Improved tea processing technology

Abstract

Belonging to the technical field of tea processing, the invention discloses an improved tea processing technology, which comprises the following steps: (1) fixation pretreatment; (2) fixation; (3) spreading for cooling; (4) rolling; and (5) drying. According to the improved tea leaf processing technology, the tea leaves finally prepared through the method are remarkable in amino acid content and tea polyphenol content, high in nutrition and health care value and relatively low in caffeine and water extract content, the bitterness of the tea leaves is effectively reduced, and the quality of the tea leaves is improved to a certain degree.

Description

Technical Field

[0001] The present invention belongs to the technical field of tea processing, and in particular to an improved tea processing technology. Background Art

[0002] Tea is made from the new leaves or buds of tea trees, without fermentation, through processes such as fixation, shaping, and drying. It retains the natural substances of fresh leaves and contains nutrients such as tea polyphenols, catechins, chlorophyll, caffeine, amino acids, and vitamins. The green color and tea soup of green tea mostly retain the green style of fresh tea leaves, hence the name. Regular drinking of tea can prevent cancer, reduce fat and aid in weight loss, and also reduce the harm of nicotine to smokers.

[0003] The processing of tea is simply divided into three steps: fixation, rolling, and drying. Among them, the key lies in fixation. Through fixation, the activity of enzymes in fresh leaves is inactivated, and various chemical components contained therein basically undergo physical and chemical changes under the action of heat without the influence of enzymes, thus forming the quality characteristics of tea. Therefore, how to improve the quality of tea through the improvement of processing technology is an urgent problem to be solved. Summary of the Invention

[0004] The purpose of the present invention is to provide an improved tea processing technology to solve the deficiencies in the prior art.

[0005] The technical solution adopted by the present invention is as follows: An improved tea processing technology includes the following steps: (1) Pretreatment before fixation: a. Place the fresh leaves in a corona discharge instrument for corona treatment, and take them out for standby after completion; b. Place the fresh leaves after corona treatment in step a in a vacuum drying oven for low-temperature vacuum drying treatment, and take them out for standby after completion; (2) Fixation: Place the tea leaves obtained after pretreatment in step (1) in a fixation machine for variable-temperature fixation treatment, and take them out for standby after completion; (3) Spreading and cooling: Place the tea leaves after fixation in step (3) in a clean bamboo utensil, and then spread and cool them under an ultrasonic environment; (4) Rolling: Place the tea leaves after spreading and cooling in step (3) in a rolling machine for rolling treatment, and take them out for standby after completion; (5) Drying: Place the tea leaves after rolling treatment in step (4) in a vacuum freeze-drying oven for vacuum drying treatment, and then perform stem picking and packaging after completion.

[0006] Further, during the corona treatment in operation a of step (1), the voltage is controlled at 4 - 6 kV, and the corona treatment time is 30 - 40 s.

[0007] Further, during the low - temperature vacuum drying treatment in operation b of step (1), the vacuum degree is controlled at 1.3 - 1.7 Pa, the temperature is 34 - 38 °C, and it is dried until the moisture content is 70 - 80%.

[0008] By adopting the above - mentioned technical solution, the fresh leaves are placed in a corona discharge instrument for corona treatment. Through discharge, a low - temperature plasma region will be formed on the surface of the fresh leaves, and dense micro - concave holes will be formed on the surface of the fresh leaves, thereby increasing the pit membranes of epidermal cells, which helps the loss of moisture in subsequent operations. Then, it is dried under low - temperature vacuum conditions. The fresh leaves are slowly heated from the outside to the inside, generating a certain vapor pressure. These vapor pressures break through the pit membranes of some ray parenchyma cells and some sclerenchyma cells, thus opening the cell liquid flow channels, improving the permeability of the fresh leaves, further accelerating the loss of moisture, thereby improving the efficiency of fixation, preventing enzymatic reactions, and preventing the loss of nutritional components and active ingredients.

[0009] Further, the program of the variable - temperature fixation treatment in step (2) is to treat at 160 - 180 °C for 10 - 20 s, at 180 - 200 °C for 6 - 8 s, and at 160 - 180 °C for 15 - 21 s.

[0010] By adopting the above - mentioned technical solution, on the premise of pretreatment, through variable - temperature fixation, carrying out the fixation treatment under lower variable - temperature conditions can not only effectively prevent the inactivation of active ingredients and nutritional components in the tea leaves, but also dissipate the moisture inside the leaves, inactivate the activity of enzymes, inhibit enzymatic reactions, and cause certain chemical changes in the internal substances of the fresh leaves, thereby forming the quality characteristics of the tea leaves and maintaining the color and flavor of the tea leaves.

[0011] Further, the frequency of the ultrasonic wave in step (3) is 30 - 40 kHz, and it is cooled to a temperature of 30 - 40 °C.

[0012] By adopting the above - mentioned technical solution, while cooling, ultrasonic treatment with a specific frequency is carried out. By controlling the frequency of the ultrasonic wave, the movement speed of molecules is accelerated, the fibers in the tea leaves are softened, the toughness of the tea leaves is improved, which is beneficial for them to be rolled into strips, thereby increasing the finished product rate.

[0013] Further, during the vacuum drying treatment in step (5), the freezing temperature is controlled at - 10 - - 4 °C, the freezing time is 4 - 5 min, the drying temperature is 50 - 56 °C, and it is dried until the moisture content is 5 - 7%.

[0014] By adopting the above technical solution, the tea leaves are subjected to vacuum freeze-drying treatment after rolling, avoiding the inactivation of active ingredients caused by high-temperature drying, and maintaining good color and aroma.

[0015] The present invention has the following beneficial effects: This application provides an improved tea processing technology. The tea leaves finally prepared by the method of this application have significant amino acid content and tea polyphenol content, high nutritional and health care value, relatively low caffeine and water extract content, effectively reducing the bitterness of the tea leaves, and improving the quality of the tea leaves to a certain extent. Specific embodiments

[0016] The technical solutions of the embodiments of the present invention will be described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention. Embodiment 1

[0017] An improved tea processing technology includes the following steps: (1) Pretreatment before fixation: a. Place the fresh tea leaves in a corona discharge instrument for corona treatment, and take them out for standby after completion; b. Place the fresh tea leaves after corona treatment in operation a in a vacuum drying oven for low-temperature vacuum drying treatment, and take them out for standby after completion; (2) Fixation: Place the tea leaves obtained after pretreatment in step (1) in a fixation machine for variable-temperature fixation treatment, and take them out for standby after completion; (3) Spreading and cooling: Place the tea leaves after fixation in step (3) in a clean bamboo utensil, and then spread and cool them under an ultrasonic environment; (4) Rolling: Place the tea leaves after spreading and cooling in step (3) in a rolling machine for rolling treatment, and take them out for standby after completion; (5) Drying: Place the tea leaves after rolling treatment in step (4) in a vacuum freeze-drying oven for vacuum drying treatment, and then carry out stem picking and packaging.

[0018] During the corona treatment in operation a of step (1), the voltage is controlled at 4 kV, and the corona treatment time is 30 s.

[0019] During the low-temperature vacuum drying treatment in operation b of step (1), the vacuum degree is controlled at 1.3 Pa, the temperature is 34 °C, and the drying is carried out until the moisture content is 70%.

[0020] In step (2), the program of temperature-variable fixation treatment is to treat at 160°C for 10 s, at 180°C for 6 - 8 s, and at 160°C for 15 s.

[0021] In step (3), the frequency of the ultrasonic wave is 30 kHz, and it is cooled to 30°C.

[0022] In step (5), during the vacuum drying treatment, the freezing temperature is controlled at -10°C, the freezing time is 4 min, the drying temperature is 50°C, and it is dried until the moisture content is 5%. Example 2

[0023] An improved tea processing technology, including the following steps: (1) Pretreatment before fixation: a. Place the fresh leaves in a corona discharge instrument for corona treatment, and take them out for standby after completion; b. Place the fresh leaves after corona treatment in operation a in a vacuum drying oven for low-temperature vacuum drying treatment, and take them out for standby after completion; (2) Fixation: Place the tea obtained after pretreatment in step (1) into a fixation machine for temperature-variable fixation treatment, and take it out for standby after completion; (3) Cooling: Place the tea after fixation in step (3) into a clean bamboo utensil, and then cool it in an ultrasonic environment; (4) Rolling: Place the tea after cooling in step (3) into a rolling machine for rolling treatment, and take it out for standby after completion; (5) Drying: Place the tea after rolling treatment in step (4) into a vacuum freeze-drying oven for vacuum drying treatment, and then perform stem picking and packaging after completion.

[0024] During the corona treatment in operation a of step (1), the voltage is controlled at 5 kV, and the corona treatment time is 35 s.

[0025] During the low-temperature vacuum drying treatment in operation b of step (1), the vacuum degree is controlled at 1.5 Pa, the temperature is 36°C, and it is dried until the moisture content is 75%.

[0026] In step (2), the program of temperature-variable fixation treatment is to treat at 170°C for 15 s, at 190°C for 7 s, and at 170°C for 18 s.

[0027] In step (3), the frequency of the ultrasonic wave is 35 kHz, and it is cooled to 35°C.

[0028] During the vacuum drying treatment described in step (5), the freezing temperature was controlled at -7°C, the freezing time was 4.5 minutes, the drying temperature was 53°C, and the drying was carried out until the moisture content reached 6%. Example 3

[0029] An improved tea processing technology includes the following steps: (1) Pretreatment before fixation: a. Place the fresh tea leaves in a corona discharge instrument for corona treatment, and take them out for standby after completion; b. Place the fresh tea leaves after corona treatment in operation a in a vacuum drying oven for low-temperature vacuum drying treatment, and take them out for standby after completion; (2) Fixation: Place the tea leaves obtained after pretreatment in step (1) in a fixation machine for variable-temperature fixation treatment, and take them out for standby after completion; (3) Spreading and cooling: Place the tea leaves after fixation in step (3) in a clean bamboo utensil, and then carry out spreading and cooling under an ultrasonic environment; (4) Rolling: Place the tea leaves after spreading and cooling in step (3) in a rolling machine for rolling treatment, and take them out for standby after completion; (5) Drying: Place the tea leaves after rolling treatment in step (4) in a vacuum freeze-drying oven for vacuum drying treatment, and then carry out stem picking and packaging.

[0030] During the corona treatment described in operation a of step (1), the voltage was controlled at 6 kV and the corona treatment time was 40 s.

[0031] During the low-temperature vacuum drying treatment described in operation b of step (1), the vacuum degree was controlled at 1.7 Pa, the temperature was 38°C, and the drying was carried out until the moisture content reached 80%.

[0032] The program of the variable-temperature fixation treatment described in step (2) was 180°C for 20 s, 200°C for 8 s, and 180°C for 21 s.

[0033] The frequency of the ultrasonic wave described in step (3) was 40 kHz, and the spreading and cooling was carried out until the temperature reached 40°C.

[0034] During the vacuum drying treatment described in step (5), the freezing temperature was controlled at -4°C, the freezing time was 5 minutes, the drying temperature was 56°C, and the drying was carried out until the moisture content reached 7%.

[0035] Comparative Example 1 Compared with Example 2, in the pretreatment before fixation in step (1) of this Comparative Example 1, the entire process of operation a was omitted, and the method steps except this were the same.

[0036] Comparative Example 2 Compared with Example 2, in the pre - fixation treatment of step (1) of this Comparative Example 2, the whole process of operation b is omitted, and the other method steps are the same.

[0037] Comparative Example 3 Compared with Example 2, in this Comparative Example 3, the whole process of the pre - fixation treatment in step (1) is omitted, and the other method steps are the same.

[0038] Comparative Example 4 Compared with Example 2, in step (2) fixation of this Comparative Example 4, the variable - temperature fixation treatment is replaced with a constant - temperature fixation treatment at 200 °C, and the other method steps are the same.

[0039] Comparative Example 5 Compared with Example 2, in step (3) cooling of this Comparative Example 5, the ultrasonic treatment is omitted, and the other method steps are the same.

[0040] Comparative Example 6 Compared with Example 2, in step (5) drying of this Comparative Example 6, the vacuum drying treatment is replaced with a conventional drying treatment, and the drying temperature is 60 - 70 °C.

[0041] Control Group A production method of high - nutrition and good - taste tea disclosed in the application number: CN201610799076.4. Specifically, refer to the method of Example 1 in the specific implementation part of this invention.

[0042] In order to compare the technical effects of this application, the same batch of freshly picked tea leaves are selected as the test objects. The freshly picked tea leaves are randomly divided into 8 equal - quality and equal - quantity portions, and then the tea leaves are prepared according to the methods of Example 2, Comparative Examples 1 - 6 and the control group respectively. Then, the biochemical components of each group of tea leaves are tested according to the content of "Physical and Chemical Analysis of Tea Quality", the total amount of amino acids is tested according to the method of GB / T 8314 - 2002 (determined by ninhydrin colorimetry), the total amount of caffeine is determined according to the method of GB / T 8312 - 2002 (determined by lead acetate precipitation method), the total amount of water extracts is tested according to the method of GB / T 8305 - 2002 (determined by weighing the difference of tea residues), and the total amount of tea polyphenols is determined according to the method of GB / T 8313 - 2008 (determined by Folin - Ciocalteu reagent colorimetry). The specific test comparison data are shown in Table 1 below: Table 1

[0043] As can be seen from Table 1 above, the present application provides an improved tea processing technology. The tea prepared by the method of the present application has significant amino acid content and tea polyphenol content, high nutritional and health care value, relatively low caffeine and water extract content, effectively reducing the bitterness of the tea, and improving the quality of the tea to a certain extent.

[0044] The above are only the preferred embodiments of the present invention, but the present invention is not limited to the scope of the embodiments shown. Any changes made according to the concept of the present invention, or equivalent embodiments modified into equivalent changes, still within the spirit covered by the specification, shall be within the protection scope of the present invention.

Claims

1. An improved tea processing technology, characterized in that: The steps include: (1) Pre-treatment: a. Place the fresh leaves in a corona discharge apparatus for corona treatment, and remove them for later use after completion; b. The fresh leaves after corona treatment in operation a are placed in a vacuum drying oven for low-temperature vacuum drying, and after completion, remove and set aside; (2) Finishing: The tea leaves obtained after the pretreatment in step (1) are placed in a tea-withering machine for temperature-variable withering treatment, and after completion, the tea leaves are taken out for later use; (3) Let it cool: Place the tea leaves after withering in step (3) in a clean bamboo container and then spread them out to cool under an ultrasonic environment; (4) Kneading: Place the tea leaves after cooling in step (3) in a rolling machine for rolling, and take them out for later use after rolling. (5) Drying: The tea leaves after the rolling treatment in step (4) are placed in a vacuum freeze drying oven for vacuum drying, and after completion, the tea leaves are picked out and packaged.

2. The improved tea processing technology according to claim 1, characterized in that: During the corona treatment described in step (1) operation a, the voltage is controlled to be 4-6 kV, and the corona treatment time is 30-40 s.

3. The improved tea processing technology according to claim 1, characterized in that: During the low-temperature vacuum drying treatment described in step (1) operation b, the vacuum degree is controlled to be 1.3-1.7 Pa, the temperature is 34-38° C., and the drying is performed until the moisture content is 70-80%.

4. The improved tea processing technology according to claim 1, characterized in that: The procedure of the variable temperature fixing treatment in step (2) is 160-180°C for 10-20s, 180-200°C for 6-8s, and 160-180°C for 15-21s.

5. The improved tea processing technology according to claim 1, characterized in that: The frequency of the ultrasonic wave in step (3) is 30-40 kHz, and the mixture is cooled to a temperature of 30-40°C.

6. The improved tea processing technology according to claim 1, characterized in that: During the vacuum drying process in step (5), the freezing temperature is controlled to be -10 to -4°C, the freezing time is 4 to 5 minutes, the drying temperature is 50 to 56°C, and the moisture content is dried to 5 to 7%.

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