Processing technology of ground tea

Abstract

The invention discloses a ground tea processing technology, and relates to the technical field of tea processing. The processing technology of the ground tea comprises the following steps: shading, picking, withering, de-enzyming, cooling scattered leaves, dehydrating, drying, re-drying and separating stems and leaves. According to the invention, the green fresh leaves of a whitening tea tree variety 'Baiyan No.1' with relatively high free amino acid content are used as raw materials for processing the matcha, and the prepared matcha finished product is fresh and mellow in taste, relatively low in bitterness and relatively suitable for making the matcha. According to the method, the utilization rate of the'white-leaf No.1 'tea leaves in the non-whitening period is increased, the variety advantages of the'white-leaf No.1' tea leaves are fully played, the economic benefits of the tea industry are increased, the diversified utilization of'white-leaf No.1 'tea tree resources is realized, and the method has a wide market popularization prospect.

Description

Technical Field

[0001] The invention relates to the technical field of tea processing, and in particular to a tea rolling processing technology. Background Art

[0002] Matcha refers to a micro-powdered tea product made from leaves (rolled tea) made from fresh tea leaves grown under shade and covered cultivation, which are steamed (hot air) and then dried. The matcha industry in my country has developed rapidly in recent years. It is not only consumed as a matcha beverage, but also widely used as an additive in various industries such as food, beverages, cosmetics, and health care products. The tea varieties used to process matcha in Guizhou are mainly Fuding Da Baicha and Longjing 43. The processed matcha meets the requirements of high-quality matcha with bright green appearance, dark green soup, and fresh taste. At present, Guizhou matcha is developing rapidly and is in short supply in the market. Therefore, the output of raw rolled tea needs to be increased urgently.

[0003] "Baiye No. 1" is a temperature-sensitive albino tea variety with a temperature threshold of 17-25℃. The "white leaves with green veins" phenomenon usually only occurs around April each year, and the leaves gradually turn green as the temperature rises in the later period. Baiye No. 1 has the characteristics of "high ammonia and low phenol". The Anji white tea made from it is rich in 18 kinds of amino acids required by the human body, and the total amount of amino acids is as high as 6.25%-10.6%, which is 3-5 times higher than that of ordinary green tea. The tea polyphenols are only 1 / 3-1 / 2 of that of ordinary green tea. The ground tea processed with it as raw material tastes fresh, has a high-mellow aroma, and is less bitter. For the Baiye No. 1 tea variety, only the green tea leaves in the spring albino period are often used to process high-end famous teas, while the tea leaves in the non-albino period in summer and autumn are less developed and utilized. They are usually directly pruned and returned to the tea garden, resulting in low utilization rate and failure to play their due value.

[0004] In the prior art, the invention patent application with application number CN117296934A discloses a tea manufacturing process based on tender shoots and leaves of Baiye No. 1, and the process steps are: picking; threading; withering; micro-fermentation; drying; pausing; drying; cooling, arranging, and bagging. This processing technology makes full use of the tender shoots or semi-lignified tea leaves of Baiye No. 1 in the tea tree, but the process is time-consuming and requires a lot of manpower, which limits its large-scale industrial production.

[0005] Based on the above problems, the present invention provides a tea grinding processing technology based on Baiye No. 1, in order to improve the utilization rate of non-albinosis period green tea leaves of "Baiye No. 1", give full play to its variety advantages, increase the economic benefits of the tea industry, realize the diversified utilization of "Baiye No. 1" tea tree resources, and provide technical reference for large-scale industrial production. Summary of the invention

[0006] The purpose of the present invention is to provide a grinding tea processing technology.

[0007] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0008] The grinding tea processing technology of the present invention comprises the following steps:

[0009] S1 Shading: After the tea leaves grow to one bud, two leaves or three leaves, use a black PVC sunshade net with a shading rate of 80-90% for 6-10 days;

[0010] S2 picking: After the shading is over, the new shoots of 15-20cm after the tea leaves turn green are picked mechanically;

[0011] S3 withering: placing the fresh tea leaves picked in step S2 in a green storage tank, blowing cold air at 15°C for 2-6 hours, until the moisture content of the tea leaves is 60-70%;

[0012] S4 Fixing: Place the withered tea leaves in a steam fixing machine for steam fixing. The operating parameters are: drum speed 38-46r / min; stirring speed 380-460r / min; steam temperature 90-105℃; steam flow 90-120kg / h; fixing time 15-25s;

[0013] S5 Loose leaf cooling: The leaves after withering are immediately transported to the loose tea cooling machine for loose leaf cooling;

[0014] S6 Dehydration: The loose leaves are cooled and transported to a hot air dehydrator, where they are dehydrated at 200-250°C until the moisture content of the tea leaves reaches 40%-50%;

[0015] S7 Drying: Set the parameters of the tea-grinding furnace, and use the tea-grinding furnace to dry the tea leaves after preliminary dehydration in stages. The operating parameters are: the drying temperature of stage I is 150-180℃, and the drying time is 5-10min; the drying temperature of stage II is 80-120℃, and the drying time is 5-10min; the drying temperature of stage III is 50-80℃, and the drying time is 15-25min;

[0016] S8 re-drying: the tea leaves dehydrated by the tea milling furnace are transported to the hot air dryer and re-dried at a temperature of 40-60°C until the moisture content of the tea leaves is 4%-6%;

[0017] S9 Stem and Leaf Separation: Winnowing separates the tea leaf pulp from the leaf stem.

[0018] Preferably, in the grinding tea processing technology of the present invention, the shading in step S1 is specifically: after the tea leaves grow to one bud and two or three leaves, use a polyvinyl chloride black sunshade net with a shading rate of 85% for 8 days.

[0019] Preferably, in the grinding tea processing technology of the present invention, the time of blowing 15° C. cold air for withering in step S3 is 6 hours.

[0020] Preferably, in the tea grinding process of the present invention, the operating parameters of the steam killing in step S4 are: drum speed of 38-42r / min; stirring speed of 380-420r / min; steam temperature of 95-100°C; steam flow rate of 100-110kg / h; and killing time of 20-25s.

[0021] Further preferably, in the tea grinding processing technology of the present invention, the operating parameters of the steam fixing in step S4 are: drum speed of 40r / min; stirring speed of 400r / min; steam temperature of 100°C; steam flow rate of 110kg / h; and fixing time of 20s.

[0022] Preferably, in the grinding tea processing technology of the present invention, the dehydration temperature in step S6 is 230°C.

[0023] Preferably, in the grinding tea processing technology of the present invention, the operating parameters of the staged drying in step S7 are: the drying temperature of stage I is 160-170°C, and the drying time is 5-8 min; the drying temperature of stage II is 90-110°C, and the drying time is 5-8 min; the drying temperature of stage III is 60-70°C, and the drying time is 20-25 min.

[0024] Further preferably, in the grinding tea processing technology of the present invention, the operating parameters of the staged drying in step S7 are: the drying temperature of stage I is 160°C, and the drying time is 5 minutes; the drying temperature of stage II is 100°C, and the drying time is 8 minutes; the drying temperature of stage III is 70°C, and the drying time is 20 minutes.

[0025] Preferably, in the grinding tea processing technology of the present invention, the temperature of the re-drying in step S8 is 40-50°C.

[0026] Further preferably, in the grinding tea processing technology of the present invention, the temperature of the re-drying in step S8 is 45°C.

[0027] Beneficial effects of the present invention:

[0028] 1. The present invention explores the shading time, withering time, and green-fixing process parameters in the processing of rolling tea based on "Bai Ye No. 1", and finally determines the optimal process conditions as follows: 85% shade net shading for 8 days; withering time for 6 hours; the drum speed of the steam green-fixing machine is 40r / min, the stirring speed is 400r / min, the steam temperature is 100℃, and the steam flow rate is 110kg / h. The finished rolling tea prepared under the above optimal process conditions has a greener color, a strong aroma, a mellow taste, and a lower bitterness, which is suitable for the production of matcha.

[0029] 2. The tea grinding process provided by the present invention has a high degree of mechanization, which can improve the efficiency of large-scale industrial production. In addition, the present invention improves the utilization rate of "Bai Ye No. 1" tea leaves in the non-albinosis period, gives full play to its variety advantages, increases the economic benefits of the tea industry, realizes the diversified utilization of "Bai Ye No. 1" tea tree resources, and has broad market promotion prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a process flow chart for manufacturing tea based on Baiye No. 1;

[0031] Figure 2 The results of amino acid content determination of different tea samples are shown below;

[0032] Figure 3 The results of tea polyphenol content determination of different tea samples;

[0033] Figure 4 Phenol-ammonia ratio of different tea samples. DETAILED DESCRIPTION

[0034] The technical solution of the present invention is described in detail below in conjunction with specific embodiments. The following embodiments are only used for explanation and illustration, and do not constitute a limitation on the technical solution of the present invention.

[0035] Example 1

[0036] The process of grinding tea is as follows:

[0037] S1 Shading: After the tea leaves grow to one bud, two leaves, or three leaves, use a black PVC sunshade net with a shading rate of 85% for 8 days;

[0038] S2 picking: After the shading is over, the new shoots of 15-20cm after the tea leaves turn green are picked mechanically;

[0039] S3 withering: placing the fresh tea leaves picked in step S2 in a green storage tank, blowing cold air at 15°C for 6 hours, until the moisture content of the tea leaves reaches 65%;

[0040] S4 Fixing: Place the withered tea leaves in a steam fixing machine for steam fixing. The operating parameters are: drum speed 40r / min; stirring speed 400r / min; steam temperature 100℃; steam flow rate 110kg / h; fixing time 20s;

[0041] S5 Loose leaf cooling: The leaves after withering are immediately transported to the loose tea cooling machine for loose leaf cooling;

[0042] S6 Dehydration: The loose leaves are cooled and transported to a hot air dehydrator, where they are dehydrated at 230°C until the moisture content of the leaves reaches 45%;

[0043] S7 Drying: Set the parameters of the tea-grinding furnace, and use the tea-grinding furnace to dry the tea leaves after preliminary dehydration in stages. The operating parameters are: the drying temperature of stage I is 160℃, and the drying time is 5min; the drying temperature of stage II is 100℃, and the drying time is 8min; the drying temperature of stage III is 70℃, and the drying time is 20min;

[0044] S8 re-drying: the tea leaves dehydrated by the tea milling furnace are transported to the hot air dryer and re-dried at a temperature of 45°C until the moisture content of the tea leaves is 4%-6%;

[0045] S9 Stem and Leaf Separation: Winnowing separates the tea leaf pulp from the leaf stem.

[0046] Example 2

[0047] The process of grinding tea is as follows:

[0048] S1 Shading: After the tea leaves grow to one bud, two leaves, or three leaves, use a black PVC sunshade net with a shading rate of 80% for 10 days;

[0049] S2 picking: After the shading is over, the new shoots of 15-20cm after the tea leaves turn green are picked mechanically;

[0050] S3 withering: placing the fresh tea leaves picked in step S2 in a green storage tank, blowing cold air at 15°C for 2 hours, until the moisture content of the tea leaves reaches 70%;

[0051] S4 Fixing: Place the withered tea leaves in a steam fixing machine for steam fixing. The operating parameters are: drum speed 38r / min; stirring speed 380r / min; steam temperature 90°C; steam flow 90kg / h; fixing time 25s;

[0052] S5 Loose leaf cooling: The leaves after withering are immediately transported to the loose tea cooling machine for loose leaf cooling;

[0053] S6 Dehydration: The loose leaves are cooled and transported to a hot air dehydrator, where they are dehydrated at 200°C until the moisture content of the leaves reaches 50%;

[0054] S7 Drying: Set the parameters of the tea-grinding furnace, and use the tea-grinding furnace to dry the tea leaves after preliminary dehydration in stages. The operating parameters are: the drying temperature of stage I is 150℃, and the drying time is 10min; the drying temperature of stage II is 80℃, and the drying time is 10min; the drying temperature of stage III is 50℃, and the drying time is 25min;

[0055] S8 re-drying: the tea leaves dehydrated by the tea milling furnace are transported to the hot air dryer and re-dried at a temperature of 40°C until the moisture content of the tea leaves is 4%-6%;

[0056] S9 Stem and Leaf Separation: Winnowing separates the tea leaf pulp from the leaf stem.

[0057] Example 3

[0058] The process of grinding tea is as follows:

[0059] S1 Shading: After the tea leaves grow to one bud, two leaves, or three leaves, use a 90% shading polyvinyl chloride black sunshade net for 6 days;

[0060] S2 picking: After the shading is over, the new shoots of 15-20cm after the tea leaves turn green are picked mechanically;

[0061] S3 withering: placing the fresh tea leaves picked in step S2 in a green storage tank, blowing cold air at 15°C for 6 hours, until the moisture content of the tea leaves reaches 60%;

[0062] S4 Fixing: Place the withered tea leaves in a steam fixing machine for steam fixing. The operating parameters are: drum speed 46r / min; stirring speed 460r / min; steam temperature 105°C; steam flow rate 120kg / h; fixing time 15s;

[0063] S5 Loose leaf cooling: The leaves after withering are immediately transported to the loose tea cooling machine for loose leaf cooling;

[0064] S6 Dehydration: The loose leaves are cooled and transported to a hot air dehydrator, where they are dehydrated at 250°C until the moisture content of the leaves reaches 40%;

[0065] S7 Drying: Set the parameters of the tea-grinding furnace, and use the tea-grinding furnace to dry the tea leaves after preliminary dehydration in stages. The operating parameters are: the drying temperature of stage I is 180℃, and the drying time is 5min; the drying temperature of stage II is 120℃, and the drying time is 5min; the drying temperature of stage III is 80℃, and the drying time is 15min;

[0066] S8 re-drying: the tea leaves dehydrated by the tea grinding furnace are transported to the hot air dryer and re-dried at a temperature of 60°C until the moisture content of the tea leaves is 4%-6%;

[0067] S9 Stem and Leaf Separation: Winnowing separates the tea leaf pulp from the leaf stem.

[0068] Example 4

[0069] The process of grinding tea is as follows:

[0070] S1 Shading: After the tea leaves grow to one bud, two leaves, or three leaves, use a black PVC sunshade net with a shading rate of 85% for 8 days;

[0071] S2 picking: After the shading is over, the new shoots of 15-20cm after the tea leaves turn green are picked mechanically;

[0072] S3 withering: placing the fresh tea leaves picked in step S2 in a green storage tank, blowing cold air at 15°C for 6 hours, until the moisture content of the tea leaves reaches 65%;

[0073] S4 Fixing: Place the withered tea leaves in a steam fixing machine for steam fixing. The operating parameters are: drum speed 38r / min; stirring speed 380r / min; steam temperature 95°C; steam flow rate 100kg / h; fixing time 20s;

[0074] S5 Loose leaf cooling: The leaves after withering are immediately transported to the loose tea cooling machine for loose leaf cooling;

[0075] S6 Dehydration: The loose leaves are cooled and transported to a hot air dehydrator, where they are dehydrated at 230°C until the moisture content of the leaves reaches 45%;

[0076] S7 Drying: Set the parameters of the tea-grinding furnace, and use the tea-grinding furnace to dry the tea leaves after preliminary dehydration in stages. The operating parameters are: the drying temperature of stage I is 160℃, and the drying time is 8min; the drying temperature of stage II is 90℃, and the drying time is 8min; the drying temperature of stage III is 60℃, and the drying time is 25min;

[0077] S8 re-drying: the tea leaves dehydrated by the tea milling furnace are transported to the hot air dryer and re-dried at a temperature of 45°C until the moisture content of the tea leaves is 4%-6%;

[0078] S9 Stem and Leaf Separation: Winnowing separates the tea leaf pulp from the leaf stem.

[0079] Example 5

[0080] The process of grinding tea is as follows:

[0081] S1 Shading: After the tea leaves grow to one bud, two leaves, or three leaves, use a black PVC sunshade net with a shading rate of 85% for 8 days;

[0082] S2 picking: After the shading is over, the new shoots of 15-20cm after the tea leaves turn green are picked mechanically;

[0083] S3 withering: placing the fresh tea leaves picked in step S2 in a green storage tank, blowing cold air at 15°C for 4 hours, until the moisture content of the tea leaves reaches 65%;

[0084] S4 Fixing: Place the withered tea leaves in a steam fixing machine for steam fixing. The operating parameters are: drum speed 42r / min; stirring speed 420r / min; steam temperature 100℃; steam flow rate 110kg / h; fixing time 25s;

[0085] S5 Loose leaf cooling: The leaves after withering are immediately transported to the loose tea cooling machine for loose leaf cooling;

[0086] S6 Dehydration: The loose leaves are cooled and transported to a hot air dehydrator, where they are dehydrated at 230°C until the moisture content of the leaves reaches 45%;

[0087] S7 Drying: Set the parameters of the tea-grinding furnace, and use the tea-grinding furnace to dry the tea leaves after preliminary dehydration in stages. The operating parameters are: the drying temperature of stage I is 170℃, and the drying time is 5min; the drying temperature of stage II is 110℃, and the drying time is 5min; the drying temperature of stage III is 70℃, and the drying time is 20min;

[0088] S8 re-drying: the tea leaves dehydrated by the tea milling furnace are transported to the hot air dryer and re-dried at a temperature of 45°C until the moisture content of the tea leaves is 4%-6%;

[0089] S9 Stem and Leaf Separation: Winnowing separates the tea leaf pulp from the leaf stem.

[0090] In order to further verify the reliability of the present invention and screen out the best solution, the inventor conducted a series of experiments, as follows:

[0091] 1. The manufacturing process of ground tea based on "White Leaf No. 1"

[0092] "Baiye No. 1" is a temperature-sensitive albino tea variety with a temperature threshold of 17-25℃. The "white leaves with green veins" phenomenon usually only occurs around April each year, and the leaves gradually turn green as the temperature rises in the later period. Baiye No. 1 has the characteristics of "high ammonia and low phenol". The Anji white tea made from it is rich in 18 kinds of amino acids required by the human body, and the total amount of amino acids is as high as 6.25%-10.6%, which is 3-5 times higher than that of ordinary green tea. The tea polyphenols are only 1 / 3-1 / 2 of that of ordinary green tea. The ground tea processed with it as raw material tastes fresh, has a high-mellow aroma, and is less bitter. For the Baiye No. 1 tea variety, only the green tea leaves in the spring albino period are often used to process high-end famous teas, while the tea leaves in the non-albino period in summer and autumn are less developed and utilized. They are usually directly pruned and returned to the tea garden, resulting in low utilization rate and failure to play their due value.

[0093] In response to the above problems, this research team developed a grinding tea manufacturing process based on the non-albino tea leaves of "Bai Ye No. 1". After a lot of research, the process flow was initially determined (see the flow chart). Figure 1 )as follows:

[0094] (1) Shading: After the tea leaves grow to one bud, two or three leaves, use a black polyvinyl chloride shade net with a shading rate of 85% for 10 days.

[0095] (2) Picking: After shading, mechanically pick the new 15-20cm shoots of tea leaves after they turn green.

[0096] (3) Withering: Place the fresh tea leaves obtained in the above step in a green tea storage tank and blow cold air at 15°C to wither for 6 hours until the moisture content of the tea leaves is 60-70%.

[0097] (4) Withering: Place the withered fresh tea leaves in a steam withering machine for steam withering. The operating parameters are: drum speed 42r / min; stirring speed 420r / min; steam temperature 90℃; steam flow rate 110kg / h; withering time 20s. After withering, the tea leaves are bright green, soft when pinched, with no excess moisture on the leaf surface, the green taste disappears, and there is no watery smell.

[0098] (5) Loose leaf cooling: The withered leaves are immediately transported to the loose tea cooling machine for loose leaf cooling.

[0099] (6) Dehydration: The loose leaves are cooled and transported to a hot air dehydrator, where they are dehydrated at 230°C until the moisture content of the leaves is 40%-50%;

[0100] (7) Drying: Setting the parameters of the tea-grinding furnace, the tea leaves after preliminary dehydration are dried in stages using the tea-grinding furnace. The operating parameters are as follows: the drying temperature of stage I is 160°C and the drying time is 5 min; the drying temperature of stage II is 100°C and the drying time is 8 min; the drying temperature of stage III is 70°C and the drying time is 20 min;

[0101] (8) Re-drying: The tea leaves dehydrated by the tea mill are transported to a hot air dryer and re-dried at 45°C until the moisture content of the tea leaves is 4%-6%;

[0102] (9) Separation of stems and leaves: The mesophyll of tea leaves is separated from the stems by air separation.

[0103] 2. Investigation of tea-grinding process factors

[0104] 2.1 Determination method

[0105] 2.1.1 Sensory evaluation test

[0106] According to DB5205 / T 129-2020 "Fanjing Matcha Evaluation Technical Specifications", an evaluation team composed of 5 tea tasters holding national senior tea taster certificates will conduct a sensory evaluation of the finished ground tea products. The tea tasters will evaluate the tea samples based on 5 evaluation factors: tea appearance, soup color, aroma, taste, and leaf bottom, and assign points based on weighted method according to each factor. The total score = appearance × 0.4 + soup color × 0.1 + aroma × 0.2 + taste × 0.25 + leaf bottom × 0.5.

[0107] 2.1.2 Determination of free amino acids and tea polyphenols

[0108] The mass concentration of tea polyphenols was determined according to the ferrous tartrate colorimetric method in GB / T 21733-2008 "Tea Beverages". The mass concentration of amino acids was determined according to the ninhydrin colorimetric method in GB / T 8314-2013 "Determination of the total amount of free amino acids in tea".

[0109] 2.2 Single factor investigation

[0110] 2.2.1 Shading time investigation

[0111] Shading can inhibit the conversion of amino acids in tea into catechins, making the color and taste of rolled tea better. After preliminary research, this study used a polyvinyl chloride black shade net with a shading rate of 85% and directly covered the tea trees to shade them. After the spring picking, the tea trees were lightly pruned. When the average daily temperature was higher than 22°C and the tea leaves grew to one bud, two or three leaves, the tea trees were shaded. The tea leaves were harvested on the 6th, 8th and 10th days of shading, and rolled tea was made. The sensory evaluation test was conducted according to the method under "2.1.1".

[0112] 2.2.2 Investigation of withering time

[0113] Different withering temperatures and withering times can affect the color, taste and sensory quality of rolled tea products. In this study, the withering temperature was fixed at 15°C, and the effects of withering times of 2h, 4h and 6h on the quality of rolled tea products were explored.

[0114] 2.2.3 Investigation of the process parameters for fixing the green tea

[0115] Steaming is currently a common method for rolling tea. High-temperature steam can quickly inactivate enzymes in fresh leaves, better retain chlorophyll in leaves, and play a role in color fixation. Under the condition of a standard speed ratio of 1:10 between the drum and the stirring shaft of the tea-fixing machine, this study investigated the effects of speeds (drum speed / stirring speed, in r / min) of 38 / 380, 40 / 400, 42 / 420, 44 / 440, and 46 / 460 on the quality of the finished rolling tea. Under the optimal speed condition, the effects of steam temperatures of 90°C, 95°C, 100°C, and 105°C and steam flow rates of 90kg / h, 100kg / h, 110kg / h, and 120kg / h on the quality of the finished rolling tea were investigated in turn.

[0116] 2.3 Results and Analysis

[0117] 2.3.1 Effect of shading time on tea quality

[0118] Tea leaves were harvested on the 6th, 8th and 10th day of shading, and rolled tea was made. Sensory evaluation tests were conducted according to the method in "2.1.1". The results are shown in Table 1.

[0119] Table 1 Sensory evaluation test results (shading time)

[0120]

[0121] The results show that the finished tea product scored the highest when harvested on the 8th day under shading, so the optimal parameter for shading time is 8 days.

[0122] 2.3.2 Investigation of withering time

[0123] The shading time was fixed at 8 days and the withering temperature was 15°C. The free amino acid content and tea polyphenol content in the finished tea products made with withering time of 2h, 4h and 6h were determined according to the method under "2.1.2". The effect of different withering time on the quality of the finished tea products was investigated. The results are shown in Table 2.

[0124] Table 2 Determination results of free amino acids and tea polyphenols content (withering time)

[0125]

[0126] The results show that when the withering time is 6 hours, the phenol-ammonia ratio of the finished tea is the lowest, which is 1.76. Therefore, 6 hours is selected as the optimal process parameter for withering time.

[0127] 2.3.3 Investigation of the process parameters for fixing the green tea

[0128] In this study, under the condition of a standard speed ratio of 1:10 between the drum and the stirring shaft of the withering machine, the free amino acid content and tea polyphenol content in the finished rolled tea products were determined according to the method under "2.1.2" when the drum speed / stirring speed (unit: r / min) was 38 / 380, 40 / 400, 42 / 420, 44 / 440, and 46 / 460, respectively. The effect of different drum speeds / stirring speeds on the quality of the finished rolled tea products was investigated. The results are shown in Table 3.

[0129] Table 3 Determination results of free amino acids and tea polyphenols content (fixing speed)

[0130]

[0131] It can be seen from Table 3 that when the drum speed is 40r / min and the stirring speed is 400r / min, the phenol-ammonia ratio of the finished tea is the lowest, which is 1.73. Therefore, the optimal process parameters of the speed are determined as follows: the drum speed is 40r / min and the stirring speed is 400r / min.

[0132] Under the above-mentioned optimal rotation speed conditions, the effects of steam temperatures of 90°C, 95°C, 100°C, and 105°C and steam flow rates of 90kg / h, 100kg / h, 110kg / h, and 120kg / h on the quality of the finished ground tea products were investigated in turn. The results are shown in Tables 4 and 5.

[0133] Table 4 Determination results of free amino acids and tea polyphenols content (steam temperature)

[0134]

[0135] Table 5 Determination results of free amino acids and tea polyphenols content (steam flow rate)

[0136]

[0137]

[0138] From the results in Table 4 and Table 5, it can be seen that the optimal process parameter of steam temperature is 100 degrees Celsius, and the optimal process parameter of steam flow rate is 110 kg / h.

[0139] 2.4 Verification of optimal process parameters

[0140] From the single factor investigation test, it can be known that the optimal process parameters of this study are: shading time is 8d; withering time is 6h; steam-fixing drum speed is 40r / min, stirring speed is 400r / min, steam temperature is 100℃, and steam flow rate is 110kg / h. Example 1 is to prepare rolling tea according to the optimal process parameters of this study, and the spring middle and upper rolling tea samples made from spring Fuding Dabai tea purchased from the market are used as the control example. According to the method under "2.1 Determination Method", the finished rolling tea products prepared in Examples 1 to 5 and the control example are subjected to sensory evaluation, and the contents of amino acids and tea polyphenols in the finished rolling tea products are determined. The results are shown in Tables 6 and 7. Figure 2 .

[0141] Table 6 Sensory evaluation test results

[0142]

[0143]

[0144] Table 7 Determination results of free amino acids and tea polyphenols content

[0145]

[0146] From Tables 6 and 7, we can see that the sensory evaluation score of the finished tea prepared under the optimal process conditions in this study is the highest, and the phenol-amino ratio is the lowest. Figure 2-4 .

[0147] 3. Discussion

[0148] In this study, "Bai Ye No. 1" was used as the raw material for the processing and preparation of rolling tea. When the average daily temperature in late spring was about 22 degrees Celsius, a shade net with a shading rate of 85% was used for 8 days to ensure the greenness, tenderness and yield of the tea leaves, and the phenol and ammonia of Bai Ye No. 1 during this period were relatively low. Appropriate shading can make Bai Ye No. 1 turn green better, with relatively low phenol and ammonia. The rolling tea tastes fresh, green and has low bitterness. The storage tank is blown and withered at low temperature. Low temperature inhibits the activity of enzymes involved in chlorophyll degradation. Appropriate withering makes the rolling tea greener. At the same time, withering can make the grass smell disappear and enhance the fresh and fragrant flavor. The higher dehydration temperature can play a role in killing and supplementing the tenderer tea leaves. At the same time, it can make the tea leaves enter the rolling tea furnace with a lower water content for baking. While reducing the baking time of the rolling tea furnace, it can ensure that the tea leaves can be baked in place, which can reduce the loss of chlorophyll in the rolling tea leaves and make them have better color performance. The finished tea produced by the optimal process parameters provided by this study has a greener color, a fresh and mellow taste, and a low bitterness, which is very suitable for the production of matcha. This study not only improves the utilization rate of non-albinosis period green tea leaves of "White Leaf No. 1", gives full play to its variety advantages, increases the economic benefits of the tea industry, but also realizes the diversified utilization of "White Leaf No. 1" tea tree resources, which has great market promotion prospects.

[0149] Although the present invention has been described in detail above by means of general description, specific implementation methods and tests, it is obvious to those skilled in the art that some modifications or improvements can be made to the present invention. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of protection claimed by the present invention.

Claims

1. A grinding tea processing technology, characterized in that: The steps include: S1 Shading: After the tea leaves grow to one bud, two leaves or three leaves, use a black PVC sunshade net with a shading rate of 80-90% for 6-10 days; S2 picking: After the shading is over, the new shoots of 15-20cm after the tea leaves turn green are picked mechanically; S3 withering: placing the fresh tea leaves obtained in step S2 in a green storage tank, blowing cold air at 15°C for withering for 2-6 hours until the moisture content of the tea leaves reaches 60-70%; S4 Fixing: Place the withered tea leaves in a steam fixing machine for steam fixing. The operating parameters are: drum speed 38-46r / min; stirring speed 380-460r / min; steam temperature 90-105℃; steam flow 90-120kg / h; fixing time 15-25s; S5 Loose leaf cooling: The leaves after withering are immediately transported to the loose tea cooling machine for loose leaf cooling; S6 Dehydration: The loose leaves are cooled and transported to a hot air dehydrator, where they are dehydrated at 200-250°C until the moisture content of the leaves reaches 40%-50%; S7 Drying: Set the parameters of the tea-grinding furnace, and use the tea-grinding furnace to dry the tea leaves after preliminary dehydration in stages. The operating parameters are: the drying temperature of stage I is 150-180℃, and the drying time is 5-10min; the drying temperature of stage II is 80-120℃, and the drying time is 5-10min; the drying temperature of stage III is 50-80℃, and the drying time is 15-25min; S8 re-drying: the tea leaves dehydrated by the tea milling furnace are transported to the hot air dryer and re-dried at a temperature of 40-60°C until the moisture content of the tea leaves is 4%-6%; S9 Stem and Leaf Separation: Winnowing separates the tea leaf pulp from the leaf stem.

2. The tea grinding process according to claim 1, characterized in that: The shading in step S1 specifically includes: after the tea leaves grow to one bud, two leaves or three leaves, a polyvinyl chloride black sunshade net with a shading rate of 85% is used for shading for 8 days.

3. The tea grinding process according to claim 1, characterized in that: The time for withering with cold air at 15° C. in step S3 is 6 hours.

4. The tea processing process according to claim 1, characterized in that: The operating parameters of the steam killing in step S4 are: drum speed of 38-42r / min; stirring speed of 380-420r / min; steam temperature of 95-100°C; steam flow rate of 100-110kg / h; and killing time of 20-25s.

5. The tea grinding process according to claim 4, characterized in that: The operating parameters of the steam killing in step S4 are: drum speed of 40r / min; stirring speed of 400r / min; steam temperature of 100°C; steam flow rate of 110kg / h; and killing time of 20s.

6. The tea making process according to claim 1, characterized in that: The dehydration temperature in step S6 is 230°C.

7. The tea grinding process according to claim 1, characterized in that: The operating parameters of the staged drying in step S7 are: the drying temperature of stage I is 160-170°C, and the drying time is 5-8 minutes; the drying temperature of stage II is 90-110°C, and the drying time is 5-8 minutes; the drying temperature of stage III is 60-70°C, and the drying time is 20-25 minutes.

8. The tea making process according to claim 7, characterized in that: The operating parameters of the staged drying in step S7 are: the drying temperature of stage I is 160°C and the drying time is 5 minutes; the drying temperature of stage II is 100°C and the drying time is 8 minutes; the drying temperature of stage III is 70°C and the drying time is 20 minutes.

9. The tea making process according to claim 1, characterized in that: The temperature of the re-drying in step S8 is 40-50°C.

10. The tea grinding process according to claim 9, characterized in that: The temperature of the re-drying in step S8 is 45°C.

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