A method for improving quality of zhangping narcissus tea by carbonization

Abstract

The application belongs to the technical field of tea processing, and discloses a carbon roasting quality improving method for Zhangping Shuixian tea, which comprises the following steps: taking charcoal, and burning until the charcoal is red and has no residual smoke; transferring the stable charcoal fire to a roasting furnace, and covering a layer of wood ash on the stable charcoal fire; taking Zhangping Shuixian tea cakes with a water content of 55%-65%, and uniformly spreading the tea cakes on the roasting furnace; adopting a three-stage step-down temperature process for roasting, and the first stage is to control the ambient temperature above the roasting furnace to be 90-100 DEG C, and the roasting time is 60 minutes; the second stage is to control the ambient temperature above the roasting furnace to be 80-90 DEG C, and the roasting time is 100-120 minutes; and the third stage is to take the leaf surface temperature of the Zhangping Shuixian tea cake as a target, control the leaf surface temperature to be 70-75 DEG C, and the roasting time is 180-240 minutes, and during the roasting process, each Zhangping Shuixian tea cake is turned over 1-2 times; through the three-stage step-down temperature process and taking the leaf surface temperature as the final control target, the roasting parameters are quantified, the product quality is stable and consistent, the aroma and the taste thickness of the Zhangping Shuixian tea are improved, and the Zhangping Shuixian tea is more resistant to storage.

Description

Technical Field

[0001] This invention relates to the field of tea processing technology, and in particular to a method for charcoal roasting and quality improvement of Zhangping Narcissus tea. Background Technology

[0002] Zhangping Narcissus Tea is a specialty oolong tea from Zhangping City, Fujian Province. It is renowned for its unique compressed tea cake shape and elegant orchid and osmanthus aromas. Traditional charcoal roasting is crucial in achieving its characteristic "mellow, smooth, sweet, and full-bodied" quality. Currently, the roasting of Zhangping Narcissus Tea is mainly divided into two methods: traditional charcoal roasting and conventional electric roasting. Traditional charcoal roasting relies heavily on the personal experience of tea masters, resulting in problems such as difficulty in quantifying the heat, poor stability, and large fluctuations in product quality, making it difficult to meet the needs of standardized and large-scale production. While conventional electric roasting allows for temperature control, the tea aroma is dull, lacking the unique activity and complexity of charcoal roasting, and the finished tea is prone to "returning to green" (a reappearance of a grassy taste) during storage, which is detrimental to later transformation. Therefore, how to preserve the unique flavor advantages of traditional charcoal roasting while overcoming its reliance on experience, difficulty in quantification, and limitations in large-scale production is a pressing technical problem that needs to be solved in this field. Summary of the Invention

[0003] The present invention aims to provide a method for improving the quality of Zhangping Narcissus tea by charcoal roasting, in order to solve the problems of traditional charcoal roasting relying on experience and having unstable quality, as well as conventional electric roasting having poor flavor and poor storage resistance.

[0004] To achieve the above objectives, the present invention provides the following technical solution:

[0005] A method for improving the quality of Zhangping Narcissus tea through charcoal roasting includes the following steps:

[0006] S1. Charcoal preparation: Take charcoal and burn it until it is red-hot and there is no residual smoke to obtain a stable charcoal fire.

[0007] S2. Covering with ash to control temperature: Spread a layer of wood ash in the roasting furnace, then transfer the stable charcoal fire into the roasting furnace and place it on the wood ash layer, and then cover it with another layer of wood ash to form a smoldering fire.

[0008] S3. Baking: Take a Zhangping Narcissus tea cake with a moisture content of 55%-65%, spread it evenly on the baking tray, and then place the baking tray in the baking oven.

[0009] S4. Baking and Turning: Baking is carried out using a three-stage stepped cooling process, specifically including:

[0010] S4a, Stage 1: Control the ambient temperature above the baking stem to 90-100℃ and bake for 60 minutes. After baking, turn each Zhangping Narcissus tea cake over.

[0011] S4b, Second stage: Control the ambient temperature above the baking stem to 80-90℃ and bake for 100-120 minutes. After baking, turn each Zhangping Narcissus tea cake over.

[0012] S4c, Stage 3: With the leaf surface temperature of Zhangping Narcissus tea cake as the target, control the leaf surface temperature to 70-75℃ and roast for 180-240 minutes. During the roasting process, turn each Zhangping Narcissus tea cake over 1-2 times.

[0013] S5. Baking: After the Zhangping Narcissus tea cake has been baked and reached a sufficiently dry state, remove the Zhangping Narcissus tea cake from the baking tray, let it cool, put it into an aluminum foil bag, seal it, and store it in a cool and dry place.

[0014] Furthermore, the charcoal is lychee charcoal, and the amount used is 20 kg.

[0015] Furthermore, the plant ash is dry, sieved rice husk ash, with a covering thickness of 3 cm.

[0016] Furthermore, in step S3, the moisture content of the tea leaves in the Zhangping Narcissus Tea Cake is 60%, the thickness of the spread tea is 10-15cm, and the total weight is 8-10kg.

[0017] Furthermore, in steps S4a and S4b, a temperature measuring device is placed inside the baking tray to detect the ambient temperature above the baking tray.

[0018] Furthermore, in step S4c, a temperature measuring device is used to continuously or periodically detect the leaf surface temperature of the Zhangping Narcissus Tea Cake, with a detection interval not exceeding 40 minutes.

[0019] Furthermore, in step S5, the fully dried state is that the moisture content of the tea leaves in the Zhangping Narcissus Tea Cake is less than 5%.

[0020] The principles and beneficial effects of the technical solution are as follows:

[0021] This invention provides a method for charcoal roasting to improve the quality of Zhangping Narcissus tea.

[0022] 1. By using a three-stage stepped cooling method combined with leaf surface temperature as the final control target, the roasting parameters are quantified, reducing the reliance on oral transmission of experience from others, making the product quality stable and consistent, and easy to promote. Blind selection experiments have shown that Zhangping Narcissus Tea prepared using this method has an aroma score that is more than 15% higher and a taste mellowness score that is more than 20% higher than that of conventional electric roasted tea. It retains the activity and layering of traditional charcoal roasting while achieving stable large-scale production.

[0023] 2. Precise step-by-step cooling and leaf temperature control enable tea leaves to be roasted to a fully dry state (moisture content below 5%), allowing for complete transformation of internal substances, reducing the likelihood of re-greening, and maximizing the potential for later transformation. Attached Figure Description

[0024] Figure 1 This is a process flow diagram of a charcoal roasting method for improving the quality of Zhangping Narcissus tea according to the present invention.

[0025] Figure 2 This is a comparison diagram of the dry tea samples in the embodiments of the present invention;

[0026] Figure 3 This is a comparison diagram of the tea infusions of various tea samples in the embodiments of the present invention; Detailed Implementation

[0027] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments:

[0028] Example 1

[0029] like Figures 1-3 As shown, a method for improving the quality of Zhangping Narcissus tea through charcoal roasting includes the following steps:

[0030] Step S1, Charcoal preparation: Select 20 kg of high-quality lychee charcoal with uniform density, no branches or knots, and fully dried. Burn it in an iron pot until it is completely red-hot and smokeless to obtain charcoal for stable heating.

[0031] Step S2, covering with ash and controlling temperature: Spread a layer of dry, sieved rice husk ash in the roasting furnace, then transfer the red-hot charcoal into the roasting furnace and place it on the rice husk ash layer. Level the charcoal fire, and then cover it with another layer of dry, sieved rice husk ash about 3cm thick to form a smoldering fire. Use an infrared thermometer to detect the ambient temperature above the roasting furnace. By changing the thickness of the rice husk ash layer, the temperature can be adjusted to keep the furnace temperature within 95-105℃.

[0032] Step S3, Baking: Take a Zhangping Narcissus tea cake with a moisture content of about 60% and a total weight of about 9 kg. Each tea cake is a square of about 10cm×10cm. Spread it evenly on the baking tray with an average thickness of 12cm. Then place the baking tray on the baking oven.

[0033] Step S4, roasting and turning: The three-stage stepped cooling process is used for roasting. The thermocouple temperature probe is suspended and fixed in the center above the roasting base, about 3-4cm away from the upper surface of the tea cake layer.

[0034] Step S4a, First Stage (High Temperature Aroma Fixation): The ambient temperature inside the roasting cake is detected by a thermocouple temperature probe. The ambient temperature inside the roasting cake is increased or decreased by adjusting the size of the air inlet at the bottom of the roasting oven or by increasing or decreasing the thickness of the wood ash on the charcoal fire, so that the internal temperature rises rapidly and is controlled at 95℃±2℃, and roasting is continued for 60 minutes. After this stage, the first turning roasting is carried out: the roasting cake is removed from the roasting oven. The operator, wearing clean gloves, picks up each tea cake from the roasting cake one by one, turns it 180 degrees up and down, and then puts it back in its original position. This operation ensures that the top and bottom sides of each tea cake are heated evenly.

[0035] Step S4b, Second Stage (Gentle Roasting for Aroma Enhancement): After removing the roasting base in the first stage, use an infrared thermometer to detect the ambient temperature above the roasting oven. By covering the oven with rice husk ash, the temperature above the oven is lowered, keeping the oven temperature between 85-95℃. After the first stage of roasting is completed, the roasting base is placed back on the roasting oven, keeping its internal temperature at 85℃±2℃, and roasting continues for 120 minutes. After this stage, a second roasting is performed, repeating the roasting operation in step S4a, turning all the tea cakes over one by one.

[0036] Step S4c, Stage Three (Low-Temperature Preservation): Repeat the cooling operation in Step S4b to lower the oven temperature to 70-80℃. After the second stage of roasting is completed, place the tea cake back on the oven. After 10 minutes, press the tip of the insertable thermocouple probe firmly against and gently pierce the tea leaves in the center of the tea cake to measure the true surface temperature of the tea leaves. By adjusting the size of the air inlet at the bottom of the oven or increasing or decreasing the thickness of the wood ash on the charcoal fire, strictly control the surface temperature of the tea cake at 73-75℃ and continue roasting for 210 minutes. During this period, probe the surface temperature of the tea cake every 30 minutes to guide the adjustment of the heat. Turn all the tea cakes over once every 70 minutes, for a total of 2 times, using the same roasting method as in S4a.

[0037] Step S5, Roasting: After roasting, check that the moisture content of the tea cake is less than 5%. Remove the tea cake from the roasting tray, spread it out in a clean environment to cool to room temperature, then put it into an aluminum foil bag, seal it, and store it in a cool and dry place.

[0038] Comparative Example 1

[0039] This comparative example uses a commercially available electric roasting cage for oolong tea to roast the same Zhangping Narcissus tea cake (with a moisture content of approximately 60%) as in Example 1.

[0040] The specific roasting process is as follows: Place the tea cakes evenly into each layer of the electric roasting cage, set the ambient temperature inside the roasting cage to 85℃ (constant), and roast continuously for about 24 hours; during this period, based on operational experience, turn all the tea cakes over once every 3-4 hours until the moisture content of the tea cakes is below 6%, then remove them from the roasting process, cool them, and seal them in packaging.

[0041] Experimental Example 1

[0042] Experimental Methods: Five qualified tea tasters were invited to evaluate the tea samples of Example 1 and the electric roasted tea samples of Comparative Example 1 using a double-blind method (i.e., the tea tasters did not know which processing method the tea samples corresponded to). One group of tea samples from Example 1 (numbered A) and two groups of tea samples from Comparative Example 1 (numbered B and C) were set up. The evaluation focused on aroma (evaluated in terms of purity, aroma layering, etc., 40 points), taste (evaluated in terms of tea soup mellowness, presence of "green" taste, etc., 40 points), appearance and soup color (10 points each). Each tea sample was evaluated three times, and the average score was taken.

[0043] Please refer to Table 1 for a summary of the experimental results.

[0044]

[0045] Table 1: Summary Table of Double-Blind Evaluation Scores for Charcoal Roasting Process of Zhangping Narcissus Tea

[0046] The evaluation results show that the aroma score of the tea sample in Example 1 was 38.5 and the taste score was 37.5; while the aroma score of the tea sample in Comparative Example 1 was 33.5 and the taste score was 31. The tea sample prepared in Example 1 improved the aroma score by about 15% and the taste score by about 20% compared with the tea sample prepared by electric roasting. The tea sample in Example 1 was significantly better than the conventional electric roasted tea sample in terms of aroma and mellow taste, with a total score that was about 11.5 points higher.

[0047] Experiment Example 2

[0048] Experimental method: Take 500g of tea samples from Example 1 and Comparative Example 1, pack them into aluminum foil bags, and store them in a constant temperature and humidity chamber at 40℃ and 75% relative humidity for 3 months to simulate the storage and aging process of about 12 months at room temperature. After 3 months, take out the tea samples, test their moisture content and conduct sensory evaluation.

[0049] Experimental results: The initial moisture content of the tea sample in Example 1 was 4.9%, and the final moisture content was 5.7%. The sensory evaluation showed that although the aroma was weakened, it was still clearly identifiable. The tea soup was mellow and there were no signs of "return to green" (green taste). The initial moisture content of the tea sample in Experiment 2 was 5.2%, and the final moisture content was 7.4%. The sensory evaluation showed that there was a distinct green and musty taste (i.e., "return to green") in the aroma. The taste became weak and had an off-flavor.

[0050] Therefore, the method proposed in this invention can significantly improve the quality of Zhangping Narcissus Tea and make it more resistant to storage.

[0051] The above descriptions are merely embodiments of the present invention, and common knowledge regarding specific technical solutions or characteristics is not elaborated upon here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the technical solutions of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A method for charcoal roasting and quality improvement of Zhangping Narcissus tea, characterized in that: Includes the following steps: S1. Charcoal preparation: Take charcoal and burn it until it is red-hot and there is no residual smoke to obtain a stable charcoal fire. S2, covering with ash to control temperature: lay a layer of wood ash in the roasting furnace, then transfer the stabilized charcoal fire into the roasting furnace and place it on the wood ash layer, and then cover it with another layer of wood ash to form a smoldering fire; S3. Baking: Take a Zhangping Narcissus tea cake with a moisture content of 55%-65%, spread it evenly on the baking tray, and then place the baking tray in the baking oven. S4. Baking and Turning: Baking is carried out using a three-stage stepped cooling process, specifically including: S4a, Stage 1: Control the ambient temperature above the baking stem to 90-100℃ and bake for 60 minutes. After baking, turn each Zhangping Narcissus tea cake over. S4b, Second stage: Control the ambient temperature above the baking stem to 80-90℃ and bake for 100-120 minutes. After baking, turn each Zhangping Narcissus tea cake over. S4c, Stage 3: With the leaf surface temperature of Zhangping Narcissus tea cake as the target, control the leaf surface temperature to 70-75℃ and roast for 180-240 minutes. During the roasting process, turn each Zhangping Narcissus tea cake over 1-2 times. S5. Baking: After the Zhangping Narcissus tea cake has been baked and reached a sufficiently dry state, remove the Zhangping Narcissus tea cake from the baking tray, let it cool, put it into an aluminum foil bag, seal it, and store it in a cool, dry place.

2. The method for charcoal roasting and quality improvement of Zhangping Narcissus tea according to claim 1, characterized in that: The charcoal is lychee charcoal, and the amount used is 20 kg.

3. The method for charcoal roasting and quality improvement of Zhangping Narcissus tea according to claim 1, characterized in that: The plant ash is dry, sieved rice husk ash, with a covering thickness of 3 cm.

4. The method for charcoal roasting and quality improvement of Zhangping Narcissus tea according to claim 1, characterized in that: In step S3, the tea leaves in the Zhangping Narcissus Tea Cake have a moisture content of 60%, a spread thickness of 10-15cm, and a total weight of 8-10kg.

5. The method for charcoal roasting and quality improvement of Zhangping Narcissus tea according to claim 1, characterized in that: In steps S4a and S4b, a temperature measuring device is placed inside the baking tray to detect the ambient temperature above the baking tray.

6. The method for charcoal roasting and quality improvement of Zhangping Narcissus tea according to claim 1, characterized in that: In step S4c, a temperature measuring device is used to continuously or periodically detect the leaf surface temperature of the Zhangping Narcissus Tea Cake, with a detection interval not exceeding 40 minutes.

7. The method for charcoal roasting and quality improvement of Zhangping Narcissus tea according to claim 1, characterized in that: In step S5, the fully dried state means that the moisture content of the tea leaves in the Zhangping Narcissus Tea Cake is less than 5%.

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