Preparation method and application of pericarpium citri reticulatae

Abstract

The invention provides a preparation method and application of pericarpium citri reticulatae, and belongs to the technical field of traditional Chinese medicine preparation. The invention provides a preparation method of dried orange peel, and the preparation method realizes efficient drying and aging treatment of peel raw materials within a short time by optimizing drying process parameters and combining technical means such as microwave and heat-moisture treatment. According to the method, the drying efficiency is remarkably improved, the preparation time is shortened, and flavonoid compound effective components in the dried orange peel are effectively reserved, so that the dried orange peel is equivalent to commercially available dried orange peel for many years in the anti-oxidation and anti-inflammatory effects and even superior to dried orange peel prepared by a traditional method. Meanwhile, by accurately controlling process parameters, the stability and consistency of the quality of the dried orange peel are ensured, and an efficient and reliable solution is provided for industrial production and application of the dried orange peel.

Description

Technical Field

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

[0002] Tangerine peel, as a traditional Chinese medicine and spice, has a long application history. It is mainly derived from the dried mature pericarp of the citrus plant (Citrus reticulata) and its cultivated varieties. Among them, the tangerine peel of Chazhigan in Xinhui, Guangdong is the most famous, with unique medicinal value and flavor. Tangerine peel contains rich volatile oils, flavonoid compounds and other components, and has the effects of regulating qi and strengthening the spleen, drying dampness and resolving phlegm. It is widely used in the field of traditional Chinese medicine and also has important applications in the food, health care products and other industries.

[0003] The traditional preparation methods of tangerine peel mainly include two methods: sun-drying and drying. The sun-drying method relies on natural sunlight, spreading the orange peel in the open air and allowing it to gradually lose moisture and age through natural drying over several days or even weeks. However, the sun-drying method is greatly restricted by weather conditions, with a long drying time and is easily contaminated by dust, microorganisms, etc., resulting in unstable quality of tangerine peel. In addition, some of the active ingredients in the orange peel may be partially lost due to long-term exposure to the natural environment during the sun-drying process, affecting its medicinal value and flavor.

[0004] The drying method accelerates the drying process of orange peel by artificial heating. Although it is not restricted by weather and has a relatively short drying time, it usually requires a high temperature and a long time, which may cause damage to heat-sensitive components in the orange peel such as some flavonoid compounds and essential oils, reducing its quality. At the same time, the dried orange peel often needs to be aged for a long time to achieve a flavor and efficacy similar to that of sun-dried tangerine peel, increasing the production cost and time cost.

[0005] With the continuous improvement of people's requirements for the quality and efficacy of tangerine peel, and the deepening of the understanding of the limitations of traditional preparation methods, developing 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] Aiming at the defects in the prior art, the purpose of the present invention is to provide a preparation method of tangerine peel that can significantly shorten the preparation time of tangerine peel and improve the quality of tangerine peel at the same time.

[0007] The purpose of the present invention is achieved by the following technical solutions: The present invention provides a preparation method of tangerine peel, comprising the following steps: Performing a first microwave treatment on the pericarp to obtain a first microwave-treated pericarp; After turning the skin of the pericarp after the first microwave treatment, continue with 2 - 3 times of microwave treatment to obtain the pericarp with microwave treatment completed; during the continuous microwave treatment process, after each microwave treatment is completed, remove the moisture on the inner and outer sides of the pericarp after microwave treatment. After subjecting the pericarp with microwave treatment completed to a hydrothermal treatment, perform drying to obtain tangerine peel.

[0008] Preferably, the power of each microwave treatment is 500 - 1000W; the time of each microwave treatment is 120 - 180s.

[0009] Preferably, the method of the hydrothermal treatment includes covering the hydrothermal carrier on the pericarp or on the container containing the pericarp; the time of the hydrothermal treatment is 20 - 40min; the initial temperature of the hydrothermal treatment is 40 - 60°C; the hydrothermal treatment is carried out at room temperature.

[0010] Preferably, the temperature of the drying is 55 - 65°C; the time of the drying is 3 - 6h.

[0011] Preferably, during the process of microwave and hydrothermal treatment of the pericarp, stack 5 - 20 pericarps together for treatment.

[0012] Preferably, when performing the first microwave treatment, the outer pericarp faces upward or bulges upward; when continuing with 2 - 3 times of microwave treatment, the inner pericarp faces upward or bulges upward.

[0013] Preferably, before the first microwave treatment, divide the pericarp into 3 petals and connect them at the fruit stalk.

[0014] Preferably, the pericarp is cleaned before being divided into petals; the cleaning method includes ultrasonic cleaning.

[0015] The present invention provides the application of the preparation method described in the above technical solution in improving the preparation efficiency of tangerine peel and / or improving the quality of tangerine peel.

[0016] Preferably, the improvement of the quality of tangerine peel includes any one or more of the following (1) - (4): (1) Increase the flavonoid content of tangerine peel; (2) Reduce the essential oil content of tangerine peel; (3) Increase the antioxidant capacity of tangerine peel; (4) Increase the anti-inflammatory capacity of tangerine peel.

[0017] The beneficial effects of the present invention: The present invention provides a method for preparing tangerine peel, comprising the following steps: subjecting the fruit peel to a first microwave treatment to obtain the fruit peel after the first microwave treatment; turning over the fruit peel after the first microwave treatment and then continuing with 2 to 3 microwave treatments to obtain the fruit peel after the microwave treatment is completed; during the continuous microwave treatment, after each microwave treatment is completed, removing the moisture on the inner and outer sides of the fruit peel after the microwave treatment; subjecting the fruit peel after the microwave treatment is completed to a moist heat treatment and then drying to obtain tangerine peel. Based on in-depth research on the key factors in the preparation process of tangerine peel, the present invention realizes the efficient drying and aging treatment of the fruit peel raw material in a short time by optimizing the drying process parameters and combining technical means such as microwave and moist heat treatment. This method not only significantly improves the drying efficiency and shortens the preparation time, but also effectively retains the active ingredients of flavonoids in tangerine peel, making its antioxidant and anti-inflammatory effects equivalent to those of tangerine peel sold on the market for many years, and even superior to tangerine peel prepared by traditional methods. At the same time, by precisely controlling the process parameters, the stability and consistency of the quality of tangerine peel are ensured, providing an efficient and reliable solution for the industrial production and application of tangerine peel. Description of the Drawings

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0019] Figure 1 It is a process flow chart of the method for preparing tangerine peel in Example 1; Figure 2 It is a drying time chart of different methods for preparing tangerine peel in Application Example 1; Figure 3 It is a fruit peel weight chart of different methods for preparing tangerine peel in Application Example 1; Figure 4 It is a fruit peel water content result chart of different methods for preparing tangerine peel in Application Example 1; Figure 5 It is an HPLC chromatogram of flavonoids in the tangerine peel prepared in Example 1; Figure 6 It is a detection result chart of flavonoid content in different tangerine peels in Application Example 2; Figure 7 It is a detection result chart of essential oil content in different tangerine peels in Application Example 2; Figure 8 It is a detection result chart of the cell antioxidant capacity of different tangerine peels in Application Example 3; Figure 9 It is a detection result chart of the cell antioxidant enzyme activity of different tangerine peels in Application Example 3; Figure 10 It is a graph showing the test results of the anti-inflammatory ability of different tangerine peels in Application Example 4; Figure 11 It is a graph showing the drying time of tangerine peels prepared by different methods in Application Example 5. Specific Embodiments

[0020] The present invention provides a method for preparing tangerine peel, comprising the following steps: Perform the first microwave treatment on the fruit peel to obtain the fruit peel after the first microwave treatment; After turning over the fruit peel after the first microwave treatment, continue to perform 2 to 3 times of microwave treatment to obtain the fruit peel after the microwave treatment is completed; during the continuous microwave treatment process, after each microwave treatment is completed, remove the moisture on the inner and outer sides of the fruit peel after the microwave treatment; Perform heat-moisture treatment on the fruit peel after the microwave treatment is completed, and then perform drying to obtain tangerine peel.

[0021] The present invention performs the first microwave treatment on the fruit peel to obtain the fruit peel after the first microwave treatment. As an optional embodiment of the present invention, the fruit peel includes citrus reticulata blanco peel. The present invention has no special limitation on the source of the citrus reticulata blanco peel, and conventional commercially available products in the art can be used. In the embodiments of the present invention, the citrus reticulata blanco peel from the citrus reticulata blanco resource nursery in Xinhui, Guangdong is taken as an example to specifically illustrate the preparation method of the present invention. Before processing the fruit peel raw material, the present invention preferably cleans the fruit peel raw material. The present invention has no special limitation on the cleaning method, and any conventional cleaning method in the art can be used. As an optional embodiment of the present invention, the cleaning method can be ultrasonic cleaning; the frequency during the ultrasonic cleaning can be 40 to 80 kHz, or can be 40, 50, 60, 70 or 80 kHz; the power of the ultrasonic cleaning is 160 W to 500 W, or can be 160, 180, 200, 250, 300, 350, 400, 450 or 500 W; the time of the ultrasonic cleaning can be 100 to 180 s, or can be 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 fruit peel raw material and then performs peeling. The present invention has no special limitation on the peeling method, and any conventional peeling method in the art can be used. As an optional embodiment of the present invention, peeling the fruit peel can be dividing the fruit peel into 3 petals and connecting the fruit peel at the fruit stalk, or dividing the fruit peel into 3 petals according to 120°. In the embodiments of the present invention, the fruit peel connected at the fruit stalk is taken as an example to illustrate the process of preparing tangerine peel.

[0022] As an alternative embodiment of the present invention, during the first microwave treatment, the exocarp faces upward or bulges upward. In the present invention, the exocarp refers to the oil cell layer of the pericarp; the exocarp facing upward or bulging upward means the oil cell layer facing upward or bulging upward. As an alternative embodiment of the present invention, after obtaining the pericarp with the exocarp facing upward or bulging upward, the pericarps are stacked together for the first microwave treatment; the number of the stacked pericarps 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 alternative embodiment of the present invention, the frequency of the first microwave is 2450 MHz; the power of the first microwave is 500 to 1000 W, or can be 500, 600, 700, 800, 900 or 1000 W; the time of the first microwave is 120 to 180 s, or can be 120, 130, 140, 150, 160, 170 or 180 s. When the exocarp faces upward or bulges upward during the first microwave treatment of the present invention, it is mainly to dehydrate the pericarp and remove the essential oil, which is beneficial to maintaining the integrity of the pericarp shape and thus beneficial to the subsequent operations.

[0023] After obtaining the pericarp treated by the first microwave, the present invention turns over the pericarp treated by the first microwave and then continues to perform 2 to 3 times of microwave treatment on the pericarp after the microwave treatment is completed. As an alternative embodiment of the present invention, the number of times of continuing to perform 2 to 3 times of microwave treatment can be 2 times or 3 times. When the number of times of continuing the microwave treatment is 2 times, the 2 times of microwave treatment are respectively called the second microwave and the third microwave. When the number of times of continuing the microwave treatment is 3 times, the 3 times of microwave treatment are respectively called the second microwave, the third microwave and the fourth microwave.

[0024] As a preferred embodiment of the present invention, the number of times of continuing the microwave treatment is preferably 2 times. In the following technical solutions, taking the continuation of the microwave treatment 2 times as an example, the technical solutions of the present invention will be specifically described.

[0025] After obtaining the pericarp after the first microwave treatment, the present invention turns the pericarp after the first microwave treatment and then performs a second microwave treatment to obtain the pericarp after the second microwave treatment. As an optional implementation manner of the present invention, the turning of the pericarp may be to turn the pericarp from the oil cell layer (outer pericarp) facing upward or bulging upward to the white cortical layer (inner pericarp) facing upward or bulging upward. When the present invention performs the second microwave treatment, it is preferably carried out with the pericarps stacked together; the number of the stacked pericarps may be 5 to 20, or may be 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20. As an optional implementation manner of the present invention, the frequency of the second microwave is 2450 MHz; the power of the second microwave is 500 to 1000 W, or may be 500, 600, 700, 800, 900 or 1000 W; the time of the second microwave is 120 to 180 s, or may be 120, 130, 140, 150, 160, 170 or 180 s. The second microwave treatment of the present invention is mainly to further remove the moisture and essential oil in the pericarp.

[0026] After obtaining the pericarp after the second microwave treatment, the present invention removes the moisture on the inner and outer sides of the pericarp after the second microwave treatment and then performs a third microwave treatment to obtain the pericarp after the third microwave treatment. As an optional implementation manner of the present invention, the method for removing the moisture on the inner and outer sides of the pericarp after the second microwave treatment may be wiping; the wiping may be to wipe the moisture on the inner and outer sides of the pericarp with kitchen paper; the wiping is preferably carried out gently without damaging the pericarp structure. The main purpose of wiping the moisture on the inner and outer sides of the pericarp of the present invention is to prevent the moisture on the surface of the pericarp from generating high temperature under microwave conditions and scalding the pericarp; on the other hand, it helps the moisture to volatilize. After wiping the moisture on the inner and outer sides of the pericarp, the present invention performs the third microwave treatment. When the present invention performs the third microwave treatment, it is preferably carried out with the pericarps stacked together; the number of the stacked pericarps may be 5 to 20, or may be 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20. As an optional implementation manner of the present invention, the frequency of the third microwave is 2450 MHz; the power of the third microwave is 500 to 1000 W, or may be 500, 600, 700, 800, 900 or 1000 W; the time of the third microwave is 120 to 180 s, or may be 120, 130, 140, 150, 160, 170 or 180 s. The third microwave treatment of the present invention is mainly to further remove the moisture and essential oil in the pericarp.

[0027] After obtaining the pericarp after the third microwave treatment, the present invention can directly perform hydrothermal treatment on the pericarp after the third microwave treatment, or can wipe the moisture on the inner and outer sides of the pericarp after the third microwave treatment and then perform the fourth microwave to obtain the pericarp after the fourth microwave treatment. As an optional implementation manner of the present invention, kitchen paper can be used to wipe the moisture on the inner and outer sides of the pericarp; the wiping is preferably carried out gently without damaging the pericarp structure. After wiping the moisture on the inner and outer sides of the pericarp, the present invention performs the fourth microwave. When the present invention performs the fourth microwave, it is preferably carried out with the pericarps stacked together; the number of the stacked pericarps 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 implementation manner of the present invention, the frequency of the fourth microwave is 2450 MHz; the power of the fourth microwave is 500 to 1000 W, or can be 500, 600, 700, 800, 900 or 1000 W; the time of the fourth microwave is 120 to 180 s, or can be 120, 130, 140, 150, 160, 170 or 180 s. The fourth microwave treatment of the present invention is mainly to further remove the moisture and essential oil in the pericarp.

[0028] After obtaining the pericarp after the third microwave treatment or after obtaining the pericarp after the fourth microwave treatment, the present invention performs hydrothermal treatment on the pericarp after the third microwave treatment or the pericarp after the fourth microwave treatment and then performs drying to obtain tangerine peel. As an optional implementation manner of the present invention, the method of the hydrothermal treatment includes covering the hydrothermal carrier on the pericarp or on the container containing the pericarp; the hydrothermal carrier includes a hydrothermal towel. As an optional implementation manner of the present invention, the hydrothermal towel is a hydrothermal towel that has been disinfected with boiling water and wrung dry until it does not drip. The time of the hydrothermal treatment can be 20 to 40 min, or can be 30 min; the initial temperature of the hydrothermal treatment can be 40 to 60 °C, or can be 50 °C, that is, the initial temperature of the hydrothermal towel can be 40 to 60 °C, or can be 50 °C; the hydrothermal treatment is carried out at room temperature. The main purpose of the present invention to perform hydrothermal treatment on the pericarp is to convert pigments, soften cell walls, release pigments and other components inside cells, change enzyme activity, etc., thereby improving the color of the tangerine peel and making it present a dark gray color. After the hydrothermal treatment is completed, the present invention preferably uses kitchen paper to wipe the moisture on the inner and outer sides of the obtained pericarp; the wiping is preferably carried out gently without damaging the pericarp structure. After wiping the moisture on the inner and outer sides of the pericarp, the present invention dries the obtained pericarp. The temperature of the drying of the present invention can be 55 to 65 °C, or can be 55, 56, 57, 58, 59, 60, 61, 62, 63, 64 or 65 °C; the time of the drying can be 3 to 6 h, or can be 3, 4, 5 or 6 h. The present invention can reduce the moisture of the obtained pericarp to less than 5% through the drying and protect the complete state of the commercial tangerine peel. After the drying is completed, the present invention obtains tangerine peel.

[0029] The rapid preparation method of tangerine peel proposed by the present invention aims to solve the problems of low drying efficiency, unstable quality, and long aging time in the existing preparation methods. Among them, the low drying efficiency: the traditional sun-drying method is greatly affected by the weather and has a long drying time. Although the drying method has a shorter time, it causes greater damage to the active ingredients and cannot balance the drying efficiency and quality. Unstable quality: The sun-drying method is easily interfered by external environmental factors, resulting in uneven quality of tangerine peel; the drying method may reduce the content of active ingredients and flavor of tangerine peel due to high-temperature long-term treatment. Long aging time: Whether it is sun-drying or drying, a long aging time is required to achieve the ideal quality, which increases the production cost and time cost.

[0030] Based on in-depth research on the key factors in the preparation process of tangerine peel, the present invention realizes the efficient drying and aging treatment of tea branch citrus peel in a short time by optimizing the drying process parameters and combining technical means such as microwave and hydrothermal treatment. The preparation method described in the present invention can process tea branch citrus peel within 5 hours, and simultaneously complete functions such as drying and removing essential oils; compared with sun-drying, the preparation method has a faster drying speed, can increase the drying rate by 25 times, and has a higher flavonoid content and a lower moisture content; compared with drying, the preparation method can remove essential oils faster and simultaneously achieve the aging effect of orange peel. The tangerine peel prepared by the preparation method has better antioxidant effects compared with the tangerine peel prepared by sun-drying and drying, and is comparable to the commercially available five-year and ten-year tangerine peel. The tangerine peel prepared by the preparation method has better anti-inflammatory effects compared with the tangerine peel prepared by sun-drying and drying, and is comparable to the commercially available five-year and ten-year tangerine peel.

[0031] The present invention provides the application of the preparation method described in the above technical solution in improving the preparation efficiency of tangerine peel and / or improving the quality of tangerine peel. The preparation method provided by the present invention can significantly improve the drying efficiency of tangerine peel and shorten the preparation time of tangerine peel. As an optional implementation manner of the present invention, the improvement of the quality of tangerine peel includes any one or more of the following (1) to (4): (1)Increase the flavonoid content of tangerine peel; (2)Reduce the essential oil content of tangerine peel; (3)Improve the antioxidant capacity of tangerine peel; (4)Improve the anti-inflammatory capacity of tangerine peel.

[0032] The preparation method provided by the present invention can significantly increase the flavonoid content of tangerine peel. The results of the examples of the present invention show that the flavonoid content of the tangerine peel prepared by using the preparation method provided by the present invention is significantly increased compared with the tangerine peel prepared by using the sun-drying or drying method. The flavonoid content in the tangerine peel prepared by the present invention is between that of the five-year tangerine peel and the ten-year tangerine peel.

[0033] The preparation method provided by the present invention can significantly reduce the content of essential oil in tangerine peel. The results of the examples of the present invention show that, compared with the tangerine peel prepared by the sun-drying or drying method, the essential oil content of the tangerine peel prepared by the preparation method provided by the present invention is significantly reduced. The content of essential oil in the tangerine peel prepared by the present invention is between that of three-year-old tangerine peel and five-year-old tangerine peel.

[0034] The preparation method provided by the present invention can significantly improve the antioxidant capacity of tangerine peel. The results of the examples of the present invention show that, compared with the tangerine peel prepared by the sun-drying or drying method, the DPPH free radical scavenging ability, FRAP ferric ion reducing ability and ABTS free radical scavenging ability of the tangerine peel prepared by the preparation method provided by the present invention are all significantly improved. The antioxidant capacity of the tangerine peel prepared by the preparation method provided by the present invention is comparable to that of commercially available five-year-old and ten-year-old tangerine peels. In the examples of the present invention, the antioxidant capacity of the cells of the tangerine peel prepared by the preparation method was also evaluated. The results show that the obtained tangerine peel can significantly improve the cell survival rate under the influence of H2O2, and its effect is comparable to that of commercially available five-year-old tangerine peel; the obtained tangerine peel can significantly inhibit the content of ROS under the influence of H2O2, and its effect is comparable to that of commercially available five-year-old and ten-year-old tangerine peels; the obtained tangerine peel can significantly enhance the activities of SOD enzyme, CAT enzyme and GSH-Px enzyme under the influence of H2O2, and its effect is comparable to that of commercially available five-year-old and ten-year-old tangerine peels.

[0035] The preparation method provided by the present invention can significantly improve the anti-inflammatory ability of tangerine peel. The results of the examples of the present invention show that, compared with the tangerine peel prepared by the sun-drying or drying method, the tangerine peel prepared by the preparation method provided by the present invention can significantly inhibit the increase in the content of nitric oxide (NO) induced by LPS, and significantly inhibit the increase in the content of three kinds of cell inflammatory factors, interleukin-1β (IL-1β), interleukin-6 (IL-6) and tumor necrosis factor-α (TNFα), and its effect is comparable to that of commercially available ten-year-old tangerine peel.

[0036] In order to further illustrate the present invention, the technical solutions provided by the present invention will be described in detail below with reference to the drawings and examples, but they should not be construed as limiting the protection scope of the present invention.

[0037] The source of the Citrus reticulata Blanco cv. Chachiensis used in the following scheme is the Citrus reticulata Blanco cv. Chachiensis resource nursery in Xinhui, Guangdong.

[0038] Example 1 A preparation method of tangerine peel is as Figure 1 shown, and the specific steps are as follows: Wash the Citrus reticulata Blanco cv. Chachiensis, and at room temperature, clean it with ultrasonic parameters of 40 kHz and 200 W for 120 s.

[0039] After cleaning and draining the water, peel the fruit. Use a peeler or a peeling knife to cut the fruit peel into 3 pieces at 120°, and connect them at the fruit stalk.

[0040] Stack 10 fruit peels together. At this time, the fruit peels are in the un-turned state (that is, the oil cell layer bulges upward), and perform the first microwave treatment. The microwave frequency is 2450 MHz, the microwave power is fixed at 700 W, and the microwave time is 150 s.

[0041] After completing the first microwave treatment, turn the fruit peels over, that is, turn the fruit peels from the state where the oil cell layer (the outer yellow part of the fruit peel, that is, the exocarp) bulges upward to the state where the white peel layer (the inner white part of the fruit peel) bulges upward.

[0042] Stack 10 fruit peels together. At this time, the fruit peels are in the turned state, and perform the second microwave treatment. The microwave frequency is 2450 MHz, the microwave power is fixed at 700 W, and the microwave time is 150 s.

[0043] After completing the second microwave treatment, dry the inside and outside of the fruit peels with kitchen paper, that is, gently dry the inside and outside of the fruit peels with paper.

[0044] Stack 10 fruit peels together. At this time, the fruit peels are in the turned state (the white peel layer bulges upward, that is, the endocarp bulges upward), and perform the third microwave treatment. The microwave frequency is 2450 MHz, the microwave power is fixed at 700 W, and the microwave time is 150 s.

[0045] After completing the third microwave treatment, use a hot and humid towel with an initial temperature of 50°C (the hot and humid towel is a hot and humid towel that has been disinfected with boiling water and wrung dry until it does not drip water) to cover the fruit peels treated by microwave for 30 min at room temperature, that is, cover the container containing the fruit peels with the corresponding hot towel and keep it for 30 min, and then dry the water with kitchen paper.

[0046] Dry the fruit peels. The drying parameters are 60°C and 4 h. At this time, the moisture content of the fruit peels is reduced to less than 5%, and the fruit peels maintain a complete commercial dried tangerine peel state, obtaining dried tangerine peel.

[0047] Store the dried dried tangerine peel.

[0048] Comparative Example 1 A method for preparing dried tangerine peel by a drying method, the steps are as follows: After washing the Citrus reticulata Blanco cv. Chachiensis Hort. with water and draining the water, peel the fruit. Use a peeler or a peeling knife to cut the fruit peel into 3 pieces at 120°, connect them at the fruit stalk, and then dry the fruit peel at 60°C for 12 h.

[0049] Comparative Example 2 A method for preparing dried tangerine peel by a sun-drying method, the steps are as follows: After washing the Citrus reticulata Blanco cv. Chachiensis with water and draining the water, then peel it. Use a peeling tool or a peeling knife to cut the fruit peel into 3 petals at 120°, and connect them at the fruit stalk. Then spread the fruit peel on a drying net and dry it in the sun from December 14, 2024 to December 18, 2024 until the fruit peel becomes hard and there is no obvious moisture, and then collect it. The weather conditions from December 14 to December 18, 2024 are as follows: On December 14, 2024, sunny, 1 - 7°C, maximum wind force 3; On December 15, 2024, sunny, 0 - 11°C, maximum wind force 3; On December 16, 2024, sunny, 1 - 12°C, maximum wind force 3; On December 17, 2024, sunny, 3 - 13°C, maximum wind force 3; On December 18, 2024, sunny, 1 - 10°C, maximum wind force 4.

[0050] Application Example 1 Compare the drying efficiency of the method for making tangerine peel in Example 1 with the drying method in Comparative Example 1 and the sun-drying method in Comparative Example 2, and compare the moisture content of the tangerine peel made in Example 1 with the tangerine peel prepared by the drying and sun-drying methods.

[0051] 1. The drying times of different methods are as Figure 2 shown. The sun-drying time, drying time, and the drying time of Example 1 are 120 hours, 12 hours, and 4.75 hours respectively. Among them, 4.75h is the result of multiple actual operations using the method of Example 1, and the time of each actual operation is about 285 minutes. The preparation method of the tangerine peel in Example 1 has improved the drying efficiency by 2.5 times and 25 times compared with the direct drying method and the sun-drying method respectively.

[0052] 2. Moisture measurement method: Use a halogen rapid moisture analyzer to detect the moisture. The main detection method is as follows: Connect the power supply of the halogen lamp moisture content analyzer, turn on the instrument switch, and preheat for 30 minutes to make the instrument reach a stable working state to ensure the accuracy of the measurement results. Randomly select 2 - 5g of tangerine peel samples and place them on the sample tray of the instrument. Place the sample tray with the samples steadily on the weighing platform of the halogen lamp moisture content analyzer, and close the windproof cover of the instrument. After the weight value displayed by the instrument is stable, record the initial weight m1. Set the heating temperature to 105°C and start the heating program. The halogen lamp starts to heat the sample, and the moisture in the sample gradually evaporates. When the sample weight no longer changes significantly, it can be considered that the moisture evaporation is basically complete and the measurement end point is reached. Wait until the weight value displayed by the instrument is stable, and record the final weight m2. Calculate the moisture rate (%) of the fruit peel or tangerine peel = (m1 - m2) / m1 × 100%.

[0053] The weights of the fruit peels obtained by different drying methods are shown in Table 1 and Figure 3 shown. The water contents of the fruit peels obtained by different drying methods are shown in Table 2 and Figure 4 shown.

[0054] Table 1 Peel weights obtained by different drying methods

[0055] The peel weights obtained by different drying methods are shown in Table 1 and Figure 3 as follows. The original fruit weights of the peels for 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 obtained were 6.21 ± 0.13 g (this method), 7.91 ± 0.27 g (drying method), and 8.89 ± 0.82 g (sun-drying method). The final product weights accounted for 21.78% (this method), 27.40% (drying method), and 33.67% (sun-drying method) of the original weights. 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).

[0056] Table 2 Moisture contents of peels obtained by different drying methods

[0057] The moisture contents obtained by different drying methods are shown in Table 2 and Figure 4 as follows. The original fruit moisture contents of the peels for the three methods were 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 final product moisture contents obtained were 4.93 ± 0.30% (this method), 6.29 ± 0.47% (drying method), and 11.88 ± 0.47% (sun-drying method). The water loss rates were 73.79 ± 0.55% (this method), 71.14 ± 0.30% (drying method), and 65.68 ± 1.66% (sun-drying method). The water loss rate of this method was 2.25% lower than that of the drying method (p = 0.069) and was significantly lower than that of the sun-drying method (p < 0.01).

[0058] In summary, this method (Example 1) can complete the drying of peels into tangerine peel in a shorter time, greatly improving the drying rate compared with the existing methods, and this method can make the moisture content of the peels lower.

[0059] Application Example 2 Comparison of flavonoid and essential oil contents in tangerine peel obtained by different methods The flavonoid and essential oil contents of the tangerine peel prepared in Example 1, Comparative Examples 1 - 2, and commercially available one-year, two-year, three-year, five-year, and ten-year tangerine peels were measured. The one-year, two-year, three-year, five-year, and ten-year tangerine peels were purchased from Tianma Tangerine Peel Chamber of Commerce in Xinhui, Guangdong.

[0060] 1. Method for detecting flavonoid content Extraction method of flavonoids from tangerine peel: Weigh 100 g of the above tangerine peel sample and grind it into dry powder in a Chinese medicine grinder. After it is ground into powder, pass it through a 60-mesh sieve, and place the obtained powder in a cool and dry place for later use. Accurately weigh 50 g of the powder, add 500 mL of absolute ethanol (solid-liquid ratio 1:10) respectively, and perform ultrasonic-assisted extraction at room temperature for 1 h (53 kHz). After the extraction is completed, let the precipitate stand overnight. First, filter the extract through 4 layers of gauze, and then through 3 layers of filter paper to collect the clear filtrate. Place the obtained filtrate in a rotary evaporator and concentrate it under reduced pressure until there is no ethanol phase (35 °C, 80 rpm). Add an appropriate amount of double-distilled water to the residue for re-dissolution, collect the aqueous phase liquid and store it at 4 °C for later use. Use a Sep-pak® C18 column for solid-phase extraction to remove impurities. The specific steps are as follows: Activate the column with 2 bed volumes (BV) of methanol, balance the column with 2 BV (2 bed volumes) of double-distilled water, load 0.75 BV of the aqueous phase liquid, remove impurities such as sugars and acids with 20 BV of double-distilled water, and finally elute with 1 BV of methanol, and collect the eluate for later use. Place the eluate in a vacuum concentrator (30 °C) and evaporate it until all the methanol volatilizes, collect the residual solid, which is the component rich in bioactive substances, and store it at -20 °C for subsequent experiments.

[0061] Use HPLC method to detect the flavonoid content in tangerine peel. In the detection system, a Waters BEH C18 liquid chromatography column is used as the stationary phase; the mobile phases are water (mobile phase A) and acetonitrile (mobile phase B). The gradient elution program is as follows: 0 - 5 min, 20% B; 5 - 10 min, 20 - 34% B; 10 - 18 min, 34 - 60% B; 18 - 30 min, 60 - 100% B; 30 - 31 min, 100% B; 31 - 33 min, 100 - 20% B; 33 - 35 min, 20% B. The scanning wavelength is 200 - 600 nm, the flow rate is 0.1 mL / min, the column temperature is 25 °C, and the sample injection volume is 10 μL. During the quantification process, naringin rutinoside, hesperidin, isoswertisin, swertisin, nobiletin, tangeretin, 5-demethylnobiletin, etc. are quantified by the standard curve method.

[0062] The HPLC chromatogram of flavonoids in the tangerine peel prepared in Example 1 is as Figure 5 shown. Figure 5 Peak 1 in is naringin rutinoside; peak 2 is hesperidin; peak 3 is isoswertisin; peak 4 is swertisin; peak 5 is nobiletin; peak 6 is tangeretin; peak 7 is 5-demethylnobiletin. The flavonoid content of tangerine peel is calculated by the sum of the peak areas of the 7 main flavonoid peaks in Figure 5 .

[0063] The detection results of flavonoid contents in tangerine peel obtained by different methods are shown in Table 3 and Figure 6 as follows.

[0064] Table 3 Detection results of flavonoid contents in tangerine peel obtained by different methods

[0065] From Table 3 and Figures 5 - 6 it can be seen that by the standard substance comparison method, 7 main flavonoids were detected in tangerine peel, namely naringin rutinoside, hesperidin, isosinensetin, sinensetin, nobiletin, tangeretin, and 5-demethylnobiletin. After quantification by the standard curve method, the sum of the contents of the 7 main flavonoids was taken as the total flavonoid content of tangerine peel. The results showed that different drying methods were comparable in terms of flavonoid types and proportions, but there were differences in the ratio of flavonoid content to pericarp mass. The flavonoid content of the final product of this method was 135.29 ± 4.43 mg / g DW (dry weight), which was significantly higher than that of the final product dried by baking, 102.93 ± 5.51 mg / g DW (p < 0.05), and that of the final product dried by sunning, 82.53 ± 5.14 mg / g DW (p < 0.01).

[0066] The content of commercially available tangerine peel increased year by year with the increase of years, being 82.69 ± 1.54 mg / g DW (one-year tangerine peel), 85.65 ± 3.81 mg / g DW (two-year tangerine peel), 91.79 ± 2.95 mg / g DW (three-year tangerine peel), 102.08 ± 6.53 mg / g DW (five-year tangerine peel), and 145.51 ± 2.82 mg / g DW (ten-year tangerine peel). From the results, it can be seen that the flavonoid content obtained by this method was between that of five-year and ten-year tangerine peel.

[0067] 2. Essential oil content detection method The essential oil content was calculated by weighing using the distillation method. A certain amount of fresh orange peel was weighed and crushed into uniform small pieces to increase the contact area with water. The sample was placed in a distillation device, an appropriate amount of water was added, and steam distillation was carried out. During the distillation process, the orange peel essential oil was distilled out together with the steam. After being cooled by a condenser, it was collected in a receiving bottle. An appropriate amount of petroleum ether was added to the receiving bottle and shaken thoroughly for extraction to transfer the essential oil to the organic solvent phase. Then the organic phase was separated through a separating funnel, and the water in it was removed with desiccants such as anhydrous sodium sulfate. The dried organic phase was transferred to a pre-weighed evaporating dish, and the organic solvent was naturally volatilized in a fume hood or removed by vacuum distillation to obtain the orange peel essential oil. Finally, the weight of the essential oil was weighed to calculate the content of the orange peel essential oil.

[0068] The essential oil contents in tangerine peel obtained by different methods are shown in Figure 4 and Figure 7 as follows.

[0069] Table 4 Essential oil contents in tangerine peel obtained by different methods

[0070] Essential oil is the main aroma component of citrus peel, and its content is also one of the main indicators of the aging of tangerine peel. The essential oil content in the peel of lower-aged fruits is higher than that of higher-aged ones. Therefore, the decrease in essential oil content is also a phenomenon of tangerine peel aging. As shown in Table 4 and Figure 7 as can be seen, the essential oil content in the peel of fresh fruits of Citrus reticulata 'Chachi' is about 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 that of the final products obtained by the drying method (2.92 ± 0.07%) and the sun-drying method (2.29 ± 0.25%) (p < 0.05).

[0071] The content of commercially available tangerine peel decreases year by year with the increase of years, which are 2.71 ± 0.13% (one-year tangerine peel), 2.09 ± 0.11% (two-year tangerine peel), 1.92 ± 0.10% (three-year tangerine peel), 1.20 ± 0.02% (five-year tangerine peel), 1.01 ± 0.02% (ten-year tangerine peel) respectively. From the results, it can be seen that the essential oil content obtained by this method is between that of three-year and five-year tangerine peels.

[0072] From the above, it can be obtained that this method can significantly increase the content of the main nutritional component flavonoids in tangerine peel and significantly reduce the content of essential oil, which is a marker negatively correlated with aging in tangerine peel, compared with the drying and sun-drying processes, and reaches similar indicators to commercially available tangerine peel aged for more than 3 years.

[0073] Application Example 3 Comparison of antioxidant capacities of tangerine peel obtained by different methods The tangerine peel is the same as that in Application Example 2.

[0074] 1. Evaluate the antioxidant capacity of tangerine peel by chemical antioxidant methods (1) Evaluate the DPPH radical scavenging ability by the DPPH method. Add 2 μL of appropriately diluted sample (the sample is specifically the powder obtained by extracting tangerine peel with absolute ethanol and solid-phase extraction, and the specific method is shown in Application Example 2; then dissolve it with methanol and dilute appropriately) to 198 μL of freshly prepared 60 μM DPPH solution, react at 25 °C in the dark for 2 h, measure the absorbance at a wavelength of 517 nm with a microplate reader, make a standard curve with Trolox as the control to calculate the DPPH radical scavenging ability, and the result is expressed as mg Trolox equivalent (TE) / g. The experiment is independently repeated 3 times.

[0075] (2) Evaluation of the iron ion reducing ability by the FRAP method. First, prepare the FRAP working solution: Mix sodium acetate buffer solution (300 mM, pH 3.6), TPTZ solution (10 nM), and FeCl3 solution (20 mM) at a volume ratio of 10:1:1. Take 20 μL of the appropriately diluted sample (the sample is specifically: the powder obtained by extracting tangerine peel with absolute ethanol and solid-phase extraction, and the specific method is shown in Application Example 2; then dissolve it with methanol and dilute it appropriately) and mix it with 180 μL of the FRAP working solution. After reacting for 5 min at 25 °C in the dark, measure the absorbance at 593 nm with an enzyme-labeled instrument. Use Trolox as a control to make a standard curve to calculate the FRAP iron ion reducing ability, and the result is expressed as mg Trolox equivalent (TE) / g. The experiment is independently repeated 3 times.

[0076] (3) Evaluation of the ABTS free radical scavenging activity by the ABTS method. Mix 7 mM ABTS and 2.6 mM K2S2O8 at a volume ratio of 1:1, and react for 12 h at 25 °C in the dark, then dilute it with a solvent to an ABTS working solution with an OD 734nm ≈0.63. Take 10 μL of the appropriately diluted sample (the sample is specifically: the powder obtained by extracting tangerine peel with absolute ethanol and solid-phase extraction, and the specific method is shown in Application Example 2, then dissolve it with methanol and dilute it appropriately) and mix it with 200 μL of the ABTS working solution. After reacting for 5 min at 25 °C in the dark, measure the absorbance at 734 nm. Use Trolox as a control to make a standard curve to calculate the ABTS free radical scavenging ability, and the result is expressed as mg Troloxequivalent (TE) / g. The experiment is independently repeated 3 times.

[0077] (4) Evaluation of the oxygen free radical scavenging ability by the ORAC method. Add 25 μL of the appropriately diluted sample (the sample is specifically: the powder obtained by extracting tangerine peel with absolute ethanol and solid-phase extraction, and the specific method is shown in Application Example 2, then dissolve it with methanol and dilute it appropriately) and 150 μL of 40 nM sodium fluorescein solution into a 96-well plate. After reacting for 10 min at 37 °C in the dark, add 25 μL of 150 mM AAPH solution, and measure the fluorescence intensity (excitation wavelength 485 nm, emission wavelength 535 nm, reading interval 2 min, total duration 2 h). Use PBS as a control, and use the wells without AAPH as the fluorescence initial value reading wells. Take the difference in the area under the fluorescence decay curve (Net AUC) between the blank sample and the sample as the calculation result. The formula for Net AUC is: Net AUC = AUC sample − AUC AAPH+ , AUC = 2 × (f0 + f1 + … + f n ) − f n- f0. The standard curve was made with Trolox as the control to calculate the ORAC equivalent, and the results were expressed as mg Trolox equivalent (TE) / g. The experiment was independently repeated 3 times.

[0078] The comparison of the chemical antioxidant capacities of tangerine peel obtained by different methods is shown in Table 5.

[0079] Table 5 Chemical antioxidant capacities of tangerine peel obtained by different methods

[0080] Note: Different numbers after the values represent significant differences among different groups. As can be seen from Table 5, in the DPPH free radical scavenging ability, the antioxidant capacity of the final product of this method (tangerine peel prepared in Example 1) was significantly higher than that of the dried product and the sun-dried product, and was comparable to that of the commercially available five-year tangerine peel. In the FRAP ferric ion reducing ability, the antioxidant capacity of the final product of this method was significantly higher than that of the dried product and the sun-dried product, and was comparable to that of the commercially available five-year and ten-year tangerine peels. In the ABTS free radical scavenging ability, the antioxidant capacity of the final product of this method was significantly higher than that of the dried product and the sun-dried product, and was comparable to that of the commercially available three-year, five-year and ten-year tangerine peels. 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 dried product and the sun-dried product, and was comparable to that of the commercially available five-year and ten-year tangerine peels. The above results indicate that the chemical antioxidant capacity of the product obtained by this method is better than that of the traditional process and better than that of the tangerine peel aged for one year, with better antioxidant effects.

[0081] 2. Evaluation of the antioxidant capacity of tangerine peel by the antioxidant method of cell model The antioxidant capacity of tangerine peel was evaluated using the human normal hepatocyte cell line L02.

[0082] (1) Cell culture and activity detection L02 cells were cultured in RPMI1640 medium (containing 10% FBS, 20 mM HEPES, 100 Unit / mL penicillin and streptomycin), the temperature of the incubator was 37 °C, the CO2 concentration was 5%, and the cells were passaged when the confluence reached about 70% - 80%.

[0083] The CCK-8 kit was used to detect the cell activity. After removing the cell culture medium, the cells were washed twice with PBS. The CCK-8 solution was diluted 1:10 by volume with serum-free RPMI1640 medium and then added to the cell culture plate. After incubating in the dark for 1 h, the absorbance values at 620 nm and 450 nm were measured using a microplate reader to calculate the cell activity. DMSO was used as the solvent control, and 3 replicate wells were set for each experiment, and the experiment was independently repeated at least 3 times.

[0084] (2) Hydrogen peroxide-induced cellular oxidative stress model Powders of tangerine peel at different concentrations (the tangerine peel powder is specifically the powder obtained by extracting tangerine peel with absolute ethanol and solid-phase extraction, and the specific method can be seen in Application Example 2) were dissolved in DMSO, and the final concentration of cells contacting DMSO was 0.1%. The cells were cultured in serum-free RPMI1640 medium for 24 h, and then tangerine peel extracts were added to make the mass concentrations of tangerine peel extracts in the culture system be 12.5 μg / mL, 25 μg / mL, 50 μg / mL, 100 μg / mL, and 200 μg / mL respectively, and they were co-incubated for 6 h. After the incubation was completed, the cell viability of some cells was detected to determine the effects of tangerine peel extracts at different concentrations on the survival rate of L02 cells. The remaining cells after the above incubation were added with 0.78 mM H2O2 and co-incubated at 37 °C for 30 min. After the incubation with H2O2 was completed, the cell viability, reactive oxygen species or other indicators were detected. DMSO was used to replace tangerine peel extracts at different concentrations, and H2O2 was not added as a solvent control, that is, only DMSO was added in the solvent control.

[0085] (3) Detection of cellular reactive oxygen species The cells co-cultured with H2O2 were gently washed twice with PBS, and 10 μM DCFH-DA fluorescent probe diluted with 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 3 times with serum-free medium. The fluorescence intensity was detected using a microplate reader, with an excitation wavelength of 488 nm and an emission wavelength of 525 nm. Each experiment was independently repeated 3 times.

[0086] (4) Detection of cellular antioxidant enzyme activities The cellular antioxidant enzyme activities of antioxidant enzymes such as CAT, SOD, and GSH-Px were determined using commercial kits.

[0087] (5) Evaluation of the cellular antioxidant capacity of tangerine peel prepared by different methods using human liver cell line L02, and the results are shown in Tables 6-8 and Figure 8 as follows. Figure 8 In A, it is the effect of tangerine peel extract treatment on the survival rate (%) of L02 cells, where * indicates a significant difference from other treatment groups; Figure 8 In B, it is the effect of tangerine peel extract treatment on the decrease in the survival rate (%) of H2O2-induced L02 cells, where * indicates a significant difference from the H2O2-induced group without adding tangerine peel extract; Figure 8 In C, it is the effect of 100 μg / mL tangerine peel extract treatment on the ROS content of H2O2-induced L02 cells. Different letters in the figure represent significant differences between different groups.

[0088] Table 6 Effects of Tangerine Peel Extract Treatment on the Survival Rate (%) of L02 Cells

[0089] Table 7 Effects of Tangerine Peel Extract Treatment on the Decrease in the Survival Rate (%) of H2O2-Induced L02 Cells

[0090] Table 8 Effects of 100 μg / mL Tangerine Peel Extract Treatment on the ROS Content of H2O2-Induced L02 Cells

[0091] The cell antioxidant capacity of tangerine peel prepared by different methods was evaluated using the human liver cell line L02. As shown in Table 6 and Figure 8 Figure A, tangerine peels had no effect on the cell survival rate within a concentration of 100 mg / L. As shown in Table 7 and Figure 8 Figure B, different tangerine peel extracts at 100 mg / L could all increase the cell survival rate under the influence of H2O2. The cell survival rate of the final product of this method was 85.06%, higher than that of the dried product (76.27%) and the sun-dried product (75.49%). The cell survival rates of different commercially available tangerine peels were 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 tangerine peel prepared by this method was comparable to the commercially available tangerine peel of five years. From Figure 8 Figures A and B, 100 μg / mL tangerine peel extract had little effect on the cell survival rate and could significantly increase the survival rate of H2O2-induced L02 cells. Therefore, the ROS content of H2O2-induced L02 cells treated with 100 μg / mL tangerine peel extract was detected subsequently. Detection using the DCFH-DA probe of the ROS content of H2O2-induced L02 cells treated with 100 μg / mL tangerine peel extract found that H2O2 could significantly induce an increase in the ROS content, while the extract of the final product of this method could significantly reduce the ROS content, and the inhibitory ability was stronger than that of the extracts of the dried and sun-dried final products, and was comparable to the inhibitory ability of tangerine peels of five and ten years (see Table 8 and Figure 8 Figure C).

[0092] (6)The effects of tangerine peel extracts of tangerine peels treated differently (the final concentration of tangerine peel extract in the tangerine peel extract solution was 100 μg / mL) on the activity of cell antioxidant enzymes are shown in Table 9 and Figure 9 as follows. Figure 9 Figure A in it shows the effects of tangerine peel extracts of tangerine peels treated differently on the SOD enzyme activity of cells; Figure 9 Figure B in it shows the effects of tangerine peel extracts of tangerine peels treated differently on the CAT enzyme activity of cells; Figure 9The C in [description] shows the effects of tangerine peel extracts from different processed tangerine peels on the cell GSH-Px enzyme activity.

[0093] Table 9 Effects of tangerine peel extracts from different processed tangerine peels on cell antioxidant enzyme activities

[0094] Note: The relative enzyme activity refers to the ratio of the corresponding enzyme activity to the enzyme activity of the blank control.

[0095] Cell antioxidant enzymes are the executors of cell antioxidant capacity. Therefore, the activities of different antioxidant enzymes were detected to evaluate the ability of tangerine peels prepared by different methods to regulate cell antioxidant enzymes. The results are shown in Table 9 and Figure 9 As shown, for superoxide dismutase (SOD), hydrogen peroxide significantly inhibited the SOD activity, while all tangerine peel extracts could enhance the SOD activity. Among them, the final product of this method had a significantly higher ability to enhance SOD than the dried final product and the sun-dried final product, and there was no significant difference from the enhancing ability of five-year tangerine peel. For catalase (CAT), hydrogen peroxide significantly inhibited the CAT activity. Except for the sun-dried final product and one-year tangerine peel, the other tangerine peel extracts increased the CAT activity. Among them, the final product of this method had a significantly higher ability to enhance CAT than the dried final product and the sun-dried final product, and there was no significant difference from the enhancing ability of ten-year tangerine peel. For glutathione peroxidase (GSH-Px), hydrogen peroxide significantly inhibited the GSH-Px activity, and all tangerine peel extracts could enhance the GSH-Px activity. Among them, the final product of this method had a significantly higher ability to enhance GSH-Px than the sun-dried final product, and there was no significant difference from the enhancing abilities of five-year and ten-year tangerine peels.

[0096] Application Example 4 Comparison of the anti-inflammatory abilities of tangerine peels obtained by different methods The following two types of indicators were used to evaluate the anti-inflammatory ability of tangerine peel 1. Nitric oxide (NO) content Digest, collect, and count normal-shaped RAW264.7 cells. According to the density of 3×10 4 cells / well, inoculate the cell suspension into a 96-well plate containing DMEM complete medium and place it in an incubator for 12 h. Subsequently, add tangerine peel extract for pretreatment. The methods for preparing tangerine peel extracts from different tangerine peels are the same as in Application Example 3. After pretreatment with DMEM complete medium containing 100 mg / L tangerine peel extract for 2 h, add LPS to a final concentration of 100 ng / mL and continue culturing for 24 h. Subsequently, use a NO detection kit to measure the NO level in the medium. Use DMSO as the solvent control, set 3 replicates for each treatment, and conduct 3 independent repeated experiments.

[0097] 2. Cell inflammatory factors The cells processed in Step 1 above were detected for the inflammatory cytokines interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor α (TNFα) by the Elisa method, and the detection method was a commercial kit (Abcam).

[0098] 3. The detection results of the anti-inflammatory abilities of tangerine peels obtained by different methods are shown in Table 10 and Figure 10 . Figure 10 A in it is the effect of the extracts of tangerine peels treated differently on the content of nitric oxide (NO) in L02 cells; Figure 10 B in it is the effect of the extracts of tangerine peels treated differently on the content of interleukin-1β (IL-1β) in L02 cells; Figure 10 C in it is the effect of the extracts of tangerine peels treated differently on the content of interleukin-6 (IL-6) in L02 cells; Figure 10 D in it is the effect of the extracts of tangerine peels treated differently on the content of necrosis factor α (TNFα) in L02 cells. Different letters in the figure indicate significant differences between different treatments.

[0099] Table 10 Detection results of the anti-inflammatory abilities of tangerine peels obtained by different methods

[0100] The anti-inflammatory abilities of different tangerine peels were evaluated using the mouse macrophage cell line RAW264.7, and the results are shown in Table 10 and Figure 10 As shown, LPS significantly induced an increase in the content of nitric oxide (NO), while the extracts of all tangerine peels could significantly inhibit the content of NO. Among them, the tangerine peel obtained by this method had a stronger inhibitory ability on NO compared with the tangerine peels obtained by the drying and sun-drying methods, and was comparable to the tangerine peels of five years and ten years. Elisa detection of cytokines found that LPS could significantly induce an increase in the contents of interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-α (TNFα), while the tangerine peel obtained by this method could significantly inhibit the contents of the three inflammatory cytokines, and compared with the drying and sun-drying methods, the inhibitory ability of the tangerine peel obtained by this method was stronger. For IL-1β and IL-6, the tangerine peel obtained by this method was comparable to the tangerine peels of five years and ten years, while for TNFα, this method was comparable to the tangerine peel of ten years. Therefore, the tangerine peel obtained in Example 1 can exert a significant anti-inflammatory ability, which is stronger than the final products obtained by drying and sun-drying, and is comparable to the commercially available tangerine peels of five or ten years.

[0101] Comparative Example 3 A method for preparing tangerine peel, the steps are the same as in Example 1, the only difference is: the operation of covering with a 50°C hot towel for 30 minutes is omitted. This method is simply referred to as no hot towel treatment.

[0102] Comparative Example 4 A preparation method of tangerine peel, the steps are the same as those in Example 1, and the only difference is that: the operation of wiping with kitchen paper is omitted during the preparation process. This method is abbreviated as no wiping with kitchen paper.

[0103] Comparative Example 5 A preparation method of tangerine peel, the steps are the same as those in Example 1, and the difference is that: the first microwave is omitted, and only the second microwave and the third microwave are carried out, that is, the microwave treatment is not carried out in the state of not turning the peel, and only two microwave treatments are carried out in the state of turning the peel. This method is abbreviated as microwave 2 times.

[0104] Comparative Example 6 A preparation method of tangerine peel, the steps are the same as those in Example 1, and the difference is that: only one microwave treatment is carried out in the state of not turning the peel, and the microwave treatment is not carried out in the state of turning the peel. After the microwave treatment is completed, drying is carried out immediately. This method is abbreviated as microwave 1 time.

[0105] Example 2 A preparation method of tangerine peel, the steps are the same as those in Example 1, and the difference is that: after the third microwave treatment, a fourth microwave treatment is carried out in the state of turning the peel. That is, after the third microwave treatment, the moisture inside and outside the peel is air-dried with kitchen paper, and then the fourth microwave is carried out. The microwave frequency is 2450 MHz, the microwave power is fixed at 700 W, and the microwave time is 150 s. After the fourth microwave treatment, the peel is also covered with a 50 °C hot towel and allowed to stand at room temperature for 30 min, and then the moisture is air-dried with kitchen paper and then dried at 60 °C for 3.9 h. This method is abbreviated as microwave 4 times.

[0106] Application Example 5 Compare the preparation efficiency of the methods for preparing tangerine peel in Examples 1-2 and Comparative Examples 4-6. Among them, Example 1 is denoted as microwave 3 times, and Example 2 is denoted as microwave 4 times.

[0107] 1. Comparison of the weight and moisture content of the tangerine peel prepared in Examples 1-2 and Comparative Examples 4-6. The drying time of different methods is as Figure 11 shown. The weight of the tangerine peel obtained by different methods is shown in Table 11. The moisture content of the tangerine peel obtained by different methods is shown in Table 12.

[0108] Table 11 Peel weight of tangerine peel prepared by different preparation methods in Examples 1-2 and Comparative Examples 4-6

[0109] Table 12 Water content of tangerine peel prepared by different preparation methods in Examples 1-2 and Comparative Examples 4-6

[0110] The pericarp of tangerine peel prepared in Example 1 presented a dark gray color. After omitting the operation of covering with a hot towel at 50 °C for 30 min, the color of the dried tangerine peel was lighter than that of the tangerine peel prepared in Example 1, and the moisture content was higher, significantly higher than that of the product prepared in Example 1. This shows that the hot towel treatment plays an important role in reducing the moisture content of tangerine peel and improving the color. After omitting the wiping with kitchen paper, the moisture content of the dried tangerine peel was 11.93% ± 0.21%, significantly higher than that of the tangerine peel prepared in the example (p < 0.05), and slight scalding appeared on the surface of the tangerine peel, affecting the appearance and quality of the tangerine peel. This indicates that the step of wiping with kitchen paper is crucial for controlling the moisture content of tangerine peel and protecting the integrity of the pericarp, preventing the moisture on the surface of the pericarp from generating high temperature under microwave conditions to scald the pericarp and helping the moisture to volatilize. After omitting 1 time of microwave and performing the treatment of 2 times of microwave, 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 shows that the three - time microwave treatment has a significant effect on reducing the moisture content of tangerine peel. After only performing 1 time of microwave, the moisture content of the 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 an important role in the drying of tangerine peel. When the number of microwave times was increased from 3 times to 4 times, the drying time was 4.7 h, slightly shorter than that of the method in Example 1 (4.75 h), but the weight of the dried tangerine peel was 6.10 ± 0.11 g, lower than the weight of the tangerine peel in Example 1, which was 6.21 ± 0.13 g, and the moisture content was 4.90% ± 1.15%.

[0111] 2. The antioxidant capacities of the tangerine peels prepared in Examples 1 - 2 and Comparative Examples 4 - 6 were evaluated, and the results are shown in Table 13. For the specific method, see Application Example 3.

[0112] Table 13 Antioxidant capacities of the tangerine peels prepared in Examples 1 - 2 and Comparative Examples 4 - 6

[0113] It can be seen from Table 13 that there is no difference in the antioxidant capacities between 3 times and 4 times of microwave, which are significantly higher than those of other microwave times or the treatments without hot towel or without wiping with kitchen paper.

[0114] In summary, the preparation method of the tangerine peel provided by the present invention realizes the efficient drying of the pericarp of Citrus reticulata 'Chachi' in a short time by precisely controlling the number of microwave treatments, time and power, combined with auxiliary operations such as covering with a hot towel and wiping with kitchen paper, effectively retains the active ingredients in the tangerine peel, enhances its antioxidant and anti - inflammatory effects, and ensures the high quality and consistency of the tangerine peel.

[0115] Although the above embodiments have described the present invention in detail, they are only a part of the embodiments of the present invention, rather than all embodiments. People can also obtain other embodiments based on this embodiment without creative efforts, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A preparation method of tangerine peel, characterized in that, It includes the following steps: Perform the first microwave treatment on the pericarp to obtain the pericarp after the first microwave treatment; After turning over the pericarp after the first microwave treatment, continue to perform microwave treatment 2 to 3 times to obtain the pericarp with completed microwave treatment; During the continuous microwave treatment process, after each microwave treatment is completed, remove the moisture on the inner and outer sides of the pericarp after microwave treatment; Perform heat-moisture treatment on the pericarp with completed microwave treatment and then perform drying to obtain tangerine peel.

2. The preparation method according to claim 1, wherein The power of each microwave treatment is 500 - 1000 W; the time of each microwave treatment is 120 - 180 s.

3. The preparation method according to claim 1, characterized in that, The method of heat-moisture treatment includes covering the heat-moisture carrier on the pericarp or on the container containing the pericarp; the time of heat-moisture treatment is 20 - 40 min; the initial temperature of heat-moisture treatment is 40 - 60 °C; the heat-moisture treatment is carried out at room temperature.

4. The preparation method according to claim 1, wherein The temperature of drying is 55 - 65 °C; the time of drying is 3 - 6 h.

5. The preparation method according to claim 1, characterized in that, During the microwave and heat-moisture treatment of the pericarp, stack 5 - 20 pericarps together for treatment.

6. The preparation method according to claim 1 or 5, characterized in that When performing the first microwave treatment, the outer pericarp faces upward or bulges upward; when continuing to perform microwave treatment 2 to 3 times, the inner pericarp faces upward or bulges upward.

7. According to the preparation method described in claim 1, characterized in that, Before the first microwave treatment, divide the pericarp into 3 petals and connect them at the fruit stalk.

8. The preparation method according to claim 7, wherein The pericarp is cleaned before being divided; the cleaning method includes ultrasonic cleaning.

9. Application of the preparation method according to any one of claims 1 to 8 in improving the preparation efficiency of tangerine peel and / or improving the quality of tangerine peel.

10. The application according to claim 9, characterized in that, The improvement of the quality of tangerine peel includes any one or more of the following (1) to (4): (1) Increase the flavonoid content of tangerine peel; (2) Reduce the essential oil content of tangerine peel; (3) Increase the antioxidant capacity of tangerine peel; (4) Increase the anti-inflammatory capacity of tangerine peel.

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