The sensory evaluation was conducted with reference to GB / T 23776-2018 “Method for Sensory Evaluation of Tea”. Three senior tea tasters scored the samples separately and then calculated the average score.

[0046] 1.3.2 The taste attribute of tea samples was detected by electronic tongue, with quinine hydrochloride dihydrate, tannic acid, glutamic acid, tartaric acid and sucrose as standard substances, to detect the bitterness, astringency, umami, sourness and sweetness of the tea samples. First, the sensor was activated with 0.01M KCl aqueous solution and preheated for 20 minutes. Then, the sensor was cleaned with distilled water for 120 seconds. The tea sample (3g) was extracted with 150mL of freshly boiled water for 4 minutes. The tea water was cooled to 25±2℃ before testing. 15mL of tea soup was taken in a 30mL special beaker for testing. The taste intensity of the tea soup was measured 3 times. The sensor was cleaned for 15 seconds after each test.

[0047] 1.3.3 Biochemical component detection The determination of tea polyphenols, catechins, caffeine and gallic acid shall refer to GB / T 8313-20188 "Determination of tea polyphenols and catechins in tea"; the determination of amino acids shall adopt GB / T 8314-2013 "Determination of the total amount of free amino acids in tea"; the determination of soluble sugar shall adopt the sulfuric acid-anthrone colorimetric method; the determination of flavonoids shall adopt the aluminum chloride colorimetric method; the determination of water extract shall refer to GB / T 8305-2013 "Determination of tea water extract"; the determination of chlorophyll and carotenoids shall adopt the spectrophotometric method.

[0048] 1.4 Analysis methods

[0049] SPASS26.0 software was used for one-way analysis of variance and principal component analysis. The least significant difference (LSD) method was used to compare the significance of the differences in the mean values. The results were expressed as "mean ± standard deviation".

[0050] 2. Impact of different drying methods

[0051] 2.1 Effect of drying method on sensory quality

[0052] As shown in Table 3, different sun-drying and drying methods have a significant effect on the sensory quality of tea samples (P < 0.05). The comprehensive score of sensory quality is H > HS > SH > S. In the HS group, as the degree of drying increases, the dry tea, tea soup, and leaf bottom are greener, the sun-dried taste gradually weakens, the taste is mellower and fresher, and the overall quality is significantly improved. In the SH group, as the degree of sun-drying increases, the appearance, soup color, and leaf bottom color are yellower, the sun-dried taste becomes heavier, the mellowness of the taste decreases, and the overall quality is significantly reduced. The comprehensive sensory quality of HS3 and H tea samples is significantly better than that of other tea samples, with a green and moist appearance, a greener soup color, a fresh aroma, and a mellow taste. Among them, although the aroma of HS3 has a sun-dried taste, the taste is fresh. The comprehensive quality of SH3 and S tea samples is the worst, with a low mellow taste and a strong sun-dried taste, especially the S tea sample, which tastes bitter.

[0053] Table 3 Comparison of sensory quality of dried tea samples

[0054]

[0055] like Figure 1 As shown in the figure, electronic tongue detection analysis found that different drying treatments had no significant effect on the intensity of astringency, freshness, sourness, and sweetness of tea samples (P>0.05), but had a significant effect on the bitterness intensity (P<0.05). The bitterness intensity of SH3 tea sample was the highest, and that of H tea sample was the lowest, with a difference of 451.84 μg·mL -1 The other tea samples were in between the two, with no significant difference. The bitterness intensity of S tea sample was lower than that of SH3, which was different from the sensory results. The astringency intensity of each tea sample showed the same pattern. The umami and sourness intensity showed different patterns. The umami intensity of HS3 tea sample was the highest, while that of H was the lowest, with a difference of 413.80 μg·mL -1 HS2 has the highest sourness intensity, which is higher than H by 77.78 μg·mL -1 The sweetness values ​​of all tea samples were negative, indicating that the sweetness concentration of the tea samples was not within the model range.

[0056] 2.2 Effect of drying method on color

[0057] As shown in Table 4, different drying treatments had a significant effect on the pigment content of tea samples. In the HS and SH groups, as the degree of drying increased, the flavonoid content decreased. The SH3 tea sample had the highest content, followed by HS1, and HS3 had the lowest content, which was 1.15 and 0.73 mg·g lower than the first two. -1 In the HS group, the chlorophyll content increased with the increase of drying degree, while in the SH group, the chlorophyll content first decreased and then increased with the increase of sun drying degree. The chlorophyll a, chlorophyll b and total chlorophyll contents in the HS3 tea sample were the highest, significantly higher than those in the S tea sample by 0.26, 0.10 and 0.36 mg·g -1 The carotenoid content in H tea sample was the highest, significantly higher than that in S tea sample by 0.06 mg·g -1 .

[0058] Table 4 Pigment content of dried tea samples

[0059]

[0060] 2.3 Effect of drying method on biochemical components

[0061] As shown in Table 5, except for the water extract, different drying treatments had no significant effect on the content of other biochemical components in raw tea. In the HS and SH groups, as the degree of drying increased, the content of tea polyphenols increased, and the HS3 tea sample had the highest content, which was 16.90% higher than HS.

[0062] In the HS and SH groups, with the increase of drying degree and sun-drying degree, the contents of amino acids, soluble sugars and water extracts showed an increasing trend; HS3 tea sample had the highest amino acid content, 0.51% higher than H; HS2 had the highest soluble sugar content, 0.60% higher than H; HS3 tea sample had the highest water extract content, significantly higher than SH by 16.82%, while there were no significant differences in the other tea samples.

[0063] The phenol-ammonia ratio of H tea sample was the highest, 12.11 higher than that of HS. The caffeine content of SH2 tea sample was the highest, 11.02% higher than that of HS.

[0064] Table 5 Biochemical component content of dried tea samples

[0065]

[0066] In order to further analyze the effect of drying treatment on tea polyphenols in tea samples, the contents of catechins and gallic acid were tested. As shown in Table 6, the catechins in tea samples are mainly EGCG, followed by EGC and ECG, and the contents of other components are relatively low. The contents of GC, EGC, non-ester catechins, and catechins were significantly different among the treatments, and there were no significant differences in the contents of other catechin components. In the HS group, with the increase in the degree of drying, the total amount of ester catechins and catechins first increased and then decreased, and the content of non-ester catechins gradually increased. In the SH group, with the increase in the degree of sun drying, the total amount of ester catechins, non-ester catechins, and catechins first increased and then decreased. SH2 contains the highest catechin content, which is significantly higher than SH3 by 5.72%, showing richer contents of EGC, ECG, EGCG, ester catechins, and non-ester catechins. The content of ester catechins in HS3 tea samples is the lowest, and its EGCG content is lower than SH1 by 1.70%.

[0067] In summary, HS3 treatment is beneficial to improving the overall quality of tea leaves, with a green and moist appearance, a greener soup color, a fresh aroma, a mellow and fresh taste, and the highest umami intensity. It has high contents of tea polyphenols, amino acids, water extracts, and chlorophyll, and low contents of ester-type catechins. S treatment is not conducive to improving the overall quality of tea leaves, with low mellow taste, strong bitterness and sun-dried taste, low contents of chlorophyll and carotenoids, and high contents of ester-type catechins.

[0068] Table 6 Comparison of tea catechins and gallic acid

[0069]

[0070] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for drying raw material tea of ​​Tuocha, characterized in that: The following steps are involved: The fresh summer and autumn tea leaves are sequentially spread, withered, aged, rolled and dried to obtain Tuo tea raw material tea; The drying process is to first bake at 60° C. until 50% to 70% dry, and then dry in the sun.

2. The method for drying raw material Tuocha tea according to claim 1, characterized in that: The drying process is to first bake at 60° C. until 70% dry, and then dry in the sun.

3. The method for drying raw material Tuocha tea according to claim 1, characterized in that: The spreading thickness is 8 to 10 cm, and the spreading time is 2 hours.

4. The method for drying raw material Tuocha tea according to claim 1, characterized in that: The fixing is carried out by hot air.

5. The method for drying raw material Tuocha tea according to claim 4, characterized in that: The air inlet temperature of the killing process is 90° C. and the time is 7 to 9 minutes.

6. The method for drying raw material Tuocha tea according to claim 1, characterized in that: The alcoholization specifically comprises the following steps: the temperature of the leaves to be withered is lowered to below 40°C, the leaves are piled to a thickness of 50cm, and alcoholization is performed for 1 hour.

7. The method for drying raw material Tuocha tea according to claim 1, characterized in that: The kneading parameters are set as: 25kg / barrel, 50r / min, and light kneading for 20min.

8. A Tuocha raw material tea prepared by the Tuocha raw material tea drying method according to any one of claims 1 to 7.

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