Preparation method of substance capable of retaining heat-sensitive flavor of pepper bud tea and pepper bud tea

Abstract

The invention relates to a preparation method of a substance capable of retaining a heat-sensitive flavor of pepper bud tea and the pepper bud tea. The preparation method comprises the following steps: (a) providing a pepper bud raw material subjected to fixation and rolling treatment; (b) putting the zanthoxylum bungeanum bud raw material into microwave-vacuum drying equipment, and drying under the microwave power, vacuum degree and temperature which are controlled by a program; wherein the temperature of the materials is controlled within the range of 40-55 DEG C in the whole drying process; and (c) after the drying is finished, cooling the material to be below 35 DEG C under the condition of maintaining vacuum, so as to obtain the Chinese prickly ash bud tea. According to the technical scheme, efficient dehydration and extreme preservation can be realized at the same time through a microwave-vacuum low-temperature combined drying process, a relatively high retaining effect on heat-sensitive flavor substances in fresh buds and a relatively high retaining effect on the condition of the product are achieved, and the internal and external quality of the product is improved.

Description

Technical Field

[0001] This invention relates to the field of pepper bud tea preparation technology, specifically to a preparation method that preserves the heat-sensitive flavor substances of pepper bud tea and pepper bud tea. Background Technology

[0002] Sichuan pepper bud tea is a type of tea with a unique flavor, made from tender buds or leaves in spring. It not only inherits the traditional properties of Sichuan pepper, such as warming the body, dispelling cold, and aiding digestion, but also benefits from its rich content of vitamins, minerals, polyphenols, and characteristic flavor compounds, making it a popular health drink.

[0003] The unique flavor and health benefits of Sichuan pepper bud tea primarily stem from a series of precious heat-sensitive chemical components within it. These mainly fall into two categories: first, sanshools, which contribute to its distinctive "numbing" flavor; these are amide compounds with a unique taste and various biological activities. Second, volatile oils, such as limonene, linalool, and β-myrcene, contribute to its fresh, spicy aroma. In addition, it also contains abundant vitamin C, flavonoids, and other heat-sensitive functional components.

[0004] Currently, the large-scale production of Sichuan pepper bud tea largely draws on traditional tea processing methods. The typical process involves: picking, washing, fixation (pan-frying or steaming), rolling, and drying (sun-drying, oven drying, or chain-plate hot air drying). However, this traditional high-temperature hot air-based processing system has a fatal flaw for Sichuan pepper buds, a raw material rich in heat-sensitive substances, severely limiting the flavor, quality, and nutritional value of the final product.

[0005] Severe damage to volatile aroma compounds: The fresh aroma of Sichuan pepper buds originates from volatile monoterpenes and sesquiterpenes. Traditional hot air drying typically involves high temperatures (60°C to 80°C or even higher) and long drying times. During this process, a large amount of these low-boiling-point aroma components evaporate and dissipate. This not only results in a weak aroma in the finished tea but also transforms its aroma profile from the fresh, floral, and citrus notes of fresh buds into an unpleasant "dull grassy" or "high-temperature roasted" smell, completely losing its inherent elegant aroma.

[0006] Structural damage to trichosanthes: Trichosanthes is the core of Sichuan pepper's flavor, but its chemical properties are extremely unstable, sensitive to heat, light, and oxygen. During traditional high-temperature drying, trichosanthes molecules undergo decomposition, isomerization, and even polymerization. This not only weakens the intensity and persistence of its unique "numbing" flavor but may also alter its flavor characteristics, producing astringency or unpleasant flavors, making it impossible to truly reproduce the mellow and lingering numbing sensation of fresh Sichuan pepper buds.

[0007] Degradation of heat-sensitive nutrients: High temperatures drastically accelerate the oxidative decomposition of vitamin C, resulting in extremely low retention rates and significantly weakening the product's nutritional function. Simultaneously, antioxidants such as polyphenols undergo excessive oxidation and polymerization under high temperatures and residual enzymes, leading to a darker, more astringent color in the tea, increased astringency, and reduced antioxidant capacity.

[0008] Damage to product appearance: Sustained high temperatures melt and damage the natural waxy layer on the surface of the Sichuan pepper bud leaves, causing the finished tea to lose its bright luster and become dull. At the same time, high temperatures accelerate the degradation of chlorophyll, causing the tea leaves to change from bright green to yellowish-green or even yellowish-brown, seriously affecting the product's appearance.

[0009] In conclusion, the existing traditional high-temperature drying process is essentially a "destructive" process. It sacrifices the most valuable heat-sensitive flavor compounds and nutrients in the Sichuan pepper bud raw material in exchange for moisture removal and product preservation. This results in most Sichuan pepper bud tea products on the market having common problems such as insufficient aroma, unpleasant numbing sensation, dull color, and low nutritional value, failing to meet consumers' demand for high-quality, flavorful, and nutritious healthy beverages.

[0010] Therefore, there is an urgent need in this field to develop a new low-temperature flexible processing technology that can efficiently dehydrate while retaining the heat-sensitive flavor substances and nutrients in the raw materials of Sichuan pepper buds to the maximum extent, thereby fundamentally improving the quality of Sichuan pepper bud tea. Summary of the Invention

[0011] In view of this, the purpose of the present invention is to provide a method for preparing heat-sensitive flavor substances in Sichuan pepper bud tea and Sichuan pepper bud tea, so as to solve the problem that the high-temperature drying process in the prior art damages the heat-sensitive flavor substances.

[0012] This invention is achieved through the following technical solution:

[0013] A method for preparing Sichuan pepper bud tea that retains heat-sensitive flavor compounds includes the following steps:

[0014] (a) Provide raw materials of Sichuan pepper buds that have undergone blanching and rolling;

[0015] (b) The raw material of Sichuan pepper buds is placed in a microwave-vacuum drying equipment and dried under programmed control of microwave power, vacuum degree and temperature; wherein the temperature of the material is controlled within the range of 40°C to 55°C throughout the drying process;

[0016] (c) After drying, the material is cooled to below 35°C under vacuum to obtain the pepper bud tea.

[0017] Further specifying, the drying process described in step (b) includes the following stages:

[0018] (i) Rapid start-up period: Within 5 to 10 minutes, the material temperature is raised from room temperature to 40°C;

[0019] (ii) Constant rate dehydration main period: Within 30 to 50 minutes, the material temperature is raised from 40℃ to 55℃ at a uniform rate;

[0020] (iii) Deceleration and setting period: Maintain the material temperature at 55℃ and keep it warm for 10 to 25 minutes.

[0021] Further specifying, in step (b), the rate of increase in material temperature is controlled by programming the vacuum level.

[0022] During the constant-rate dehydration main period, the vacuum level decreased linearly from -0.090 MPa to below -0.098 MPa.

[0023] Further specified, during the rapid start-up period, the microwave power is set to 4-6kW, and the vacuum degree is controlled between -0.090MPa and -0.093MPa; during the constant-rate dehydration main period, the microwave power is adjusted to 3-4kW; during the deceleration and setting period, the microwave power is reduced to 1.0-1.8kW, and the vacuum degree is maintained between -0.098MPa and -0.100MPa.

[0024] Further specifying, the blanching process described in step (a) is steam blanching, with a blanching temperature of 100-108℃ and a blanching time of 60-120 seconds.

[0025] Further specifying, the kneading process described in step (a) adopts a "light-heavy-light" pressure mode, with a total kneading time of 15 to 25 minutes, and the cell damage rate is controlled between 50% and 60%.

[0026] Further specified, during the loading process in step (b), the material is spread evenly, and the thickness of the auxiliary material is controlled between 1.0 cm and 2.0 cm.

[0027] To further define, the “conditions for maintaining vacuum” mentioned in step (c) refers to maintaining the highest vacuum level at the end of drying until the material temperature drops below 35°C.

[0028] Further specifying, in step (a), after the kneading process and before the drying process, a pre-cooling step is also included: rapidly cooling the kneaded material to below 25°C.

[0029] A type of Sichuan pepper bud tea, prepared by a specific method.

[0030] The beneficial effects of this invention are as follows:

[0031] This invention relates to a method for preparing heat-sensitive flavor substances in Sichuan pepper bud tea and the resulting Sichuan pepper bud tea. Through a microwave-vacuum low-temperature combined drying process, it can simultaneously achieve efficient dehydration and ultimate freshness preservation, resulting in a high retention effect on the heat-sensitive flavor substances in the fresh buds and a high maintenance effect on the product's appearance, thereby improving the product's internal and external quality.

[0032] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0033] Figure 1 This is a process flow diagram of the present invention; Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0035] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0036] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0037] In the above description of the present invention, it should be noted that the terms "one side," "the other side," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of the invention is conventionally placed during use. These terms are used only for the convenience of describing the present invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0038] Furthermore, terms such as "identical" do not imply that components must be absolutely identical; minor differences are permissible. The term "perpendicular" simply means that the positional relationship between components is more perpendicular than "parallel," not that the structure must be perfectly perpendicular; a slight tilt is acceptable.

[0039] Please see Figure 1 This invention provides a technical solution: a preparation method for preserving the heat-sensitive flavor substances of Sichuan pepper bud tea, comprising the following steps:

[0040] Raw material pretreatment

[0041] Harvesting and Selection: Harvest the first batch of plump and tender spring buds (fresh buds) of the "Da Hong Pao" variety of Sichuan pepper trees, about 3-5 cm in length, with one bud and one leaf or one bud and two newly unfolded leaves. Remove old leaves, diseased leaves, and miscellaneous stems to obtain the raw material of Sichuan pepper buds.

[0042] Cleaning and rinsing: Gently soak and rinse the Sichuan pepper buds in a 0.5% food-grade baking soda solution for 60 seconds. After rinsing, rinse thoroughly with plenty of purified water at ≤10℃ and soak for 2 minutes to completely remove baking soda residue. After rinsing, place them on a 200-mesh sieve and spread them out in a cool, ventilated place to air dry for 15 minutes to drain the surface moisture.

[0043] Blanching: A continuous steam blanching machine is used for processing. The pepper buds are evenly fed into the machine, the steam temperature is adjusted to 105±2℃, and the material passes through for 90 seconds. Blanching continues until the leaves are soft, the grassy smell disappears, and a fresh aroma is released.

[0044] Rolling: After blanching and slightly cooling, the pepper buds are loaded into a 6CR-35 rolling machine, filling the machine to 70% capacity. Roll using a "light-heavy-light" pressure mode.

[0045] 0-5 minutes: No pressure, 35 rpm, initial shaping.

[0046] 6–15 minutes: Gradually increase pressure to medium pressure (you will feel obvious resistance but the leaf veins will remain intact), and rotate at 55 rpm to promote cell rupture.

[0047] 16-20 minutes: Reduce pressure to light pressure, speed 35 rpm, tighten the strip.

[0048] The total kneading time is 20 minutes, and the cell damage rate is controlled at around 55%.

[0049] Pre-cooling: Quickly spread the kneading leaves thinly (thickness ≤ 2cm) on a stainless steel workbench with 5℃ circulating cooling water and cool for 8 minutes to reduce the core temperature of the material to below 25℃.

[0050] Drying: Programmed microwave-vacuum drying

[0051] Equipment: An experimental microwave-vacuum combined dryer (microwave frequency 2450MHz, power adjustable from 0-6kW, vacuum degree adjustable from 0 to -0.099MPa, equipped with infrared real-time temperature measurement and PLC automatic control system).

[0052] Loading: Spread the pre-cooled pepper buds evenly and loosely on the rotating tray of the dryer, ensuring that the material layer thickness is 1.5±0.2cm to ensure uniform drying.

[0053] Drying program settings and execution:

[0054] Quick start phase (0-8 minutes):

[0055] The microwave power is set to 5.0kW.

[0056] Set the vacuum level to -0.092 MPa (at which point the boiling point of water is approximately 36°C).

[0057] The program runs for 8 minutes. During this stage, the material temperature rises uniformly from 25°C to 40°C. A large amount of free water begins to evaporate.

[0058] Constant-rate dehydration main phase (8–50 minutes):

[0059] Adjust the microwave power to 3.5kW.

[0060] Programmed linear vacuum enhancement: Within 42 minutes, the vacuum level is uniformly reduced from -0.092 MPa to -0.098 MPa (at which point the boiling point of water is approximately 28°C). This increases the vacuum level to compensate for the reduced dehydration kinetics caused by the decrease in microwave power.

[0061] During this stage, the material temperature slowly and uniformly rises from 40°C to 55°C under the combined control of microwave energy and vacuum. This stage is the main dehydration period.

[0062] Deceleration and setting period (50-70 minutes):

[0063] When the material temperature reaches 55℃, the system enters the heat preservation mode.

[0064] The microwave power is automatically reduced to 1.2kW (fluctuating within the range of 1.0-1.5kW) to maintain the material temperature at a stable level of 55±1℃.

[0065] Maintain the vacuum level at -0.099 MPa (near the equipment's ultimate vacuum).

[0066] Keep warm for 20 minutes. This stage aims to remove firmly bound water and allow flavor compounds and wax layers to fully set at a low temperature.

[0067] High vacuum cooling (70-80 minutes):

[0068] After the drying stage is completed, immediately turn off the microwave heating system.

[0069] Maintaining a vacuum of -0.099 MPa, the cold wall effect of the chamber and the residual heat of the material are used to continue evaporating a small amount of moisture and cooling.

[0070] Cool for 10 minutes until the material temperature naturally drops below 35°C.

[0071] Discharge: Slowly release the vacuum, open the hatch, and quickly take out the dried pepper bud tea.

[0072] Post-processing

[0073] Cooling: Transfer the extracted pepper bud tea to a low-temperature and low-humidity environment (15℃, 30%RH) and spread it out for 15 minutes to allow it to cool completely and evenly.

[0074] Packaging: Immediately use aluminum foil composite bags for automatic weighing, nitrogen filling (nitrogen purity ≥99.5%), and heat sealing. Store in a cool, dark, and dry place.

[0075] Example 1

[0076] Sample 1 was prepared using the above method, wherein the adjustable parameter value was taken as the intermediate value.

[0077] Example 2

[0078] Sample 2 was prepared using the above method, wherein the adjustable parameter value was taken as the upper limit.

[0079] Example 3

[0080] Sample 3 was prepared using the above method, wherein the adjustable parameter value was taken as the lower limit.

[0081] Comparative Example

[0082] Sample 4 was prepared using traditional methods, including: after kneading the leaves, drying them in a 70℃ hot air oven until the moisture content was ≤7%.

[0083] Sample comparison test

[0084] 1. Component determination

[0085] Samples 1, 2, 3, and 4, as well as fresh buds, were all analyzed using HS-SPME-GC-MS, HPLC (with UV or MS detectors) supplemented by UV-Vis spectrophotometry. Based on the results of the fresh bud analysis, the following results were obtained: Result 1, Result 2, Result 3, and Result 4.

[0086] Test Result 1

[0087] Vitamin C (Vc) retention: 96.3% (compared to fresh sprouts);

[0088] The total content retention rate of sanshools was 97.1% (as determined by HPLC, compared with fresh buds).

[0089] Volatile aroma compounds: The total content of key characteristic aroma components such as limonene, linalool, and β-myrcene accounts for 28.5% of the total volatile compounds;

[0090] Total flavonoid content: 12.8 mg / g.

[0091] Test Result 2

[0092] Vitamin C (Vc) retention rate: 93.5% (slightly lower due to longer heat treatment time, but still much higher than that of traditional processes);

[0093] The total content retention rate of Sichuan pepper sesame extract was 94.8%.

[0094] Volatile aroma compounds: Key characteristic aroma components accounted for 26.1% of the total;

[0095] Total flavonoid content: 12.1 mg / g.

[0096] Test Result 3

[0097] Vitamin C (Vc) retention rate: 95.1%.

[0098] The total content retention rate of Sichuan pepper sesame extract was 96.0%.

[0099] Volatile aroma compounds: Key characteristic aroma components account for as high as 29.2% of the total;

[0100] Total flavonoid content: 13.0 mg / g.

[0101] Test Result 4

[0102] Vitamin C (Vc) retention rate: 48.7%

[0103] Retention rate of total Sichuan pepper extract content: 52.3% (severe degradation).

[0104] Volatile aroma compounds: Key characteristic aroma components account for only 9.8% of the total.

[0105] Measurement results

[0106] Samples 1-3 showed differences in the content of heat-sensitive flavor substances due to fine-tuning of the combination of production parameters, but all of them had a high retention rate of vitamin C, ephedrine, etc., and the richness of flavor substances far exceeded that of traditional production methods.

[0107] 2. Sensory evaluation

[0108] Test Result 1

[0109] Appearance: The strips are tightly rolled, uniform, bright green, and glossy.

[0110] Aroma: The dry tea has a fresh, sharp, and long-lasting aroma, with a pure numbing and spicy flavor characteristic of Sichuan peppercorns, and no off-flavors.

[0111] The soup color is clear, bright, and a tender light yellow-green.

[0112] Taste: Fresh and mellow on the palate, with very low astringency, mild, pure and long-lasting numbing sensation, and a rapid and long-lasting sweet aftertaste.

[0113] Leaf base: tender green, soft, even and shiny, and elastic.

[0114] Test Result 2

[0115] Compared with Example 1, the aroma is slightly weaker, the taste is more mellow, and the numbing sensation is still mild and lasting.

[0116] Test Result 3

[0117] Compared with Example 1, the aroma has the best freshness and sharpness, and the taste is excellent, but the mellowness is slightly lacking.

[0118] Test Result 4

[0119] Appearance: The strips are tightly rolled, uniform, dark yellow in color, and oily and glossy;

[0120] Aroma: The dry tea has a pure, numbing Sichuan pepper aroma with a distinct roasted flavor;

[0121] Soup color: Clear, with a deep yellow-green hue;

[0122] Taste: It has a numbing and stimulating taste upon first bite, but it is short-lived, with a slightly bitter aftertaste;

[0123] Leaf base: Deep yellow, leaf shape intact, and stiff texture.

[0124] Measurement results

[0125] Samples 1-3 are significantly superior to traditionally processed Sichuan pepper bud tea products (Sample 4) in terms of sensory quality. Due to slight adjustments in the combination of production parameters, Samples 1-3 exhibit some differences in their stylistic orientation (such as the intensity of aroma and the mellowness of taste), but their core quality far surpasses that of Sample 4.

[0126] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for preparing Sichuan pepper bud tea while retaining its heat-sensitive flavor compounds, characterized in that, Includes the following steps: (a) Provide raw materials of Sichuan pepper buds that have undergone blanching and rolling; (b) The raw material of Sichuan pepper buds is placed in a microwave-vacuum drying equipment and dried under programmed control of microwave power, vacuum degree and temperature; wherein the temperature of the material is controlled within the range of 40°C to 55°C throughout the drying process; (c) After drying, the material is cooled to below 35°C under vacuum to obtain the pepper bud tea.

2. The preparation method for preserving the heat-sensitive flavor substances of Sichuan pepper bud tea according to claim 1, characterized in that, The drying process described in step (b) includes the following stages: (i) Rapid start-up period: Within 5 to 10 minutes, the material temperature is raised from room temperature to 40°C; (ii) Constant rate dehydration main period: Within 30 to 50 minutes, the material temperature is raised from 40℃ to 55℃ at a uniform rate; (iii) Deceleration and setting period: Maintain the material temperature at 55℃ and keep it warm for 10 to 25 minutes.

3. The preparation method for preserving the heat-sensitive flavor substances of Sichuan pepper bud tea according to claim 2, characterized in that, In step (b), the rate of temperature rise of the material is controlled by programming the vacuum level. During the constant-rate dehydration main period, the vacuum level decreased linearly from -0.090 MPa to below -0.098 MPa.

4. The preparation method for preserving the heat-sensitive flavor substances of Sichuan pepper bud tea according to claim 3, characterized in that, During the rapid start-up phase, the microwave power is set to 4-6 kW, and the vacuum level is controlled between -0.090 MPa and -0.093 MPa. During the constant-rate dehydration phase, the microwave power is adjusted to 3-4 kW. During the deceleration and setting phase, the microwave power is reduced to 1.0-1.8 kW, and the vacuum level is maintained between -0.098 MPa and -0.100 MPa.

5. The preparation method for preserving the heat-sensitive flavor substances of Sichuan pepper bud tea according to claim 1, characterized in that, The blanching process described in step (a) is steam blanching, with a blanching temperature of 100-108℃ and a blanching time of 60-120 seconds.

6. The preparation method for preserving the heat-sensitive flavor substances of Sichuan pepper bud tea according to claim 1 or 5, characterized in that, The kneading process described in step (a) adopts a "light-heavy-light" pressure mode, with a total kneading time of 15 to 25 minutes, and the cell damage rate is controlled between 50% and 60%.

7. The preparation method for preserving the heat-sensitive flavor substances of Sichuan pepper bud tea according to claim 1, characterized in that, When loading materials in step (b), spread the materials evenly and control the thickness of the auxiliary materials between 1.0cm and 2.0cm.

8. The preparation method for preserving the heat-sensitive flavor substances of Sichuan pepper bud tea according to claim 1, characterized in that, The "conditions for maintaining vacuum" mentioned in step (c) refer to maintaining the highest vacuum level at the end of drying until the material temperature drops below 35°C.

9. The preparation method for preserving the heat-sensitive flavor substances of Sichuan pepper bud tea according to claim 1, characterized in that, In step (a), after the kneading process and before the drying process, a pre-cooling step is also included: rapidly cooling the kneaded material to below 25°C.

10. A kind of Sichuan pepper bud tea, characterized in that, Prepared by the method described in any one of claims 1-9.

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