Jingyang Fuzhuan tea and preparation method thereof

Abstract

The invention discloses a preparation process of Jingyang Fuzhuan tea, and relates to the technical field of tea processing. The process comprises the following steps: by taking raw dark green tea as a raw material, adding a compound enzymatic hydrolysate consisting of cellulase and papain to perform infiltration treatment, performing enzymolysis, adding an oat beta-glucan solution, performing uniform mixing, performing pile fermentation, performing pressing to obtain green bricks, inoculating aspergillus oryzae and eurotium cristatum to perform double-bacterium synergistic eurotium cristatum fermentation, and performing drying to obtain the green tea. And finally, performing staged drying (low-temperature drying in the first stage inactivates microbial metabolic enzymes, and heating drying in the second stage retains small-molecular flavor substances) to obtain a finished product. Through the process combination of composite enzymolysis, double-bacterium synergistic fermentation and gradient drying, the content of functional polysaccharides and free amino acids in the Fuzhuan tea is effectively increased, and the sensory quality of the Fuzhuan tea is effectively improved.

Description

Technical Field

[0001] The invention relates to the technical field of tea processing, in particular to Jingyang Fu brick tea and a preparation method thereof. Background Art

[0002] Jingyang Fuzhuan Tea is an important category of traditional fermented tea in China. Its preparation process usually includes steps such as black tea processing, fermentation, pressing and shaping, flowering and drying. In the existing technology, in order to improve the quality and functionality of Fuzhuan Tea, a single enzymatic hydrolysis treatment (such as cellulase or protease) is often used to promote the release of effective ingredients in the raw materials, or polysaccharides (such as glucan, pectin, etc.) are added to improve the taste and nutritional properties of the tea soup; the fermentation process mostly relies on the natural or artificial inoculation of a single strain of fungus (such as Eurotium cristatum), and the formation of "golden flowers" (fruiting bodies of Eurotium cristatum) is promoted by regulating parameters such as temperature and humidity; the drying process is mainly based on a single temperature gradient, aiming to quickly reduce the moisture content of the product to extend the shelf life.

[0003] However, the existing technology has the following shortcomings: First, the efficiency of single enzymatic hydrolysis in decomposing the cell wall structure and protein of dark tea is limited, and there is a lack of synergistic mechanism with functional additives, resulting in a low dissolution rate of effective ingredients and an insignificant increase in the content of functional substances (such as polysaccharides and amino acids); second, in a single-strain fermentation system, the microbial metabolic pathway is single, making it difficult to fully utilize the complex substrates in the raw materials, and it is easily contaminated by miscellaneous bacteria, affecting the fermentation stability; third, the matching of traditional pressing and drying processes is insufficient, and uneven density of bricks or too fast drying rate can easily lead to the destruction of the "golden flower" structure and thermal decomposition of functional ingredients, affecting the uniformity and functional activity of product quality. These problems jointly restrict the comprehensive improvement of the nutritional characteristics, flavor quality and production efficiency of Jingyang Fuzhuan Tea. Summary of the Invention

[0004] In view of the above-mentioned shortcomings of the prior art, the object of the present invention is to provide a Jingyang Fuzhuan tea and a preparation method thereof to solve one or more problems in the prior art.

[0005] To achieve the above object, the technical solution of the present invention is as follows:

[0006] A Jingyang Fu brick tea, comprising:

[0007] The raw materials include dark tea crushed to a particle size of 2-5 mm and oat beta-glucan added in an amount of 6%-10% of the dry weight of the dark tea. The oat beta-glucan has a purity of ≥70% on a dry basis and a molecular weight of 60,000-2,000,000 Daltons.

[0008] Fermentation: Microorganisms include Aspergillus oryzae and Eurotium cristatum, with inoculation amounts of (0.5-2)×10 6 CFU / g dry tea and (2-8)×105 CFU / g dry tea.

[0009] Specifically, the oat beta-glucan has a moisture content of ≤5.0%, an ash content of ≤8.0%, and a hydroxyl functional group density of 1.0-1.5 mmol / g.

[0010] Specifically, the Aspergillus oryzae is a CICC 2012 strain, and the Eurotium cristatum is a CGMCC 3.4668 strain.

[0011] Specifically, the dark tea is treated with a composite enzymatic hydrolysis solution, which contains cellulase and papain, with an activity ratio of 1:1 to 3:1, and the total enzyme addition amount is 1.5%-3% of the dry weight of the dark tea.

[0012] Furthermore, the composite enzymatic hydrolysis solution also includes 0.1%-0.3% vitamin C as an enzyme protectant.

[0013] In order to make the technical effect complete, the second set of technical solutions of the present invention is a method for preparing Jingyang Fuzhuan tea, based on the above-mentioned Jingyang Fuzhuan tea, comprising the following steps:

[0014] (1) Dark tea processing: crush the dark tea into particles of 2-5 mm.

[0015] (2) Infiltration of composite enzymatic hydrolysate: Add composite enzymatic hydrolysate to the crushed dark tea at a material-liquid ratio of 1:20 to 1:40 (g / mL), perform enzymatic hydrolysis at pH 5.0-6.0 and temperature 50-60°C for 40-80 minutes, inactivate and filter.

[0016] (3) Addition of oat β-glucan: Add oat β-glucan solution with a concentration of 1.5%-3% (w / v) to the enzymatically hydrolyzed dark tea.

[0017] (4) Pile fermentation: Pile for 4-8 hours at a temperature of 28-35°C and a humidity of 75-85%.

[0018] (5) Pressing and shaping: Maintaining pressure at 2-4 MPa for 20-40 seconds to make bricks with specifications of 30-40 cm × 15-20 cm × 4-6 cm.

[0019] (6) Double bacteria synergistic flowering: Inoculate Aspergillus oryzae and Eurotium cristatum into the bricks and culture them at a temperature of 25-35°C and a humidity of 70-90% for 6-12 days.

[0020] (7) Staged drying: First dry at 35-45℃ for 4-6 hours, then dry at 55-65℃ for 8-12 hours until the moisture content of the finished product is ≤8%.

[0021] Specifically, the cellulase activity of the composite enzymatic hydrolysate in step (2) is 1×105 -3×10 5 U / g, papain activity is 2-4×10 5 U / g. Use acetic acid-sodium acetate buffer to adjust the pH. After enzymatic hydrolysis, filter with a 100-mesh filter. Inactivate by heating at 90-100°C for 8-15 minutes.

[0022] Specifically, the oat β-glucan solution in step (3) is prepared by dissolving oat β-glucan powder in deionized water at 60-70° C., stirring for 20-40 minutes until completely dissolved, and cooling to room temperature.

[0023] Specifically, the temperature for the dual-bacteria collaborative flowering in step (6) is controlled as follows: 25-30°C for the first 3 days, 30-35°C for the 4th to 8th days, and 25-30°C for the last 2 days. Ventilate 1-3 times a day, each time for 20-40 minutes, and maintain a CO2 concentration of <0.5%.

[0024] Specifically, the relative humidity of the staged drying in step (7) is controlled to be 40-50% in the first stage and 30-40% in the second stage. Hot air circulation drying is adopted, and the wind speed is controlled to be 1.0-1.5 m / s.

[0025] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0026] (1) The pretreatment of dark tea with a composite enzymatic hydrolysate (cellulase and papain) is combined with the addition of oat β-glucan. On the one hand, the enzymatic hydrolysis can efficiently decompose the cell wall structure and protein macromolecules of dark tea, promoting the release of functional ingredients. On the other hand, oat β-glucan, as a prebiotic, can regulate the microecological environment of the fermentation system and promote the colonization and metabolism of the target flora, thereby synergistically increasing the content of functional polysaccharides and amino acids in Fuzhuan tea, and improving the taste and nutritional properties of the tea soup.

[0027] (2) Through the combination of the dual-bacteria synergistic flowering process of Aspergillus oryzae and Eurotium cristatum and the segmented drying technology, Aspergillus oryzae can quickly decompose large molecular substances into small molecular metabolites in the early stage of fermentation, providing a nutritional basis for the growth of Eurotium cristatum, while Eurotium cristatum forms a dominant bacterial community in the subsequent stage and produces a characteristic "golden flower" structure; segmented drying uses gradient temperature control to first promote the accumulation of secondary metabolites of microorganisms, and then quickly reduce moisture to inhibit the growth of miscellaneous bacteria, thereby achieving a synergistic improvement in fermentation efficiency and product stability.

[0028] (3) Through the coordination of temperature and humidity control of pile fermentation and pressing and shaping process, the pile fermentation process promotes the initial metabolism and material transformation of microorganisms under specific temperature and humidity conditions, laying a material foundation for subsequent flowering. Pressing and shaping, by controlling the density of bricks, not only provides a suitable spatial environment for microbial growth, but also ensures the physical strength of brick tea, reduces the risk of breakage during storage, and improves the uniformity of product quality.

[0029] (4) By combining vitamin C as an enzyme protectant in the composite enzymatic hydrolysate with the dual-bacteria step-by-step inoculation strategy, vitamin C can effectively maintain the activity of cellulase and papain and improve the enzymatic hydrolysis efficiency, while the step-by-step inoculation of Aspergillus oryzae and Eurotium cristatum can avoid competitive inhibition of the bacterial community, allowing the two strains to play a leading role in different fermentation stages, further optimizing the metabolite composition and enhancing the functional activity of Fuzhuan tea. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic flow diagram of the preparation method of the present invention. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and exemplary explanations. It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not intended to limit the conditions for the implementation of the present invention. Therefore, they have no technical significance. Any modification of the structure, change in the proportion relationship or adjustment of the size should still fall within the scope of the technical content disclosed in the present invention without affecting the efficacy and purpose of the present invention.

[0032] Application Overview

[0033] In the traditional production of Jingyang Fu brick tea, the industry usually adopts single enzymatic hydrolysis treatment (such as using cellulase or protease alone) to promote the release of raw material ingredients, or adds a single polysaccharide (such as glucan) to improve the taste in order to improve the technical problem of improving product quality. The fermentation process mostly relies on the natural inoculation of a single bacterial species (such as Aspergillus niger), and the drying process is mainly constant temperature drying.

[0034] However, conventional solutions have obvious limitations: the efficiency of single enzymatic hydrolysis in decomposing the complex components of black tea is limited, and there is a lack of synergistic effect with additives, resulting in a low dissolution rate of functional ingredients; the single-species fermentation system has a single metabolic pathway, is easily contaminated by miscellaneous bacteria, and has insufficient fermentation stability; the traditional drying process is difficult to balance the accumulation of microbial metabolites and product moisture control, which can easily lead to the destruction of the "golden flower" structure or the loss of effective ingredients, which overall restricts the nutritional characteristics and quality uniformity of Fuzhuan tea.

[0035] Comprehensive description

[0036] This proposal involves a preparation process for Jingyang Fuzhuan Tea. Through the coordinated optimization of raw material pretreatment, compound enzymatic hydrolysis, functional ingredient addition, multi-stage fermentation, and precision drying, the product quality and functional activity are improved. The following describes the detailed steps and key operating points of this process:

[0037] Raw material pretreatment and enzymatic hydrolysis

[0038] First, the dark tea is crushed to a particle size of 2-5 mm to increase the specific surface area of ​​the raw material, which is convenient for subsequent enzymatic hydrolysis and fermentation reactions. The crushed dark tea is soaked in a composite enzymatic hydrolysis solution, which contains cellulase and papain with an activity ratio of 1:1 to 3:1, and the total enzyme addition amount is 1.5%-3% of the dry weight of the dark tea; to improve enzyme stability, 0.1%-0.3% vitamin C is also added to the composite enzymatic hydrolysis solution as an enzyme protectant. During the enzymatic hydrolysis process, the material-liquid ratio is controlled at 1:20 to 1:40 (g / mL), and the reaction is carried out at a pH of 5.0-6.0 and a temperature of 50-60°C for 40-80 minutes, followed by heating at 90-100°C for 8-15 minutes to inactivate the enzyme activity, and filtering with a 100-mesh filter to remove the residue.

[0039] Functional ingredient addition and composting fermentation

[0040] An oat beta-glucan solution (1.5%-3% w / v) with a dry-base purity of ≥70% and a molecular weight of 60,000-2,000,000 Daltons is added to the enzymatically hydrolyzed dark tea. Before addition, the oat beta-glucan powder is dissolved in deionized water at 60-70°C, stirred for 20-40 minutes until completely dissolved, and then cooled to room temperature. After mixing, the mixture is fermented at 28-35°C and 75-85% humidity for 4-8 hours to promote initial microbial metabolism and material conversion.

[0041] Pressing and shaping and double-bacteria synergistic flowering

[0042] The piled material is kept under pressure of 2-4 MPa for 20-40 seconds and pressed into bricks with specifications of 30-40 cm × 15-20 cm × 4-6 cm. The bricks are inoculated with Aspergillus oryzae (CICC 2012 strain) and Eurotium cristatum (CGMCC 3.4668 strain), with the inoculation amount of (0.5-2) × 10 6 CFU / g dry tea and (2-8)×10 5CFU / g dry tea. The flowering process uses staged temperature control: maintained at 25-30°C for the first three days, raised to 30-35°C on days 4-8, and returned to 25-30°C for the final two days. Humidity is maintained at 70-90% throughout the process, with ventilation 1-3 times daily (20-40 minutes each time) to ensure a CO2 concentration of <0.5%. The incubation period is 6-12 days.

[0043] Staged drying and quality control

[0044] After blooming, the bricks undergo staged drying: the first stage is dried at 35-45°C and 40-50% relative humidity for 4-6 hours. The second stage is dried at 55-65°C and 30-40% relative humidity for 8-12 hours. Hot air circulation is used at a controlled wind speed of 1.0-1.5 m / s until the finished product moisture content is ≤8%. The drying process uses a gradient of temperature and humidity to balance the retention of microbial metabolites with product stability, ultimately yielding Jingyang Fuzhuan tea with both flavor and functional properties.

[0045] This process achieves a comprehensive improvement in raw material utilization, fermentation efficiency and product quality through the synergy of composite enzymatic hydrolysis and addition of functional ingredients, microecological regulation of dual-bacteria step-by-step fermentation, and precise control of segmented drying. The resulting Fu brick tea has the characteristics of full "golden flowers", mellow taste, and rich functional ingredients.

[0046] Experimental verification and transition

[0047] To verify the impact of key process parameters in this protocol on the quality and functional properties of Jingyang Fuzhuan tea, a comparative experiment was conducted to examine the technical effects of three key variables: the ratio of combined enzymatic hydrolysis, the dual-bacteria inoculum level, and the drying temperature gradient. Key performance indicators were determined in strict accordance with national standard methods to ensure objectivity and reproducibility. The specific experimental design and testing methods are as follows.

[0048] Experimental design and testing methods

[0049] 1. Experimental Materials and Grouping

[0050] Experimental materials: dark tea (produced in Jingyang, Shaanxi, grade 3), cellulase (activity ≥ 5000 U / g), papain (activity ≥ 8000 U / g), oat β-glucan (purity ≥ 70%), Aspergillus oryzae (CICC 2012), and Eurotium cristatum (CGMCC3.4668). All other reagents were of analytical grade.

[0051] Variable selection:

[0052] Variable A: activity ratio of cellulase to papain in the composite enzymatic hydrolysate (setting range: 1:1 to 3:1);

[0053] Variable B: Inoculum ratio of A. oryzae to E. turcicum (set range: (0.5-2) x 10 6 CFU / g: (2-8) x 10 5 CFU / g);

[0054] Variable C: Temperature of first stage of fractional drying (set range: 35-45℃).

[0055] Experimental group settings (a total of 10 groups, 3 repeats for each group):

[0056] Conventional group (1-5 groups): Variables A, B, and C are within the above-mentioned limited range, and the specific parameters are shown in Table 1.

[0057] Control group (6-9 groups): Single variable exceeds the limited range (such as variable A = 0.5:1 or 4:1, variable B inoculum ratio imbalance, variable C = 30℃ or 50℃);

[0058] Blank control group (10th group): Use existing technology (single cellulase hydrolysis, E. turcicum single strain fermentation, constant temperature drying at 50℃).

[0059] 2. Test standards and methods

[0060] Functional polysaccharide content: Referring to GB 5009.8-2016 "National Food Safety Standard Determination of Fructose, Glucose, Sucrose, Maltose, and Lactose in Foods", determined by high performance liquid chromatography (HPLC);

[0061] Total amino acid content: Referring to GB 5009.124-2016 "National Food Safety Standard Determination of Amino Acids in Foods", determined by amino acid automatic analyzer;

[0062] Sensory score: Referring to GB / T 9833.3-2013 "Compressed Tea Part 3: Fuzhuan Tea", scored by 5 professional tea tasters from four dimensions of appearance (20 points), soup color (20 points), aroma (30 points), and taste (30 points), and the average value was taken.

[0063] 3. Experimental results and data records

[0064] The experimental results were based on "functional polysaccharide content (mg / g)", "total amino acid content (mg / 100g)", and "sensory score (total score 100 points)" as core indicators, and the comprehensive score was calculated according to the weight of the three (40%, 30%, 30%).

[0065] The following is Table 1, the data record table.

[0066] Table 1, Data Record Table

[0067]

[0068]

[0069] Experimental results analysis

[0070] The data in the table show that the functional polysaccharide content (28.64-35.42 mg / g), total amino acid content (326.58-389.15 mg / 100 g) and comprehensive score (78.35-88.57) of the conventional groups (groups 1-5) were significantly better than those of the control group (groups 6-9) and the blank control group (group 10); among them, group 3 (enzyme activity ratio 2.5:1, inoculum size ratio 1.5×10 6 :6×10 5 , drying temperature 42°C) achieved the best overall performance, validating the synergistic effect of variables within their defined ranges. The control group, due to a single variable exceeding the range, saw a decrease in key indicators, demonstrating the practical technical significance of this protocol's parameter limits. The blank control group, using existing technology, achieved the lowest performance across all indicators, further demonstrating the protocol's technical effectiveness.

[0071] Molecular mechanism analysis of experimental data

[0072] 1. Effect of complex enzyme ratio (variable A) on performance and molecular mechanism

[0073] In the conventional group, when the ratio of cellulase to papain activity was in the range of 1:1 to 3:1, the content of functional polysaccharides and amino acids was significantly higher than that in the control group (e.g., group 3 vs groups 6 and 7).

[0074] The role of cellulase: Cellulase (such as endoglucanase and exoglucanase) can specifically hydrolyze the cellulose β-1,4 glycosidic bonds in the cell wall of dark tea, breaking the plant fiber skeleton and making the functional polysaccharides (such as tea polysaccharides and β-glucan) in the cell easier to dissolve;

[0075] Synergistic effect of papain: Papain promotes the decomposition of tea protein into small peptides and free amino acids by hydrolyzing peptide bonds in protein molecules (preferentially breaking arginine and phenylalanine residues), while reducing the turbidity of the tea soup. When the ratio of the two is 2.5:1 (Group 3), the efficiency of cellulase in destroying the cell wall and the efficiency of protease in hydrolyzing the protein are balanced. If the ratio of cellulase is too high (such as 4:1 in Group 7), the excess cellulase will competitively bind to the substrate and inhibit the activity of the protease. If the ratio is too low (such as 0.5:1 in Group 6), the cell wall decomposition is incomplete, limiting the release of intracellular substances.

[0076] 2. Regulation mechanism of the dual bacterial inoculum ratio (variable B) on metabolites

[0077] The inoculum ratio of Aspergillus oryzae to Eurotium cristatum (variable B) directly affected the metabolic pathways of the microbial community. 6 CFU / g) and Eurotium cristatum (2~8×10 5 CFU / g) ratio is 1.5×10 6 :6×10 5 (Group 3), the polysaccharide and amino acid contents were the highest, and its molecular mechanism was as follows:

[0078] The "precursor metabolism" role of Aspergillus oryzae: At the beginning of fermentation, Aspergillus oryzae secretes a large amount of amylase, protease and cellulase, which hydrolyzes macromolecular starch into glucose (providing a carbon source for Eurotium cristatum) and decomposes protein into amino acids (such as glutamic acid and phenylalanine). At the same time, it produces organic acids (such as citric acid) to adjust the pH of the microenvironment to 5.0-6.0, providing suitable conditions for the growth of Eurotium cristatum.

[0079] Functional metabolism of Eurotium cristatum: In the microenvironment created by Aspergillus oryzae, Eurotium cristatum converts glucose into extracellular polysaccharides (such as α-glucan) through glycolysis, and uses amino acids to synthesize umami substances (such as monosodium glutamate). 6 CFU / g, insufficient carbon source supply leads to limited metabolism of Eurotium cristatum; if it is too high (such as 2.0×10 6 CFU / g), it will compete with the cristatum for nitrogen sources, inhibiting its "golden flower" (fruiting body) formation and polysaccharide synthesis.

[0080] 3. Protection mechanism of drying temperature (variable C) on molecular structure and activity

[0081] The temperature of the first stage of staged drying (35-45°C) regulates product performance by affecting the thermal stability of molecules. When the third group used 42°C, the functional ingredients were best retained. The molecular reasons for this are:

[0082] Polysaccharide structural stability: The glycosidic bonds of functional polysaccharides (such as tea polysaccharides) are not easily broken at 35-45°C, but temperatures exceeding 50°C (such as 50°C for the blank control group) will cause the polysaccharide chains to depolymerize, resulting in a decrease in molecular weight (from 60,000-2,000,000 Daltons to <50,000 Daltons), and a decrease in water solubility and biological activity;

[0083] Retention of amino acids and flavor substances: At 42°C, the amino and carboxyl groups of amino acids (such as lysine and threonine) are less likely to undergo decarboxylation or oxidation reactions. However, too low a temperature (such as 30°C in the control group) will prolong the drying time, leading to secondary metabolism of microorganisms to produce odorous substances (such as volatile acids).

[0084] Balance between enzyme inactivation and microbial dormancy: 42°C can partially inactivate residual enzymes (such as polyphenol oxidase) (to avoid excessive oxidation of tea polyphenols), while inducing the formation of dormant spores of Eurotium cristatum and reducing the decomposition of metabolites, while high temperatures (such as 50°C) will directly destroy the spore structure, causing the "golden flower" morphology to collapse.

[0085] 4. The molecular nature of synergy and nonlinear relationships

[0086] In the experiment, group 3 (enzyme ratio 2.5:1, inoculum ratio 1.5×10 6 :6×10 5 , 42℃) has the best comprehensive performance, reflecting the nonlinear synergistic effect of multiple variables:

[0087] Enzymatic hydrolysis-fermentation coupling: The pretreatment of raw materials by complex enzymes (cell wall fragmentation, protein hydrolysis) provides a "molecular substrate library" (such as oligosaccharides and free amino acids) for dual bacterial metabolism, while the metabolites of the dual bacteria (such as organic acids and enzymes) react on the substrates, forming a cascade reaction of "enzymatic hydrolysis-microbial transformation";

[0088] Temperature-metabolic balance: At 42°C drying temperature, the molecular conformation of the enzymatic hydrolysis products (such as the helical structure of polysaccharides and the zwitterionic form of amino acids) is in a stable state and is in a stable state with the hydrated ions in the tea soup (such as Ca 2+ Mg 2+ ) form a hydrogen bond network, enhancing the "bodyiness" in the sensory score. This multi-factor interaction results in a non-linear relationship between performance and a single variable (for example, although the enzyme ratio of 3:1 in Group 4 is higher than that of Group 3, the overall score decreases), confirming the scientific validity of the parameter range.

[0089] In summary, the conventional group achieved the synergistic optimization of "efficient degradation of raw materials-directional metabolism by microorganisms-protection of product structure" at the molecular level through precise regulation of the ratio of complex enzymes, dual bacteria synergy and temperature gradient. Its core mechanism lies in the dynamic matching of enzymatic hydrolysis efficiency, microbial community balance and molecular thermal stability.

[0090] Example

[0091] Example 1

[0092] Preparation method:

[0093] (1) Dark tea processing: crush the dark tea into particles of 3 mm;

[0094] (2) Infiltration with composite enzymatic hydrolysate: Add composite enzymatic hydrolysate (cellulase to papain activity ratio of 1:1, total enzyme addition amount of 2% of the dry weight of the dark tea, containing 0.2% vitamin C) to the crushed dark tea, with a material-liquid ratio of 1:30 (g / mL), adjust the pH to 5.5 with acetic acid-sodium acetate buffer, hydrolyze at 55°C for 60 minutes, then heat at 95°C for 12 minutes to inactivate, and filter with a 100-mesh filter;

[0095] (3) Addition of oat β-glucan: Add 2% (w / v) oat β-glucan solution (purity 75%, molecular weight 1,000,000 Daltons) to the enzymatically hydrolyzed dark tea. The solution was prepared by dissolving oat β-glucan powder in deionized water at 65°C, stirring for 30 minutes until completely dissolved, and cooling to room temperature.

[0096] (4) Composting and fermenting: composting for 6 hours at a temperature of 32°C and a humidity of 80%;

[0097] (5) Pressing and shaping: Maintaining the pressure at 3 MPa for 30 seconds to produce a brick with a size of 35 cm × 18 cm × 5 cm;

[0098] (6) Double bacteria synergistic blooming: The bricks were inoculated with Aspergillus oryzae CICC 2012 strain (0.5×10 6 CFU / g dry tea) and Eurotium cristatum CGMCC 3.4668 strain (2×10 5 CFU / g dry tea), cultured for 9 days at 28°C (first 3 days), 32°C (4-8 days), 28°C (last 2 days), 80% humidity, ventilated twice a day (30 minutes each time), and maintained CO2 concentration <0.5%;

[0099] (7) Staged drying: First dry at 35°C and 45% relative humidity for 5 hours, then dry at 60°C and 35% relative humidity for 10 hours, using hot air circulation drying (wind speed 1.2 m / s) until the moisture content of the finished product is 7.5%.

[0100] The implementation contents of Examples 2 to 9 are consistent with those of Example 1, and the only difference is the variable values. To avoid redundancy, they are abbreviated below.

[0101] Example 2

[0102] In step (2), the activity ratio of cellulase to papain in the composite enzymatic hydrolysis solution is 2:1;

[0103] Step (6) Aspergillus oryzae inoculum size 1.0×10 6 CFU / g dry tea, inoculation amount of Eurotium cristatum is 4×10 5 CFU / g dry tea;

[0104] The drying temperature in the first stage of step (7) is 40°C.

[0105] Example 3

[0106] The activity ratio of cellulase to papain in the composite enzymatic hydrolysate of step (2) is 2.5:1;

[0107] Step (6) Aspergillus oryzae inoculum size 1.5×10 6 CFU / g dry tea, inoculation amount of Eurotium cristatum is 6×10 5 CFU / g dry tea;

[0108] The drying temperature in the first stage of step (7) is 42°C.

[0109] Example 4

[0110] The activity ratio of cellulase to papain in the composite enzymatic hydrolysis solution of step (2) is 3:1;

[0111] Step (6) Aspergillus oryzae inoculum size 1.8×10 6 CFU / g dry tea, inoculation amount of Eurotium cristatum is 7×10 5 CFU / g dry tea;

[0112] The drying temperature in the first stage of step (7) is 45°C.

[0113] Example 5

[0114] In step (2), the activity ratio of cellulase to papain in the composite enzymatic hydrolysis solution is 2:1;

[0115] Step (6) Aspergillus oryzae inoculum size 2.0×10 6 CFU / g dry tea, inoculation amount of Eurotium cristatum is 8×10 5 CFU / g dry tea;

[0116] The drying temperature in the first stage of step (7) is 40°C.

[0117] Example 6

[0118] The activity ratio of cellulase to papain in the composite enzymatic hydrolysate of step (2) is 0.5:1 (out of range);

[0119] Step (6) Aspergillus oryzae inoculum size 1.5×10 6 CFU / g dry tea, inoculation amount of Eurotium cristatum is 6×10 5 CFU / g dry tea;

[0120] The drying temperature in the first stage of step (7) is 42°C.

[0121] Example 7

[0122] The activity ratio of cellulase to papain in the composite enzymatic hydrolysate in step (2) is 4:1 (out of range);

[0123] Step (6) Aspergillus oryzae inoculum size 1.5×10 6 CFU / g dry tea, inoculation amount of Eurotium cristatum is 6×10 5 CFU / g dry tea;

[0124] The drying temperature in the first stage of step (7) is 42°C.

[0125] Example 8

[0126] The activity ratio of cellulase to papain in the composite enzymatic hydrolysate of step (2) is 2.5:1;

[0127] Step (6) Aspergillus oryzae inoculum size 0.3×10 6 CFU / g dry tea (out of range), inoculation amount of Eurotium cristatum is 6×10 5 CFU / g dry tea;

[0128] The drying temperature in the first stage of step (7) is 42°C.

[0129] Embodiment 9

[0130] The activity ratio of cellulase to papain in the composite enzymatic hydrolysate of step (2) is 2.5:1;

[0131] Step (6) Aspergillus oryzae inoculum size 1.5×10 6 CFU / g dry tea, inoculation amount of Eurotium cristatum is 10×10 5 CFU / g dry tea (out of range);

[0132] The drying temperature in the first stage of step (7) is 42°C.

[0133] Example 10 (blank control group)

[0134] Preparation method:

[0135] (1) Dark tea processing: crush the dark tea into particles of 3 mm;

[0136] (2) Single enzymatic hydrolysis treatment: Add cellulase solution (enzyme addition amount is 2% of the dry weight of the dark tea) to the crushed dark tea, with a solid-liquid ratio of 1:30 (g / mL), pH 5.5, enzymatic hydrolysis at 55°C for 60 minutes, inactivation at 95°C for 12 minutes, and then filtration;

[0137] (3) No oat β-glucan was added, and the fermentation was carried out directly: the fermentation was carried out at a temperature of 32°C and a humidity of 80% for 6 hours;

[0138] (4) Pressing and shaping: press at 3 MPa for 30 seconds to make bricks with a size of 35 cm × 18 cm × 5 cm;

[0139] (5) Single-bacteria fermentation: Only the CGMCC 3.4668 strain of Eurotium cristatum was inoculated (inoculation volume 5×10 5 CFU / g dry tea), cultured at 30°C and 80% humidity for 9 days;

[0140] (6) Constant temperature drying: Dry at 50°C for 16 hours with a wind speed of 1.2 m / s until the finished product has a moisture content of 7.5%.

[0141] Specific working process

[0142] After the dark tea is crushed, a composite enzymatic solution composed of cellulase and papain is added for soaking. Cellulase disintegrates the plant cell wall structure by hydrolyzing the β-1,4 glycosidic bonds in the cellulose molecules, releasing intracellular polysaccharides and proteins. At the same time, papain breaks the protein peptide bonds to generate small molecular peptides and free amino acids. The enzyme activity is then inactivated by heating and the residue is removed by filtration. Oat β-glucan solution is added to the enzymatically hydrolyzed material. The β-glucan molecules form a composite system with tea polysaccharides through hydrogen bonds, which improves the colloidal stability of the system. The mixed material is subjected to composting and fermentation. In the initial stage, Aspergillus oryzae secretes amylase to hydrolyze starch into glucose and secretes protease. The white enzyme further decomposes the protein into amino acids and produces organic acids to regulate the pH value of the microenvironment; the materials after the fermentation are pressed into bricks and inoculated with Aspergillus oryzae and Eurotium cristatum. The glucose produced by the metabolism of Aspergillus oryzae provides a carbon source for Eurotium cristatum, promoting it to synthesize α-glucan through the glycolysis pathway. The two bacteria form a synergistic symbiotic relationship through the cross-supply of metabolites; the bricks after the blooming are dried in stages. The low-temperature drying in the first stage gradually inactivates the microbial metabolic enzymes and reduces the thermal depolymerization of the polysaccharide chains. The high-temperature drying in the second stage promotes water evaporation while retaining small-molecule flavor substances. Finally, the synergistic optimization of functional ingredients and sensory quality is achieved through gradient temperature and humidity control.

[0143] The various technical features described in the above exemplary embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the various technical features in the above exemplary embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

Claims

1. A Jingyang Fuzhuan tea, characterized by: Raw materials: dark tea crushed to a particle size of 2-5 mm, and oat beta-glucan added in an amount of 6%-10% of the dry weight of the dark tea; the oat beta-glucan has a purity of ≥70% on a dry basis and a molecular weight of 60,000-2,000,000 Daltons; Fermentation: Microorganisms include Aspergillus oryzae and Eurotium cristatum, with inoculation amounts of (0.5-2)×10 6 CFU / g dry tea and (2-8)×10 5 CFU / g dry tea.

2. The Jingyang Fuzhuan tea according to claim 1, wherein: The oat beta-glucan has a moisture content of ≤5.0%, an ash content of ≤8.0%, and a hydroxyl functional group density of 1.0-1.5 mmol / g.

3. The Jingyang Fuzhuan tea according to claim 1, wherein: The Aspergillus oryzae is a CICC 2012 strain, and the Eurotium cristatum is a CGMCC 3.4668 strain.

4. The Jingyang Fuzhuan tea according to claim 1, wherein: The dark tea is treated with a composite enzymatic hydrolysis solution containing cellulase and papain with an activity ratio of 1:1 to 3:1, and the total enzyme addition amount is 1.5%-3% of the dry weight of the dark tea.

5. The Jingyang Fuzhuan tea according to claim 4, characterized in that: The composite enzymatic hydrolysis solution also includes 0.1%-0.3% vitamin C as an enzyme protective agent.

6. A method for preparing Jingyang Fuzhuan tea, based on the Jingyang Fuzhuan tea according to any one of claims 1 to 5, characterized in that: The following steps are involved: (1) Dark tea processing: crush the dark tea into particles of 2-5 mm; (2) Infiltration with composite enzymatic hydrolysate: Add composite enzymatic hydrolysate to the crushed dark tea at a material-liquid ratio of 1:20 to 1:40 (g / mL), perform enzymatic hydrolysis at pH 5.0-6.0 and 50-60°C for 40-80 minutes, inactivate, and filter; (3) Adding oat β-glucan: adding oat β-glucan solution with a concentration of 1.5%-3% (w / v) to the enzymatically hydrolyzed dark tea; (4) Composting and fermenting: composting for 4-8 hours at a temperature of 28-35°C and a humidity of 75-85%; (5) Pressing and shaping: Maintaining pressure at 2-4 MPa for 20-40 seconds to produce bricks with specifications of 30-40 cm × 15-20 cm × 4-6 cm; (6) Double bacteria synergistic flowering: Inoculate Aspergillus oryzae and Eurotium cristatum into the bricks and culture them at a temperature of 25-35°C and a humidity of 70-90% for 6-12 days; (7) Staged drying: First dry at 35-45℃ for 4-6 hours, then dry at 55-65℃ for 8-12 hours until the moisture content of the finished product is ≤8%.

7. The method for preparing Jingyang Fuzhuan tea according to claim 6, wherein: The cellulase activity of the composite enzymatic hydrolysate in step (2) is 1×10 5 -3×10 5 U / g, papain activity is 2-4×10 5 U / g; the pH was adjusted with acetic acid-sodium acetate buffer, and after enzymatic hydrolysis, the enzyme was filtered with a 100-mesh filter. The inactivation condition was heating at 90-100°C for 8-15 minutes.

8. The method for preparing Jingyang Fuzhuan tea according to claim 6, wherein: The oat β-glucan solution in step (3) is prepared by dissolving oat β-glucan powder in deionized water at 60-70° C., stirring for 20-40 minutes until completely dissolved, and cooling to room temperature.

9. The method for preparing Jingyang Fuzhuan tea according to claim 6, wherein: The temperature control for the dual-bacteria collaborative flowering in step (6) is: 25-30°C for the first 3 days, 30-35°C for the 4th to 8th days, and 25-30°C for the last 2 days; ventilation is performed 1-3 times a day, each time for 20-40 minutes, and the CO2 concentration is maintained at <0.5%.

10. The method for preparing Jingyang Fuzhuan tea according to claim 6, wherein: The relative humidity of the staged drying in step (7) is controlled as follows: 40-50% in the first stage and 30-40% in the second stage; hot air circulation drying is adopted, and the wind speed is controlled at 1.0-1.5 m / s.

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