Method for preparing rose white tea and identifying flavor substances of rose white tea

Abstract

The invention provides rose white tea and a preparation method thereof, and belongs to the field of scented tea preparation. The preparation method of the rose white tea comprises the following steps: (1) sorting and scattering petals; (2) withering: flatly laying rose petals in a plastic tray with leaking holes, wherein the thickness is about 3-5cm; (3) drying: drying a sample obtained after withering; and (4) packaging a finished product: cooling the dried petals to obtain the rose white tea. The rose white tea is detected by adopting a gas chromatography-mass spectrometry method, and is quantified by adopting an internal standard method. The content of each flavor component in the withering process and after drying of the rose white tea is obtained, and the OAV value of each component is calculated, so that the dynamic change of the flavor components in the withering process of the rose white tea is obtained. The rose white tea prepared by the preparation method disclosed by the invention not only can well retain effective components in roses, but also has rich rose fragrance and fresh taste, the economic value of the rose white tea is expanded, and the rose white tea has a good market prospect.

Description

Technical Field

[0001] The invention relates to a method for preparing rose white tea and identifying its flavor substances, and belongs to the fields of scented tea production and analytical chemistry. Background Art

[0002] Rose is a perennial deciduous shrub belonging to the genus Rosa of the Rosaceae family. It is mainly produced in France, Russia, Bulgaria and other countries. The main planting areas in my country are Shandong, Gansu and Yunnan. Pingyin County, Jinan City, Shandong Province is rich in roses, which are not only for people to appreciate, but also have high economic value. Food, medicine and chemical products made from roses have formed a series of rose products, which are sold at home and abroad.

[0003] Currently, the main processing method of rose tea is to select fresh rose petals or rose buds and directly dry them. However, the rose tea made by this method tastes bitter and has a poor taste. In addition, the flavor is greatly lost after brewing 1-2 times, and the tea soup no longer has the color and aroma of roses. Summary of the invention

[0004] In order to overcome the shortcomings of existing analysis technology, the purpose of the present invention is to provide a method for preparing rose white tea and its flavor substances, which uses floribunda roses as raw materials and is made into rose white tea through the traditional white tea process of withering and drying. The rose white tea has a richer rose fragrance and a refreshing taste of white tea.

[0005] The second object of the present invention is to provide a rose white tea prepared by the above preparation method, and to identify the flavor substances therein.

[0006] To achieve the above object, the present invention is implemented through the following technical solutions:

[0007] A method for preparing rose white tea and identifying its flavor substances, comprising the following steps:

[0008] (1) Petal sorting and breaking up: sorting the freshly picked roses, removing yellow and incomplete petals, and breaking up and separating the overlapping petals;

[0009] (2) Withering: The sorted petals are placed in a plastic perforated tray for natural withering, with the petals stacked to a thickness of 3-5 cm, the indoor temperature range being 25-28° C., and the air humidity range being 40-50%;

[0010] (3) Drying: The rose petals after withering are subjected to forced air drying for 4.5 h;

[0011] (4) Packaging finished product: Cooling the dried tea to obtain rose white tea;

[0012] (5) The internal standard method was used for quantification, and the rose white tea after withering WT0h, WT12h, WT24h, WT36h, WT48h and drying was detected by gas chromatography-mass spectrometry to obtain the trace components in the rose white tea, and the OAV value of each trace component was calculated, thereby obtaining the dynamic changes of the trace components during the withering process.

[0013] Furthermore, during the withering process, the petals are turned over every two hours, and the thickness of the petals is controlled to be uniform when placed on the plate, and the petals are fluffy. The above control is conducive to air flow and uniform distribution of moisture.

[0014] Furthermore, the moisture content of the petals after withering is 47%-50%.

[0015] Furthermore, the drying temperature during the drying process is 80°C.

[0016] Further, the gas chromatography-mass spectrometry measurement conditions are:

[0017] GC: The oven temperature was maintained at 40°C for 5 minutes, then increased to 50°C at a rate of 2°C / min, then to 130°C at a rate of 8°C / min, and finally to 280°C at a rate of 10°C / min for 10 minutes. No injection was performed. The temperature of the injector and the interface were set to 280°C.

[0018] MS: The ionization mode was EI, the electron energy was set to 70 eV, the scan range was 40–600 m / z, and the solvent delay time of the detector was 8 min to avoid solvent overload in the mass spectrometer. The temperatures of the mass spectrometer source and quadrupole were set to 250 °C and 280 °C, respectively.

[0019] Weigh 0.5g of rose tea powder into a 20mL headspace bottle, add 1μL of 2-methyl-3-heptanone (internal standard 0.816μg / μL, purchased from SIGMA), and extract in a 60℃ constant temperature water bath for 45 minutes. After the extraction is completed, insert the aged extraction head into the headspace bottle, adjust the position of the top extraction head in the headspace bottle (suspend the needle 1cm above the sample to be tested), and adsorb the extraction components. The extraction temperature is 60℃. The extraction time is 60 minutes. After adsorption, remove the extraction head, quickly insert it into the GC injection port for analysis for 5 minutes, and measure the sample under the conditions of setting various GC-MS experimental parameters.

[0020] Furthermore, the identification obtained OAVs of 54 rose white tea flavor substances, and the specific components are shown in Table 1.

[0021] Beneficial effects of the present invention:

[0022] The present invention relates to the preparation of rose white tea and a method for identifying its flavor substances. While not containing other biological raw materials, the rose component taste can be fully displayed, and the preparation method and required equipment are simple. During the preparation process, a simple method is used to avoid the disadvantages of bitterness and poor taste of single-type flower tea. In short, the rose white tea prepared by the preparation method of the present invention can not only well retain the effective ingredients in the rose, but also has an excellent taste, overcomes many problems of poor taste, bitterness, and unsightly appearance of white radix schizonepetae flower tea in the prior art, expands the economic value of rose tea, and has a good market prospect. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 GC-MS spectrum of rose white tea withering 0h;

[0024] Figure 2 GC-MS spectrum of rose white tea withered for 12 hours;

[0025] Figure 3 GC-MS spectrum of rose white tea withered for 24 hours;

[0026] Figure 4 GC-MS spectrum of rose white tea withered for 36 hours;

[0027] Figure 5 GC-MS spectrum of rose white tea withered for 48 hours.

[0028] Figure 6 GC-MS spectrum of rose white tea after drying. DETAILED DESCRIPTION

[0029] In order to better understand the present invention, the content of the present invention is further explained below in conjunction with the embodiments and drawings, but the content of the present invention is not limited to the following embodiments, and the embodiments should not be regarded as limiting the protection scope of the present invention.

[0030] Example:

[0031] A method for preparing rose white tea and identifying its flavor substances, which is prepared by using floribunda rose petals as raw materials and processing through the following steps:

[0032] 1. Petal sorting and breaking up: sort the freshly picked roses, remove the yellow and incomplete petals, and break up and separate the overlapping petals;

[0033] 2. Withering: Put the sorted petals into a plastic perforated tray for natural withering. The petals are piled up to a thickness of 3-5 cm. The indoor temperature range is 25-28°C, and the air humidity range is 40-50%. Turn them over every two hours. At the same time, the petals are placed in the tray with uniform thickness and fluffy between the petals. The above control is conducive to air flow and uniform distribution of moisture. The moisture content of the petals after withering is 47%-50%;

[0034] 3. Drying: The withered rose petals are dried by blast drying at a temperature of 80°C for 4.5 hours;

[0035] 4. Packaging of finished products: Cool the dried tea and put it into a moisture-proof sealed bag to obtain rose white tea. The prepared rose white tea is subjected to sensory evaluation in accordance with GB / T 23776-2018 "Tea Sensory Evaluation Method". Specifically, 3g of tea sample is taken, 150mL of boiling water is added and brewed for 5 minutes, and then a team of 15 reviewers evaluates the appearance, soup color, taste, aroma, and leaf bottom, and scores them according to the weighted method (total score = appearance × 25% + soup color ×

[0036] 10% + aroma × 25% + flavor × 30% + leaf bottom × 10%), the sensory evaluation results are shown in Table 1 below:

[0037] Table 1 Sensory evaluation results of rose white tea

[0038] Appearance (25%) Soup color (10%) Aroma (25%) Taste (30%) Leaf bottom (10%) Total score Purple and red Bright brown Rich floral scent Strong and mellow Purple yellow, even 21.3 7.2 22.6 24.7 7.5 83.3

[0039] Refer to GB 5009.3-2016 "Determination of Water in Food" and "Comparative Study on Extraction Methods of Total Flavonoids in Rose"

[0040] The total flavonoid content was detected by the method described in (Li Shufang, Sang Xiaojun, Chinese Modern Drug Application, 2012, 6(08):12-13.), and the results are shown in Table 2.

[0041] Table 2 Moisture and total flavonoids content of rose white tea during withering

[0042]

[0043]

[0044] The results showed that the moisture content of rose white tea was decreasing during the withering process, and the total flavonoids content increased with the withering time. After high-temperature drying, the moisture content of rose white tea dropped sharply, and the total flavonoids content increased exponentially, which shows that the rose white tea prepared in this way has better quality.

[0045] 5. Identification of flavor substances in rose white tea during withering and after drying

[0046] 5.1 Equipment: Therom TSQ 8000Evo gas chromatography-mass spectrometer.

[0047] 5.2GC-MS measurement conditions:

[0048] GC: The oven temperature was maintained at 40°C for 5 minutes, then increased to 50°C at a rate of 2°C / min, then to 130°C at a rate of 8°C / min, and finally to 280°C at a rate of 10°C / min for 10 minutes. No injection was performed. The temperature of the injector and the interface were set to 280°C.

[0049] MS: The ionization mode was EI, the electron energy was set to 70 eV, the scan range was 40–600 m / z, and the solvent delay time of the detector was 8 min to avoid solvent overload in the mass spectrometer. The temperatures of the mass spectrometer source and quadrupole were set to 250 °C and 280 °C, respectively.

[0050] Use a portable blender to crush the rose white tea during withering and after drying, accurately weigh 1g of the crushed tea sample (recorded as 0h, 12h, 24h, 36h, 48h and HAD respectively), place it in a 20mL headspace sample bottle, add 1mL of saturated NaCl solution, and then add 1μL of 2-methyl-3-heptanone (internal standard 0.816μg / μL, purchased from SIGMA), and extract it in a 60℃ constant temperature water bath for 45 minutes. After the extraction is completed, insert the aged extraction head into the headspace bottle, adjust the position of the top extraction head in the headspace bottle (suspend the needle 1cm above the sample to be tested), and adsorb the extraction components. The extraction temperature is 60℃. The extraction time is 60 minutes. After adsorption, take out the extraction head, quickly insert it into the GC injection port for analysis for 5 minutes, and measure the sample under the conditions of setting various experimental parameters of GC-MS.

[0051] Results and Analysis

[0052] 1.1 Analysis of flavor substances in rose white tea during withering and after drying

[0053] The main aroma substances in the withering process of rose white tea were determined by gas chromatography-mass spectrometry as follows, see Table 3. The table shows that 36 flavor substances were identified in rose tea, including 9 aldehydes, 4 ketones, 12 alcohols, 5 esters, 1 acid, 1 furan, 2 phenols, and 1 oxygen-containing compound.

[0054] Table 3 OAV values ​​of flavor substances in rose white tea during withering

[0055]

[0056]

[0057] Aldehydes contribute greatly to the overall flavor of rose white tea. They usually have floral, sour and sweet aromas, which may be caused by the automatic oxidation of oils during hot air drying; ketones are also an important component of the flavor substances in rose white tea, and ketones usually contain fruity aromas; esters also bring fragrance to the samples.

[0058] As shown in Table 3, the OAV values ​​of citral, linalool, citronellol and geraniol are relatively high. Citral has the fragrance of lemon, and linalool, citronellol and geraniol all have the typical fragrance of rose, indicating that they are typical flavor substances in rose; n-nonanal, 2-nonenal, trans-nerolidol, phenylethyl acetate, benzyl benzoate and 4-methylpentanoic acid exist in the early stage of withering and disappear with the increase of withering time; 2-hexenal, 2-heptanol, benzyl alcohol and 2-undecanone are decomposed into other types of flavor substances by heat after high-temperature drying to make rose white tea; 2-phenylacetaldehyde, cyclotridecanone and trans-linalool oxide only appear in rose white tea after high-temperature drying.

[0059] 2. Conclusion

[0060] This study used rose white tea after withering and drying as raw materials, and analyzed the changes in flavor substances between them based on GC-MS. The results showed that high-temperature drying processing would affect the flavor substances in rose white tea.

[0061] Obviously, according to the above contents of the present invention, according to the common technical knowledge and customary means in this field, without departing from the above basic technical ideas of the present invention, other various forms of modification, replacement or change can also be made. The above contents of the present invention are further described in detail through the specific implementation methods in the form of embodiments. However, this should not be understood as the scope of the above subject matter of the present invention being limited to the following examples. All technologies implemented based on the above contents of the present invention belong to the scope of the present invention.

Claims

1. A method for preparing rose white tea, characterized in that: Here are the steps: (1) Sorting and breaking up rose petals: Roses are produced in Pingyin County, Jinan City, Shandong Province, and purchased from a local market. The purchased roses are sorted, yellowed and incomplete petals are removed, and overlapping petals are broken up and separated; (2) Withering: The sorted petals were placed in a plastic perforated tray for natural withering. The petals were piled to a thickness of 3-5 cm and turned over every two hours. The thickness of the petals was controlled to be uniform when placed in the tray. Samples were taken at 0 h, 12 h, 24 h, 36 h, and 48 h of withering. (3) Drying: Drying the rose petals after withering by air blast; (4) Packaging the finished product: Cool the dried tea to obtain rose white tea.

2. The method for preparing rose white tea according to claim 1, characterized in that: Select Floribunda rose flowers for picking.

3. The method for preparing rose white tea according to claim 1, characterized in that: In the step (2), the indoor temperature range of the withering process is 25-28° C., the air humidity range is 40-50%, and the moisture content after withering is 47%-50%.

4. The method for preparing rose white tea according to claim 1, characterized in that: In the step (3), the drying temperature is 80° C. and the drying time is 4.5 h.

5. A method for identifying flavor substances in rose white tea, characterized in that: In the preparation process described in claim 1, the internal standard method is used for quantification, and the rose white tea after withering for 0h, 12h, 24h, 36h, 48h and drying is detected by gas chromatography-mass spectrometry to obtain the trace components in the rose white tea, and the OAV value of each trace component is calculated, thereby obtaining the dynamic changes of the trace components during the withering process.

6. The method for identifying flavor substances in rose white tea according to claim 5, characterized in that: The gas chromatography conditions in step (5) are as follows: the column box temperature is maintained at 40°C for 5 minutes, then increased to 50°C at a rate of 2°C / min, then increased to 130°C at a rate of 8°C / min, and finally increased to 280°C at a rate of 10°C / min for 10 minutes. No injection is performed in batches. The temperatures of the injector and the interface are both set to 280°C; the mass spectrometry conditions are as follows: the ionization mode is EI, the electron energy is set to 70eV, the scanning range is 40-600m / z, and the solvent delay time of the detector is 8 minutes to avoid solvent overload in the mass spectrometer. The temperatures of the mass spectrometer source and the quadrupole are set to 250°C and 280°C, respectively.

7. The method for identifying flavor substances in rose white tea according to claim 5, characterized in that: In the step (5), quantitative analysis is performed using the internal standard method according to the formula: The concentration of compound (x) and the mass of the internal standard are C x and C I ; Ax and A I Represent the peak areas of compound (x) and internal standard compound respectively; V I represents the volume of the standard added (1 μL); m x is the quality of the sample.

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