Preparation method of fructus alpiniae oxyphyllae black tea

Abstract

The invention discloses a preparation method of fructus alpiniae oxyphyllae black tea, which comprises the following steps: pretreating raw materials, mixing and rolling, carrying out three-stage fermentation on the mixed and rolled mixture, and carrying out drying treatment, air-cooling dehydration and baking fragrance extraction to obtain the fructus alpiniae oxyphyllae black tea. The invention aims to combine the fructus alpiniae oxyphyllae and the black tea, and adopts a multi-stage fermentation mode, so that phenolic substances of the black tea can be fully oxidized, the black tea is rich in fragrance and mellow in taste, and the tea quality of the black tea is effectively improved; and after the fructus alpiniae oxyphyllae and the black tea are combined, flavor components of the fructus alpiniae oxyphyllae and the black tea are fused, so that the tea not only has the mellow fragrance of the black tea, but also has the fresh scent of the fructus alpiniae oxyphyllae, the taste level of the tea is enriched, and functional components of the fructus alpiniae oxyphyllae are also added, so that the requirements of consumers on taste diversification and rich efficacy of healthy tea drinks are met.

Description

Technical Field

[0001] The invention belongs to the technical field of food processing, and particularly relates to a preparation method of Alpinia oxyphylla black tea. Background Art

[0002] Black tea is a fully fermented tea and the main tea in tea culture. It contains a variety of nutrients and functional ingredients such as vitamins, caffeine, amino acids, minerals, polysaccharides, and tea polyphenols, which can help lower blood sugar, blood pressure, and blood lipids. Black tea is made from the buds and leaves of the tea plant and is refined through typical processes such as withering, rolling, fermentation, and drying. Fermentation is the key step in black tea processing. The rolled tea leaves are exposed to air to promote oxidation and maturation with tea polyphenol enzymes. The inherent tea polyphenols and tannic acid in the tea are reduced, and new ingredients such as theaflavins and thearubigins, as well as aromatic substances such as alcohols, aldehydes, ketones, and esters are produced, forming the unique color and aroma of black tea. Therefore, black tea is deeply loved by consumers for its unique flavor characteristics.

[0003] At present, the conventional black tea preparation process generally only ferments the tea leaves once. This method has poor fermentation stability and is prone to insufficient fermentation, which results in the inability to fully oxidize polyphenols during the fermentation process, causing the black tea to have a weak aroma, lack a mellow taste, and have a more prominent astringency, resulting in problems such as a lack of taste and flavor characteristics of the black tea.

[0004] As modern consumers' demand for tea drinks has shifted from traditional single flavors to diversified and personalized ones, and as their health awareness has increased, the single flavor of black tea can no longer meet consumers' demand for tea. Therefore, flavored teas with added natural spices, flowers, fruits, herbs and other ingredients have come into being.

[0005] Alpinia oxyphylla is one of the four major southern medicinal herbs in China. It is rich in active ingredients such as volatile oils and flavonoids. It has the effects of warming the spleen, appetizing, and saliva control, warming the kidneys, consolidating essence, and reducing urine, improving memory, and enhancing cognitive function. Currently, there is no literature publicly available on combining Alpinia oxyphylla with black tea to prepare flavored tea. Summary of the Invention

[0006] The object of the present invention is to provide a preparation method of Alpinia oxyphylla black tea, which can fully oxidize the phenolic substances in the black tea by combining the Alpinia oxyphylla and black tea and adopting a multi-stage fermentation method, so that the black tea has a strong aroma and a mellow taste, and the quality of the black tea is effectively improved; and after the Alpinia oxyphylla and black tea are combined, the flavor components of the two are integrated, so that the flavored tea can be attached with the fragrance of the Alpinia oxyphylla and the mellow aroma of the black tea, which not only retains the classic taste of the black tea, but also adds the herbal aroma of the Alpinia oxyphylla, forming a unique flavor, enriching the taste level of the tea, and at the same time adding the functional effects of the Alpinia oxyphylla, so as to meet the consumer's demand for diversified taste and rich efficacy of healthy tea.

[0007] The technical solution adopted in the present invention is:

[0008] A preparation method of Alpinia oxyphylla black tea comprises the following steps:

[0009] Step S1: pre-treating Alpinia oxyphylla kernel and tea leaves;

[0010] Step S2: crushing the Alpinia oxyphylla kernel; mixing the tea leaves and the Alpinia oxyphylla kernel in a weight ratio of (4-6):1 and then rolling the mixture;

[0011] Step S3: fermenting the mixed and rolled tea leaves and Alpinia oxyphylla seeds. The fermentation is carried out in three stages:

[0012] Stage 1: Fermentation at a temperature of 25°C to 27°C, with a humidity of 82% to 88%, using natural wind, for 1 to 3 hours;

[0013] The second stage: temperature is 29℃~31℃, humidity is 78%~82%, oxygen is added for 2 minutes every hour, and fermentation takes 3~5 hours;

[0014] The third stage: the temperature is 23℃~25℃, the humidity is 72%~78%, and the fermentation is carried out in a sealed state for 1~3 hours;

[0015] Step S4: drying the fermented tea leaves and Alpinia oxyphylla mixture;

[0016] Step S5: air-cooling and dehydrating the dried tea leaves and Alpinia oxyphylla mixture;

[0017] Step S6: baking the mixture of air-cooled and dehydrated tea leaves and Alpinia oxyphylla seeds to enhance aroma, thereby obtaining Alpinia oxyphylla seeds black tea.

[0018] Furthermore, in step S1, the pretreatment process of the Alpinia oxyphylla kernel is to wash the Alpinia oxyphylla kernel and then perform low-temperature baking. The low-temperature baking method is: first stage baking: baking at 58°C to 62°C for 2 to 3 hours, second stage baking: baking at 44°C to 46°C for 4 to 5 hours.

[0019] Furthermore, in step S1, the pretreatment process of the tea leaves is to wash the fresh black tea leaves and spread them in a bamboo sieve with a thickness of 3 cm to 5 cm; the ambient temperature is 22°C to 25°C, the withering time is 4 to 6 hours, and the moisture content is controlled at 66% to 70%.

[0020] Furthermore, in step S2, the particle size of the Alpinia oxyphylla pieces is 3 mm to 5 mm.

[0021] Furthermore, in step S4, the drying process is: drying is carried out using a five-layer chain plate dryer, and the temperatures of each layer are: 120℃~130℃ for the first layer, 112℃~118℃ for the second layer, 103℃~107℃ for the third layer, 93℃~97℃ for the fourth layer, and 84℃~86℃ for the fifth layer, and the drying time is 20~30 minutes.

[0022] Furthermore, in step S5, a cyclone cooling tower is used for air cooling and dehydration, with an air temperature of -5°C to -3°C, a wind speed of 8m / s, and an air cooling time of 4 to 6 minutes.

[0023] Furthermore, in step S6, the baking method is divided into the following three stages:

[0024] Stage 1: Bake at 59°C to 62°C in static air mode for 28 to 32 minutes.

[0025] Stage 2: Temperature 74°C to 76°C, wind speed 5m / s, baking for 19 to 21 minutes;

[0026] The third stage: the temperature is 89℃~91℃, the wind speed is 2m / s, and the baking time is 9~11 minutes.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] The present invention adopts a multi-stage fermentation method, which can fully oxidize the polyphenols in black tea, ensure the generation of more theaflavins and thearubigins, effectively enhance the aroma of black tea, and retain the mellow taste of black tea; and by combining Alpinia oxyphylla with black tea, the herbal aroma of Alpinia oxyphylla is added on the basis of retaining the black tea flavor, and through the proportioning, the slight bitterness of Alpinia oxyphylla and the sweetness of black tea are balanced with each other, so that it has rich taste layers, and the functional ingredients of Alpinia oxyphylla are contained in black tea, which solves the problem of the loss of black tea flavor components caused by the one-time fermentation of the traditional process, resulting in a single taste of black tea; and can also meet consumers' drinking demand for healthy tea with health benefits. DETAILED DESCRIPTION

[0029] The following examples clearly and completely describe the technical solutions of the present invention. Obviously, the described examples are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0030] Example 1:

[0031] A preparation method of Alpinia oxyphylla black tea comprises the following steps:

[0032] 1. Pre-treat the Alpinia oxyphylla kernel and tea leaves;

[0033] The Alpinia oxyphylla kernels were pre-treated according to the following steps:

[0034] First, high-pressure bubble cleaning was performed at a water temperature of 25°C and a pressure of 0.15 MPa for 3 minutes. Then, a 40 kHz ultrasonic cleaning machine was used for cleaning for 2 minutes. Finally, pure water at a flow rate of 5 L / MIN was used for rinsing for 1 minute. After cleaning, the seeds were dehydrated at 300 rpm for 30 seconds using a centrifugal dehydrator to reduce the surface moisture of the seeds to ≤3%.

[0035] The drained Alpinia oxyphylla kernels were baked in a multi-layer tray-type hot air circulation oven in two stages at low temperature: the first stage was baked at 58°C for 2 hours to make the Alpinia oxyphylla kernel volatile oil retention rate 90%, and the second stage was baked at 44°C for 4 hours to reduce the moisture content of the Alpinia oxyphylla kernels to 8.5%. After baking, the Alpinia oxyphylla kernel ketone content was 1.2 mg / g;

[0036] The black tea is pretreated according to the following steps:

[0037] The black tea is made from fresh leaves of the Wuzhishan large-leaf variety, with one bud and two leaves accounting for ≥90% and a tea leaf integrity of ≥95%. The leaves are withered in a bamboo sieve at a thickness of 3cm. The withering process is carried out for 4 hours at an ambient temperature of 22°C and a humidity of 70%, until the moisture content of the leaves is reduced to 70%.

[0038] 2. Grind the Alpinia oxyphylla kernels and sieve out Alpinia oxyphylla kernel fragments with a particle size of 3 mm through a sieve; mix the tea leaves and Alpinia oxyphylla kernels in a double-screw conical mixer at a weight ratio of 6:1, with the mixing temperature set to ≤28°C. The mixing is carried out in two stages: in the first stage, the speed is set to 10 rpm, and the tea leaves are added and mixed at a low speed for 5 minutes; in the second stage, the speed is set to 25 rpm, and the Alpinia oxyphylla kernel fragments and the tea leaves are added and mixed at a high speed for 10 minutes;

[0039] Then the mixture of tea leaves and Alpinia oxyphylla is kneaded in a 55-type stainless steel disc kneading machine in a kneading room at room temperature ≤ 30℃. The kneading is carried out in three stages: the first stage of kneading: the kneading machine pressure is set to 0.4kg / cm 2 , the speed is set to 35rpm, and light rolling is performed for 15 minutes to break the tea wall; the second stage of rolling: the rolling machine pressure is set to 1kg / cm 2 , set the speed to 45rpm, and perform moderate kneading for 30 minutes to blend the tea leaves with the Alpinia oxyphylla pieces; the third stage of kneading: set the kneading machine pressure to 1.7kg / cm 2 , set the speed to 30rpm, and perform heavy kneading for 15 minutes to shape the fused tea leaves and Alpinia oxyphylla pieces;

[0040] By rolling, the tea leaves are broken by 73%, and the tea juice overflows and adheres to the surface of the tea leaves. The amount of juice adhered is ≥65%. When pinched by hand, it overflows without dripping, and is mixed with the Alpinia oxyphylla kernel pieces into a rolled strip.

[0041] 3. Ferment the mixed and rolled tea leaves and Alpinia oxyphylla mixture in three stages: First stage fermentation: in the fermentation room, the temperature is set to 25.5°C and the humidity is set to 82%. The mixture is fermented for 2 hours by natural ventilation until the edges of the tea leaves turn red and the area reaches ≥60%; Second stage fermentation: the mixture is placed in an intelligent fermentation box for fermentation at a temperature of 29.7°C and a humidity of 78%. The fermentation is carried out for 4 hours. During the fermentation period, oxygen is supplemented for 2 minutes every hour until the tea leaves change from yellow-green to bronze and the bronze area accounts for ≥80%; Third stage fermentation: the temperature of the intelligent fermentation box is set to 23.5°C and the humidity is set to 72%. The mixture is sealed and allowed to stand for 1.5 hours. The oily gloss L* value of the mixture is ≥55;

[0042] 4. Place the fermented tea leaves and Alpinia oxyphylla mixture flat on a dryer and dry it until the moisture content of the tea leaves is reduced to 7%;

[0043] 5. Spread the dried tea leaves and Alpinia oxyphylla mixture to cool down to 25°C;

[0044] 6. The mixture of the cooled tea leaves and the Alpinia oxyphylla kernel is baked and fragrant by a far-infrared fragrance machine, and the Alpinia oxyphylla kernel black tea is obtained after drying and fragrance enhancement.

[0045] Example 2

[0046] A preparation method of Alpinia oxyphylla black tea comprises the following steps:

[0047] Step S1: pre-treating the Alpinia oxyphylla kernel and tea leaves;

[0048] The Alpinia oxyphylla kernels were pre-treated according to the following steps:

[0049] First, use high-pressure bubble cleaning at a water temperature of 25°C and a pressure of 0.15MPa for 3 minutes, then use a 40kHz ultrasonic cleaning machine to clean for 2 minutes, and finally rinse with pure water at a flow rate of 5L / MIN for 1 minute. After cleaning, use a centrifugal dehydrator at 300rpm for 30 seconds to reduce the surface moisture of the Alpinia oxyphylla to ≤3%;

[0050] The drained Alpinia oxyphylla kernels were baked in a multi-layer tray-type hot air circulation oven in two stages at low temperature: the first stage was baked at 58°C for 2 hours to make the Alpinia oxyphylla kernel volatile oil retention rate 90%, and the second stage was baked at 44°C for 4 hours to reduce the moisture content of the Alpinia oxyphylla kernels to 8.5%. After baking, the Alpinia oxyphylla kernel ketone content was 1.2 mg / g;

[0051] The black tea is pretreated according to the following steps:

[0052] The black tea is made from fresh leaves of the Wuzhishan large-leaf variety, with one bud and two leaves accounting for ≥90% and a tea leaf integrity of ≥95%. The leaves are withered in a bamboo sieve at a thickness of 3cm. The withering process is carried out for 4 hours at an ambient temperature of 22°C and a humidity of 70%, until the moisture content of the leaves is reduced to 70%.

[0053] 2. Grind the Alpinia oxyphylla kernels and sieve out Alpinia oxyphylla kernel fragments with a particle size of 3 mm through a sieve; mix the tea leaves and Alpinia oxyphylla kernels in a double-screw conical mixer at a weight ratio of 4:1, with the mixing temperature set to ≤28°C. The mixing is carried out in two stages: in the first stage, the speed is set to 10 rpm, and the tea leaves are added and mixed at a low speed for 5 minutes; in the second stage, the speed is set to 25 rpm, and the Alpinia oxyphylla kernel fragments and the tea leaves are added and mixed at a high speed for 10 minutes;

[0054] Then the mixture of tea leaves and Alpinia oxyphylla is kneaded in a 55-type stainless steel disc kneading machine in a kneading room at room temperature ≤ 30℃. The kneading is carried out in three stages: the first stage of kneading: the kneading machine pressure is set to 0.4kg / cm 2 , the speed is set to 35rpm, and light rolling is performed for 15 minutes to break the tea wall; the second stage of rolling: the rolling machine pressure is set to 1kg / cm 2 , set the speed to 45rpm, and perform moderate kneading for 30 minutes to blend the tea leaves with the Alpinia oxyphylla pieces; the third stage of kneading: set the kneading machine pressure to 1.7kg / cm 2 , set the speed to 30rpm, and perform heavy kneading for 15 minutes to shape the fused tea leaves and Alpinia oxyphylla pieces;

[0055] By rolling, the tea leaves are broken by 73%, and the tea juice overflows and adheres to the surface of the tea leaves. The amount of juice adhered is ≥65%. When pinched by hand, it overflows without dripping, and is mixed with the Alpinia oxyphylla kernel pieces into a rolled strip.

[0056] 3. Ferment the mixed and rolled tea leaves and Alpinia oxyphylla mixture in three stages: First stage fermentation: in the fermentation room, the temperature is set to 25.5°C and the humidity is set to 82%. The mixture is fermented for 2 hours by natural ventilation until the edges of the tea leaves turn red and the area reaches ≥60%; Second stage fermentation: the mixture is placed in an intelligent fermentation box for fermentation at a temperature of 29.7°C and a humidity of 78%. The mixture is fermented for 4 hours. During the fermentation period, oxygen is supplemented for 2 minutes every hour until the tea leaves change from yellow-green to bronze and the bronze area accounts for ≥80%; Third stage fermentation: the temperature of the intelligent fermentation box is set to 23.5°C and the humidity is set to 72%. The mixture is sealed and allowed to stand for 1.5 hours until the oily gloss L* value of the mixture is ≥55;

[0057] 4. The fermented tea leaves and Alpinia oxyphylla mixture were spread flat on a five-layer chain plate dryer for drying for 23 minutes. The drying temperature decreased from the feed inlet (high point) to the discharge direction (low point). The temperatures of each layer were: 120°C for the first layer, 112°C for the second layer, 103°C for the third layer, 93°C for the fourth layer, and 84°C for the fifth layer.

[0058] The fermentation is terminated by step-drying, the flavor of the mixture is fixed, over-fermentation is avoided, and excessive theabrownin is produced, which causes the loss of tea flavor. The moisture content of the tea is reduced to 7%.

[0059] 5. The dried tea leaves and Alpinia oxyphylla mixture was dehydrated by air cooling in a cyclone cooling tower. The air temperature was set to -3°C, the wind speed was set to 8m / s, and the air cooling time was 4.5 minutes, so that the mixture of leaves was cooled to 25°C.

[0060] 6. The mixture of the cooled tea leaves and the Alpinia oxyphylla is baked and flavored using a far-infrared aroma machine. The baking is carried out in three stages: the first stage is baking at a temperature of 59°C and in a static wind mode for 28 minutes to activate the endogenous enzymes in the tea leaves to promote the conversion of ester precursors and cause "frog-skin-like" wrinkles to appear on the surface of the tea leaves; the second stage is baking at a temperature of 74°C and a wind speed of 0.5m / s for 19 minutes to shape the mixture, solidify the color, enhance the honey aroma, and achieve a tightness of 90%; the third stage is baking at a temperature of 89.5°C and a wind speed of 2m / s for 9.5 minutes to volatilize the low-boiling-point small molecule impurities in the mixture, reduce the green feeling, produce beneficial flavor substances such as caramel aroma and honey aroma, and increase the oiliness L* value by 14%; after drying and flavoring, the Alpinia oxyphylla black tea is obtained.

[0061] Example 3:

[0062] A preparation method of Alpinia oxyphylla black tea comprises the following steps:

[0063] 1. Pre-treat the Alpinia oxyphylla kernel and tea leaves;

[0064] The Alpinia oxyphylla kernels were pre-treated according to the following steps:

[0065] First, use high-pressure bubble cleaning at a water temperature of 25°C and a pressure of 0.15MPa for 3 minutes, then use a 40kHz ultrasonic cleaning machine to clean for 2 minutes, and finally rinse with pure water at a flow rate of 5L / MIN for 1 minute. After cleaning, use a centrifugal dehydrator at 300rpm for 30 seconds to reduce the surface moisture of the Alpinia oxyphylla to ≤3%;

[0066] The drained Alpinia oxyphylla kernels were baked in a multi-layer tray-type hot air circulation oven in two stages at low temperature: the first stage was baked at 60°C for 2 hours to make the Alpinia oxyphylla kernel volatile oil retention rate 92%, and the second stage was baked at 45°C for 4 hours to reduce the moisture content of the Alpinia oxyphylla kernels to 8%. After baking, the Alpinia oxyphylla kernel ketone content was 1.5 mg / g;

[0067] The black tea is pretreated according to the following steps:

[0068] The black tea is made from fresh leaves of the Wuzhishan large-leaf variety, with one bud and two leaves accounting for ≥90% and a tea leaf integrity of ≥95%. The leaves are withered in a bamboo sieve at a thickness of 4cm. The withering process is carried out for 5 hours at an ambient temperature of 23.5°C and a humidity of 72.5%, until the moisture content of the leaves is reduced to 68%.

[0069] 2. Grind the Alpinia oxyphylla kernels and sieve out Alpinia oxyphylla kernel fragments with a particle size of 4 mm through a sieve; mix the tea leaves and Alpinia oxyphylla kernels in a double-screw conical mixer at a weight ratio of 5:1, with the mixing temperature set to ≤28°C. The mixing is carried out in two stages: in the first stage, set the speed to 10 rpm, add the tea leaves and mix at a low speed for 5 minutes; in the second stage, set the speed to 25 rpm, add the Alpinia oxyphylla kernel fragments and the tea leaves and mix at a high speed for 10 minutes;

[0070] Then the mixture of tea leaves and Alpinia oxyphylla is kneaded in a 55-type stainless steel disc kneading machine in a kneading room at room temperature ≤ 30℃. The kneading is carried out in three stages: the first stage of kneading: the kneading machine pressure is set to 0.5kg / cm 2 , the speed is set to 35rpm, and light rolling is performed for 15 minutes to break the tea wall; the second stage of rolling: the rolling machine pressure is set to 1.2kg / cm 2 , set the speed to 45rpm, and perform moderate kneading for 30 minutes to blend the tea leaves with the Alpinia oxyphylla pieces; the third stage of kneading: set the kneading machine pressure to 2.0kg / cm 2 , set the speed to 30rpm, and perform heavy kneading for 15 minutes to shape the fused tea leaves and Alpinia oxyphylla pieces;

[0071] By rolling, the tea leaves are broken by 75%, and the tea juice overflows and adheres to the surface of the tea leaves. The amount of juice adhered is ≥65%. When pinched by hand, it overflows without dripping, and is mixed with the Alpinia oxyphylla kernel pieces into a rolled strip.

[0072] 3. Ferment the mixed and rolled tea leaves and Alpinia oxyphylla seeds in three stages: First stage fermentation: in the fermentation room, the temperature is set to 26°C and the humidity is set to 85%. The mixture is fermented for 2 hours by natural ventilation until the edges of the tea leaves turn red and the area accounts for ≥60%; Second stage fermentation: the mixture is placed in an intelligent fermentation box for fermentation at 30°C and 80% humidity for 4 hours. During the fermentation period, oxygen is supplemented for 2 minutes every hour until the tea leaves change from yellow-green to bronze and the bronze area accounts for ≥80%; Third stage fermentation: the temperature of the intelligent fermentation box is set to 24°C and the humidity is set to 75%. It is sealed and allowed to stand for 1.5 hours to make the oily gloss L* value of the mixture ≥55;

[0073] 4. The fermented tea leaves and Alpinia oxyphylla mixture were spread flat on a five-layer chain plate dryer for drying for 25 minutes. The drying temperature decreased from the feed inlet (high point) to the discharge direction (low point). The temperatures of each layer were: 125°C for the first layer, 115°C for the second layer, 105°C for the third layer, 95°C for the fourth layer, and 85°C for the fifth layer.

[0074] The mixture is placed in a five-layer chain plate dryer through the feed port and dried in a step-by-step manner from top to bottom to stop fermentation, fix the flavor of the mixture, avoid excessive fermentation that would lead to excessive production of theabrownin and loss of tea flavor, and reduce the moisture content of the tea to 6%.

[0075] 5. The dried tea leaves and Alpinia oxyphylla mixture was dehydrated by air cooling in a cyclone cooling tower. The air temperature was set to -4°C, the wind speed was set to 8m / s, and the air cooling time was 5 minutes, so that the mixture of leaves was cooled to 24°C.

[0076] 6. The mixture of the cooled tea leaves and the Alpinia oxyphylla is baked and flavored using a far-infrared aroma machine. The baking is carried out in three stages: the first stage is baking at a temperature of 60°C and in a static wind mode for 30 minutes to activate the endogenous enzymes in the tea leaves to promote the conversion of ester precursors and cause "frog-skin-like" wrinkles to appear on the surface of the tea leaves; the second stage is baking at a temperature of 75°C and a wind speed of 0.5m / s for 20 minutes to shape the mixture, solidify the color, enhance the honey aroma, and achieve a tightness of 90% or more of the tea leaves; the third stage is baking at a temperature of 90°C and a wind speed of 2m / s for 10 minutes to volatilize the low-boiling-point small molecule impurities in the mixture, reduce the green feeling, produce beneficial flavor substances such as caramel aroma and honey aroma, and increase the oiliness L* value by 15%; after drying and flavoring, the Alpinia oxyphylla black tea is obtained.

[0077] Example 4:

[0078] A preparation method of Alpinia oxyphylla black tea comprises the following steps:

[0079] 1. Pre-treat the Alpinia oxyphylla kernel and tea leaves;

[0080] The Alpinia oxyphylla kernels were pre-treated according to the following steps:

[0081] First, use high-pressure bubble cleaning at a water temperature of 25°C and a pressure of 0.15MPa for 3 minutes, then use a 40kHz ultrasonic cleaning machine to clean for 2 minutes, and finally rinse with pure water at a flow rate of 5L / MIN for 1 minute. After cleaning, use a centrifugal dehydrator at 300rpm for 30 seconds to reduce the surface moisture of the Alpinia oxyphylla to ≤3%;

[0082] The drained Alpinia oxyphylla kernels were baked in a multi-layer tray-type hot air circulation oven in two stages at low temperature: the first stage was baked at 62°C for 2 hours, so that the volatile oil retention rate of the Alpinia oxyphylla kernels was 93%, and the second stage was baked at 46°C for 4 hours, so that the moisture content of the Alpinia oxyphylla kernels was reduced to 7.5%. After baking, the ketone content of the Alpinia oxyphylla kernels was 1.6 mg / g;

[0083] The black tea is pretreated according to the following steps:

[0084] The black tea is made from fresh leaves of the Wuzhishan large-leaf variety, with one bud and two leaves accounting for ≥90% and a tea leaf integrity of ≥95%. The leaves are withered in a bamboo sieve with a thickness of 5cm. The withering process is carried out for 6 hours at an ambient temperature of 25°C and a humidity of 75%, until the moisture content of the leaves is reduced to 66%.

[0085] 2. Grind the Alpinia oxyphylla kernels and sieve out Alpinia oxyphylla kernel fragments with a particle size of 5 mm through a sieve; mix the tea leaves and Alpinia oxyphylla kernels in a double-screw conical mixer at a weight ratio of 6:1, with the mixing temperature set to ≤28°C. The mixing is carried out in two stages: in the first stage, the speed is set to 10 rpm, and the tea leaves are added and mixed at a low speed for 5 minutes; in the second stage, the speed is set to 25 rpm, and the Alpinia oxyphylla kernel fragments and the tea leaves are added and mixed at a high speed for 10 minutes;

[0086] Then the mixture of tea leaves and Alpinia oxyphylla is kneaded in a 55-type stainless steel disc kneading machine in a kneading room at room temperature ≤ 30℃. The kneading is carried out in three stages: the first stage of kneading: the kneading machine pressure is set to 0.6kg / cm 2 , the speed is set to 35rpm, and light rolling is performed for 15 minutes to break the tea wall; the second stage of rolling: the rolling machine pressure is set to 1.4kg / cm 2, set the speed to 45rpm, and perform moderate kneading for 30 minutes to blend the tea leaves with the Alpinia oxyphylla pieces; the third stage of kneading: set the kneading machine pressure to 2.3kg / cm 2 , set the speed to 30rpm, and perform heavy kneading for 15 minutes to shape the fused tea leaves and Alpinia oxyphylla pieces;

[0087] By rolling, the tea leaves are broken by 78%, and the tea juice overflows and adheres to the surface of the tea leaves. The amount of juice adhered is ≥65%. When pinched by hand, it overflows without dripping, and is mixed with the Alpinia oxyphylla kernel pieces into a rolled strip.

[0088] 3. Ferment the mixed and rolled tea leaves and Alpinia oxyphylla seeds in three stages: First stage fermentation: in the fermentation room, the temperature is set to 26.5°C and the humidity is set to 88%. The mixture is fermented for 2 hours by natural ventilation until the edges of the tea leaves turn red and the area accounts for ≥60%; Second stage fermentation: the mixture is placed in an intelligent fermentation box for fermentation at a temperature of 30.3°C and a humidity of 82%. The fermentation is carried out for 4 hours. During the fermentation period, oxygen is supplemented for 2 minutes every hour through an oxygen supplement device until the tea leaves change from yellow-green to bronze and the bronze area accounts for ≥80%; Third stage fermentation: the temperature of the intelligent fermentation box is set to 24.5°C and the humidity is set to 78%. The mixture is sealed and allowed to stand for 1.5 hours, so that the oily gloss L* value of the mixture is ≥55;

[0089] 4. The fermented tea leaves and Alpinia oxyphylla mixture were spread flat on a five-layer chain plate dryer for drying for 27 minutes. The drying temperature decreased from the feed inlet (high point) to the discharge direction (low point). The temperatures of each layer were: 130°C for the first layer, 118°C for the second layer, 107°C for the third layer, 97°C for the fourth layer, and 86°C for the fifth layer.

[0090] The mixture is placed in a five-layer chain plate dryer through the feed port and dried in a step-by-step manner from top to bottom to stop fermentation, fix the flavor of the mixture, avoid excessive fermentation that would lead to excessive production of theabrownin and loss of tea flavor, and reduce the moisture content of the tea to 5%.

[0091] 5. The dried tea leaves and Alpinia oxyphylla mixture was dehydrated by air cooling in a cyclone cooling tower. The air temperature was set to -5°C, the wind speed was set to 8m / s, and the air cooling time was 5.5 minutes, so that the mixture of leaves was cooled to 23°C.

[0092] 6. The mixture of the cooled tea leaves and the Alpinia oxyphylla is baked and flavored using a far-infrared aroma machine. The baking is carried out in three stages: the first stage is baking at a temperature of 61°C and baking in a static wind mode for 32 minutes to activate the endogenous enzymes in the tea leaves to promote the conversion of ester precursors and cause "frog-skin-like" wrinkles to appear on the surface of the tea leaves; the second stage is baking at a temperature of 76°C and a wind speed of 0.5m / s for 21 minutes to shape the mixture, solidify the color, enhance the honey aroma, and achieve a tightness of 90% or more; the third stage is baking at a temperature of 90.5°C and a wind speed of 2m / s for 10.5 minutes to volatilize the low-boiling-point small molecular impurities in the mixture, reduce the green feeling, produce beneficial flavor substances such as caramel aroma and honey aroma, and increase the oiliness L* value by 15%; after drying and flavoring, the Alpinia oxyphylla black tea is obtained.

[0093] Quality inspection:

[0094] The characteristics and index detection methods obtained in the above Examples 1-4 are shown in Table 1:

[0095] Table 1

[0096]

[0097] Sensory evaluation:

[0098] The Alpinia oxyphylla black tea prepared in Examples 1-4 was given to volunteers for drinking and sensory evaluation and scoring. A total of 10 volunteers, 5 men and 5 women, aged between 20 and 50 years old, were evaluated based on appearance, soup color, aroma, flavor concentration, and leaf base. Scores were scored from 0 to 100 from poor to excellent, with the highest and lowest scores removed and the average value taken. The traditional black tea described in the table was made from fresh leaves of the Wuzhishan large-leaf variety of black tea with one bud and two leaves fermented using traditional technology. The scoring results are shown in Table 2:

[0099] Table 2

[0100]

Claims

1. A method for preparing Alpinia oxyphylla black tea, characterized by: The steps include: Step S1: pre-treating Alpinia oxyphylla kernel and tea leaves; Step S2: crushing the Alpinia oxyphylla kernel; mixing the tea leaves and the Alpinia oxyphylla kernel in a weight ratio of (4-6):1 and then rolling the mixture; Step S3: fermenting the mixed and rolled tea leaves and Alpinia oxyphylla seeds. The fermentation is carried out in three stages: Stage 1: Fermentation at a temperature of 25°C to 27°C, with a humidity of 82% to 88%, using natural wind, for 1 to 3 hours; The second stage: temperature is 29℃~31℃, humidity is 78%~82%, oxygen is added for 2 minutes every hour, and fermentation takes 3~5 hours; The third stage: the temperature is 23℃~25℃, the humidity is 72%~78%, and the fermentation is carried out in a sealed state for 1~3 hours; Step S4: drying the fermented tea leaves and Alpinia oxyphylla mixture; Step S5: air-cooling and dehydrating the dried tea leaves and Alpinia oxyphylla mixture; Step S6: baking the mixture of air-cooled and dehydrated tea leaves and Alpinia oxyphylla seeds to enhance aroma, thereby obtaining Alpinia oxyphylla seeds black tea.

2. The method for preparing the Alpinia oxyphylla black tea according to claim 1, wherein: In step S1, the pretreatment process of the Alpinia oxyphylla kernel is to wash the Alpinia oxyphylla kernel and then perform low-temperature baking. The low-temperature baking method is as follows: first stage baking: baking at 58°C to 62°C for 2 to 3 hours, second stage baking: baking at 44°C to 46°C for 4 to 5 hours.

3. The method for preparing the Alpinia oxyphylla black tea according to claim 1, wherein: In step S1, the tea pretreatment process is to wash the fresh black tea leaves and spread them in a bamboo sieve with a thickness of 3 cm to 5 cm; the ambient temperature is 22° C. to 25° C., the withering time is 4 to 6 hours, and the moisture content is controlled at 66% to 70%.

4. The method for preparing the Alpinia oxyphylla black tea according to claim 1, wherein: In step S2, the particle size of the Alpinia oxyphylla kernel fragments is 3 mm to 5 mm.

5. The method for preparing the Alpinia oxyphylla black tea according to claim 1, wherein: In step S4, the drying process is: drying is carried out using a five-layer chain plate dryer, and the temperatures of each layer are: 120℃~130℃ for the first layer, 112℃~118℃ for the second layer, 103℃~107℃ for the third layer, 93℃~97℃ for the fourth layer, and 84℃~86℃ for the fifth layer. The drying time is 20~30 minutes.

6. The method for preparing the Alpinia oxyphylla black tea according to claim 1, wherein: In step S5, a cyclone cooling tower is used for air cooling and dehydration, with an air temperature of -5°C to -3°C, a wind speed of 8m / s, and an air cooling time of 4 to 6 minutes.

7. The method for preparing the Alpinia oxyphylla black tea according to claim 1, wherein: In step S6, the baking method is divided into the following three stages: Stage 1: Bake at 59°C to 62°C in static air mode for 28 to 32 minutes. Stage 2: Temperature 74°C to 76°C, wind speed 5m / s, baking for 19 to 21 minutes; The third stage: the temperature is 89℃~91℃, the wind speed is 2m / s, and the baking time is 9~11 minutes.

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