A method for reducing the content of 5-hydroxymethylfurfural in aged pericarpium citri reticulatae

Abstract

This invention discloses a method for reducing the 5-hydroxymethylfurfural content in aged tangerine peel, belonging to the field of tangerine peel aging technology. The method involves cyclically aging the tangerine peel in a medium-temperature, high-humidity environment, a ceramic jar, and a high-temperature, low-humidity environment. The medium-temperature, high-humidity environment has a temperature of 15-30°C, a humidity of 60-80%, and an aging time of 12-36 hours. The ceramic jar environment has a temperature of 15-28°C, a humidity of 20-50%, and an aging time of 2-7 days. The high-temperature, low-humidity environment has a temperature of 45-55°C, a humidity of 20-40%, and an aging time of 1-3 hours. The cycle is repeated 4-8 times. By controlling the overall temperature below 55°C and primarily using ceramic jar aging supplemented by a medium-high temperature environment, this invention achieves a uniform aging process and accelerates aging, thus preserving the intrinsic quality and aroma of the tangerine peel.

Description

Technical Field

[0001] This invention belongs to the field of tangerine peel aging technology, and particularly relates to a method for reducing the 5-hydroxymethylfurfural content in aged tangerine peel. Background Technology

[0002] Dried tangerine peel (Chenpi) is the dried, mature peel of the citrus fruit (Citrus reticulata) and its cultivated varieties, belonging to the Rutaceae family. It is widely recognized for its medicinal and edible value, possessing properties that regulate qi, strengthen the spleen, and resolve dampness and phlegm. Modern research indicates that during the long-term natural aging process, the volatile oils and flavonoids contained within the tangerine peel undergo slow oxidation, hydrolysis, and polymerization, resulting in a reduction of pungent odors and a gradual enhancement of mellow and aged aromas. Furthermore, its pharmacological activity is optimized, leading to the consensus that "the older the better."

[0003] However, natural aging typically takes several years, a lengthy process that struggles to meet market demand. To shorten this period, current technologies often employ methods such as increasing ambient temperature and humidity to accelerate aging. However, these methods, especially prolonged high-temperature treatments, lead to the formation and accumulation of significant amounts of 5-hydroxymethylfurfural (5-HMF) in the tangerine peel. This substance, a typical marker of high-temperature accelerated aging, exhibits a burnt or musty odor. Excessive accumulation of 5-HMF results in a significant difference between accelerated-aged and naturally aged tangerine peel in terms of mellow and pure aroma, leading to a decline in quality.

[0004] Therefore, how to effectively accelerate aging while inhibiting the excessive accumulation of 5-HMF, and simulate the gentle transformation process of natural aging, so as to obtain products with aroma and internal quality close to those of traditional naturally aged tangerine peel, has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] To address the shortcomings of the existing technology, a method for reducing the 5-hydroxymethylfurfural content in aged tangerine peel is provided. The overall temperature of this method is controlled below 55℃, and the aging process is mainly carried out in ceramic jars, supplemented by medium-high temperature aging. The aging process is uniform, which helps to ensure the internal quality and aroma of the tangerine peel.

[0006] The above method for reducing the 5-hydroxymethylfurfural content in aged tangerine peel includes the following steps: The tangerine peel to be aged is sequentially placed in environments of medium temperature and high humidity, a ceramic jar, and a high temperature and low humidity for cyclical aging, wherein...

[0007] The medium-temperature and high-humidity temperature is 15~30℃, the humidity is 60~80%, and the aging time is 12~36 hours;

[0008] The ambient temperature of the ceramic jar is 15~30℃, the ambient humidity is 20~50%, and the aging time is 2~7 days;

[0009] The high-temperature and low-humidity conditions are characterized by a temperature of 45-55°C, a humidity of 20-40%, and an aging time of 1-3 hours.

[0010] Furthermore, the cyclic aging process is repeated 4 to 8 times.

[0011] Firstly, the overall temperature is controlled below 55℃, and the high-temperature time during the entire aging process is relatively short. This helps to suppress the production and accumulation of 5-HMF, a typical marker of aging in aged tangerine peel, which is characterized by burnt and musty smells. This helps to ensure a flavor similar to that of traditionally naturally aged tangerine peel. Secondly, the method mainly involves aging in earthenware jars. The permeability, buffering properties of earthenware jars against temperature and humidity, and light protection facilitate a uniform aging process and prevent photo-oxidation. Furthermore, the medium-temperature and high-humidity environment before aging in earthenware jars is not only conducive to changes in volatile oils and flavonoids but also to the reproduction of microorganisms. Such a large number of microorganisms helps to ensure the degree of biochemical reaction in the subsequent earthenware jar aging stage. The high-temperature and low-humidity environment after earthenware jar aging can reduce the number of microorganisms to a certain extent, thereby avoiding the problems of mold and over-reaction caused by excessive microbial reproduction. Therefore, cyclical aging in a medium-temperature and high-humidity environment, an earthenware jar, and a high-temperature and low-humidity environment can achieve uniform aging under non-long-term high-temperature conditions and achieve the purpose of accelerating aging, which helps to ensure the internal quality and aroma of tangerine peel.

[0012] In some embodiments of the present invention, the dried tangerine peel to be aged is produced in Xinhui District, Jiangmen City, Guangdong Province, and its moisture content is ≤30wt%.

[0013] In some embodiments of the present invention, the tangerine peel to be aged is obtained by drying the peel of the tea branch mandarin orange at 38-42°C, and / or by sun-drying the peel of the tea branch mandarin orange until its moisture content is ≤30wt%.

[0014] In some embodiments of the present invention, the temperature of the medium temperature and high humidity is 20~25°C.

[0015] In some embodiments of the present invention, the aging time under medium temperature and high humidity is 18 to 30 hours.

[0016] In some embodiments of the present invention, the ambient temperature of the ceramic jar is 20~25°C.

[0017] In some embodiments of the present invention, the aging time of the ceramic jar is 3 to 5 days.

[0018] In some embodiments of the present invention, the earthenware jar is a coarse earthenware jar.

[0019] In some embodiments of the invention, the mouth of the earthenware jar is sealed with an earthenware lid.

[0020] In some embodiments of the present invention, the volume of the ceramic jar is 50-250L.

[0021] In some embodiments of the present invention, the amount of the tangerine peel to be aged added to the ceramic jar is such that the vertical distance between the surface of the tangerine peel to be aged and the plane containing the rim of the ceramic jar is 10-30 cm.

[0022] In some embodiments of the present invention, the high temperature and low humidity temperature is 45~50°C.

[0023] In some embodiments of the present invention, the high temperature and low humidity aging time is 1.5 to 2.5 hours.

[0024] In some embodiments of the present invention, the cyclic aging is repeated 5 to 7 times.

[0025] In some embodiments of the invention, the cyclic aging is carried out in a ventilated environment, and the oxygen volume fraction of the ventilated environment is 20% to 45%.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] (1) The method of the present invention has a temperature of less than 55°C and a short high-temperature time during the entire aging process, which is conducive to inhibiting the generation and accumulation of 5-HMF with burnt and musty smells, thereby ensuring a flavor similar to that of traditional naturally aged tangerine peel.

[0028] (2) The method of the present invention optimizes the aging environment, which is beneficial to control the uniformity and degree of biochemical reaction in the aging process and can achieve the purpose of accelerating aging, thereby ensuring the intrinsic quality and aroma of tangerine peel. Detailed Implementation

[0029] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0030] Freshly picked citrus fruits (Xinhui tea branch citrus) are peeled using the three-cut method, and the peel is dried at 40℃ until its moisture content is below 30wt%, thus obtaining aged tangerine peel.

[0031] The moisture content of the dried tangerine peel used in the following examples and comparative examples was 22.8 wt%.

[0032] Example 1

[0033] This embodiment provides a method for reducing the 5-hydroxymethylfurfural content in aged tangerine peel, including the steps of cyclically aging the tangerine peel in a medium-temperature, high-humidity environment, a ceramic jar, and a high-temperature, low-humidity environment, with the entire cyclic aging process carried out in a ventilated environment with an oxygen volume fraction of 25%, and repeated 5 times. The specific steps are as follows:

[0034] Medium temperature and high humidity: Lay a layer of dried tangerine peel to be aged on a wire mesh and place it in a temperature and humidity controlled room with a temperature of 15℃ and a humidity of 80% for 36 hours;

[0035] Earthenware jars: The dried tangerine peel obtained from the medium-temperature and high-humidity aging process is packaged into 150L coarse earthenware jars. The vertical distance between the surface of the dried tangerine peel and the plane of the mouth of the coarse earthenware jar is 20cm. The coarse earthenware jars are covered with earthenware lids and placed in a temperature and humidity controlled room with a temperature of 20℃ and a humidity of 30% for aging for 3 days.

[0036] High temperature and low humidity: Spread a layer of dried tangerine peel obtained from the earthenware jar aging process on a wire mesh and place it in a temperature and humidity controlled room with a temperature of 45℃ and a humidity of 20% for aging for 2 hours.

[0037] Example 2

[0038] This embodiment provides a method for reducing the 5-hydroxymethylfurfural content in aged tangerine peel. The differences between this method and Example 1 are: the aging conditions (temperature, humidity, and aging time) are different (medium temperature and high humidity, ceramic jar, and high temperature and low humidity), as detailed in Table 1; the entire cyclic aging process is carried out in a ventilated environment with an oxygen volume fraction of 35%, and is repeated 6 times. All other aspects remain consistent with Example 1.

[0039] Table 1: Aging conditions of Example 2

[0040] condition Medium temperature and high humidity Earthenware jar High temperature and low humidity Temperature / °C 22 22 45 humidity / % 70 40 30 time 24 hours 4 days 2 hours

[0041] Example 3

[0042] This embodiment provides a method for reducing the 5-hydroxymethylfurfural content in aged tangerine peel. The differences between this method and Example 1 are: the aging conditions (temperature, humidity, and aging time) are different (medium temperature and high humidity, ceramic jar, and high temperature and low humidity), as detailed in Table 2; the entire cyclic aging process is carried out in a ventilated environment with an oxygen volume fraction of 21%, and is repeated 7 times. All other aspects remain consistent with Example 1.

[0043] Table 2: Aging conditions of Example 3

[0044] condition Medium temperature and high humidity Earthenware jar High temperature and low humidity Temperature / °C 25 25 48 humidity / % 80 50 40 time 30 hours 3 days 3 hours

[0045] Example 4

[0046] This embodiment provides a method for reducing the 5-hydroxymethylfurfural content in aged tangerine peel. The differences between this method and Example 1 are: the aging conditions (temperature, humidity, and aging time) are different (medium temperature and high humidity, ceramic jar, and high temperature and low humidity), as detailed in Table 3; the entire cyclic aging process is carried out in a ventilated environment with an oxygen volume fraction of 35%, and is repeated 5 times. All other aspects remain consistent with Example 1.

[0047] Table 3: Aging conditions of Example 4

[0048] condition Medium temperature and high humidity Earthenware jar High temperature and low humidity Temperature / °C 30 25 50 humidity / % 70 40 30 time 18 hours 6 days 1 hour

[0049] Example 5

[0050] This embodiment provides a method for reducing the 5-hydroxymethylfurfural content in aged tangerine peel. The differences between this method and Example 1 are: the aging conditions (temperature, humidity, and aging time) are different (medium temperature and high humidity, ceramic jar, and high temperature and low humidity), as detailed in Table 4; the entire cyclic aging process is carried out in a ventilated environment with an oxygen volume fraction of 45%, and is repeated 5 times. All other aspects remain consistent with Example 1.

[0051] Table 4: Aging conditions of Example 5

[0052] condition Medium temperature and high humidity Earthenware jar High temperature and low humidity Temperature / °C 22 28 50 humidity / % 80 40 30 time 12 hours 5 days 3 hours

[0053] Example 6

[0054] This embodiment provides a method for reducing the 5-hydroxymethylfurfural content in aged tangerine peel. The differences between this method and Example 1 are: the aging conditions (temperature, humidity, and aging time) are different (medium temperature and high humidity, ceramic jar, and high temperature and low humidity), as detailed in Table 5; the entire cyclic aging process is carried out in a ventilated environment with an oxygen volume fraction of 25%, and is repeated 5 times. All other aspects remain consistent with Example 1.

[0055] Table 5: Aging conditions of Example 6

[0056] condition Medium temperature and high humidity Earthenware jar High temperature and low humidity Temperature / °C 22 22 50 humidity / % 60 40 40 time 36 hours 5 days 2 hours

[0057] Example 7

[0058] This embodiment provides a method for reducing the 5-hydroxymethylfurfural content in aged tangerine peel. The differences between this method and Example 1 are: the aging conditions (temperature, humidity, and aging time) are different (medium temperature and high humidity, ceramic jar, and high temperature and low humidity), as detailed in Table 6; the entire cyclic aging process is carried out in a ventilated environment with an oxygen volume fraction of 35%, and is repeated 6 times. All other aspects remain consistent with Example 1.

[0059] Table 6: Aging conditions of Example 7

[0060] condition Medium temperature and high humidity Earthenware jar High temperature and low humidity Temperature / °C 22 22 55 humidity / % 70 40 30 time 24 hours 4 days 2 hours

[0061] Comparative Example 1

[0062] This comparative example provides a method for aging dried tangerine peel, which differs from Example 1 in that the aging time at high temperature and low humidity is different, as detailed in Table 7; and the cycle is repeated 6 times. Everything else remains the same as in Example 1.

[0063] Table 7: Aging conditions of Comparative Example 1

[0064] condition Medium temperature and high humidity Earthenware jar High temperature and low humidity Temperature / °C 22 22 55 humidity / % 70 40 30 time 24 hours 4 days 4 hours

[0065] Comparative Example 2

[0066] This comparative example provides a method for aging dried tangerine peel, which differs from Example 1 only in that it includes the step of cyclically aging the tangerine peel to be aged in environments of medium temperature and high humidity, high temperature and low humidity, and a ceramic jar. Everything else remains the same as in Example 1.

[0067] Comparison Example

[0068] Our company produces naturally aged tangerine peel that has been aged for 3 years.

[0069] Performance testing

[0070] 1. Sensory testing

[0071] Twenty trained individuals aged 10-60 years were randomly selected as the judging panel. 50g of aged tangerine peel from Examples 1-7, Comparative Examples 1-2, and the control example were weighed and placed into 1L cups respectively. 700mL of boiling water was added to each cup, and the tea was steeped for 5 minutes before being poured out. Each judge evaluated the differences between the tea made from the aged tangerine peel of Examples 1-7 and Comparative Examples 1-4 and the tea made from the aged tangerine peel of the control example in terms of aroma, taste, and color. The scoring range was 1-10 points, where 1 point indicates completely different and 10 points indicates completely the same. The average score was calculated, and the judging results are shown in Table 8.

[0072] Table 8: Sensory test results of aged tangerine peel obtained in Examples 1-7 and Comparative Examples 1-2

[0073]

[0074] 2. Test for total phenol content

[0075] The total phenol content of aged tangerine peel in Examples 1-7, Comparative Examples 1-2, and Control Examples, as well as unaged tangerine peel (i.e., the aforementioned tangerine peel to be aged), was determined using the Folin-Ciocalteu colorimetric method. An 80% methanol aqueous solution was used as the extraction solvent, and gallic acid (GA) was used as the standard. The absorbance at 765 nm was measured. The results are expressed as gallic acid equivalents (mg GAE / g), as detailed in Table 9.

[0076] 3. Test for total flavonoid content

[0077] The total flavonoid content of aged tangerine peel in Examples 1-7, Comparative Examples 1-2, and Control Examples, as well as unaged tangerine peel (i.e., the aforementioned tangerine peel to be aged), was determined using the NaNO2-Al(NO3)3 colorimetric method. An 80% (v / v) methanol aqueous solution was used as the extraction solvent, and rutin was used as the standard. The absorbance at 510 nm was measured. The results are expressed as rutin equivalents (mg RE / g), as detailed in Table 9.

[0078] 4. Test of 5-HMF content

[0079] The 5-HMF content in aged tangerine peel of Examples 1-7, Comparative Examples 1-2, and Control Examples, as well as unaged tangerine peel (i.e., the aforementioned tangerine peel to be aged), was determined by HPLC-MS (SIM mode). A 10% (v / v) methanol aqueous solution was used as the extraction solvent, and methanol (phase A)-pure water (phase B) was used as the mobile phase. The test results are shown in Table 9.

[0080] Table 9: Component content test results of aged tangerine peel obtained from Examples 1-7, Comparative Examples 1-2, and Control Examples

[0081]

[0082] As shown in Tables 8-9, the aged tangerine peel obtained in Examples 1-7 of this invention is quite similar to naturally aged tangerine peel aged for three years in terms of sensory characteristics such as aroma, taste, and color, as well as in terms of total phenolic content, total flavonoid content, and 5-HMF content. In contrast, Comparative Example 1, which underwent excessively long high-temperature aging, although its total phenolic and total flavonoid content was similar to that of naturally aged tangerine peel, showed a significant increase in 5-HMF content, resulting in a clear difference in aroma, taste, and color compared to naturally aged tangerine peel. Comparative Example 2, where the high-temperature, low-humidity aging process was adjusted to the level before aging in the ceramic jar, exhibited a lower degree of biochemical reaction during the ceramic jar aging process due to the unfavorable high temperature for microbial growth, thus failing to effectively accelerate aging. Consequently, its total flavonoid content was significantly lower than that of naturally aged tangerine peel, indicating a lower level of active ingredients.

[0083] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that after reading this application specification, they can still modify or make equivalent substitutions to the specific implementation of the present invention, but these modifications or changes do not depart from the protection scope of the pending claims of the present invention.

Claims

1. A method for reducing the 5-hydroxymethylfurfural content in aged tangerine peel, characterized in that, Includes the following steps: The dried tangerine peel to be aged is placed in a series of environments: medium temperature and high humidity, earthenware jar, and high temperature and low humidity, in a cyclical manner. The medium-temperature and high-humidity temperature is 15~30℃, the humidity is 60~80%, and the aging time is 12~36 hours; The ambient temperature of the ceramic jar is 15~28℃, the ambient humidity is 20~50%, and the aging time is 2~7 days; The high-temperature and low-humidity conditions are characterized by a temperature of 45-55°C, a humidity of 20-40%, and an aging time of 1-3 hours. Furthermore, the cyclic aging process is repeated 4 to 8 times.

2. The method according to claim 1, characterized in that, The dried tangerine peel to be aged is produced in Xinhui District, Jiangmen City, Guangdong Province, and its moisture content is ≤30wt%.

3. The method according to claim 1, characterized in that, The aged tangerine peel is obtained by the following methods: drying the peel of the tea branch mandarin orange at 38~42℃, and / or sun-drying the peel of the tea branch mandarin orange until its moisture content is ≤30wt%.

4. The method according to claim 1, characterized in that, The temperature of the medium-temperature and high-humidity environment is 20~25℃; and / or the aging time of the medium-temperature and high-humidity environment is 18~30 hours.

5. The method according to claim 1, characterized in that, The ambient temperature of the ceramic jar is 20~25℃; and / or the aging time of the ceramic jar is 3~5 days.

6. The method according to claim 1, characterized in that, The pottery jar is a coarse pottery jar.

7. The method according to claim 1, characterized in that, The mouth of the earthenware jar is sealed with an earthenware lid.

8. The method according to claim 1, characterized in that, The high temperature and low humidity temperature is 45~50℃; and / or the aging time of the high temperature and low humidity is 1.5~2.5 hours.

9. The method according to claim 1, characterized in that, The cyclic aging process is repeated 5 to 7 times.

10. The method according to claim 1, characterized in that, The cyclic aging process is carried out in a ventilated environment with an oxygen volume fraction of 20% to 45%.

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