Preparation method and application of dried tangerine peel

Abstract

The present invention provides a preparation method and application of dried tangerine peel, belonging to the technical field of traditional Chinese medicine preparation. The present invention provides a preparation method of dried tangerine peel, which achieves efficient drying and aging of the peel raw material in a short time by optimizing drying process parameters and combining technical means such as microwave and wet heat treatment. This method not only significantly improves drying efficiency and shortens preparation time, but also effectively retains the flavonoid compound active ingredients in the dried tangerine peel, making its antioxidant and anti-inflammatory effects comparable to those of commercially available multi-year dried tangerine peel, and even superior to dried tangerine peel prepared by traditional methods. At the same time, by precisely controlling the process parameters, the stability and consistency of the dried tangerine peel quality are ensured, providing an efficient and reliable solution for the industrial production and application of dried tangerine peel.

Description

Technical Field

[0001] The invention belongs to the technical field of traditional Chinese medicine preparation, and particularly relates to a preparation method and application of dried tangerine peel. Background Art

[0002] Tangerine peel, a traditional Chinese medicinal ingredient and spice, has a long history of use. It primarily originates from the dried, mature peel of the citrus fruit (Citrus reticulata) and its cultivated varieties. The most famous of these is the tea-branch tangerine peel from Xinhui, Guangdong, which boasts unique medicinal properties and flavor. Rich in volatile oils and flavonoids, tangerine peel boasts benefits such as regulating qi and strengthening the spleen, and dispelling dampness and resolving phlegm. It is widely used in Traditional Chinese Medicine and also has important applications in the food and health supplement industries.

[0003] Traditional methods for preparing tangerine peel mainly include sun-drying and oven-drying. The sun-drying method relies on natural sunlight, spreading the tangerine peels out in the open air. After several days or even weeks of natural drying, the tangerine peels gradually lose moisture and age. However, the sun-drying method is significantly restricted by weather conditions, takes a long drying time, and is susceptible to contamination from dust, microorganisms, and other factors, resulting in unstable tangerine peel quality. In addition, the active ingredients in the tangerine peels may be partially lost during the sun-drying process due to prolonged exposure to the natural environment, affecting their medicinal value and flavor.

[0004] The drying method uses artificial heat to accelerate the drying process of orange peel. While this method is not restricted by weather and has a relatively short drying time, it typically requires higher temperatures and longer drying times. This can damage heat-sensitive components in the peel, such as some flavonoids and essential oils, and thus reduce its quality. Furthermore, dried orange peel often requires a longer aging period to achieve a flavor and efficacy similar to sun-dried orange peel, increasing production costs and time.

[0005] As people's requirements for the quality and efficacy of tangerine peel continue to increase, and their understanding of the limitations of traditional preparation methods deepens, the development of a new method that can quickly, efficiently and stably prepare high-quality tangerine peel has become an urgent need in the industry. Summary of the Invention

[0006] In view of the defects in the prior art, the object of the present invention is to provide a method for preparing tangerine peel, which can significantly shorten the preparation time of tangerine peel and improve the quality of tangerine peel.

[0007] The purpose of the present invention is achieved through the following technical solutions:

[0008] The present invention provides a method for preparing dried tangerine peel, comprising the following steps:

[0009] subjecting the peel to a first microwave treatment to obtain a first microwave-treated peel;

[0010] After the first microwave treatment, the peel is turned over, and microwave treatment is continued for 2 to 3 times to obtain a microwave-treated peel; during the microwave treatment, after each microwave treatment, moisture inside and outside the microwave-treated peel is removed;

[0011] The peel after microwave treatment is subjected to wet heat treatment and then dried to obtain dried tangerine peel.

[0012] Preferably, the power of each microwave treatment is 500-1000 W; and the time of each microwave treatment is 120-180 s.

[0013] Preferably, the wet heat treatment method includes covering the wet heat carrier on the peel or on the container containing the peel; the wet heat treatment time is 20~40min; the initial temperature of the wet heat treatment is 40~60℃; and the wet heat treatment is carried out at room temperature.

[0014] Preferably, the drying temperature is 55-65° C., and the drying time is 3-6 hours.

[0015] Preferably, during the microwave and moist heat treatment of the peels, 5 to 20 peels are stacked together for treatment.

[0016] Preferably, the exocarp faces upward or bulges upward during the first microwave treatment; and the endocarp faces upward or bulges upward during the second to third microwave treatments.

[0017] Preferably, before the first microwave treatment, the peel is divided into three parts and connected at the fruit base.

[0018] Preferably, the peel is cleaned before being split; the cleaning method includes ultrasonic cleaning.

[0019] The present invention provides application of the preparation method described in the above technical solution in improving the preparation efficiency and / or quality of tangerine peel.

[0020] Preferably, the method of improving the quality of dried tangerine peel includes any one or more of the following (1) to (4):

[0021] (1) Increase the content of flavonoids in dried tangerine peel;

[0022] (2) Reduce the content of tangerine peel essential oil;

[0023] (3) Improve the antioxidant capacity of dried tangerine peel;

[0024] (4) Improve the anti-inflammatory ability of dried tangerine peel.

[0025] Beneficial effects of the present invention:

[0026] The present invention provides a method for preparing dried tangerine peel, comprising the following steps: subjecting the peel to a first microwave treatment to obtain a first microwave-treated peel; after turning the first microwave-treated peel, subjecting the peel to two to three subsequent microwave treatments to obtain a microwave-treated peel; during the subsequent microwave treatments, after each microwave treatment, removing moisture from the inner and outer surfaces of the microwave-treated peel; subjecting the microwave-treated peel to a wet-heat treatment, and then drying the peel to obtain the dried tangerine peel. Based on in-depth research on key factors in the preparation of dried tangerine peel, the present invention optimizes drying process parameters and combines microwave and wet-heat treatment techniques to achieve efficient drying and aging of the peel material in a short period of time. This method not only significantly improves drying efficiency and shortens preparation time, but also effectively retains the active ingredients of flavonoid compounds in the dried tangerine peel, making its antioxidant and anti-inflammatory properties comparable to those of commercially available aged dried tangerine peel, and even superior to those of dried tangerine peel prepared by traditional methods. Furthermore, by precisely controlling the process parameters, the stability and consistency of the dried tangerine peel's quality are ensured, providing an efficient and reliable solution for the industrial production and application of dried tangerine peel. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0028] Figure 1 The process flow chart of the preparation method of dried tangerine peel of embodiment 1 is shown;

[0029] Figure 2 This is a drying time diagram for different tangerine peel preparation methods in Application Example 1;

[0030] Figure 3 This is a graph showing the weight of the peel obtained by using different methods for preparing dried tangerine peel in Application Example 1;

[0031] Figure 4 This is a graph showing the moisture content of tangerine peel obtained by different tangerine peel preparation methods in Application Example 1;

[0032] Figure 5 HPLC spectrum of flavonoids in dried tangerine peel prepared in Example 1;

[0033] Figure 6 This is a graph showing the test results of flavonoid content in different dried tangerine peels in Application Example 2;

[0034] Figure 7 The figure is the test result of essential oil content in different dried tangerine peels in Application Example 2;

[0035] Figure 8This is a graph showing the results of the cellular antioxidant capacity test of different dried tangerine peels in Application Example 3;

[0036] Figure 9 The figure is the result of the cell antioxidant enzyme activity test of different dried tangerine peels in Application Example 3;

[0037] Figure 10 This is a graph showing the anti-inflammatory ability test results of different dried tangerine peels in Application Example 4;

[0038] Figure 11 This is a drying time chart for dried tangerine peel prepared using different methods in Application Example 5. DETAILED DESCRIPTION

[0039] The present invention provides a method for preparing dried tangerine peel, comprising the following steps:

[0040] subjecting the peel to a first microwave treatment to obtain a first microwave-treated peel;

[0041] After the first microwave treatment, the peel is turned over, and microwave treatment is continued for 2 to 3 times to obtain a microwave-treated peel; during the microwave treatment, after each microwave treatment, moisture inside and outside the microwave-treated peel is removed;

[0042] The peel after the microwave treatment is subjected to a wet heat treatment and then dried to obtain the dried tangerine peel.

[0043] The present invention subjects the peel to a first microwave treatment to obtain a first microwave-treated peel. As an optional embodiment of the present invention, the peel includes tea-branch citrus peel. The present invention does not particularly limit the source of the tea-branch citrus peel, and conventional commercially available products in the field can be used. In the embodiment of the present invention, the tea-branch citrus peel from the Guangdong Xinhui Tea-branch Citrus Resource Garden is used as an example to specifically illustrate the preparation method of the present invention. Before the present invention processes the peel raw material, the peel raw material is preferably cleaned. The present invention does not particularly limit the cleaning method, and conventional cleaning methods in the field can be used. As an optional embodiment of the present invention, the cleaning method may be ultrasonic cleaning; the frequency of the ultrasonic cleaning may be 40-80 kHz, or 40, 50, 60, 70, or 80 kHz; the power of the ultrasonic cleaning may be 160 W-500 W, or 160, 180, 200, 250, 300, 350, 400, 450, or 500 W; the time of the ultrasonic cleaning may be 100-180 s, or 100, 110, 120, 130, 140, 150, 160, 170, or 180 s. After the ultrasonic cleaning is completed, the present invention preferably drains the water from the peel raw material and then peels it. The present invention does not specifically limit the peeling method, and conventional peeling methods in the art may be used. As an optional embodiment of the present invention, the peeling may be performed by dividing the peel into three lobes, connecting the peel at the fruit base, or dividing the peel into three lobes at 120°. In the embodiment of the present invention, the process of preparing tangerine peel is described by taking the peel connected at the fruit base as an example.

[0044] As an optional embodiment of the present invention, during the first microwave treatment, the exocarp is facing upward or bulging upward. In the present invention, the exocarp refers to the oil cell layer of the peel; the exocarp facing upward or bulging upward refers to the oil cell layer facing upward or bulging upward. As an optional embodiment of the present invention, after obtaining the peels with the exocarp facing upward or bulging upward, the peels are stacked together for the first microwave treatment; the number of stacked peels can be 5 to 20, or can be 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20. As an optional embodiment of the present invention, the frequency of the first microwave is 2450 MHz; the power of the first microwave is 500-1000 W, and may also be 500, 600, 700, 800, 900, or 1000 W; and the duration of the first microwave is 120-180 seconds, and may also be 120, 130, 140, 150, 160, 170, or 180 seconds. The purpose of the first microwave treatment of the present invention is to orient the outer peel upward or to bulge upward, primarily to dehydrate the peel and remove essential oils, thereby maintaining the integrity of the peel shape and facilitating subsequent operations.

[0045] After obtaining the first microwave-treated peel, the present invention flips the first microwave-treated peel and then continues to microwave-treat the peel 2-3 times to complete the microwave treatment. As an optional embodiment of the present invention, the present invention can continue to microwave-treat 2-3 times twice or 3 times. When the present invention continues to microwave-treat 2 times, the two microwave treatments are respectively referred to as the second microwave and the third microwave. When the present invention continues to microwave-treat 3 times, the three microwave treatments are respectively referred to as the second microwave, the third microwave, and the fourth microwave.

[0046] As a preferred embodiment of the present invention, the number of times of continuing the microwave treatment is preferably 2. The following technical solution is specifically described by taking continuing the microwave treatment for 2 times as an example.

[0047] After obtaining the first microwave-treated peel, the present invention flips the first microwave-treated peel and then performs a second microwave treatment to obtain the second microwave-treated peel. As an optional embodiment of the present invention, the flipping can be performed by flipping the peel from the oil cell layer (exocarp) facing upward or convex to the white skin layer (endocarp) facing upward or convex. During the second microwave treatment, the peels are preferably stacked together; the number of stacked peels can be 5 to 20, or can be 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20. As an optional embodiment of the present invention, the second microwave frequency is 2450 MHz; the second microwave power is 500-1000 W, and can also be 500, 600, 700, 800, 900, or 1000 W; and the second microwave duration is 120-180 seconds, and can also be 120, 130, 140, 150, 160, 170, or 180 seconds. The second microwave treatment of the present invention is primarily intended to further remove moisture and essential oils from the peel.

[0048] After obtaining the second microwave-treated peel, the present invention removes moisture from the interior and exterior of the second-microwave-treated peel and then performs a third microwave treatment to obtain the third-microwave-treated peel. As an optional embodiment of the present invention, the method for removing moisture from the interior and exterior of the second-microwave-treated peel can be wiping; the wiping can be performed using kitchen paper to wipe the interior and exterior of the peel; the wiping is preferably performed gently to avoid damaging the peel structure. Wiping moisture from the interior and exterior of the peel in the present invention is primarily intended to prevent surface moisture from generating high temperatures under microwave conditions, potentially scalding the peel; it also facilitates moisture evaporation. After wiping moisture from the interior and exterior of the peel, the present invention performs a third microwave treatment. The present invention preferably stacks the peels for the third microwave treatment; the number of peels stacked can range from 5 to 20, or can be 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20. As an optional embodiment of the present invention, the third microwave frequency is 2450 MHz; the third microwave power is 500-1000 W, and can also be 500, 600, 700, 800, 900, or 1000 W; and the third microwave duration is 120-180 seconds, and can also be 120, 130, 140, 150, 160, 170, or 180 seconds. The third microwave treatment of the present invention is primarily intended to further remove moisture and essential oils from the peel.

[0049] After obtaining the third microwave-treated peel, the present invention can directly perform a wet heat treatment on the third microwave-treated peel, or can wipe the moisture from the inside and outside of the third microwave-treated peel and then perform a fourth microwave treatment to obtain a fourth microwave-treated peel. As an optional embodiment of the present invention, the moisture from the inside and outside of the peel can be wiped with kitchen paper; the wiping is preferably performed gently to avoid damaging the peel structure. After wiping the moisture from the inside and outside of the peel, the present invention performs a fourth microwave treatment. When performing the fourth microwave treatment, the peels are preferably stacked together; the number of stacked peels can be 5 to 20, or can be 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20. As an optional embodiment of the present invention, the fourth microwave frequency is 2450 MHz; the fourth microwave power is 500-1000 W, and may also be 500, 600, 700, 800, 900, or 1000 W; and the fourth microwave duration is 120-180 seconds, and may also be 120, 130, 140, 150, 160, 170, or 180 seconds. The fourth microwave treatment of the present invention is primarily intended to further remove moisture and essential oils from the peel.

[0050] After obtaining the peel treated with microwaves for the third time, or after obtaining the peel treated with microwaves for the fourth time, the present invention performs a wet heat treatment on the peel treated with microwaves for the third time or the fourth time, followed by drying to obtain dried tangerine peel. As an optional embodiment of the present invention, the wet heat treatment comprises covering the peel or a container containing the peel with a wet heat carrier; the wet heat carrier comprises a wet heat towel. As an optional embodiment of the present invention, the wet heat towel is a wet heat towel that has been sterilized with boiling water and wrung out until no water drips. The wet heat treatment duration can be 20-40 minutes, or 30 minutes; the initial temperature of the wet heat treatment can be 40-60°C, or 50°C; that is, the initial temperature of the wet heat towel can be 40-60°C, or 50°C; and the wet heat treatment is performed at room temperature. The wet heat treatment of the peel in the present invention primarily converts pigments, softens cell walls, releases intracellular pigments and other components, and alters enzyme activity, thereby improving the color of the tangerine peel, giving it a dark gray appearance. After the wet heat treatment is completed, the present invention preferably uses kitchen paper to wipe the inner and outer surfaces of the peel to remove moisture; the wiping is preferably performed gently to avoid damaging the peel structure. After wiping the inner and outer surfaces of the peel, the present invention then dries the peel. The drying temperature of the present invention can be 55-65°C, or 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, or 65°C; the drying time can be 3-6 hours, or 3, 4, 5, or 6 hours. The present invention reduces the moisture content of the peel to below 5% through drying, while preserving the integrity of the commercial tangerine peel. After drying, the present invention produces tangerine peel.

[0051] The rapid preparation method of tangerine peel proposed in the present invention is intended to solve the problems of low drying efficiency, unstable quality and long aging time in existing preparation methods. Among them, the drying efficiency is low: the traditional sun-drying method is greatly affected by the weather and takes a long time to dry. Although the oven-drying method takes a shorter time, it causes greater damage to the effective ingredients and cannot take into account both drying efficiency and quality. Unstable quality: the sun-drying method is easily affected by external environmental factors, resulting in uneven quality of tangerine peel; the oven-drying method may reduce the effective ingredient content and flavor of tangerine peel due to long-term high-temperature treatment. Long aging time: whether it is sun-drying or oven-drying, a long aging period is required to achieve the ideal quality, which increases production costs and time costs.

[0052] Based on in-depth research on key factors in the preparation process of dried tangerine peel, the present invention optimizes drying process parameters and combines microwave, wet heat treatment and other technical means to achieve efficient drying and aging of tea branch tangerine peel in a short time. The preparation method of the present invention can process tea branch tangerine peel within 5 hours, while simultaneously completing functions such as drying and removing essential oils. Compared with sun-drying, the preparation method has a faster drying speed, which can increase the drying rate by 25 times, and has a higher flavonoid content and a lower moisture content. Compared with oven-drying, the preparation method can remove essential oils faster while achieving the aging effect of the tangerine peel. The dried tangerine peel prepared by the preparation method has a better antioxidant effect than sun-dried or oven-dried dried tangerine peel, and is comparable to commercially available five-year and ten-year dried tangerine peel. The dried tangerine peel prepared by the preparation method has a better anti-inflammatory effect than sun-dried or oven-dried dried tangerine peel, and is comparable to commercially available five-year and ten-year dried tangerine peel.

[0053] The present invention provides the use of the preparation method described in the above technical solution in improving the preparation efficiency and / or quality of dried tangerine peel. The preparation method provided by the present invention can significantly improve the drying efficiency of dried tangerine peel and shorten the preparation time of dried tangerine peel. As an optional embodiment of the present invention, the improvement of the quality of dried tangerine peel includes any one or more of the following (1) to (4):

[0054] (1) Increase the content of flavonoids in dried tangerine peel;

[0055] (2) Reduce the content of tangerine peel essential oil;

[0056] (3) Improve the antioxidant capacity of dried tangerine peel;

[0057] (4) Improve the anti-inflammatory ability of dried tangerine peel.

[0058] The preparation method provided by the present invention can significantly increase the flavonoid content of dried tangerine peel. The present invention demonstrates that dried tangerine peel prepared using the preparation method provided by the present invention has a significantly higher flavonoid content than dried tangerine peel prepared using sun-drying or oven-drying methods. The flavonoid content of dried tangerine peel prepared by the present invention is between that of five-year-old and ten-year-old tangerine peel.

[0059] The preparation method provided by the present invention can significantly reduce the essential oil content of dried tangerine peel. The present invention demonstrates that the essential oil content of dried tangerine peel prepared using the preparation method provided by the present invention is significantly lower than that of dried tangerine peel prepared using sun-drying or oven-drying methods. The essential oil content of the dried tangerine peel prepared by the present invention is between that of three-year-old and five-year-old tangerine peel.

[0060] The preparation method provided by the present invention can significantly improve the antioxidant capacity of dried tangerine peel. The present invention demonstrates that dried tangerine peel prepared using the preparation method provided by the present invention exhibits significantly improved DPPH free radical scavenging ability, FRAP iron ion reduction ability, and ABTS free radical scavenging ability compared to dried tangerine peel prepared by sun-drying or oven-drying methods. The antioxidant capacity of dried tangerine peel prepared using the preparation method provided by the present invention is comparable to that of commercially available five-year-old and ten-year-old dried tangerine peel. In the examples of the present invention, the cellular antioxidant capacity of dried tangerine peel prepared using the preparation method was also evaluated, and the results showed that the obtained dried tangerine peel significantly increased cell survival rate under the influence of H₂O₂, comparable to that of commercially available five-year-old dried tangerine peel; significantly inhibited ROS content under the influence of H₂O₂, comparable to that of commercially available five-year-old and ten-year-old dried tangerine peel; and significantly increased SOD, CAT, and GSH-Px enzyme activities under the influence of H₂O₂, comparable to that of commercially available five-year-old and ten-year-old dried tangerine peel.

[0061] The preparation method provided by the present invention can significantly enhance the anti-inflammatory ability of dried tangerine peel. The present invention demonstrates that, compared with dried tangerine peel prepared by sun-drying or oven-drying, dried tangerine peel prepared by the preparation method provided by the present invention can significantly inhibit the LPS-induced increase in nitric oxide (NO) content and the increase in the content of three inflammatory factors, interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-α (TNFα). The effect is comparable to that of commercially available 10-year-old dried tangerine peel.

[0062] In order to further illustrate the present invention, the technical solution provided by the present invention is described in detail below with reference to the accompanying drawings and embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0063] The tea-branch tangerines used in the following scheme are sourced from the Guangdong Xinhui Tea-branch Tangerine Resource Garden.

[0064] Example 1

[0065] A preparation method of dried tangerine peel Figure 1 The specific steps are as follows:

[0066] The tea branch orange was cleaned at room temperature using ultrasonic parameters of 40 kHz and 200 W for 120 s.

[0067] After cleaning and draining the water, peel the fruit. Use a peeler or peel knife to cut the peel into three pieces at 120 degrees and connect them at the base.

[0068] Ten peels were stacked together. At this time, the peels were in an un-turned state (i.e., the oil cell layer bulged upwards). The first microwave treatment was performed with a microwave frequency of 2450 MHz, a microwave power of 700 W, and a microwave time of 150 s.

[0069] After the first microwave is completed, the peel is turned over, that is, the peel is raised from the oil cell layer (the outer side of the peel is yellow, i.e. the exocarp) to the white skin layer (the inner side of the peel is white) that is raised upward.

[0070] Ten peels were stacked together. At this time, the peels were in the flipped state and microwaved for the second time. The microwave frequency was 2450 MHz, the microwave power was fixed at 700 W, and the microwave time was 150 s.

[0071] After the second microwave, use kitchen paper to dry the moisture inside and outside the peel, that is, gently wipe the moisture inside and outside the peel with paper.

[0072] Ten peels were stacked together. At this time, the peels were in a flipped state (the white skin layer bulged upward, that is, the inner peel bulged upward). The third microwave treatment was performed with a microwave frequency of 2450 MHz, a microwave power of 700 W, and a microwave time of 150 s.

[0073] After the third microwave treatment, use a hot and damp towel with an initial temperature of 50°C (the hot and damp towel is a hot and damp towel that has been sterilized with boiling water and wrung out until no water drips) to microwave the peels at room temperature for 30 minutes. That is, use the corresponding hot towel to cover the container containing the peels, keep it for 30 minutes, and then use kitchen paper to dry the moisture in the shade.

[0074] The peel is dried at 60°C for 4 h, at which point the peel moisture is reduced to below 5% while maintaining a complete commercial tangerine peel state, thereby obtaining tangerine peel.

[0075] Store the dried tangerine peel.

[0076] Comparative Example 1

[0077] A method for preparing dried tangerine peel by a drying method, comprising the following steps:

[0078] After washing the tea-branch oranges with water and draining the water, peel them. Use a peeler or peeling knife to split the peel into three pieces at 120 degrees, connect them at the base, and then dry the peel at 60℃ for 12 hours.

[0079] Comparative Example 2

[0080] A method for preparing dried tangerine peel by sun-drying, comprising the following steps:

[0081] Wash the tea-branch oranges with water, drain, and peel them. Use a peeler or peel knife to split the peel into three pieces at a 120-degree angle, connecting them at the stem. Spread the peels out on a drying net from December 14 to 18, 2024, until the peels are hard and free of visible moisture. The weather conditions from December 14 to 18, 2024, are as follows: December 14, 2024: Sunny, 1-7°C, Maximum Wind Force 3; December 15, 2024: Sunny, 0-11°C, Maximum Wind Force 3; December 16, 2024: Sunny, 1-12°C, Maximum Wind Force 3; December 17, 2024: Sunny, 3-13°C, Maximum Wind Force 3; December 18, 2024: Sunny, 1-10°C, Maximum Wind Force 4.

[0082] Application Example 1

[0083] The efficiency of the method for preparing tangerine peel in Example 1 was compared with that of the drying method in Comparative Example 1 and the sun-drying method in Comparative Example 2. The moisture content of the tangerine peel prepared in Example 1 was compared with that prepared by the drying and sun-drying methods.

[0084] 1. Drying time of different methods Figure 2 As shown. The drying time for sun drying, oven drying and Example 1 is 120 hours, 12 hours and 4.75 hours respectively. Among them, 4.75 hours is the time for multiple practical operations using the method of Example 1, and each practical operation lasts about 285 minutes. The preparation method of dried tangerine peel in Example 1 improves the drying efficiency by 2.5 and 25 times respectively compared with the direct drying method and the sun drying method.

[0085] 2. Moisture determination method:

[0086] Moisture content was tested using a halogen moisture meter. The main testing method is as follows: Connect the halogen moisture meter to the power supply, turn on the instrument, and preheat for 30 minutes to allow the instrument to reach a stable operating state to ensure accurate measurement results. Randomly select a 2-5g sample of tangerine peel and place it in the instrument's sample tray. Place the sample tray steadily on the halogen moisture meter's weighing platform and close the instrument's windshield. After the weight displayed on the instrument stabilizes, record the initial weight (m1). Set the heating temperature to 105°C and start the heating program. The halogen lamp will begin heating the sample, gradually evaporating the moisture from the sample. When the sample weight no longer changes significantly, the moisture is considered to have evaporated, and the measurement endpoint has been reached. After the weight displayed on the instrument stabilizes, record the final weight (m2). Calculate the moisture content (%) of the peel or tangerine peel as (m1 - m2) / m1 × 100%.

[0087] The weight of peel obtained by different drying methods is shown in Table 1 and Figure 3The water content of the peel obtained by different drying methods is shown in Table 2 and Figure 4 shown.

[0088] Table 1 Peel weight obtained by different drying methods

[0089]

[0090] The weight of peel obtained by different drying methods is shown in Table 1 and Figure 3 As shown, the original fruit weights of the peels of the three methods were 28.52±1.01 g (this method, i.e., Example 1), 28.87±0.41 g (drying method), and 26.40±1.29 g (sun-drying method), while the final product weights were 6.21±0.13 g (this method), 7.91±0.27 g (drying method), and 8.89±0.82 g (sun-drying method), respectively. The weights of the final products accounted for 21.78% (this method), 27.40% (drying method), and 33.67% (sun-drying method) of the original weight. The proportion of this method was significantly lower than that of the drying method (p<0.05) and the sun-drying method (p<0.01).

[0091] Table 2 Water content of peel obtained by different drying methods

[0092]

[0093] The moisture content obtained by different drying methods is shown in Table 2 and Figure 4 As shown, the original fruit moisture content of the peel of the three methods was 78.72±0.42% (this method, i.e., Example 1), 77.43±0.77% (drying method), and 77.56±1.22% (sun-drying method), while the moisture content of the final product obtained was 4.93±0.30% (this method), 6.29±0.47% (drying method), and 11.88±0.47% (sun-drying method), and the water loss rate was 73.79±0.55% (this method), 71.14±0.30% (drying method), and 65.68±1.66% (sun-drying method), respectively. The water loss rate of this method was 2.25% lower than that of the drying method (p=0.069), and significantly lower than that of the sun-drying method (p<0.01).

[0094] In summary, this method (Example 1) can complete the drying from peel to tangerine peel in a shorter time, greatly improving the drying rate compared to the existing method, and this method can make the moisture content of the peel lower.

[0095] Application Example 2 Comparison of flavonoids and essential oil contents in dried tangerine peel obtained by different methods

[0096] The flavonoid and essential oil contents of the dried tangerine peel prepared in Example 1 and Comparative Examples 1-2 and commercially available one-year dried tangerine peel, two-year dried tangerine peel, three-year dried tangerine peel, five-year dried tangerine peel and ten-year dried tangerine peel were measured, wherein the one-year dried tangerine peel, two-year dried tangerine peel, three-year dried tangerine peel, five-year dried tangerine peel and ten-year dried tangerine peel were purchased from Guangdong Xinhui Tianma Tangerine Peel Chamber of Commerce.

[0097] 1. Flavonoid content detection method

[0098] Extraction of flavonoids from dried tangerine peel: Weigh 100 g of the above dried tangerine peel sample and grind it into a dry powder in a traditional Chinese medicine grinder. After grinding into a powder, pass it through a 60-mesh sieve and store the resulting powder in a cool, dry place until ready for use. Accurately weigh 50 g of the powder and add 500 mL of anhydrous ethanol (solid-to-liquid ratio of 1:10). Ultrasonic extraction (53 kHz) was performed at room temperature for 1 hour. After extraction, the extract was allowed to settle overnight. The extract was filtered through four layers of gauze and then through three layers of filter paper, and the clear filtrate was collected. The filtrate was concentrated under reduced pressure on a rotary evaporator (35°C, 80 rpm) to an ethanol-free phase. An appropriate amount of double-distilled water was added to the residual liquid for reconstitution. The aqueous phase was collected and stored at 4°C until ready for use. A Sep-pak® C18 column was used for solid-phase extraction and impurity removal. The specific steps were as follows: 2 column volumes (BV) of methanol were used to activate the column, 2 BV of double-distilled water was used to equilibrate the column, 0.75 BV of the aqueous phase was loaded, 20 BV of double-distilled water was used to remove impurities such as sugars and acids, and finally 1 BV of methanol was used to elute the sample. The eluate was then evaporated in a vacuum concentrator (30°C) until all the methanol was evaporated. The residual solid, representing the bioactive compound-rich fraction, was collected and stored at -20°C for subsequent experiments.

[0099] The flavonoid content in dried tangerine peel was determined by HPLC. A Waters BEH C18 liquid chromatography column was used as the stationary phase, and the mobile phases were water (mobile phase A) and acetonitrile (mobile phase B). The gradient elution program was as follows: 20% B (0–5 min); 20–34% B (5–10 min); 34–60% B (10–18 min); 60–100% B (18–30 min); 100% B (30–31 min); 100–20% B (31–33 min); and 20% B (33–35 min). The scanning wavelength was 200–600 nm, the flow rate was 0.1 mL / min, the column temperature was 25°C, and the sample load was 10 μL. The quantification of naringin, hesperidin, iso-sweet aurantin, aurantin, nobiletin, tangeretin, and 5-demethylnobiletin was performed using a standard curve method.

[0100] The HPLC spectrum of flavonoids in dried orange peel prepared in Example 1 is as follows: Figure 5 shown. Figure 5Peak 1 is naringin; Peak 2 is hesperidin; Peak 3 is isosweet orange flavonoids; Peak 4 is sweet orange flavonoids; Peak 5 is nobiletin; Peak 6 is tangeretin; Peak 7 is 5-demethylnobiletin. The flavonoid content of tangerine peel is as follows: Figure 5 The sum of the peak areas of the seven main flavonoid peaks was calculated.

[0101] The test results of flavonoid content in dried tangerine peel obtained by different methods are shown in Table 3 and Figure 6 shown.

[0102] Table 3 Detection results of flavonoid content in dried tangerine peel obtained by different methods

[0103]

[0104] From Table 3 and Figures 5 and 6 Seven major flavonoids were detected in dried tangerine peel by standard comparison: naringin, hesperidin, iso-auricularin, auricularin, nobiletin, tangeretin, and 5-demethylnobiletin. After quantification using a standard curve, the sum of the seven major flavonoids was taken as the total flavonoid content of dried tangerine peel. The results showed that the different drying methods produced comparable flavonoid types and proportions, but differed in the ratio of flavonoid content to peel weight. The flavonoid content of the final product obtained by this method was 135.29 ± 4.43 mg / g DW (dry weight), significantly higher than the flavonoid content of the oven-dried product (102.93 ± 5.51 mg / g DW) (p < 0.05) and the sun-dried product (82.53 ± 5.14 mg / g DW) (p < 0.01).

[0105] The flavonoid content of commercially available tangerine peel increased with age, reaching 82.69±1.54 mg / g DW (one-year-old tangerine peel), 85.65±3.81 mg / g DW (two-year-old tangerine peel), 91.79±2.95 mg / g DW (three-year-old tangerine peel), 102.08±6.53 mg / g DW (five-year-old tangerine peel), and 145.51±2.82 mg / g DW (ten-year-old tangerine peel). The results indicate that the flavonoid content obtained by this method is between that of five-year-old and ten-year-old tangerine peel.

[0106] 2. Essential oil content detection method

[0107] Essential oil content is calculated by weight using the distillation method. A certain amount of fresh orange peel is weighed and crushed into small, uniform pieces to increase its contact area with water. The sample is placed in a distillation apparatus, an appropriate amount of water is added, and steam distillation is performed. During the distillation process, the orange peel essential oil is distilled out along with the water vapor, cooled through a condenser, and collected in a receiving flask. An appropriate amount of petroleum ether is added to the receiving flask and thoroughly shaken for extraction, transferring the essential oil to the organic solvent phase. The organic phase is then separated using a separatory funnel and desiccant such as anhydrous sodium sulfate is used to remove the moisture. The dried organic phase is transferred to a weighed evaporating dish. The organic solvent is allowed to evaporate naturally in a fume hood or removed by vacuum distillation to obtain the orange peel essential oil. Finally, the essential oil is weighed to calculate the orange peel essential oil content.

[0108] The essential oil content of dried tangerine peel obtained by different methods is as follows: Figure 7 shown.

[0109] Table 4 Essential oil content in dried tangerine peel obtained by different methods

[0110]

[0111] Essential oil is the main aroma component of citrus peel, and its content is also one of the main indicators of aging in tangerine peel. The essential oil content in younger peels is higher than that in older peels. Therefore, the decrease in essential oil content is also a phenomenon of tangerine peel aging. Figure 7 As shown in the results, the essential oil content of the peel of fresh tea-branch orange fruit is approximately 3.57%-3.63%. The essential oil content of the final product obtained by this method is 1.23±0.07%, which is significantly lower than the essential oil content of the final products obtained by the oven-drying method (2.92±0.07%) and the sun-drying method (2.29±0.25%) (p<0.05).

[0112] The essential oil content of commercially available tangerine peel decreased with age, reaching 2.71±0.13% (one-year-old tangerine peel), 2.09±0.11% (two-year-old tangerine peel), 1.92±0.10% (three-year-old tangerine peel), 1.20±0.02% (five-year-old tangerine peel), and 1.01±0.02% (ten-year-old tangerine peel). The results indicate that the essential oil content obtained by this method is between that of three-year-old and five-year-old tangerine peel.

[0113] From the above, it can be concluded that this method can significantly increase the content of flavonoids, the main nutritional component in tangerine peel, and significantly reduce the content of essential oil, a negatively correlated marker of aging, in tangerine peel compared with the oven drying and sun drying processes, and achieve similar indicators to commercially available tangerine peel aged for more than 3 years.

[0114] Application Example 3 Comparison of the antioxidant capacity of dried tangerine peel obtained by different methods

[0115] Tangerine peel is used in the same manner as in Example 2.

[0116] 1. Evaluation of the antioxidant capacity of dried tangerine peel by chemical antioxidant method

[0117] (1) DPPH method to evaluate DPPH free radical scavenging ability. 2 μL of appropriately diluted sample (specifically, the sample is the powder obtained by extracting tangerine peel with anhydrous ethanol and solid phase extraction, see Application Example 2 for the specific method; then dissolved in methanol and appropriately diluted) was added to 198 μL of freshly prepared 60 μM DPPH solution. The reaction was carried out at 25°C in the dark for 2 h. The absorbance at a wavelength of 517 nm was measured by a microplate reader. The DPPH free radical scavenging ability was calculated using Trolox as a standard curve. The results were expressed as mg Trolox equivalent (TE) / g. The experiment was repeated three times independently.

[0118] (2) Evaluation of iron ion reducing ability by FRAP method. First, prepare the FRAP working solution: sodium acetate buffer solution (300 mM, pH 3.6), TPTZ solution (10 nM), and FeCl3 solution (20 mM) in a volume ratio of 10:1:1. Take 20 μL of appropriately diluted sample (specifically, the sample is the powder obtained by extracting tangerine peel with anhydrous ethanol and solid phase extraction, see Application Example 2 for the specific method; then dissolve it in methanol and dilute it appropriately) and mix it with 180 μL of FRAP working solution. After reacting at 25℃ in the dark for 5 min, the absorbance at 593 nm was measured by microplate reader. Trolox was used as the control to make a standard curve to calculate the FRAP iron ion reducing ability. The results were expressed as mg Trolox equivalent (TE) / g. The experiment was repeated three times independently.

[0119] (3) ABTS method to evaluate the free radical scavenging activity of ABTS. 7 mM ABTS and 2.6 mM K2S2O8 were mixed in a volume ratio of 1:1, reacted at 25°C in the dark for 12 h, and then diluted with solvent to OD 734nm ABTS working solution with a concentration of ≈0.63. Take 10 μL of appropriately diluted sample (specifically, the sample is a powder obtained by extracting dried tangerine peel with anhydrous ethanol and solid-phase extraction (see Application Example 2 for specific methods), then dissolve it in methanol and dilute it appropriately) and mix it with 200 μL of ABTS working solution. Incubate at 25°C in the dark for 5 minutes, then measure the absorbance at 734 nm. A standard curve was constructed using Trolox as a control to calculate the ABTS free radical scavenging capacity. The results are expressed as mg Trolox equivalent (TE) / g. The experiment was repeated three times.

[0120] (4) ORAC method was used to evaluate the oxygen free radical scavenging activity. 25 μL of appropriately diluted sample (specifically, the sample is the powder obtained by extracting dried tangerine peel with anhydrous ethanol and solid phase extraction, see Application Example 2 for the specific method, and then dissolved in methanol and appropriately diluted) and 150 μL of 40 nM sodium fluorescein solution were added to a 96-well plate. After reacting in the dark at 37°C for 10 min, 25 μL of 150 mM AAPH solution was added and the fluorescence intensity was measured (excitation wavelength 485 nm, emission wavelength 535 nm, reading interval 2 min, total time 2 h). PBS was used as a control, and the well without AAPH was used as the fluorescence initial value reading well. The difference in the area under the sodium fluorescein decay curve (Net AUC) between the blank sample and the sample was used as the calculation result. The Net AUC calculation formula is: Net AUC = AUC sample − AUC AAPH+ , AUC = 2 × (f0+ f1+ … +f n ) − f n The ORAC equivalent was calculated using Trolox as a standard curve and the results were expressed as mg Trolox equivalent (TE) / g. The experiment was repeated three times.

[0121] The comparison of chemical antioxidant capacity of dried tangerine peel obtained by different methods is shown in Table 5.

[0122] Table 5 Chemical antioxidant capacity of dried tangerine peel obtained by different methods

[0123]

[0124] Note: Different numbers after the value represent significant differences between different groups

[0125] As shown in Table 5, the antioxidant capacity of the final product of this method (tangerine peel prepared in Example 1) was significantly higher than that of the oven-dried and sun-dried products in terms of DPPH free radical scavenging ability, and was comparable to commercially available five-year-old tangerine peel. In terms of FRAP iron ion reduction ability, the antioxidant capacity of the final product of this method was significantly higher than that of the oven-dried and sun-dried products, and was comparable to commercially available five-year-old tangerine peel and ten-year-old tangerine peel. In terms of ABTS free radical scavenging ability, the antioxidant capacity of the final product of this method was significantly higher than that of the oven-dried and sun-dried products, and was comparable to commercially available three-year-old, five-year-old, and ten-year-old tangerine peel. In the ORAC oxygen free radical scavenging activity evaluation, the antioxidant capacity of the final product of this method was significantly higher than that of the oven-dried and sun-dried products, and was comparable to commercially available five-year-old tangerine peel and ten-year-old tangerine peel. These results demonstrate that the chemical antioxidant capacity of the product obtained by this method is superior to that of traditional processes, and is superior to tangerine peel aged for one year, demonstrating a superior antioxidant effect.

[0126] 2. Evaluation of the antioxidant capacity of dried tangerine peel using a cell model antioxidant method

[0127] The antioxidant capacity of dried tangerine peel was evaluated using the human normal liver cell line L02.

[0128] (1) Cell culture and activity detection

[0129] L02 cells were cultured in RPMI1640 medium (containing 10% FBS, 20 mM HEPES, 100 Unit / mL penicillin and streptomycin) at 37°C and 5% CO2. Cells were passaged when they reached a confluency of approximately 70% to 80%.

[0130] Cell viability was assessed using a CCK-8 kit. After removing the cell culture medium, cells were washed twice with PBS. The CCK-8 solution was diluted 1:10 by volume with serum-free RPMI 1640 medium and added to the cell culture plate. Incubated in the dark for 1 hour, absorbance at 620 nm and 450 nm was measured using a microplate reader to calculate cell viability. DMSO was used as a solvent control. Each experiment was performed in triplicate and repeated at least three times.

[0131] (2) Hydrogen peroxide-induced cellular oxidative stress model

[0132] Different concentrations of tangerine peel powder (specifically, tangerine peel powder obtained by extracting tangerine peel with anhydrous ethanol and then solid-phase extraction, as described in Application Example 2) were dissolved in DMSO. The final DMSO concentration exposed to cells was 0.1%. Cells were cultured in serum-free RPMI1640 medium for 24 hours. Tangerine peel extract was then added to the culture system at concentrations of 12.5 μg / mL, 25 μg / mL, 50 μg / mL, 100 μg / mL, and 200 μg / mL, respectively, and incubated for 6 hours. After incubation, the viability of a portion of the cells was assayed to determine the effect of different concentrations of tangerine peel extract on L02 cell viability. The remaining cells were incubated at 37°C in 0.78 mM H2O2 for 30 minutes. After the addition of H2O2, cell viability, reactive oxygen species, and other indicators were measured. DMSO was used in place of different concentrations of tangerine peel extract, and a solvent control (no H2O2 added, i.e., only DMSO) was used as a solvent control.

[0133] (3) Cellular reactive oxygen species detection

[0134] After incubation with H₂O₂, cells were gently washed twice with PBS. A 10 µM solution of DCFH-DA fluorescent probe diluted in serum-free RPMI1640 medium was added to the wells. After incubation at 37°C for 20 min, the DCFH-DA solution was removed, and the cells were washed three times with serum-free medium. Fluorescence intensity was measured using a microplate reader at an excitation wavelength of 488 nm and an emission wavelength of 525 nm. Each experiment was repeated three times.

[0135] (4) Detection of cellular antioxidant enzyme activity

[0136] The activities of cellular antioxidant enzymes such as CAT, SOD, and GSH-Px were determined using commercial kits.

[0137] (5) The antioxidant capacity of tangerine peel prepared by different methods was evaluated using human liver cell line L02. The results are shown in Tables 6 to 8 and Figure 8 shown. Figure 8 A in the figure is the effect of tangerine peel extract treatment on the survival rate (%) of L02 cells, where * indicates significant difference compared with other treatment groups; Figure 8 B in the figure shows the effect of tangerine peel extract treatment on the decrease in L02 cell survival rate induced by H2O2 (%), where * indicates a significant difference compared with the H2O2-induced group without tangerine peel extract; Figure 8 C in the figure represents the effect of 100 μg / mL tangerine peel extract on the ROS content of L02 cells induced by H2O2. Different letters in the figure represent significant differences among different groups.

[0138] Table 6 Effects of tangerine peel extract treatment on L02 cell survival rate (%)

[0139]

[0140] Table 7 Effect of tangerine peel extract treatment on H2O2-induced decrease in L02 cell survival rate (%)

[0141]

[0142] Table 8 Effects of 100 μg / mL tangerine peel extract on ROS content in L02 cells induced by H2O2

[0143]

[0144] The antioxidant capacity of tangerine peel prepared by different methods was evaluated using human liver cell line L02. Figure 8 As shown in A, different dried tangerine peels had no effect on cell viability within a concentration of 100 mg / L. Figure 8As shown in Figure B, 100 mg / L of different dried tangerine peel extracts can all improve cell survival rates under the influence of H2O2. The cell survival rate of the final product of this method is 85.06%, which is higher than that of the oven-dried product (76.27%) and the sun-dried product (75.49%). The cell survival rates of different commercially available dried tangerine peels are 71.25% (one year), 78.59% (two years), 75.79% (three years), 85.09% (five years), and 86.67% (ten years). It can be seen that the dried tangerine peel prepared by this method is comparable to the commercially available five-year-old dried tangerine peel. Figure 8 From A and B in the figure, it can be seen that 100 μg / mL tangerine peel extract has little effect on cell survival rate and can significantly improve the survival rate of L02 cells induced by H2O2. Therefore, the ROS content of L02 cells induced by H2O2 with 100 μg / mL tangerine peel extract was subsequently detected. The ROS content of L02 cells induced by H2O2 with 100 μg / mL tangerine peel extract was detected using a DCFH-DA probe. It was found that H2O2 can significantly induce an increase in the content of ROS, while the extract of the final product of this method can significantly reduce the content of ROS, and its inhibitory ability is stronger than that of the extract of the final product of drying and sun-drying, and is comparable to the inhibitory ability of five-year and ten-year tangerine peel on ROS (see Tables 8 and 8 for details). Figure 8 C in ).

[0145] (6) The effects of tangerine peel extracts with different treatments (the final concentration of tangerine peel extract in the tangerine peel extract solution was 100 μg / mL) on the antioxidant enzyme activities of cells are shown in Tables 9 and Figure 9 shown. Figure 9 A in the figure shows the effect of tangerine peel extracts with different treatments on cellular SOD activity; Figure 9 B in the figure shows the effect of tangerine peel extracts with different treatments on CAT enzyme activity in cells; Figure 9 C in the figure shows the effect of tangerine peel extracts with different treatments on cellular GSH-Px enzyme activity.

[0146] Table 9 Effects of tangerine peel extracts from different treatments on cellular antioxidant enzyme activities

[0147]

[0148] Note: Relative enzyme activity refers to the ratio of the corresponding enzyme activity to the blank control enzyme activity.

[0149] Cellular antioxidant enzymes are the executors of cellular antioxidant capacity, so the activities of different antioxidant enzymes were detected to evaluate the regulatory capacity of tangerine peels prepared by different methods on cellular antioxidant enzymes. The results are shown in Table 9 and Figure 9As shown, for superoxide dismutase SOD, hydrogen peroxide significantly inhibited SOD activity, while all tangerine peel extracts could enhance SOD activity, among which the final product of the present method had a significantly higher SOD enhancing ability than the final product of drying and sun-dried products, and had no significant difference from the enhancing ability of five-year tangerine peel. For catalase CAT, hydrogen peroxide significantly inhibited CAT activity. Except for the final product of sun-dried and one-year tangerine peel, the remaining tangerine peel extracts all enhanced CAT activity, among which the final product of the present method had a significantly higher CAT enhancing ability than the final product of drying and sun-dried products, and had no significant difference from the enhancing ability of ten-year tangerine peel. For glutathione peroxidase GSH-Px, hydrogen peroxide significantly inhibited GSH-Px activity. All tangerine peel extracts could enhance GSH-Px activity, among which the final product of the present method had a significantly higher GSH-Px enhancing ability than the final product of sun-dried products, and had no significant difference from the enhancing ability of five-year tangerine peel and ten-year tangerine peel.

[0150] Application Example 4 Comparison of the anti-inflammatory ability of dried tangerine peel obtained by different methods

[0151] The anti-inflammatory ability of dried tangerine peel was evaluated using the following two indicators:

[0152] 1. Nitric oxide (NO) content

[0153] RAW264.7 cells with normal morphology were digested, collected and counted. The cell concentration was 3×10 4 The cell suspension was seeded into a 96-well plate containing DMEM complete medium at a density of 100 cells / well and cultured in an incubator for 12 hours. Subsequently, tangerine peel extract was added for pretreatment. The method for preparing tangerine peel extract with different tangerine peels was the same as in Application Example 3. After pretreatment with DMEM complete medium containing 100 mg / L tangerine peel extract for 2 hours, LPS was added to a final concentration of 100 ng / mL and cultured for another 24 hours. The NO level in the culture medium was then determined using a NO detection kit. DMSO was used as a solvent control, 3 replicates were set for each treatment, and the experiment was repeated 3 times independently.

[0154] 2. Cellular inflammatory factors

[0155] The cells treated in step 1 were assayed for inflammatory factors such as interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor α (TNFα) using the ELISA method using a commercial kit (Abcam).

[0156] 3. The anti-inflammatory ability test results of dried orange peel obtained by different methods are shown in Table 10 and Figure 10 . Figure 10 A in the figure shows the effects of different treatments of tangerine peel extracts on the nitric oxide (NO) content in L02 cells; Figure 10 B in the figure shows the effects of different treatments of tangerine peel extracts on the interleukin-1β (IL-1β) content in L02 cells; Figure 10 C in the figure shows the effects of different treatments of tangerine peel extracts on the interleukin-6 (IL-6) content in L02 cells; Figure 10 Figure D shows the effect of different treatments on the necrosis factor α (TNFα) content in L02 cells after extracts from dried tangerine peel. Different letters in the figure indicate significant differences among the treatments.

[0157] Table 10 Anti-inflammatory ability test results of dried tangerine peel obtained by different methods

[0158]

[0159] The anti-inflammatory ability of different dried tangerine peels was evaluated using the mouse macrophage cell line RAW264.7. The results are shown in Table 10 and Figure 10 As shown, LPS significantly induced an increase in nitric oxide (NO) levels, while all tangerine peel extracts significantly inhibited NO levels. Tangerine peel obtained by this method exhibited a stronger inhibitory ability against NO compared to tangerine peel obtained by oven-drying and sun-drying, and was comparable to tangerine peel aged five and ten years. Elisa assays for cytokines revealed that LPS significantly induced increases in interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-α (TNFα), while tangerine peel obtained by this method significantly inhibited the levels of these three inflammatory factors. Compared to oven-drying and sun-drying, the tangerine peel obtained by this method exhibited a stronger inhibitory ability. For IL-1β and IL-6, the tangerine peel obtained by this method was comparable to tangerine peel aged five and ten years, while for TNFα, it was comparable to tangerine peel aged ten years. Therefore, the tangerine peel obtained in Example 1 exhibited significant anti-inflammatory activity, more potent than the oven-drying and sun-drying final products, and comparable to commercially available tangerine peel aged five or ten years.

[0160] Comparative Example 3

[0161] A method for preparing dried tangerine peel has the same steps as in Example 1, except that the process of using a 50°C hot towel to suffocate for 30 minutes is omitted. This method is referred to as "no hot towel treatment".

[0162] Comparative Example 4

[0163] A method for preparing dried tangerine peel has the same steps as in Example 1, except that the wiping with kitchen paper is omitted during the preparation process. This method is referred to as "no wiping with kitchen paper."

[0164] Comparative Example 5

[0165] A method for preparing dried tangerine peel, comprising the same steps as in Example 1, except that the first microwave treatment is omitted and only the second and third microwave treatments are performed, i.e., microwave treatment is not performed in an un-peeled state, but only in a two-times-peeled state. This method is referred to as "microwave twice."

[0166] Comparative Example 6

[0167] A method for preparing dried tangerine peel, comprising the same steps as in Example 1, except that the tangerine peel is subjected to a single microwave treatment in an unpeeled state, and not in a peeled state. Following the microwave treatment, the tangerine peel is dried. This method is referred to as "microwave once."

[0168] Example 2

[0169] A method for preparing dried tangerine peel comprises the same steps as in Example 1, except that after the third microwave treatment, a fourth microwave treatment is performed while the peel is turned over. Specifically, after the third microwave treatment, the inner and outer surfaces of the peel are dried in the shade with kitchen paper. The peel is then microwaved for a fourth time at a microwave frequency of 2450 MHz, a power of 700 W, and a microwave duration of 150 seconds. Following the fourth microwave treatment, the peel is similarly suffocated with a 50°C hot towel at room temperature for 30 minutes. The peel is then dried in the shade with kitchen paper and then oven-dried at 60°C for 3.9 hours. This method is referred to as "microwave 4 times."

[0170] Application Example 5

[0171] The efficiency of the method for preparing dried tangerine peel was compared between Examples 1 and 2 and Comparative Examples 4 to 6. Example 1 was recorded as microwave 3 times, and Example 2 was recorded as microwave 4 times.

[0172] 1. The weight and moisture content of the dried tangerine peel prepared in Examples 1-2 and Comparative Examples 4-6 were compared. Figure 11 The weight of dried tangerine peel obtained by different methods is shown in Table 11. The moisture content of dried tangerine peel obtained by different methods is shown in Table 12.

[0173] Table 11 Weight of dried tangerine peel prepared by different preparation methods in Examples 1-2 and Comparative Examples 4-6

[0174]

[0175] Table 12 Water content of dried tangerine peel prepared by different preparation methods in Examples 1-2 and Comparative Examples 4-6

[0176]

[0177] The dried tangerine peel prepared in Example 1 exhibited a dark gray color. When the 30-minute hot towel suffocation at 50°C was omitted, the dried tangerine peel exhibited a lighter color than that prepared in Example 1 and a higher moisture content, significantly higher than that of the product prepared in Example 1. This indicates that the hot towel treatment plays an important role in reducing the moisture content and improving the color of the tangerine peel. When the paper towel wiping was omitted, the moisture content of the dried tangerine peel was 11.93% ± 0.21%, significantly higher than that of the tangerine peel prepared in Example 1 (p < 0.05). The peel also showed slight surface burns, affecting its appearance and quality. This demonstrates that the paper towel wiping step is crucial for controlling the moisture content and protecting the peel's integrity. It prevents surface moisture from burning the peel under microwave conditions and facilitates moisture evaporation. When the microwave treatment was repeated twice, omitting one microwave cycle, the moisture content of the dried tangerine peel was 15.38% ± 1.30%, significantly higher than that of the method of the present invention (p < 0.01). This demonstrates that three microwave treatments are significantly effective in reducing the moisture content of tangerine peel. After only one microwave treatment, the moisture content of dried tangerine peel was 19.9% ± 0.02%, significantly higher than that of the method of the present invention (p < 0.01). This indicates that multiple microwave treatments play a significant role in drying tangerine peel. Increasing the number of microwave treatments from three to four times resulted in a drying time of 4.7 h, slightly shorter than the method of Example 1 (4.75 h). However, the dried tangerine peel weighed 6.10 ± 0.11 g, lower than the 6.21 ± 0.13 g obtained in Example 1, and had a moisture content of 4.90% ± 1.15%.

[0178] 2. The antioxidant capacity of the dried tangerine peels prepared in Examples 1-2 and Comparative Examples 4-6 was evaluated, and the results are shown in Table 13. The specific method is detailed in Application Example 3.

[0179] Table 13 Antioxidant capacity of dried tangerine peels prepared in Examples 1-2 and Comparative Examples 4-6

[0180]

[0181] As shown in Table 13, there is no difference in antioxidant capacity between microwave treatments 3 and 4 times, which is significantly higher than that of treatments with other microwave times or without hot towel or kitchen paper wiping.

[0182] In summary, the preparation method of the tangerine peel provided by the present invention achieves efficient drying of the tangerine peel in a short time by precisely controlling the number, time and power of microwave treatments, combined with auxiliary operations such as steaming with a hot towel and wiping with kitchen paper, while effectively retaining the effective ingredients in the tangerine peel, improving its antioxidant and anti-inflammatory effects, and ensuring the high quality and consistency of the tangerine peel.

[0183] Although the above embodiment provides a detailed description of the present invention, it is only a part of the embodiments of the present invention, not all of the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the scope of protection of the present invention.

Claims

1. A method for preparing dried tangerine peel, characterized in that: The following steps are involved: subjecting the peel to a first microwave treatment to obtain a first microwave-treated peel; After the peel is turned over after the first microwave treatment, microwave treatment is continued for 2 to 3 times to obtain the peel that has been microwave treated; During the microwave treatment process, after each microwave treatment, the moisture inside and outside the peel is removed; The microwave-treated peel is subjected to a wet heat treatment and then dried to obtain dried tangerine peel; The power of each microwave treatment is 500~1000W; the time of each microwave treatment is 120~180s; The wet heat treatment method includes covering the peel with a wet heat carrier or covering the container containing the peel; the wet heat treatment time is 20 to 40 minutes; the initial temperature of the wet heat treatment is 40 to 60° C.; the wet heat treatment is carried out at room temperature; The drying temperature is 55-65°C; the drying time is 3-6 hours; During the first microwave treatment, the outer peel faces upward or bulges upward; during the second or third microwave treatment, the inner peel faces upward or bulges upward; The peel is the peel of the tea-branch citrus fruit.

2. The preparation method according to claim 1, characterized in that During the microwave and moist heat treatment of the peels, 5 to 20 peels are stacked together for treatment.

3. The preparation method according to claim 1, characterized in that: Before the first microwave treatment, the peel was divided into three parts and connected at the fruit stem.

4. The preparation method according to claim 3, characterized in that The peel is cleaned before being split; the cleaning method includes ultrasonic cleaning.

5. the dried tangerine peel prepared by the preparation method described in any one of claims 1 to 4.

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