Fermentation processing method and production equipment system for kungfu black tea

Abstract

A kind of fermentation processing method and production equipment system of Gongfu black tea, the Gongfu black tea is formed tea mixture by adding lophatherum gracile, dried tangerine or orange peel and jasmine petals in tea leaves, withering, fermentation, shaping and drying, the fermentation includes pre-fermentation and complete fermentation, wherein pre-fermentation is the self-oxidation fermentation of tea leaves, complete fermentation is microbial fermentation, specifically, first step fermentation is carried out by using acetic acid bacteria and enterococcus faecalis to form compound microbial inoculant, then abnormal hansenula is added to carry out second step fermentation.In the present application, the differences in raw material fermentation process of each component during fermentation are overcome, which leads to the problems of sour and stale taste, etc.in tea leaves.The types and content of aroma substances are increased, and the problem of insufficient infusion resistance of loose tea is solved.The Gongfu black tea prepared by the present application has red and bright golden ring tea soup color, the ratio of teaflavins, theabrownins and thearubigins is coordinated, so that the tea soup is sweet and smooth with honey aroma when entering the mouth, and the aroma is long-lasting in cold cup.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of black tea preparation process and equipment system, and particularly relates to a fermentation processing method and production equipment system of Gongfu black tea. BACKGROUND

[0002] Black tea belongs to one of the six tea categories and is a fully fermented tea, which has the special quality of tea red, soup red and liquid red, thus is named "black tea". Chinese black tea includes Gongfu black tea, black broken tea and small species black tea, and the preparation methods of the teas are similar. Black tea contains vitamins, caffeine, hydroxy acids, minerals, polysaccharides, tea polyphenols and other nutrients and functional ingredients. Studies have shown that black tea has the effect of assisting in reducing blood sugar, blood pressure and blood lipids. Tea pigments in black tea have the effects of antioxidant, anti-tumor, anti-inflammatory and antibacterial, anti-mutation, anti-virus and deodorization.

[0003] Black tea is named after the tea-making process, rather than a single tea variety. The traditional preparation process of black tea includes four processes of withering, rolling, fermentation and drying, and fermentation is the key process of black tea processing. During the fermentation process, tea polyphenols in tea undergo oxidation reaction to form colored substances such as theaflavins and thearubigins, which make the tea leaves present the characteristics of red soup and red leaves. This unique process makes the tea have obvious differences in quality and taste from other teas, such as unfermented green tea and semi-fermented oolong tea.

[0004] Lophatherum gracile Brongn. belongs to a perennial herb and is recorded as a medicinal plant in Bencao Gangmu and other classics, with a sweet taste and cold nature, and the effects of clearing heat and reducing fire, generating saliva and relieving thirst, and promoting urination and relieving stranguria, and is often used to relieve heat symptoms (such as sores on the tongue and mouth, and short and reddish urine) or summer heat. In southern China, there is a habit of boiling or brewing bamboo leaves, especially in summer as a refreshing drink, with a light taste and natural grassy or bamboo leaf fragrance. Lophatherum gracile Pericarpium Citri Reticulatae is the pericarp of mature citrus fruits. Pericarpium Citri Reticulatae is warm in nature and bitter and acrid in taste, and is related to the spleen and stomach meridians, and can relieve abdominal distension, loss of appetite, nausea and vomiting caused by spleen and stomach qi stagnation. Drinking the tea can promote gastrointestinal peristalsis and improve indigestion, and is especially suitable for people with postprandial abdominal distension or qi stagnation type stomach pain. In addition, it is rich in flavonoids (such as hesperidin and quercetin), has anti-inflammatory and antioxidant effects, and may reduce the risk of chronic inflammation and assist in regulating metabolism (such as blood sugar and blood lipids).

[0005] Therefore, it is considered to add Lophatherum gracile Brongn. and Pericarpium Citri Reticulatae to the tea leaves of black tea to make Gongfu black tea, so as to increase the nutritional value of black tea.

[0006] SUMMARY The present application aims to provide a fermentation processing method and production system of Gongfu black tea.

[0007] The present application aims to provide a fermentation processing method and production system of Gongfu black tea.

[0008] Another object of the present application is to provide the Gongfu black tea with high nutrition, high quality and rich taste, which is mainly made of large-leaf tea.

[0009] The object of the present application is achieved by the following technical solutions.

[0010] The fermentation processing method of the Gongfu black tea is characterized in that: the Gongfu black tea is formed by adding lophatherum gracile, dried tangerine or orange peel and jasmine petals to tea leaves to form a tea mixture, withering, fermentation, shaping and drying, wherein the fermentation includes pre-fermentation and complete fermentation, the pre-fermentation is self-oxidation fermentation of the tea leaves, and the complete fermentation is microbial fermentation, specifically, a composite microbial agent composed of acetic acid bacteria and Enterococcus faecium is used for the first-step fermentation, and then abnormal Hansenula yeast is added for the second-step fermentation. Acetobacter sp. ) and Enterococcus faecium ( Enterococcus faecium ) to form a composite microbial agent for the first-step fermentation, and then abnormal Hansenula yeast ( Hansenula anomala ) is added for the second-step fermentation.

[0011] The fermentation processing production equipment system of the Gongfu black tea is composed of withering machines, fermentation boxes, steam generators, shaping molds, hydraulic machines and hot air drying machines used for withering, fermentation, shaping and drying, specifically, the tea mixture is placed in a withering tank for withering, then transferred to a fermentation box, pre-fermented, then added with the composite microbial agent for complete fermentation, placed in a steaming basket after the fermentation is completed, the valve of the steam generator is opened to pass in steam, the mixture is placed in the shaping mold after becoming soft, the tea cake is pressed by using the hydraulic equipment, finally the tea cake is moved to the hot air drying chamber for drying to obtain the Gongfu black tea.

[0012] Further, in the tea mixture, the tea is 100-120 parts, the jasmine petals are 2-4 parts, the lophatherum gracile is 8-10 parts, and the dried tangerine or orange peel is 3-5 parts by weight, wherein the tea is any one of Yunnan large-leaf species, Hainan large-leaf species or Qimen large-leaf species.

[0013] Further, the first-step fermentation is that the intermediate product obtained after pre-fermentation is twisted, the composite microbial agent composed of acetic acid bacteria and Enterococcus faecium is added to the surface of the intermediate product, and the fermentation is carried out at a temperature of 28-30℃ and a relative humidity of 85-92% for 1-2 hours.

[0014] Further, the acetic acid bacteria and Enterococcus faecium in the composite microbial agent are composed according to a mass ratio of live bacteria of 1:1-2, and the mass ratio of the total number of live bacteria of the intermediate product and the composite microbial agent is 100:0.2-0.3.

[0015] Further, the second-step fermentation is that the abnormal Hansenula yeast is added after the first-step fermentation is completed, sealed in a suitable container, and continuously fermented at a temperature of 25-28℃ and a relative humidity of 75-85% for 3-4 hours.

[0016] Further, in the second fermentation, the mass ratio of the intermediate product to the viable number of Hansenula polymorpha is 100:0.5-0.7.

[0017] Further, the pre-fermentation is carried out at a temperature of 30-32°C and a relative humidity of 45-50% for 1-2 hours.

[0018] Further, the shaping is carried out by softening the completely fermented tea leaves with steam at 80-90°C for 30-40 seconds, and then pressing the tea leaves into a mold at a pressure of 5-7 kg / cm2 to form a tea cake with a diameter of 8-10 cm and a thickness of 1.2-1.5 cm.

[0019] Further, the drying is carried out by first placing the tea cake in a hot air circulation oven at 50-55°C for 1 hour, and then placing the tea cake in a vacuum drying oven at 30-35°C, with a vacuum degree of -0.05 to -0.08 MPa, for 10-12 hours to ensure that the product has a water content of 1-3%, and then taking out the product to obtain the finished product.

[0020] A fermentation processing method of Gongfu black tea, characterized in that the method comprises the following steps:

[0021] (1) Tea leaf pretreatment: Yunnan large-leaf species, Hainan large-leaf species or Qimen species are selected as the main material of black tea, one-bud-two-leaf fresh leaves are picked, the length of the leaves is 3-4 cm, the tenderness is uniform, and there is no disease and insect pests, the fresh leaves are cleaned and naturally dried, the tea leaves are taken according to the formula, and formula amount of jasmine petals, lophatherum gracile and dried orange peel (cut into 2-3 cm long and 0.3-0.5 cm wide) are added, and then the tea leaf mixture is obtained and reserved;

[0022] (2) Withering and pre-fermentation: the tea leaf mixture obtained in step 1 is placed on a bamboo sieve and spread to a thickness of 1-2 cm, withered for 6-8 hours at a temperature of 25-28°C and a relative humidity of 65-75%, so that the leaves are soft, and then transferred to a pre-fermentation environment at a temperature of 30-32°C and a relative humidity of 45-50% for 1-2 hours to obtain an intermediate product, which is reserved;

[0023] (3) Complete fermentation: the intermediate product obtained in step (2) is rolled and stacked to a thickness of 12-16 cm, a compound microbial agent is added to the surface of the intermediate product, and wet cotton cloth is covered on the surface, and then the mixture is fermented at a temperature of 28-30°C and a relative humidity of 85-92% for 1-2 hours, taken out, mixed uniformly, and then Hansenula polymorpha is added, and the mixture is sealed in a suitable container and further fermented at a temperature of 25-28°C and a relative humidity of 75-85% for 3-4 hours to obtain fermented tea leaves; the compound microbial agent is composed of acetic acid bacteria and Enterococcus faecium at a viable number mass ratio of 1:1-2; the mass ratio of the total viable number of the compound microbial agent to the intermediate product in step 2 is 100:0.2-0.3; and the mass ratio of the viable number of Hansenula polymorpha to the intermediate product is 100:0.5-0.7.

[0024] (4) Shaping: After fermentation, the tea leaves are softened by steam at 80-90°C for 30-40 seconds, and then pressed into a suitable mold at a pressure of 5-7 kg / cm2 to form a round cake with a diameter of 8-10 cm and a thickness of 1.2-1.5 cm;

[0025] (5) Drying: first placed in a hot air circulating oven at 50-55°C for 1 hour; then taken out and placed in a vacuum drying oven at 30-35°C, with a vacuum degree of -0.05 to -0.08 MPa, dried for 10-12 hours to ensure that the product contains 1-3% of water, and then taken out to obtain the finished product Gongfu black tea.

[0026] In the present application, through two-stage drying treatment, the surface moisture can be quickly determined and removed, and the vacuum reduced pressure drying can reduce the volatilization of aromatic substances (such as jasmonate, benzyl phenylacetate, etc. in jasmine flowers) and effective components (such as limonene, aurantiamarin, etc. in pericarpium citri reticulatae), so as to retain the original flavor and nutritional value.

[0027] In the present application, jasmine petals, lophatheri herba and pericarpium citri reticulatae are added to improve the nutritional value of black tea, but these components will have adverse effects on the sensory quality of black tea in the traditional complete self-oxidation fermentation process. Specifically, the differences in water content of various components cause the tea leaves to stick and clump during fermentation, making it difficult to dissipate heat, causing a sudden rise in local temperature, resulting in the "burning heart" phenomenon (leaf bottom becomes focused, producing a burnt taste); secondly, since lophatheri herba, jasmine petals and pericarpium citri reticulatae do not contain tea polyphenols and have large differences in cell structure, the fermentation process is different, some parts are not fully oxidized, and some components are over-oxidized, making it difficult to control the fermentation process; in the absence of tea polyphenols for self-oxidation, relying on the self-oxidation fermentation of the main tea leaves will cause lophatheri herba, jasmine petals and other components to easily appear rancidity, mold and other problems, producing sour and stale flavors. The components of lophatheri herba and pericarpium citri reticulatae, such as sinomenine, may generate phenolic derivatives during a long period of self-oxidation fermentation, increasing the astringency or irritation of the tea soup and masking the sweet and mellow taste of black tea itself.

[0028] Therefore, after a short pre-fermentation (self-oxidation process) treatment, the present application adds microorganisms for specific fermentation treatment, so that the system reaches complete fermentation, and the fermentation flavor of the tea mixture is adjusted, solving the problem of taste and quality decline caused by the addition of lophatheri herba, pericarpium citri reticulatae and jasmine petals.

[0029] In the first step of fermentation of the mixed raw materials, acetic acid bacteria fermentation is the dominant action, Enterococcus faecium grows slowly, the pH of the fermentation system is adjusted as a whole, and the fermentation nutrient environment more conducive to yeast growth is created through metabolic differences. After the addition of Hansenula anomala, rapid and sustained fermentation can be achieved, acetic acid bacteria continue to oxidize, and Enterococcus faecium grows rapidly. In this process, Enterococcus faecium maintains the acidic environment of the fermentation system, so that the three form a stable symbiotic system. In the second step of fermentation, Hansenula anomala dominates sugar conversion, decomposes the sugar in tea into alcohol and carbon dioxide, and generates flavor substances such as esters and alcohols, giving black tea a rich taste and fruity aroma; the ethanol produced by metabolism provides raw materials for further oxidation of acetic acid bacteria, which can convert the alcohol produced by yeast into acetic acid, forming the unique sour taste of black tea. At the same time, the ethanol produced by the yeast can undergo esterification with the acetic acid, lactic acid and other substances produced in the first step of fermentation to generate ester substances with special aroma, further enriching the aroma and flavor of black tea and avoiding excessive alcohol aroma in tea, thereby synergistically enhancing the aroma levels; on the other hand, Enterococcus faecium metabolizes to produce lactic acid, regulates the pH of the fermentation system, inhibits the reproduction of harmful bacteria (such as Escherichia coli), and prolongs the shelf life. The soft sour taste of lactic acid, combined with acetic acid and tea polyphenols, balances the overall taste of black tea. In the second step of fermentation, as Hansenula anomala grows and metabolizes, and the growth and metabolism of Enterococcus faecium intensify, the metabolic process of acetic acid bacteria is gradually restricted, thereby achieving the effect of comprehensively regulating the flavor of tea, making the tea soup strong, fresh and long-lasting.

[0030] Theaflavins are the main components that make black tea soup "bright", and thearubigins are the main components that make black tea soup "red". Their formation gives black tea its red soup, red leaves, and sweet and mellow aroma. During fermentation, Hansenula anomala and acetic acid bacteria metabolize to produce antioxidant components such as tea polyphenols and polysaccharides, and promote the oxidation and polymerization of tea polyphenols to form colored substances such as theaflavins and thearubigins; the short-chain fatty acids (such as butyric acid) produced by Enterococcus faecium and the acidic environment of acetic acid bacteria together promote the balance of intestinal flora and enhance immunity; during fermentation, the three bacteria synergistically decompose macromolecular substances (such as proteins and cellulose) in tea, releasing small molecule nutrients such as amino acids and vitamin B, and improving absorption.

[0031] A Gongfu black tea made from large-leaf tea, with lophatherum gracile, dried tangerine or orange peel, and jasmine petals, is pre-fermented after withering, then fully fermented, shaped, and dried. The pre-fermentation is a self-oxidation fermentation of the tea, and the full fermentation is a microbial fermentation, specifically a first step of fermentation using a composite microbial agent composed of acetic acid bacteria and Enterococcus faecium, followed by a second step of fermentation with the addition of Hansenula anomala.

[0032] Further, in the tea mixture, tea is 100-120 parts by weight, jasmine petals are 2-4 parts by weight, lophatherum gracile is 8-10 parts by weight, and dried tangerine or orange peel is 3-5 parts by weight, wherein the tea is any one of Yunnan large-leaf species, Hainan large-leaf species or Qimen species.

[0033] Further, the first step fermentation is that after rubbing and twisting the intermediate product obtained after pre-fermentation, the complex microbial agent composed of acetic acid bacteria and Enterococcus faecium is added to the surface of the intermediate product, and the fermentation is carried out at a temperature of 28-30 DEG C and a relative humidity of 85-92% for 1-2 hours.

[0034] Further, in the complex microbial agent, the acetic acid bacteria and Enterococcus faecium are composed according to a mass ratio of 1:1-2 of viable bacterial number, and the mass ratio of the total viable bacterial number of the intermediate product and the complex microbial agent is 100:0.2-0.3.

[0035] Further, the second step fermentation is that after the first step fermentation is completed, abnormal Hansenula is added, and the mixture is sealed in a suitable container and placed in a suitable container, and the fermentation is continued for 3-4 hours under the condition of a temperature of 25-28 DEG C and a relative humidity of 75-85%.

[0036] Further, in the second step fermentation, the mass ratio of the viable bacterial number of the intermediate product and the normal Hansenula is 100:0.5-0.7.

[0037] Further, the pre-fermentation is carried out in an environment with a temperature of 30-32 DEG C and a relative humidity of 45-50% for 1-2 hours.

[0038] Further, the shaping is that the tea leaves after complete fermentation are softened by steam at 80-90 DEG C for 30-40 seconds, and then pressed into a suitable mold under a pressure of 5-7 kg / cm2 to form a round cake with a diameter of 8-10 cm and a thickness of 1.2-1.5 cm.

[0039] Further, the drying is that the tea cake is first placed in a hot air circulation oven at 50-55 DEG C and dried for 1 hour, then taken out and placed in a vacuum drying oven at 30-35 DEG C, and the vacuum degree is set to-0.05 to-0.08 MPa, and the drying is carried out for 10-12 hours to ensure that the product has a water content of 1-3%, and the finished product is obtained after taking out.

[0040] The present application has the following technical effects:

[0041] This invention incorporates bamboo leaves, dried tangerine peel, and jasmine petals into tea leaves. Through further microbial fermentation following the tea's auto-oxidative fermentation, it overcomes the problem of uneven fermentation processes among components, which can lead to sour, musty, or overly astringent tastes in the tea, masking the inherent sweetness and mellowness of black tea. This process increases the variety and content of aroma compounds and addresses the industry pain point of insufficient brewing endurance in loose-leaf tea. The resulting black tea, made using this process, produces a vibrant red liquor with a golden ring, a sweet and honey-like taste, and a long-lasting aroma even when cold. The product contains more than 1.5% theaflavins and over 15% thearubigins, with a harmonious ratio of theaflavins, thearubigins, and theabrownins, resulting in a fragrant flavor that is worthy of promotion. Attached Figure Description

[0042] Figure 1 Image of the Kung Fu black tea prepared in Example 3 of this invention.

[0043] Figure 2 Images of the tea infusion after one brewing of the black tea prepared in Example 3 and Comparative Example 3 of this invention.

[0044] Figure 3 Images of the tea infusion after six infusions of the Kung Fu black tea prepared in Example 3 and Comparative Example 3 of this invention. Detailed Implementation

[0045] The present invention will be specifically described below through embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Those skilled in the art can make some non-essential improvements and adjustments to the present invention based on the above description.

[0046] The microorganisms used in this invention are as follows:

[0047] Abnormal Hansenula polymorpha ( Hansenula anomala The accession number is GDMCC NO.: 2.19, Enterococcus faecalis ( Enterococcus faecium The accession number is GDMCC NO.: 1.130, and the acetic acid bacteria ( Acetobacter sp. The accession number is GDMCC NO.: 1.152, and all of them were purchased from the Guangdong Provincial Microbial Culture Collection Center (GDMCC).

[0048] Example 1

[0049] A fermentation processing method for Kung Fu black tea, characterized by comprising the following steps:

[0050] (1) Tea pretreatment: Hainan large-leaf variety is selected as the main material for black tea. One-bud two-leaf fresh leaves with a length of 3-4 cm are picked, and the leaves are required to be uniform in tenderness and free of pests and diseases. After cleaning, the leaves are naturally air-dried. The tea leaves are taken according to the formula amount, and the formula amount of jasmine petals, linden leaves and dried tangerine peel (cut into 2-3 cm long and 0.3-0.5 cm wide) is added. The tea mixture is mixed and prepared for use. According to the weight parts, the tea leaves are 110 parts, the jasmine petals are 3 parts, the linden leaves are 9 parts, and the dried tangerine peel is 3 parts.

[0051] (2) Withering and pre-fermentation: the tea mixture in step 1 is placed on a bamboo sieve and spread to a thickness of 1-2 cm. It is placed in an environment with a temperature of 25-28°C and a relative humidity of 65-75% for withering for 6 hours to make the leaves soft. Then it is transferred to an environment with a temperature of 30-32°C and a relative humidity of 45-50% for 1 hour to obtain an intermediate product for use.

[0052] (3) Complete fermentation: the intermediate product in step (2) is rolled and stacked to a thickness of 12-16 cm. A compound microbial agent is added to the surface of the intermediate product, and a wet cotton cloth is covered on the surface. Fermentation is carried out at a temperature of 28-30°C and a relative humidity of 85-92% for 2 hours. After taking out, the product is mixed evenly, and abnormal Hansenula yeast is added. It is placed in a suitable container and sealed, and then it is continuously fermented at a temperature of 25-28°C and a relative humidity of 75-85% for 3 hours. The compound microbial agent is composed of acetic acid bacteria and Enterococcus faecium with a mass ratio of viable bacterial numbers of 1:1. The mass ratio of the total number of viable bacteria of the intermediate product in step 2 to the compound microbial agent is 100:0.2. The mass ratio of the number of viable bacteria of the intermediate product in step 2 to the Hansenula yeast is 100:0.5.

[0053] (4) Shaping: After fermentation, the tea leaves are softened with steam at 80°C for 40 seconds, and then they are pressed into a suitable mold at a pressure of 5 kg / cm² to form a round cake with a diameter of 8 cm and a thickness of 1.2-1.5 cm.

[0054] (5) Drying: First, it is placed in a hot air circulation oven at 55°C and dried for 1 hour. Then it is taken out and placed in a vacuum drying oven at 30°C. The vacuum degree is set to -0.05 to -0.08 MPa, and it is dried for 10 hours to ensure that the product contains 1-3% of water. The finished product is obtained after taking it out.

[0055] Example 2

[0056] A fermentation processing method of Kungfu black tea, characterized by comprising the following steps:

[0057] (1) Tea pretreatment: Yunnan large-leaf species is selected as the main material of black tea, one bud and two leaves of fresh leaves are picked, the length of the leaves is 3-4 cm, the tenderness is uniform, and there is no disease and insect pests, the fresh leaves are cleaned and naturally dried, tea leaves are taken according to the formula amount, jasmine petals, lophatherum gracile and dried orange peel (cut into 2-3 cm long and 0.3-0.5 cm wide) are added according to the formula amount, and a tea mixture is obtained, which is used for standby, according to the weight part, the tea is 100 parts, the jasmine petals are 4 parts, the lophatherum gracile is 10 parts, and the dried orange peel is 5 parts;

[0058] (2) Withering and pre-fermentation: the tea mixture in step 1 is placed on a bamboo sieve and spread to a thickness of 1-2 cm, and then placed in an environment with a temperature of 25-28℃ and a relative humidity of 65-75% for withering for 6-8 hours to make the leaves soft, and then transferred to an environment with a temperature of 30-32℃ and a relative humidity of 45-50% for 1.5 hours to obtain an intermediate product, which is used for standby;

[0059] (3) Complete fermentation: the intermediate product in step (2) is rolled and stacked to a thickness of 12-16 cm, a compound microbial agent is added to the surface of the intermediate product, and wet cotton cloth is covered on the surface, and then fermented at a temperature of 28-30℃ and a relative humidity of 85-92% for 1.5 hours, and then taken out, mixed uniformly, added with an abnormal Hansenula yeast, and then sealed in a suitable container and placed in an environment with a temperature of 25-28℃ and a relative humidity of 75-85% for further fermentation for 3.5 hours; the compound microbial agent is composed of acetic acid bacteria and Enterococcus faecium with a mass ratio of viable bacteria number of 1:2; the mass ratio of the total number of viable bacteria of the intermediate product in step 2 and the compound microbial agent is 100:0.3; the mass ratio of the number of viable bacteria of the intermediate product in step 2 and the Hansenula yeast is 100:0.7;

[0060] (4) Shaping: the fermented tea is softened by steam at 90℃ for 30 seconds, and then pressed into a suitable mold at a pressure of 7 kg / cm² to form a round cake with a diameter of 10 cm and a thickness of 1.2-1.5 cm;

[0061] (5) Drying: first placed in a hot air circulation oven at 55℃ for 1 hour, then taken out and placed in a vacuum drying oven with a vacuum degree of-0.05~-0.08 MPa for 12 hours to ensure that the product contains 1%-3% of water, and then taken out to obtain the finished product.

[0062] Example 3

[0063] A fermentation processing method of Gongfu black tea, characterized by comprising the following steps:

[0064] (1) Tea pretreatment: Yunnan large-leaf species is selected as the main material for black tea. One bud and two leaves of fresh tea leaves are picked, with a leaf length of 3-4 cm, and the requirements are uniform tenderness and no pests and diseases. After cleaning, the tea leaves are naturally dried. The tea leaves are taken according to the formula amount, and the formula amount of jasmine petals, linden leaves and dried orange peel (cut into 2-3 cm long and 0.3-0.5 cm wide) is added. The tea mixture is mixed and prepared for use. According to the weight part, the tea leaves are 120 parts, the jasmine petals are 2 parts, the linden leaves are 8 parts, and the dried orange peel is 4 parts.

[0065] (2) Withering and pre-fermentation: the tea mixture in step 1 is placed on a bamboo sieve and spread to a thickness of 1-2 cm. It is placed in an environment with a temperature of 25-28°C and a relative humidity of 65-75%, and withered for 6-8 hours to make the leaves soft. Then it is transferred to an environment with a temperature of 30-32°C and a relative humidity of 45-50% for 2 hours to obtain an intermediate product for use.

[0066] (3) Complete fermentation: the intermediate product in step (2) is rolled and stacked to a thickness of 12-16 cm. A composite microbial agent is added to the surface of the intermediate product, and a wet cotton cloth is covered on the surface. It is fermented at a temperature of 28-30°C and a relative humidity of 85-92% for 1 hour. After taking it out, it is mixed evenly, and abnormal Hansenula yeast is added. It is placed in a suitable container and sealed, and is continuously fermented at a temperature of 25-28°C and a relative humidity of 75-85% for 4 hours. The composite microbial agent is composed of acetic acid bacteria and Enterococcus faecium with a mass ratio of viable bacteria of 1:1.5. The mass ratio of the total number of viable bacteria of the intermediate product in step 2 and the composite microbial agent is 100:0.25. The mass ratio of the number of viable bacteria of the intermediate product in step 2 and the Hansenula yeast is 100:0.6.

[0067] (4) Shaping: after fermentation, the tea leaves are softened with steam at 85°C for 35 seconds, and are pressed into a suitable mold at a pressure of 6 kg / cm² to form a round cake with a diameter of 9 cm and a thickness of 1.2-1.5 cm.

[0068] (5) Drying: first, it is placed in a hot air circulating oven at 50°C and dried for 1 hour (initially determined and remove surface moisture); take it out and place it in a vacuum drying oven at 35°C, set the vacuum degree to -0.05~-0.08 MPa, and dry for 10 hours to ensure that the product contains 1%-3% water. The finished product is obtained.

[0069] Comparative Example 1

[0070] Compared with Example 3, in the complete fermentation process, yeast is first used for the first step of fermentation, and then a composite microbial agent is used for the second step of fermentation. The remaining steps are the same as those of Example 3.

[0071] Comparative Example 2

[0072] Compared with Example 3, in the complete fermentation process, first step fermentation is carried out by single acetic acid bacteria, and second step fermentation is carried out by common Hansenula. The remaining steps are the same as Example 3. (That is, Enterococcus faecalis is used in the fermentation process).

[0073] Comparative Example 3

[0074] Compared with Example 3, after the complete fermentation is finished, the drying treatment is directly carried out, and the shaping is not carried out.

[0075] Effect verification:

[0076] (I) The appearance, soup color, aroma, taste and leaf bottom of Gongfu black tea in Example 1-3 and Comparative Example 1-3 are described and scored by using traditional expert sensory evaluation (evaluation standard refers to GB / T 23776 2018), and single Yunnan large-leaf tea is used as raw material, Gongfu black tea produced according to the process of Example 3 is set as control group 1, and Gongfu black tea produced by using single Yunnan large-leaf tea and through traditional self-oxidation fermentation (fermentation relative humidity is 90%, fermentation time is 3h) without microbial fermentation and the remaining steps consistent with Example 3 is set as control group 2; the sensory evaluation of the samples adopts code evaluation, adopts percentage system, tea appearance (20), soup color (10), aroma (25), taste (35), and leaf bottom (10), and the results are shown in Table 1.

[0077] Table 1:

[0078]

[0079] After the Gongfu black tea produced by each example and comparative example is compared from the appearance, the soup color of the brewed tea soup, the aroma, the taste and the like, the overall score of the black tea produced by the single tea through the conventional self-oxidation fermentation is close to the example, and the appearance score of the tea obtained by the single tea under the production process of Example 3 is equivalent to the example, but the presentation of the physicochemical properties of the brewed tea soup is obviously decreased. And the sensory score of the Gongfu black tea produced by Comparative Example 1 and Comparative Example 2 is seriously decreased due to the obvious change in the fermentation process. In Comparative Example 3, the shaping treatment is not carried out, which also has an adverse effect on the physicochemical properties of the tea and the tea soup.

[0080] (II) Detection of tea theaflavins, thearubigins and theabrownins content and brewing resistance

[0081] 1. Detection of theaflavins

[0082] National Standard GB / T 30376-2013 "Determination of Theaflavins in Tea - High Performance Liquid Chromatography"

[0083] 2. Detection of thearubigins and theabrownins

[0084] The content of thearubigin and theabrownin in black tea was determined according to the agricultural industry standard NY / T3657-2020 "Determination of thearubigin and theabrownin in black tea by spectrophotometry".

[0085] 2. Amino acid detection

[0086] According to the national standard GB / T 8314-2002 "Determination of Total Free Amino Acids in Tea", the total free amino acid content was determined by ninhydrin colorimetric reaction at a wavelength of 570 nm using a spectrophotometer.

[0087] 3. Detection of unoxidized polyphenols

[0088] According to the national standard GB / T 8313-2002 "Determination of Tea Polyphenols", the total polyphenol content was determined at a wavelength of 765 nm using Folin-Ciocalteu reagent for color development.

[0089] 4. Foaming resistance

[0090] Based on the Chinese national standard GB / T 23776-2018 "Sensory Evaluation Methods for Tea" and related specifications, the standard for brewing black tea is as follows: standardized tea-to-water ratio (1:50), boiling water temperature (100℃), and fixed brewing time (5 minutes / batch).

[0091] The color, aroma, and taste of each brew are scored. If the score of the (n+1)th brew is less than 60% of the average score of the previous n brews (e.g., if the average score of the previous n brews is 80 points, the score of the (n+1)th brew is less than 48 points), then n is determined to be the upper limit of the tea's brewing endurance.

[0092] The test results are shown in Table 2.

[0093] Table 2:

[0094]

[0095] The tea infusion of the Kung Fu black tea brewed once in Example 3 and Comparative Example 3 of this invention is as follows: Figure 2 The tea soup after being brewed 6 times is like Figure 3 As shown ( Figure 2 and Figure 3 The upper figure is Example 3, and the lower figure is Comparative Example 3. Figure 2 It can be seen that during the first brewing, the tea soup of Example 3 and Comparative Example 3 was bright orange-red with a golden ring. However, the tea soup of Example 3 was brighter red than that of Comparative Example 3. After six repeated brewings, the tea soup... Figure 3 As shown, in Example 3, the tea soup color became lighter, but it still appeared relatively bright red. This shows that the Kung Fu black tea in Example 3 has excellent brewing endurance. In contrast, the tea soup in Comparative Example 3 after the 6th brew was extremely light in color, and the amount of dissolved tea had significantly decreased, indicating a significant drop in brewing endurance.

[0096] Changes in the content of main aromatic substances in tea leaves:

[0097] Regarding the improvement of the content of aroma substances in tea leaves, the relative contents of main aroma components linalool and minor aroma components geraniol in the black tea prepared in each example and comparative example were detected by solid-phase microextraction-gas chromatography-mass spectrometry, and the results are shown in Table 3.

[0098] Table 3:

[0099]

[0100] It can be seen that, by combining short-time specific autoxidation with microbial fermentation according to the present application, the content of the characteristic aromatic components linalool, geraniol and other substances in the black tea is effectively improved, and the decomposition of these aromatic components during the shaping process is also offset, which leads to the decrease in the quality and flavor of the black tea. In Comparative Example 3, no shaping was performed, which reduced the decomposition of the aromatic components under the conditions of steam and the like, but since the tea cake was not shaped, the aromatic components were more easily volatilized, which also caused a certain degree of decrease in the content of the aromatic components.

Claims

1. A method of fermentation processing of Congou black tea, characterized in that: The Gongfu black tea is formed by adding lophatherum gracile Brongn, dried tangerine or orange peel and jasmine petals into tea leaves to form a tea mixture, withering, fermentation, shaping and drying, wherein the fermentation includes pre-fermentation and complete fermentation, the pre-fermentation is self-oxidation fermentation of the tea leaves, the pre-fermentation is carried out in an environment with a temperature of 30-32 DEG C and a relative humidity of 45-50% for 1-2 hours, the complete fermentation is microbial fermentation, specifically, a compound microbial agent composed of acetic acid bacteria and Enterococcus faecium is used for first-step fermentation, and then abnormal Hansenula yeast is added for second-step fermentation, the first-step fermentation is carried out by rubbing and twisting the intermediate product obtained after pre-fermentation, adding the compound microbial agent composed of acetic acid bacteria and Enterococcus faecium to the surface of the intermediate product, and then fermenting at a temperature of 28-30 DEG C and a relative humidity of 85-92% for 1-2 hours, and the second-step fermentation is carried out by adding the abnormal Hansenula yeast after the first-step fermentation is completed, sealing in a suitable container, and then continuing to ferment at a temperature of 25-28 DEG C and a relative humidity of 75-85% for 3-4 hours.

2. A method of fermentation processing of congou black tea as claimed in claim 1 wherein: In the tea mixture, the tea is 100-120 parts, the jasmine petals are 2-4 parts, the lophatherum gracile Brongn is 8-10 parts, and the dried tangerine or orange peel is 3-5 parts by weight, wherein the tea is any one of Yunnan large-leaf species, Hainan large-leaf species or Qimen large-leaf species.

3. A method of fermentation processing of Gongfu Black Tea as claimed in claim 1 or 2, wherein: In the compound microbial agent, the acetic acid bacteria and the Enterococcus faecium are composed of 1:1-2 by mass ratio of viable bacterial number.

4. A method of fermentation processing of congou black tea as claimed in claim 3 wherein: The drying is carried out by first placing the tea cake in a hot air circulation oven at a temperature of 50-55 DEG C for 1 hour, taking out, placing in a vacuum drying oven at a temperature of 30-35 DEG C, setting the vacuum degree to-0.05 to-0.08 MPa, and then drying for 10-12 hours to ensure that the product has a water content of 1-3%, and then taking out to obtain the finished product.

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