Tea freeze-dried powder and preparation method thereof

Abstract

The invention relates to tea freeze-dried powder and a preparation method thereof. The preparation method of the tea leaf freeze-dried powder comprises the following steps: chopping tea leaves, soaking with water, extracting with an aqueous solution of an additive, filtering, and concentrating and drying filtrate to obtain the tea leaf freeze-dried powder, the additive comprises vitamin B1, sodium erythorbate and citric acid; the soaking temperature and the extraction temperature are both 0-10 DEG C. According to the preparation method, the vitamin B1, the sodium erythorbate and the citric acid are used as additives to extract the tea leaves, and the three components are matched with one another and have a synergistic effect, so that the extraction effect of flavor substances in the tea leaves can be jointly improved. Meanwhile, a mode of combining low-temperature soaking and low-temperature extraction is adopted, so that heat-sensitive and oxidizable flavoring substances in the tea leaves are reserved to a great extent, a relatively high extraction rate can be kept while fragrant active ingredients are highly reserved, and the method is suitable for large-scale process production of the tea leaf freeze-dried powder.

Description

Technical Field

[0001] The invention belongs to the technical field of tea processing, and particularly relates to freeze-dried tea powder and a preparation method thereof. Background Art

[0002] As a new type of tea product, freeze-dried tea powder has been widely used in the fields of food, health care products and cosmetics in recent years because it can retain the active ingredients and natural aroma of tea to the greatest extent. Existing tea extraction methods include trough countercurrent extraction, tank extraction, percolation extraction, etc. Most of them use an extraction temperature of 40 to 90°C and a long extraction time.

[0003] CN117441808A discloses a freeze-dried tea powder for assisting weight loss and a production method thereof, the production method comprising: S1. crushing tea leaves to obtain tea powder; S2. placing the tea powder and water into an extractor, heating and extracting at 90°C to obtain an extract; S3. cooling the extract and filtering it to obtain an extract filtrate; S4. pre-freezing the extract filtrate, and after the pre-freezing is completed, performing low-pressure freeze-drying on the extract filtrate.

[0004] CN108478663A discloses a process for extracting tea polyphenols from fresh tea leaves at a high yield. Dry tea powder is placed in a 75% ethanol solution below 25°C, first soaked for 0.5 to 1h, then heated to boiling and maintained for 15 to 30min to obtain an ethanol water extract. When the temperature of the ethanol water extract drops to about 75°C, ethyl acetate is added and stirred to maintain 70 to 75°C for 10 to 30min, filtered to remove the residue, and a mixed extract is obtained; 75% ethanol and ethyl acetate are used for extraction, filtered to remove the residue, and a mixed extract is obtained. The mixed extract is further concentrated and filtered to obtain a tea polyphenol product. The process can achieve high purity of the extracted tea polyphenols, less impurities, and significantly reduce the maintenance cost of the resin column and improve production efficiency.

[0005] However, although the high-temperature extraction method improves the extraction efficiency, since the main flavoring substances in tea are heat-sensitive substances and easily oxidized substances, the aroma and flavor are lost significantly after extraction at high temperature and for a long time. The tea powder obtained after tea extraction has a significant difference in flavor from the original tea.

[0006] Therefore, how to retain the aroma components and tea flavor in tea to the greatest extent while ensuring the extraction efficiency and improving the quality of freeze-dried tea powder has become a technical problem that needs to be solved urgently. Summary of the invention

[0007] In view of the deficiencies of the prior art, the object of the present invention is to provide a freeze-dried tea powder and a preparation method thereof. The preparation method uses vitamin B1, sodium isoascorbate and citric acid as additives to extract tea leaves. The three components cooperate with each other and synergistically enhance the effect of extracting the aroma substances in the tea leaves. At the same time, a combination of low-temperature immersion and low-temperature extraction is adopted to retain the heat-sensitive and easily oxidizable flavor substances in the tea leaves to a large extent. While highly retaining the aroma effective components, a high extraction rate can be maintained, and the method is suitable for the large-scale process production of freeze-dried tea powder.

[0008] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0009] In a first aspect, the present invention provides a method for preparing freeze-dried tea powder, the preparation method comprising the following steps: chopping tea leaves, soaking them in water, extracting them with an aqueous solution of an additive, filtering them, concentrating the filtrate, and drying them to obtain the freeze-dried tea powder.

[0010] The additives include vitamin B1, sodium isoascorbate and citric acid.

[0011] The soaking and extraction temperatures are both between 0 and 10°C, for example, 0°C, 2°C, 4°C, 6°C, 8°C, 10°C, etc.

[0012] Vitamin B1 can be used as an auxiliary antioxidant to help reduce oxidation reactions in tea leaves and protect easily oxidizable components in tea leaves. It can also participate in the formation and transformation of flavor substances, affecting the formation of flavor substances in tea leaves. Sodium isoascorbate can effectively inhibit the oxidation reaction of tea leaves during the extraction process, improving the quality and stability of tea extracts. Citric acid, as an acidic substance, can adjust the pH value of the extract during the extraction process, thereby facilitating the dissolution and extraction of flavor substances and active ingredients in tea leaves.

[0013] The present invention creatively finds that vitamin B1, sodium isoascorbate and citric acid are used as additives to extract tea leaves, and the three components cooperate with each other to synergistically enhance the effect of extracting the aroma substances in the tea leaves. At the same time, the combination of low-temperature immersion and low-temperature extraction is adopted to retain the heat-sensitive and easily oxidizable flavor substances in the tea leaves to a large extent, and the tea aroma components are highly retained.

[0014] Preferably, the chopping is to chop the tea leaves into 8-12 meshes, for example, 8 mesh, 9 mesh, 10 mesh, 11 mesh, 12 mesh, etc.

[0015] By controlling the mesh size of the chopped tea leaves to 8 to 12 meshes, the dissolution rate and amount of the effective ingredients can be increased without over-exposing the flavor substances, thereby improving the tea extraction efficiency and better retaining the tea aroma.

[0016] Preferably, the tea leaves are subjected to far-infrared aroma treatment before chopping.

[0017] Far-infrared aroma treatment can cause the aroma precursors in the tea to vibrate and transition, which can better stimulate the release of aroma substances and evenly enhance the aroma.

[0018] Preferably, the temperature of the far-infrared aroma treatment is 70-90° C., and the time of the far-infrared aroma treatment is 2-10 min.

[0019] Among them, the specific point values ​​in 70-90°C can be selected from 70°C, 75°C, 80°C, 85°C, 90°C, etc., and the specific point values ​​in 2-10min can be selected from 2min, 4min, 6min, 8min, 10min, etc.

[0020] When the temperature and time of far-infrared aroma treatment are controlled within the above range, the aroma substances in the tea leaves can be better released.

[0021] Preferably, the soaking time is 0.5 to 2 hours, for example, 0.5 hours, 1 hour, 1.5 hours, 2 hours, etc.

[0022] Preferably, the extraction method is continuous countercurrent percolation extraction.

[0023] The present invention uses the continuous countercurrent percolation device in the patent application number 2025204246521 for continuous countercurrent percolation extraction, and utilizes the penetration and diffusion of liquid in the porous medium to make the extractant and tea leaves flow in the percolation device in a countercurrent state for extraction. Continuous countercurrent percolation extraction provides a sufficiently long contact time for low-temperature extraction, making up for the deficiency of slow molecular diffusion speed at low temperature, thereby improving the extraction rate.

[0024] Preferably, the extraction time is 2 to 4 hours, for example, 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, etc.

[0025] Preferably, during the extraction process, the mass of the additive is 0.5-2% of the mass of the tea leaves.

[0026] Preferably, the mass ratio of vitamin B1, sodium isoascorbate and citric acid is 1:(0.1-1):(0.1-0.5).

[0027] Among them, the specific point values ​​in 0.5~2% can be selected from 0.5%, 1%, 1.5%, 2%, etc., the specific point values ​​in 0.1~1 can be selected from 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, etc., and the specific point values ​​in 0.1~0.5 can be selected from 0.1, 0.2, 0.3, 0.4, 0.5, etc.

[0028] Preferably, the filtering comprises filtering using a ceramic membrane.

[0029] Ceramic membrane filtration can filter aroma components more accurately, while further removing impurities and reducing the impact of impurities on the stability of aroma components.

[0030] Preferably, the concentrating comprises concentrating using a reverse osmosis membrane.

[0031] Preferably, the concentration time is 2 to 3 hours, and the concentrated solution obtained after the concentration has a Brix of 12 to 15 brix.

[0032] Among them, the specific point values ​​in 2~3h can be selected from 2h, 2.2h, 2.4h, 2.6h, 2.8h, 3h, etc., and the specific point values ​​in 12~15brix can be selected from 12brix, 13brix, 14brix, 15brix, etc.

[0033] Preferably, the drying method comprises freeze drying.

[0034] Preferably, the tea leaves include any one of scented tea, black tea, green tea or white tea, or a combination of at least two of them.

[0035] In a second aspect, the present invention provides a freeze-dried tea powder prepared by the method for preparing freeze-dried tea powder as described in the first aspect.

[0036] The numerical range described in the present invention not only includes the point values ​​listed above, but also includes any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] The invention uses vitamin B1, sodium isoascorbate and citric acid as additives to extract tea leaves, and the three components cooperate with each other to synergistically enhance the effect of extracting flavor substances in tea leaves. At the same time, a combination of low-temperature immersion and low-temperature extraction is adopted to largely retain the heat-sensitive and easily oxidizable flavor substances in tea leaves, and a high extraction rate can be maintained while highly retaining the effective flavor components, and the invention is suitable for the large-scale process production of freeze-dried tea leaves.

[0039] Furthermore, the mesh size of the chopped tea leaves is controlled within 8 to 12 meshes, which can not only increase the dissolution rate and amount of the effective ingredients, but also prevent excessive exposure of the flavor substances, thereby improving the tea extraction efficiency while better retaining the tea aroma.

[0040] Furthermore, the far-infrared aroma treatment of the tea leaves before chopping can cause the aroma precursor substances in the tea leaves to vibrate and transition, which can better stimulate the release of aroma substances and evenly enhance the aroma; in addition, the temperature of the far-infrared aroma treatment is controlled at 70-90°C and the time is controlled at 2-10 minutes, which can better exert the effect of the far-infrared aroma treatment.

[0041] Furthermore, ceramic membrane filtration can filter aroma components more accurately, while further removing impurities and reducing the impact of impurities on the stability of aroma components. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is a comparison chart of mass spectra of different test samples in Test Example 4. DETAILED DESCRIPTION

[0043] In order to further explain the technical means and effects adopted by the present invention, the technical solution of the present invention is further described below in conjunction with the preferred embodiments of the present invention, but the present invention is not limited to the scope of the embodiments.

[0044] Example 1

[0045] This embodiment provides a method for preparing freeze-dried jasmine tea powder, comprising the following steps:

[0046] (1) Tea pretreatment: Jasmine tea leaves are treated with far-infrared aroma treatment machine at 80°C for 4 min, and then chopped by a tea cutter into 10 mesh.

[0047] (2) Soaking: Using the continuous countercurrent percolation device in the patent application number 2025204246521, add 50 kg of tea leaves according to 1 / 10 of the effective volume of a single percolation column (500 L), and spray water into the top of the percolation column (control the water temperature at 4°C). Stop adding water after the water covers the tea leaves and soak for 1 hour.

[0048] (3) Extraction: continuous countercurrent percolation extraction for 3 hours, the extraction temperature is controlled at 4°C, the extractant is an aqueous solution of an additive, wherein the mass of the additive is 1% of the mass of the tea leaves, and the additive is vitamin B1, sodium isoascorbate and citric acid in a mass ratio of 1:0.5:0.3 to obtain a jasmine tea extract.

[0049] (4) Centrifugation: The jasmine tea extract was centrifuged at 5000 rpm in a high-speed disc centrifuge to remove insoluble matter and obtain a clarified solution.

[0050] (5) Ceramic membrane filtration: The clarified liquid after centrifugation is filtered through a 500 nm ceramic membrane to obtain a filtered clarified liquid.

[0051] (6) Reverse osmosis membrane concentration: The clarified liquid after filtration was concentrated by reverse osmosis membrane. During the concentration process, the feed liquid temperature was controlled at 25°C, the concentration time was 2.5 h, the feed liquid concentration was 13 brix, and a concentrated liquid was obtained.

[0052] (7) Sterilization and drying: The concentrated solution is sterilized in a UHT sterilizer at a temperature of 110°C for 5 seconds to obtain a sterilized solution. The sterilized solution is freeze-dried in a freeze dryer at a pre-freezing temperature of -45°C and a drying temperature of 30°C. The freeze-drying step is performed for 20 hours to obtain freeze-dried jasmine tea powder.

[0053] Example 2

[0054] This embodiment provides a method for preparing freeze-dried jasmine tea powder, comprising the following steps:

[0055] (1) Tea pretreatment: The jasmine tea leaves are treated with a far-infrared aroma treatment machine at 70°C for 10 min, and then chopped into 8 meshes by a tea cutter.

[0056] (2) Soaking: Using the continuous countercurrent percolation device in the patent application number 2025204246521, add 63 kg of tea leaves according to 1 / 8 of the effective volume of a single percolation column (500 L), and spray water into the top of the percolation column (control the water temperature at 2°C). Stop adding water after the water covers the tea leaves and soak for 2 hours.

[0057] (3) Extraction: continuous countercurrent percolation extraction for 4 hours, the extraction temperature is controlled at 2°C, the extractant is an aqueous solution of an additive, wherein the mass of the additive is 2% of the mass of the tea leaves, and the additive is vitamin B1, sodium isoascorbate and citric acid in a mass ratio of 1:0.1:0.5 to obtain a jasmine tea extract.

[0058] (4) Centrifugation: The jasmine tea extract was centrifuged at 6000 rpm in a high-speed disc centrifuge to remove insoluble matter and obtain a clarified solution.

[0059] (5) Ceramic membrane filtration: The clarified liquid after centrifugation is filtered through a 500 nm ceramic membrane to obtain a filtered clarified liquid.

[0060] (6) Reverse osmosis membrane concentration: The clarified liquid after filtration is concentrated by reverse osmosis membrane. During the concentration process, the feed liquid temperature is controlled at 30°C, the concentration time is 2 hours, the feed liquid concentration is 15 brix, and a concentrated solution is obtained.

[0061] (7) Sterilization and drying: The concentrated solution is sterilized in a UHT sterilizer at a temperature of 110°C for 10 seconds to obtain a sterilized solution. The sterilized solution is freeze-dried in a freeze dryer at a pre-freezing temperature of -45°C and a drying temperature of 30°C. The freeze-drying step is performed for 15 hours to obtain freeze-dried jasmine tea powder.

[0062] Example 3

[0063] This embodiment provides a method for preparing freeze-dried jasmine tea powder, comprising the following steps:

[0064] (1) Tea pretreatment: Jasmine tea leaves are treated with far-infrared aroma treatment machine at 90°C for 3 min, and then chopped by a tea cutter into 12 mesh.

[0065] (2) Soaking: Using the continuous countercurrent percolation device in the patent application number 2025204246521, 42 kg of tea leaves were added according to 1 / 12 of the effective volume of a single percolation column (500 L). Water was sprayed into the top of the percolation column (the water temperature was controlled at 10°C). When the water covered the tea leaves, water was stopped and soaked for 0.5 h.

[0066] (3) Extraction: continuous countercurrent percolation extraction for 2 hours, the extraction temperature is controlled at 10°C, the extractant is an aqueous solution of an additive, wherein the mass of the additive is 0.5% of the mass of the tea leaves, and the additive is vitamin B1, sodium isoascorbate and citric acid in a mass ratio of 1:1:0.1 to obtain a jasmine tea extract.

[0067] (4) Centrifugation: The jasmine tea extract was centrifuged at 4000 rpm in a high-speed disc centrifuge to remove insoluble matter and obtain a clarified solution.

[0068] (5) Ceramic membrane filtration: The clarified liquid after centrifugation is filtered through a 500 nm ceramic membrane to obtain a filtered clarified liquid.

[0069] (6) Reverse osmosis membrane concentration: The clarified liquid after filtration was concentrated by reverse osmosis membrane. During the concentration process, the feed liquid temperature was controlled at 20°C, the concentration time was 3 hours, the feed liquid concentration was 12 brix, and a concentrated solution was obtained.

[0070] (7) Sterilization and drying: The concentrated solution is sterilized in a UHT sterilizer at a temperature of 110°C for 5 seconds to obtain a sterilized solution. The sterilized solution is freeze-dried in a freeze dryer at a pre-freezing temperature of -45°C and a drying temperature of 30°C. The freeze-drying step is performed for 25 hours to obtain freeze-dried jasmine tea powder.

[0071] Example 4

[0072] This embodiment provides a method for preparing freeze-dried jasmine tea powder, which differs from Embodiment 1 only in that in step (1), the tea leaves are chopped into 5 meshes, and the remaining steps are consistent with Embodiment 1.

[0073] Example 5

[0074] This embodiment provides a method for preparing freeze-dried jasmine tea powder, which differs from Embodiment 1 only in that in step (1), the tea leaves are chopped into 15 meshes, and the remaining steps are consistent with Embodiment 1.

[0075] Example 6

[0076] This embodiment provides a method for preparing freeze-dried jasmine tea powder, which differs from Embodiment 1 only in that in step (1), no far-infrared aroma treatment is performed, and the jasmine tea leaves are directly chopped into 10 meshes, and the remaining steps are consistent with Embodiment 1.

[0077] Example 7

[0078] This embodiment provides a method for preparing freeze-dried jasmine tea powder, which differs from Embodiment 1 only in that the temperature of the far-infrared aroma treatment in step (1) is adjusted to 95° C. and the time is adjusted to 1 min. The remaining steps are consistent with Embodiment 1.

[0079] Example 8

[0080] This embodiment provides a method for preparing freeze-dried jasmine tea powder, which differs from Embodiment 1 only in that the temperature of the far-infrared aroma treatment in step (1) is adjusted to 65° C. and the time is adjusted to 15 min. The remaining steps are consistent with Embodiment 1.

[0081] Example 9

[0082] This embodiment provides a method for preparing freeze-dried jasmine tea powder, which differs from Embodiment 1 only in that the ceramic membrane filtration in step (5) is not performed, that is, the clarified liquid obtained in step (4) is directly concentrated by reverse osmosis membrane in step (6), and the remaining steps are consistent with Embodiment 1.

[0083] Comparative Example 1

[0084] This comparative example provides a method for preparing freeze-dried jasmine tea powder, which differs from Example 1 only in that the additive in step (3) is adjusted to vitamin B1 and sodium isoascorbate in a mass ratio of 1:0.5, and the mass of the additive is maintained at 1% of the mass of the tea leaves. The remaining steps are consistent with Example 1.

[0085] Comparative Example 2

[0086] This comparative example provides a method for preparing freeze-dried jasmine tea powder, which differs from Example 1 only in that the additive in step (3) is adjusted to vitamin B1 and citric acid in a mass ratio of 1:0.3, and the mass of the additive is maintained at 1% of the mass of the tea leaves. The remaining steps are consistent with Example 1.

[0087] Comparative Example 3

[0088] This comparative example provides a method for preparing freeze-dried jasmine tea powder, which differs from Example 1 only in that the additive in step (3) is adjusted to sodium isoascorbate and citric acid in a mass ratio of 5:3, the mass of the additive is maintained at 1% of the mass of the tea leaves, and the remaining steps are consistent with Example 1.

[0089] Comparative Example 4

[0090] This comparative example provides a method for preparing freeze-dried jasmine tea powder, which differs from Example 1 only in that the water temperature of the soaking in step (2) and the extraction temperature in step (3) are both adjusted to 15° C., and the remaining steps are consistent with Example 1.

[0091] Test Example 1

[0092] Test on the retention degree of aroma components of freeze-dried tea powder

[0093] (1) Test samples: jasmine tea freeze-dried powder prepared in Examples 1 to 9 and Comparative Examples 1 to 4 and commercially available jasmine tea freeze-dried powder (jasmine tea freeze-dried powder from Yunnan Jinsabao Biotechnology Co., Ltd.).

[0094] (2) Test method:

[0095] (2.1) The aroma substances of each jasmine tea freeze-dried powder were extracted by solid phase microextraction (SPME) technology, and the aroma substances were detected by gas chromatography-mass spectrometry (GC-MS).

[0096] Qualitative detection: The experimental data are processed by the GC-MSD chemical workstation, and the unknown compounds are matched with the NIST spectral library and the Wiley spectral library for qualitative analysis. The identification result of the compound is determined only when both the positive and negative matching degrees are greater than 80 (the maximum value is 100).

[0097] Quantitative detection: The relative content of each volatile component in the freeze-dried jasmine tea powder was obtained by the Excel data processing system according to the internal standard method.

[0098] Determination of key flavor compounds: The relative odor activity value (ROAV) method was used to define the components that contribute most to the flavor of the sample.

[0099] (2.2) Using the above analytical method, the contents of the five key aroma substances of jasmine tea (benzyl acetate, linalool, methyl anthranilate, methyl salicylate, methyl benzoate) in the above test samples were detected, and the retention of each aroma substance was calculated. Retention of aroma substance (%) = a x / a 0 × 100%, where a x is the content of different aroma substances in the jasmine tea freeze-dried powder prepared in each embodiment and comparative example or the commercially available jasmine tea freeze-dried powder, a0 It is the content of aroma substances in the raw materials of jasmine tea.

[0100] The test results of the retention of different aroma substances are shown in Table 1:

[0101] Table 1

[0102]

[0103]

[0104] Test Example 2

[0105] Jasmine tea aroma JTF index test

[0106] (1) Test samples: untreated jasmine tea leaves, jasmine tea freeze-dried powder prepared in Examples 1 to 9 and Comparative Examples 1 to 4, and commercially available jasmine tea freeze-dried powder (jasmine tea freeze-dried powder from Yunnan Jinsabao Biotechnology Co., Ltd.).

[0107] (2) Test method: The relative contents of α-farnesene, cis-3-yl benzoate, methyl anthranilate, indole and linalool in the above test samples were tested with reference to the method of Test Example 1, and the jasmine tea aroma index was calculated.

[0108] The calculation formula of the jasmine tea aroma index (JTF index) is: JTF index=(relative content of α-farnesene+relative content of cis-3-benzoyl leaf alcohol+relative content of methyl anthranilate+relative content of indole) / relative content of linalool×100%.

[0109] The higher the JTF index, the higher the grade of the freeze-dried tea powder. The JTF indexes of different test samples are shown in Table 2:

[0110] Table 2

[0111]

[0112]

[0113] It can be seen from the test results in Tables 1 and 2 that the freeze-dried tea powder prepared by the preparation method of the present invention can well retain the aroma substances in the tea leaves. Compared with the tea raw materials, the contents of benzyl acetate, linalool, and methyl benzoate with floral and fruity aroma in the freeze-dried tea powder increased instead of decreased (the retention of aroma substances was >100%), indicating that the above aroma components were enriched in the preparation process of the present invention.

[0114] From the data comparison between Example 1 and Comparative Examples 1 to 3, it can be seen that vitamin B1, sodium isoascorbate and citric acid are added as additives to extract tea leaves, and the three components cooperate with each other and synergistically enhance the effect, which can improve the extraction effect of the aroma substances in the tea leaves; from the data comparison between Example 1 and Comparative Example 4, it can be seen that the immersion and extraction temperatures are controlled at 0 to 10°C, and a combination of low-temperature immersion and low-temperature extraction is adopted, so that the aroma components of the tea leaves are highly retained.

[0115] From the data comparison of Example 1 and Examples 4 to 5, it can be seen that chopping the tea leaves into 8 to 12 meshes before soaking and extraction can retain the aroma components in the tea leaves to a greater extent while ensuring the extraction rate; from the data comparison of Example 1 and Examples 6 to 8, it can be seen that the far-infrared aroma treatment is more conducive to stimulating the release of aroma substances, and at the same time, the temperature of the far-infrared aroma treatment is controlled at 70 to 90° C. and the time is controlled at 2 to 10 min, which can better retain the aroma components and improve the grade of the freeze-dried tea powder; from the comparison of Example 1 and Example 9, it can be seen that ceramic membrane filtration can filter the aroma components more accurately, and at the same time further remove impurities, reduce the influence of impurities on the stability of the aroma components, and ultimately improve the retention of the aroma components and the JTF index of the freeze-dried tea powder.

[0116] Test Example 3

[0117] Tea Extraction Rate Test

[0118] This test example tests the extraction rate of the jasmine tea freeze-dried powder prepared in Examples 1 to 9 and Comparative Examples 1 to 4. Extraction rate (%) = m 1 / m 0 ×100%, where m 1 is the mass of the prepared jasmine tea freeze-dried powder, m 0 is the mass of the tea leaves put in. The extraction rates of the freeze-dried jasmine tea powders prepared in each embodiment are shown in Table 3:

[0119] Table 3

[0120] Lyophilized powder samples Extraction rate Example 1 20.13％ Example 2 19.57％ Example 3 20.67％ Example 4 19.13％ Example 5 20.25％ Example 6 20.02％ Example 7 19.97％ Example 8 19.88％ Example 9 20.54％ Comparative Example 1 20.09％ Comparative Example 2 19.91％ Comparative Example 3 19.85％ Comparative Example 4 19.98％

[0121] It can be seen from the data in Table 3 that the preparation method involved in the present invention, in the large-scale production of large quantities of tea leaves (50kg level), the prepared jasmine tea freeze-dried powder still has a high extraction rate, indicating that the low-temperature extraction process involved in the present invention can maintain a high extraction rate while highly retaining the aroma effective ingredients, and is suitable for the process production of large-scale tea freeze-dried powder.

[0122] Test Example 4

[0123] In this test example, the untreated jasmine tea leaves, the jasmine tea freeze-dried powder prepared in Example 1, and the commercially available jasmine tea freeze-dried powder (jasmine tea freeze-dried powder of Yunnan Jinsabao Biotechnology Co., Ltd.) were subjected to mass spectrometry detection according to the method of Test Example 1, and their mass spectra were compared. The results are as follows: Figure 1 As shown, the similarity of each component in the sample was calculated based on the spectrum, and the results are shown in Table 4:

[0124] Table 4

[0125]

[0126] By the attached Figure 1 It can be seen from the data in Table 4 that the jasmine tea freeze-dried powder prepared in Example 1 of the present invention and the untreated jasmine tea raw material have a similarity of up to 94% in volatile components, which further proves that the preparation process of the jasmine tea freeze-dried powder of the present invention can well retain the components in the tea raw material and has a high degree of flavor retention.

[0127] The applicant declares that the present invention illustrates the technical solution of the present invention through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned embodiments, that is, it does not mean that the present invention must rely on the above-mentioned embodiments to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of various raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

[0128] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0129] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

Claims

1. A method for preparing freeze-dried tea powder, characterized in that: The preparation method comprises the following steps: chopping tea leaves, soaking them in water, extracting them with an aqueous solution of an additive, filtering them, concentrating the filtrate, and drying them to obtain the freeze-dried tea powder; The additives include vitamin B1, sodium isoascorbate and citric acid; The temperatures for soaking and extracting are both 0-10°C.

2. The preparation method according to claim 1, characterized in that: The chopping is to chop the tea leaves into 8-12 meshes.

3. The preparation method according to claim 1 or 2, characterized in that: The tea leaves are subjected to far-infrared aroma treatment before being chopped; Preferably, the temperature of the far-infrared aroma treatment is 70-90° C., and the time of the far-infrared aroma treatment is 2-10 min.

4. The preparation method according to any one of claims 1 to 3, characterized in that: The soaking time is 0.5 to 2 hours; Preferably, the extraction method is continuous countercurrent percolation extraction; Preferably, the extraction time is 2 to 4 hours.

5. The preparation method according to any one of claims 1 to 4, characterized in that: During the extraction process, the mass of the additive is 0.5-2% of the mass of the tea leaves; Preferably, the mass ratio of vitamin B1, sodium isoascorbate and citric acid is 1:(0.1-1):(0.1-0.5).

6. The preparation method according to any one of claims 1 to 5, characterized in that: The filtration includes filtration using a ceramic membrane.

7. The preparation method according to any one of claims 1 to 6, characterized in that: The concentration includes concentration using a reverse osmosis membrane; Preferably, the concentration time is 2 to 3 hours, and the concentrated solution obtained after the concentration has a Brix of 12 to 15 brix.

8. The preparation method according to any one of claims 1 to 7, characterized in that: The drying method includes freeze drying.

9. The preparation method according to any one of claims 1 to 8, characterized in that: The tea leaves include any one of scented tea, black tea, green tea or white tea, or a combination of at least two of them.

10. A freeze-dried tea powder prepared by the method for preparing freeze-dried tea powder according to any one of claims 1 to 9.

Images