Mushroom flower fragrance type loose black tea and preparation method thereof

Abstract

The invention discloses a preparation method of fungus flower fragrance type loose black tea, which comprises the following steps: (1) steaming treatment: adding water into a tea leaf raw material, and then steaming to obtain sterilized tea leaves; (2) inoculated fermentation: cooling the sterilized tea leaves to room temperature, then mixing an eurotium cristatum leavening agent and a pichia pastoris leavening agent, then uniformly spraying the mixture on the sterilized tea leaves, and then performing fermentation treatment to obtain fermented tea leaves; and (3) drying the tea leaves: drying the fermented tea leaves to obtain the fungus flower fragrance type loose black tea. According to the preparation method, the eurotium cristatum and the pichia pastoris are co-fermented to prepare the fungus flower fragrance type loose dark tea, the defect that single eurotium cristatum fermented tea is thin in flavor is overcome, a mixed fungus co-fermentation mode is adopted, the fragrance of the fermented tea can be enriched, the fungus flower fragrance is improved, and the tea flavor is improved. Compared with loose black tea fermented by single eurotium cristatum, the loose black tea fermented by mixed bacteria has the advantages that the content of volatile compounds is greatly increased, and the aroma quality of the fermented tea is greatly improved.

Description

Technical Field

[0001] The invention relates to the technical field of microbial fermented tea, and in particular to a kind of mushroom flower fragrance loose black tea and a preparation method thereof. Background Art

[0002] Dark tea is one of the six major types of tea in China, which is made from tea leaves fermented by microorganisms. Varieties include Kangzhuan tea, Pu'er tea, Liubao tea, Fuzhuan tea, Qingzhuan tea, etc. During the initial processing or the later reprocessing, microbial communities grow and reproduce on the tea substrate. Microbial fermentation and the moist heat effect together form the unique quality of dark tea.

[0003] Fuzhuan tea is a representative variety of dark tea, originating from Jingyang, Shaanxi. Fuzhuan tea has the sensory characteristics of smooth brick surface, luxuriant golden flowers, pure internal aroma, fungus flower fragrance, orange-yellow soup color, mellow taste, etc. The core functional microorganism of Fuzhuan tea, Eurotium cristatum, improves the aroma of fungus flower, mint, woody, etc. of fermented tea by growing and metabolizing flavor metabolites in the tea matrix. However, compared with traditional fermented Fuzhuan tea, the aroma of Eurotium cristatum fermented loose tea is still relatively weak. Summary of the invention

[0004] The main purpose of the invention is to provide a mushroom flower aroma type loose black tea with higher aroma quality and a preparation method thereof.

[0005] To achieve the above object, the present invention provides a method for preparing a loose black tea with a fungus-flower aroma, comprising the following steps:

[0006] (1) Steaming treatment

[0007] Adding water to the tea raw material, and then performing high temperature sterilization treatment to obtain sterilized tea leaves;

[0008] (2) Inoculation and fermentation

[0009] The sterilized tea leaves are cooled to room temperature, and then the Eurotium cristatum fermentation agent and the Pichia pastoris fermentation agent are mixed and sprayed evenly on the sterilized tea leaves, and then fermented to obtain fermented tea leaves;

[0010] (3) Tea drying

[0011] The fermented tea leaves are dried to obtain the mushroom-flower fragrance loose black tea.

[0012] Furthermore, the Aspergillus cristatus was selected from the Aspergillus cristatus G39 (disclosed in Chinese patent ZL201510160451.6), which was deposited in the General Microbiology Center of the China Microorganism Culture Collection Administration, with a deposit number of CGMCC No. 10610 and a deposit date of March 11, 2015; the Pichia pastoris was selected from the Pichia pastoris Z9Y-3 (disclosed in Chinese patent ZL202210024281.9), which was deposited in the China Center for Type Culture Collection, with a deposit number of CCTCC NO: M2019857 and a deposit date of October 28, 2019.

[0013] Colony characteristics of G39: The colonies are relatively regular and round, with a dense velvety surface, ranging from light yellow to dark brown in color, with lighter edges, and the center of the colony is slightly raised, with a small amount of dark brown exudate secreted.

[0014] Colony characteristics of Pichia pastoris Z9Y-3: The colonies are milky white and creamy, with a sticky texture, radial wrinkles on the surface and irregular edges.

[0015] Furthermore, in step (1), the tea raw material is any one of green tea, black tea, oolong tea, white tea and yellow tea, the mass ratio of the added water to the tea raw material is 30-35:100, and the conditions for high temperature sterilization treatment are temperature 121° C. and time 20 min.

[0016] Furthermore, in step (2), the weight ratio of the Eurotium cristatum fermentation agent, the Pichia pastoris fermentation agent and the dry tea leaves is 4:1:100, and the concentration of live bacteria in the Eurotium cristatum fermentation agent is ≥1.0×10 7 CFU / g, the live bacteria concentration of Pichia yeast culture is ≥1.0×10 7 CFU / g.

[0017] Furthermore, in step (2), the fermentation treatment conditions are 23-30° C., 55-80% air humidity, and 6-15 days.

[0018] Furthermore, in step (3), the drying treatment conditions are a temperature of 60 to 70° C. and a time of 2 to 3 hours.

[0019] Furthermore, the Eurotium cristatum fermentation agent is prepared by the following method: dry tea powder and water are mixed, the mixture is sterilized and then cooled to room temperature, and then the Eurotium cristatum seed liquid is inoculated for expansion culture, and then vacuum freeze-dried to obtain the Eurotium cristatum fermentation agent;

[0020] The Pichia yeast starter is prepared by the following method: dry tea powder and water are mixed, sterilized and cooled to room temperature, then the Pichia yeast seed liquid is inoculated for expansion culture, and then vacuum freeze-dried to obtain the Eurotium cristatum starter.

[0021] Furthermore, in the preparation process of the Eurotium cristatum fermentation agent and the Pichia pastoris fermentation agent: the particle size of the dry tea powder is 40-60 mesh, the mass ratio of the dry tea powder to water is 2:1, and the sterilization conditions are temperature 121°C and time 20 minutes.

[0022] Furthermore, in the preparation process of the Eurotium cristatum fermentation agent: the concentration of the Eurotium cristatum seed solution is 1.0×10 4 ~1.0×10 6 CFU / mL, the inoculation amount is 0.01-0.05mL / g, and the conditions for expanded culture are temperature 28°C, air humidity 70%, and time 5-7 days.

[0023] Furthermore, in the preparation process of Pichia yeast starter: the concentration of Pichia yeast seed solution is 1.0×10 7 ~1.0×10 9 CFU / mL, the inoculation amount is 0.01-0.05mL / g, and the conditions for expanded culture are temperature 28°C, air humidity 70%, and time 3-5 days.

[0024] The invention also provides a mushroom flower fragrance type loose black tea, which is prepared according to the preparation method.

[0025] The beneficial effects of the present invention are embodied in:

[0026] The present invention utilizes the co-fermentation of Eurotium cristatum and Pichia pastoris to prepare the loose black tea with fungus flower aroma, which solves the defect that the tea fermented with single Eurotium cristatum has a thin flavor. The mixed bacteria co-fermentation method is adopted to enrich the aroma of the fermented tea and enhance the fungus flower aroma. Compared with the loose black tea fermented with single Eurotium cristatum, the content of volatile compounds in the mixed bacteria co-fermented loose black tea is greatly increased, thereby greatly improving the aroma quality of the fermented tea.

[0027] The invention solves the problems of easy contamination, long fermentation cycle, unstable product quality, etc. of traditional fermented tea. The invention adopts artificial inoculation in a sterile environment to avoid contamination by miscellaneous bacteria, shorten the fermentation cycle, and stabilize product quality.

[0028] The invention obtains artificially cultured Eurotium cristatum fermentation agent and Pichia pastoris fermentation agent, which can be used for extracting effective components of Eurotium cristatum and Pichia pastoris and can also be used for blooming loose tea, thereby shortening the fermentation cycle and reducing the occurrence of contamination by miscellaneous bacteria. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 The tea soup color and dry tea color diagram of four different loose black teas prepared in Example 3.

[0030] Figure 2 This is a comparison chart of the volatile compound contents of four different loose black teas prepared in Example 3. DETAILED DESCRIPTION

[0031] In order to make the technical scheme of the present invention more clearly understood by those skilled in the art, the following embodiments are listed for illustration. It should be pointed out that the following embodiments do not limit the protection scope of the present invention.

[0032] Unless otherwise specified, the raw materials, reagents or devices used in the following examples can be obtained from conventional commercial sources or by existing known methods; unless otherwise specified, the methods used in the examples of the present invention are methods known to those skilled in the art. Among them:

[0033] Coarse old roasted green tea was purchased from Huangshan Shuigong Tea Co., Ltd.

[0034] Example 1

[0035] Preparation of Eurotium cristatum fermentation agent

[0036] The preparation method is as follows:

[0037] (1) CGMCC No.10610 was inoculated into PDA medium and activated and cultured at 28°C for 3 days to obtain seed culture. Sterile saline was added in small amounts and multiple times. The bacterial cells on the surface of the culture medium were scraped and collected using an inoculation loop and transferred into a triangular flask containing 100 mL of sterile saline and glass beads. The suspension was fully shaken to obtain the seed solution of CGMCC No.10610. The concentration was 1.0×10 6 CFU / mL;

[0038] (2) Crush the dry tea leaves, sieve out 50-mesh dry tea powder, and then mix it with purified water at a material-liquid mass ratio of 2:1, stir evenly, put it into a sterilizer, sterilize it at 121°C for 20 minutes, and then cool it to room temperature to use as an expansion culture medium;

[0039] (3) Inoculate the seed liquid of Eurotium cristatum into the expansion culture medium at an inoculation amount of 0.03 mL / g, stir evenly, cover the outlet of the culture container with a breathable sealing film, expand the culture in a constant temperature and humidity incubator at 28° C. and 70% air humidity for 6 days, and finally dry at 60° C. for 3 hours to obtain a Eurotium cristatum fermentation agent, wherein the viable bacteria concentration is ≥1.0×10 7 CFU / g.

[0040] Example 2

[0041] Preparation of Pichia yeast starter culture

[0042] The preparation method is as follows:

[0043] (1) Pichia pastoris CCTCC NO: M2019857 was inoculated into PDA medium and activated and cultured at 28°C for 5 days to obtain seed culture. Sterile saline was added in small amounts and multiple times. The bacterial cells on the surface of the culture medium were scraped and collected using an inoculation loop and transferred into a triangular flask containing 100 mL of sterile saline and glass beads. The suspension was fully shaken to obtain a bacterial suspension, which was the Pichia pastoris seed solution with a concentration of 1.0×10 9 CFU / mL;

[0044] (2) Crush the dry tea leaves, sieve out 50-mesh dry tea powder, and then mix it with purified water at a material-liquid mass ratio of 2:1, stir evenly, put it into a sterilizer, sterilize it at 121°C for 20 minutes, and then cool it to room temperature to use as an expansion culture medium;

[0045] (3) The Pichia seed liquid was inoculated into the expansion medium at an inoculation amount of 0.05 mL / g, and the culture medium was stirred evenly. The outlet of the culture container was covered with a breathable sealing film, and the culture was expanded in a constant temperature and humidity incubator at 28° C. and an air humidity of 70% for 4 days. Finally, the culture medium was sublimated and dried at a vacuum degree of 0.7 mbar and a temperature of −25° C. for 48 hours to obtain a Pichia starter culture, wherein the viable bacteria concentration was ≥1.0×10 7 CFU / g.

[0046] Example 3

[0047] Preparation of loose black tea with fungus and flower aroma

[0048] The preparation method is as follows:

[0049] (1) Steaming treatment

[0050] Adding purified water to the raw material of coarse old roasted green tea, the mass ratio of purified water to tea raw material is 32:100, and then sterilizing at 121°C for 20 minutes to obtain sterilized tea leaves;

[0051] (2) Inoculation and fermentation

[0052] The sterilized tea leaves were cooled to room temperature, and then the mixture of the Eurotium guanidinum fermentation agent and the Pichia yeast fermentation agent was evenly sprayed on the sterilized tea leaves. The mass ratio of the Eurotium guanidinum fermentation agent, the Pichia yeast fermentation agent and the coarse old roasted green tea raw material was 4:1:100, and the live bacteria concentration of the Eurotium guanidinum fermentation agent was 2.0×10 7 CFU / g, the live bacteria concentration of Pichia yeast culture is 2.0×10 7 CFU / g, and then fermented in a constant temperature and humidity incubator at 28°C and 70% air humidity for 10 days to obtain fermented tea leaves;

[0053] (3) Tea drying

[0054] The fermented tea leaves were placed in an oven and dried at 65° C. for 2.5 h to obtain loose black tea with a mushroom-flower aroma.

[0055] Example 4

[0056] Preparation of loose black tea with fungus and flower aroma

[0057] The preparation method is as follows:

[0058] (1) Steaming treatment

[0059] Adding purified water to the raw material of coarse old roasted green tea, the mass ratio of purified water to tea raw material is 30:100, and then sterilizing at 121°C for 20 minutes to obtain sterilized tea leaves;

[0060] (2) Inoculation and fermentation

[0061] The sterilized tea leaves were cooled to room temperature, and then the mixture of the Eurotium guanidinium fermentation agent and the Pichia yeast fermentation agent was evenly sprayed on the sterilized tea leaves. The mass ratio of the Eurotium guanidinium fermentation agent, the Pichia yeast fermentation agent and the coarse old roasted green tea raw material was 4:1:100, and the live bacteria concentration of the Eurotium guanidinium fermentation agent was 1.0×10 7 CFU / g, the live bacteria concentration of Pichia yeast culture is 1.0×10 7 CFU / g, and then fermented in a constant temperature and humidity incubator at 23°C and 60% air humidity for 15 days to obtain fermented tea leaves;

[0062] (3) Tea drying

[0063] The fermented tea leaves were placed in an oven and dried at 70° C. for 2 h to obtain loose black tea with a mushroom-flower aroma.

[0064] Example 5

[0065] Preparation of loose black tea with fungus and flower aroma

[0066] The preparation method is as follows:

[0067] (1) Steaming treatment

[0068] Adding purified water to the raw material of coarse old roasted green tea, the mass ratio of purified water to tea raw material is 35:100, and then sterilizing at 121°C for 20 minutes to obtain sterilized tea leaves;

[0069] (2) Inoculation and fermentation

[0070] The sterilized tea leaves were cooled to room temperature, and then the mixture of the Eurotium guanidinium fermentation agent and the Pichia yeast fermentation agent was evenly sprayed on the sterilized tea leaves. The mass ratio of the Eurotium guanidinium fermentation agent, the Pichia yeast fermentation agent and the coarse old roasted green tea raw material was 4:1:100, and the live bacteria concentration of the Eurotium guanidinium fermentation agent was 3.0×10 7CFU / g, the live bacteria concentration of Pichia yeast culture is 3.0×10 7 CFU / g, and then fermented in a constant temperature and humidity incubator at 30°C and 80% air humidity for 6 days to obtain fermented tea leaves;

[0071] (3) Tea drying

[0072] The fermented tea leaves were placed in an oven and dried at 60° C. for 3 h to obtain loose black tea with a mushroom-flower aroma.

[0073] Experimental Example 1

[0074] Component Analysis of Junhua Aroma Loose Black Tea

[0075] The loose black tea with fungus and flower fragrance prepared in Example 3 is recorded as EP;

[0076] On the basis of Example 3, only the addition of the Eurotium cristatum fermentation agent and the Pichia pastoris fermentation agent was omitted, and the obtained loose black tea product was recorded as UF;

[0077] On the basis of Example 3, only the addition of Pichia yeast fermentation agent was omitted, and the Eurotium cristatum fermentation agent was added in a ratio of 5:100 to the raw material of rough old roasted green tea, and the obtained loose black tea product was recorded as EC;

[0078] On the basis of Example 3, only the addition of the Eurotium cristatum fermentation agent was omitted, and the Pichia yeast fermentation agent was added in a ratio of 5:100 to the raw material of rough old roasted green tea, and the obtained loose black tea product was recorded as PF;

[0079] On the basis of Example 3, the Pichia yeast fermentation agent was replaced with an equal amount of Debaryomyces hansenii fermentation agent with an equal concentration of viable bacteria, and the obtained loose black tea product was recorded as DM;

[0080] On the basis of Example 3, the Pichia pastoris starter was replaced with an equal amount of Delbur's spore yeast with an equal live bacteria concentration, and the obtained loose black tea product was recorded as DN.

[0081] The physical and chemical components, tea pigment components, etc. of the above-mentioned loose black tea products were analyzed, and the results are shown in Tables 1 to 4 below.

[0082] Table 1 Physicochemical components of different loose black teas

[0083]

[0084]

[0085] Table 2 Tea pigment components of different loose black teas

[0086]

[0087] Table 3 Relative odor activity values ​​of fungus and flower aroma components of different loose black teas

[0088]

[0089] Table 4 Content of fungus and flower aroma components in different loose black teas

[0090]

[0091] From the above, it can be seen that the co-fermentation of Eurotium cristatum and Pichia pastoris can effectively transform and degrade catechins and tea polyphenols, promote the formation of theabrownin, and increase the content of floral aroma components of tea fungi. The content of floral aroma chemical components of EP fungi, such as methyl salicylate, hexanal, heptadienal, and phenylethanol, is higher than that of loose black tea UF, EC, PF, DM, and DN, indicating that the ability of EP mixed bacteria co-fermentation to enhance the floral aroma of tea fungi is better than that of other mixed bacteria co-fermentation combinations and single bacteria fermentation.

[0092] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a mushroom flower fragrance loose black tea, characterized in that: The following steps are involved: (1) Steaming treatment Adding water to the tea raw material, and then performing high temperature sterilization treatment to obtain sterilized tea leaves; (2) Inoculation and fermentation The sterilized tea leaves are cooled to room temperature, and then the Eurotium cristatum fermentation agent and the Pichia pastoris fermentation agent are mixed and sprayed evenly on the sterilized tea leaves, and then fermented to obtain fermented tea leaves; (3) Tea drying The fermented tea leaves are dried to obtain the mushroom-flower fragrance loose black tea.

2. The method for preparing the mushroom flower fragrance loose black tea according to claim 1, characterized in that: In step (1), the tea raw material is any one of green tea, black tea, oolong tea, white tea and yellow tea, the mass ratio of the added water to the tea raw material is 30-35:100, and the conditions for high temperature sterilization treatment are temperature 121° C. and time 20 min.

3. The method for preparing the mushroom flower fragrance loose black tea according to claim 1, characterized in that: In step (2), the weight ratio of the Eurotium cristatum fermentation agent, the Pichia pastoris fermentation agent and the dry tea leaves is 4:1:100, and the concentration of live bacteria in the Eurotium cristatum fermentation agent is ≥1.0×10 7 CFU / g, the live bacteria concentration of Pichia yeast culture is ≥1.0×10 7 CFU / g.

4. The method for preparing the mushroom flower fragrance loose black tea according to claim 1, characterized in that: In step (2), the fermentation treatment conditions are 23-30° C., 55-80% air humidity, and 6-15 days.

5. The method for preparing the mushroom flower fragrance loose black tea according to claim 1, characterized in that: In step (3), the drying treatment conditions are a temperature of 60 to 70° C. and a time of 2 to 3 hours.

6. The method for preparing the mushroom flower fragrance loose black tea according to any one of claims 1 to 5, characterized in that: The Eurotium cristatum fermentation agent is prepared by the following method: dry tea powder and water are mixed, sterilized and cooled to room temperature, then inoculated with Eurotium cristatum seed liquid for expansion culture, and then vacuum freeze-dried to obtain the Eurotium cristatum fermentation agent; The Pichia yeast starter is prepared by the following method: dry tea powder and water are mixed, sterilized and cooled to room temperature, then the Pichia yeast seed liquid is inoculated for expansion culture, and then vacuum freeze-dried to obtain the Eurotium cristatum starter.

7. The method for preparing the mushroom flower fragrance loose black tea according to claim 6, characterized in that: In the preparation process of Eurotium cristatum fermentation agent and Pichia pastoris fermentation agent: the particle size of dry tea powder is 40-60 mesh, the mass ratio of dry tea powder to water is 2:1, and the sterilization conditions are temperature 121°C and time 20 minutes.

8. The method for preparing the mushroom flower fragrance loose black tea according to claim 6, characterized in that: In the preparation process of the Eurotium cristatum fermentation agent: the concentration of the Eurotium cristatum seed solution is 1.0×10 4 ~1.0×10 6 CFU / mL, the inoculation amount is 0.01-0.05mL / g, and the conditions for expanded culture are temperature 28°C, air humidity 70%, and time 5-7 days.

9. The method for preparing the mushroom flower fragrance loose black tea according to claim 6, characterized in that: In the preparation process of Pichia yeast starter culture: the concentration of Pichia yeast seed solution is 1.0×10 7 ~ 1.0×10 9 CFU / mL, the inoculation amount is 0.01-0.05mL / g, and the conditions for expanded culture are temperature 28°C, air humidity 70%, and time 3-5 days.

10. A kind of loose black tea with mushroom flower fragrance, characterized in that: Prepared according to the preparation method according to any one of claims 1 to 9.

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