Black tea processing method based on long-wave-band illumination withering and combined drying mode

Abstract

The invention discloses a black tea processing method based on a long-wave-band illumination withering and combined drying mode, and relates to the technical field of black tea processing, and the black tea processing method comprises the following steps: long-wave-band illumination withering: fresh leaves are placed in a withering trough internally provided with a red light emitting lamp tube, the leaf layer thickness is 5-10 cm, the power of the red light emitting lamp tube is 20 W, and red light illumination is carried out for 2.5-3.5 h; the fresh leaves are placed in a withering trough with a yellow light emitting lamp tube, the leaf layer thickness is 5-10 cm, the power of the yellow light emitting lamp tube is 20 W, and the fresh leaves are illuminated by yellow light for 2.5-3.5 h; microwave combined drying: putting the moderately fermented tea leaves into a microwave machine with the power of 15-18kW, and treating the tea leaves for 2-3 minutes by using the microwave machine for rapid enzyme deactivation; and putting the tea leaves subjected to microwave treatment into a baking machine, and carrying out hot air drying at 105-115 DEG C for 20-30 minutes until the water content of the tea leaves is 5%. The black tea prepared by the method is sweet and thick in aroma, mellow in taste and red and bright in soup color, and the quality of the black tea is superior to that of traditional hot-air dried black tea.

Description

Technical Field

[0001] This invention relates to the field of black tea processing technology, and in particular to a black tea processing method based on long-wavelength light withering and combined drying. Background Technology

[0002] The current production process for Gongfu black tea is as follows: fresh leaves – withering – rolling – fermentation – drying. Among these, withering and drying play crucial roles in the quality of the black tea. In the withering stage, the traditional method is to conduct it indoors under natural climatic conditions. The tea leaves are placed on withering racks and withered for approximately 18 hours in an environment with a room temperature of 20-24℃ and a relative humidity of 60%-70%. Temperature and humidity are regulated by opening and closing doors and windows, using diffused natural light. However, research shows that different wavelengths of natural light have varying effects on the withering of black tea, leading to differences in processing quality. The traditional method suffers from the problem of long withering time and limited quality improvement. In the drying stage, the traditional method uses a dryer for two stages: initial drying at 110-120℃ for 10 minutes and final drying at 85-95℃ for 15 minutes. Although this method is shorter, the long temperature rise time during hot air drying can cause insufficient enzyme inactivation, thus affecting the freshness and flavor of the tea, resulting in a need to improve the quality of the black tea. Summary of the Invention

[0003] This invention provides a black tea processing method based on long-wavelength light withering and combined drying, which can improve the color, aroma and taste of black tea.

[0004] To solve the technical problem, the present invention adopts the following technical solution: A method for processing black tea based on long-wavelength light withering and combined drying includes the following steps: (1) Long-wavelength light withering First, place the fresh leaves in a withering trough equipped with red light tubes, with a leaf layer thickness of 5-10cm and a red light tube power of 20W, and irradiate with red light for 2.5-3.5 hours; then place the fresh leaves in a withering trough equipped with yellow light tubes, with a leaf layer thickness of 5-10cm and a yellow light tube power of 20W, and irradiate with yellow light for 2.5-3.5 hours. (2) Microwave and hot air combined drying ① Place the properly fermented tea leaves into a microwave oven with a power of 15-18kW and microwave for 2-3 minutes to quickly inactivate the enzymes. ② Place the microwaved tea leaves in a roasting machine and dry them with hot air at 105-115℃ for 20-30 minutes until the moisture content of the tea leaves is 5%.

[0005] The beneficial effects of this invention are as follows: This invention uses long-wavelength red and yellow light to irradiate the tea leaves sequentially for a total duration of 5-7 hours, which significantly shortens the withering time and improves production efficiency. At the same time, the synergistic effect of red and yellow light can effectively improve the concentration and persistence of aroma, enhance the freshness and sweetness of the taste, reduce bitterness, and significantly improve the quality of tea leaves during the withering process. In the combined microwave and hot air drying process, microwaves rapidly inactivate enzymes, ensuring that the enzymatic reaction in the tea leaves stops in time, thus maintaining their fresh and crisp taste. The subsequent hot air drying not only achieves thorough drying but also further enhances the aroma of the tea leaves, resulting in a black tea with a sweet and rich aroma, mellow taste, and bright red color, making it of higher quality than black tea dried by traditional hot air drying. Detailed Implementation

[0006] The technical solutions in the embodiments of the present invention will be clearly and completely described below.

[0007] Example 1 A method for processing black tea based on long-wavelength light withering and combined drying includes the following steps: (1) Long-wavelength light withering: First, place the fresh leaves in a withering trough with red light tubes installed inside. The leaf layer thickness is 5cm, the power of the red light tubes is 20W, and the leaves are irradiated with red light for 2.5h. Then, place the fresh leaves in a withering trough with yellow light tubes. The leaf layer thickness is 5cm, the power of the yellow light tubes is 20W, and the leaves are irradiated with yellow light for 2.5h. After withering under long-wavelength light, the fresh leaves undergo traditional rolling and fermentation processes to obtain tea leaves that are properly fermented. (2) Microwave and hot air combined drying ① Place the properly fermented tea leaves into a microwave oven with a power of 15kW and microwave for 3 minutes to quickly inactivate the enzymes. ② Place the microwaved tea leaves in a roasting machine and dry them with hot air at 105℃ for 30 minutes until the moisture content of the tea leaves is 5%.

[0008] Example 2 A method for processing black tea based on long-wavelength light withering and combined drying includes the following steps: (1) Long-wavelength light withering: First, place the fresh leaves in a withering trough with red light tubes installed inside. The leaf layer thickness is 8cm, the power of the red light tubes is 20W, and the leaves are irradiated with red light for 3 hours. Then, place the fresh leaves in a withering trough with yellow light tubes. The leaf layer thickness is 8cm, the power of the yellow light tubes is 20W, and the leaves are irradiated with yellow light for 3 hours. After withering under long-wavelength light, the fresh leaves undergo traditional rolling and fermentation processes to obtain tea leaves that are properly fermented. (2) Microwave and hot air combined drying ① Place the properly fermented tea leaves into a microwave oven with a power of 18kW and microwave for 2 minutes to quickly inactivate the enzymes. ② Place the microwaved tea leaves in a roasting machine and dry them with hot air at 110℃ for 25 minutes until the moisture content of the tea leaves is 5%.

[0009] Example 3 A method for processing black tea based on long-wavelength light withering and combined drying includes the following steps: (1) Long-wavelength light withering: First, place the fresh leaves in a withering trough with red light tubes installed inside, with a leaf layer thickness of 10cm and a red light tube power of 20W, and irradiate with red light for 3.5h; then place the fresh leaves in a withering trough with yellow light tubes, with a leaf layer thickness of 10cm and a yellow light tube power of 20W, and irradiate with yellow light for 3.5h. After withering under long-wavelength light, the fresh leaves undergo traditional rolling and fermentation processes to obtain tea leaves that are properly fermented. (2) Microwave and hot air combined drying ① Place the properly fermented tea leaves into a microwave oven with a power of 18kW and microwave for 2 minutes to quickly inactivate the enzymes. ② Place the microwaved tea leaves in a roasting machine and dry them with hot air at 115℃ for 20 minutes until the moisture content of the tea leaves is 5%.

[0010] The distance between the light-emitting tube and the surface of the fresh leaf as described in this invention is usually between 8 and 12 cm.

[0011] The light tube described in this invention is an existing product, manufactured by Haining Haishi Lighting & Electrical Factory, and the light tube is a T8 product under the brand name Xinshuo, with a power of 20W.

[0012] The microwave oven described in this invention is an existing product, manufactured by Nanjing Aorun Microwave Technology Co., Ltd. The microwave oven is model ORW6S-3C with a power of 15-18kW.

[0013] The baking machine described in this invention is an existing product, manufactured by Fujian Jingcheng Food Machinery Co., Ltd., and has an internal drying area of ​​15 m².

[0014] Comparative Example: Traditional withering method: Under natural climate conditions, withering is carried out indoors. The tea leaves are placed on withering racks and withered for about 18 hours at a room temperature of 20-24℃ and a relative humidity of 60%-70%. Temperature and humidity are regulated by opening and closing doors and windows. The light source is diffused natural light. Traditional drying method: The drying process uses a dryer with two stages: initial drying and final drying. The initial drying is controlled at 110-120℃ for 10 minutes, and the final drying is controlled at 85-95℃ for 15 minutes.

[0015] Example 2 and the traditional process of the comparative example were compared in terms of withering time, aroma, taste, and soup color, as shown in Table 1 below:

[0016] As shown in Table 1, the process innovation of this invention has led to a significant improvement in efficiency, as detailed below: Withering process: Red light with a wavelength of 630-640nm (3 hours of illumination) and yellow light with a wavelength of 585-590nm (3 hours of illumination) are used for treatment in sequence. The total withering time is only 6 hours, which is 66.7% shorter than the traditional natural withering time of 18 hours, greatly improving production efficiency. Drying process: Rapid enzyme inactivation is achieved by microwave (model ORW6S-3C, power 15-18kW, processing time 2min) combined with 110℃ hot air drying (20-30min), which solves the problem of slow enzyme inactivation caused by slow temperature rise in traditional hot air drying. Although the total drying time is similar to the traditional process (about 25min for the traditional process, about 22-32min for this invention), the enzyme inactivation efficiency and aroma enhancement effect are better.

[0017] Comparison table of evaluation scores for the processed black tea of ​​Example 2 and the traditional processed black tea of ​​the comparative example:

[0018] As shown in Table 2, the quality optimization and effect verification of this invention are as follows: Aroma: The synergistic effect of red and yellow light significantly improves the aroma concentration and persistence, resulting in a "sweet and rich" aroma in the finished black tea, which is a significant improvement in aroma quality compared to traditional processing methods. Flavor: Microwave treatment quickly deactivates enzymes while preserving umami substances, and light treatment promotes the transformation of internal substances, enhancing the freshness and sweetness of the flavor, reducing bitterness, and resulting in a richer taste. Soup color: Optimized processing reduces the loss of substances due to oxidation, resulting in a soup color with significantly better red brightness than traditional processes, presenting a clear and bright red hue; Leaf base: The leaf base is soft and shows buds, with a uniform purplish-copper color, which is superior to the leaf base produced by traditional processes.

[0019] Based on the above description, any simple changes and modifications made by those skilled in the art without departing from the technical concept of this invention should fall within the protection scope of this invention.

Claims

1. A method for processing black tea based on long-wavelength light withering and combined drying, characterized in that, Includes the following steps: (1) Long-wavelength light withering First, place the fresh leaves in a withering trough equipped with red light tubes, with a leaf layer thickness of 5-10cm and a red light tube power of 20W, and irradiate with red light for 2.5-3.5 hours; then place the fresh leaves in a withering trough equipped with yellow light tubes, with a leaf layer thickness of 5-10cm and a yellow light tube power of 20W, and irradiate with yellow light for 2.5-3.5 hours. (2) Microwave and hot air combined drying ① Place the properly fermented tea leaves into a microwave oven with a power of 15-18kW and microwave for 2-3 minutes to quickly inactivate the enzymes. ② Place the microwaved tea leaves in a roasting machine and dry them with hot air at 105-115℃ for 20-30 minutes until the moisture content of the tea leaves is 5%.

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