A freeze-dried powder of a flavoured fresh tea liquor and a method for its preparation

Abstract

The application discloses a kind of seasoning fresh tea juice freeze-dried powder and preparation method thereof, belong to tea deep processing technical field.The application is with fresh tea leaf as raw material, by wilting, rolling, fermentation, hot water infiltration, filter pressing extraction to obtain clear tea juice;Another take jasmine, rose, sweet-scented osmanthus or mint to prepare clear seasoning liquid;Clear tea juice and clear seasoning liquid are mixed according to specific proportion, and are prepared by pre-freezing and vacuum freeze drying, and seasoning fresh tea juice freeze-dried powder is prepared.The application is with fresh tea leaf, combined with twice hot water infiltration filter pressing extraction and vacuum freeze drying process, maximum degree retains tea polyphenol and theanine active ingredient, and the tea polyphenol content of obtained product is significantly higher than that of dry tea prepared freeze-dried powder.Meanwhile, by the specific proportion of tea juice and flower extract, multi-component synergistic antioxidant effect is realized, and the technical problems of low active ingredient content, lack of synergistic effect, flavor and function difficult to consider of existing tea powder product are solved.

Description

Technical Field

[0001] This invention relates to the field of deep processing technology of tea, specifically to a freeze-dried powder of flavored fresh tea juice and its preparation method. Background Technology

[0002] Tea powder, as a convenient deep-processed tea product, is widely used in solid beverages, health foods, and flavor additives. Tea is rich in polyphenols, especially catechins, which are known potent natural antioxidants. These compounds effectively scavenge free radicals in the body and possess various physiological activities such as anti-oxidation, anti-inflammation, and anti-aging. Furthermore, theanine in tea not only gives tea its fresh and refreshing taste but also has calming, soothing, and immune-boosting effects.

[0003] However, existing tea powder products have the following obvious technical defects and shortcomings: The antioxidant activity of single tea powder is limited. Conventional tea powder or tea powder prepared from ordinary dried tea leaves often suffers significant loss of its heat-sensitive active ingredients during processing (such as drying, reconstitution, and high-temperature extraction). The low content of tea polyphenols directly limits its antioxidant capacity per unit mass.

[0004] Lack of synergistic effect of multiple components Current tea powder technologies typically rely solely on the antioxidant components of tea leaves themselves. While tea leaves contain various phenolic compounds, the potential for synergistic effects between different antioxidants has not been fully explored. Currently, there is no mature technical solution for scientifically combining specific high-quality tea powder with specific flower extracts and verifying their synergistic antioxidant effects.

[0005] It's difficult to balance product flavor and functionality. Many commercially available tea products with added floral ingredients are simply blends to improve flavor (such as jasmine tea and rose tea), with the purpose of aroma enhancement rather than functional enhancement. Furthermore, ordinary tea powder often lacks theanine content, resulting in a bitter and astringent taste with low freshness; even adding floral extracts cannot completely mask these undesirable flavors. More importantly, current technologies do not consider the molecular interactions between the antioxidants in floral extracts and tea polyphenols and theanine, failing to achieve a balance between flavor improvement and enhanced antioxidant function.

[0006] Therefore, developing a high-quality tea powder base material that simultaneously possesses high levels of tea polyphenols, high levels of theanine, and good flavor characteristics, and then scientifically blending it with suitable flower extracts to achieve synergistic antioxidant effects among the components while also optimizing the taste, is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0007] In view of the technical problems existing in the background art, the present invention addresses the above-mentioned deficiencies in the prior art by providing a method for preparing freeze-dried flavored fresh tea juice powder and the freeze-dried flavored fresh tea juice powder obtained by the method.

[0008] The present invention achieves the above objectives through the following technical solutions: A method for preparing a freeze-dried powder of flavored fresh tea juice includes the following steps: S1. The fresh tea leaves are withered until the moisture content of the withered leaves reaches 50% to 60%. S2. After withering, the withered leaves are kneaded for 30 to 60 minutes. S3. After kneading, spread the kneaded leaves out thickly and let them ferment for 2-3 hours. S4. After fermentation, place the fermented leaves in hot water for 20-25 minutes. S5. Place the soaked fermented leaves in a 200-300 mesh non-woven bag for the first pressure filtration. S6. After the first filter press, the fermented leaves are placed back into hot water for a second soaking for 15-20 minutes. S7. After the second soaking, the fermented leaves are placed in a 200-300 mesh non-woven bag for a second pressure filtration. S8. Mix the tea juice obtained from the first pressing and the tea juice obtained from the second pressing and filter it by centrifugation to obtain clear tea juice. S9. Take one of the following: jasmine, rose, mint or osmanthus flowers, wash and dry them, and use them as seasonings. Soak the dried seasonings in hot water for 30 to 40 minutes. S10. Place the soaked seasoning in a 200-300 mesh non-woven bag for pressure filtration to obtain seasoning filtrate; S11. The flavoring filtrate is centrifuged and filtered to obtain a clear flavoring liquid; S12. Mix the clarified tea juice obtained in step S8 with the clarified flavoring liquid obtained in step S11 evenly to obtain flavored tea juice. The mass ratio of the clarified flavoring liquid made from jasmine, mint and osmanthus to the clarified tea juice is 3:17, and the mass ratio of the clarified flavoring liquid made from rose to the clarified tea juice is 2:3. Pre-freeze the flavored tea juice in an environment of -45℃ to -10℃. S13. Place the pre-frozen flavored tea juice in a vacuum freeze dryer for drying to obtain freeze-dried flavored fresh tea juice powder.

[0009] Furthermore, in step S1, the fresh tea leaves are either large-leaf or small-leaf varieties.

[0010] Furthermore, in step S3, the thickness of the rolled leaves is 10-20 cm, and the fermentation temperature is 20-25℃.

[0011] Furthermore, in steps S4 and S6, the hot water temperature is 95–100 °C, and the mass ratio of fermented leaves to hot water is 1:2–1:3.

[0012] Furthermore, the centrifuge speed is the same in steps S8 and S11, which is 7000-15000 r / min.

[0013] Furthermore, in step S9, the hot water temperature is 95–100 °C, and the mass ratio of seasoning to hot water is 1:15–1:25.

[0014] Furthermore, in step S12, during pre-freezing, the mass of each plate of flavored tea juice is 3.3–4 kg, and the pre-freezing time is 6–10 h.

[0015] Furthermore, in step S13, the vacuum degree of the vacuum freeze dryer is 10-20 Pa, and the freeze drying time is 30-50 h.

[0016] The present invention also provides a freeze-dried powder of flavored fresh tea juice, which is prepared by any one of the above-described methods for preparing freeze-dried powder of flavored fresh tea juice.

[0017] Compared with the prior art, the beneficial effects of the present invention are: 1. High Retention of Active Ingredients: This invention uses fresh tea leaves as raw material. Through pretreatment such as withering, rolling, and fermentation, the soluble solids in the tea leaves are fully transformed and released. Then, the tea juice is obtained by hot water soaking combined with pressure filtration. Since the raw material is fresh leaves and pressure filtration is used instead of extraction, heat-sensitive active ingredients such as tea polyphenols and theanine are preserved to the maximum extent. The tea polyphenol content of tea powder 1# reaches 26.4% and theanine content reaches 1.19%, which is significantly higher than that of the freeze-dried powder made from dry tea in the comparative example (tea polyphenols 16.1% and theanine 0.98%).

[0018] 2. Synergistic Antioxidant Effect: This invention has determined the optimal blending ratio of clarified tea juice to clarified flavoring liquids from different flowers (jasmine, mint, and osmanthus: 3:17, rose: 2:3), which enables the antioxidant components in the flowers to have a synergistic effect with the tea polyphenols and theanine in the tea leaves, significantly improving the total antioxidant activity of the product.

[0019] 3. This invention, through the scientifically formulated ratio of flower extracts, not only endows the product with a natural floral aroma but also synergistically enhances its antioxidant function, solving the technical challenge of simultaneously improving flavor and enhancing function in existing technologies. This invention uses natural plants such as jasmine, rose, mint, or osmanthus as flavorings. A clear flavoring liquid is obtained through independent hot water infusion (95-100℃, 30-40 min), pressure filtration, and centrifugation processes, which is then mixed with tea juice. Compared to existing technologies that directly add fragrances or dried flower powder, the product obtained by this invention has a fresh, natural, and long-lasting aroma, avoiding the chemical feel of fragrances or the turbidity caused by powders. Furthermore, by preparing the flavoring liquid and tea juice separately before mixing, the ratio of tea to flowers can be flexibly adjusted according to needs, achieving controllable and stable flavor. Attached Figure Description

[0020] Figure 1 This is a flowchart illustrating the preparation method of the freeze-dried flavored fresh tea juice powder of the present invention. Figure 2 The results of the detection of tea polyphenols and theanine in the freeze-dried powder of jasmine flavored fresh tea juice in Example 1 are shown. Figure 3 The results show the detection of tea polyphenols and theanine in the freeze-dried tea powder of Comparative Example 1. Figure 4 This is a photograph of the freeze-dried jasmine-flavored fresh tea juice powder from Example 1. Figure 5 This is a photograph of the freeze-dried powder of rose-flavored fresh tea juice in Example 2; Figure 6 This is a photograph of the freeze-dried powder of osmanthus-flavored fresh tea juice in Example 3; Figure 7 This is a photograph of the freeze-dried powder of peppermint-flavored fresh tea juice from Example 4. Detailed Implementation

[0021] The technical solution of the present invention will be described in detail below through specific embodiments. These embodiments are for illustrative purposes only and should not be considered as limiting the scope of the invention. Experimental methods not specifically described in the embodiments are generally performed under conventional conditions or as recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0022] Reference Figure 1 Example 1: Freeze-dried powder of jasmine-flavored fresh tea juice S1. Withering treatment Take 100 kg of fresh leaves of large-leaf tea and place them in a withering trough for withering treatment. Control the ambient temperature at 25-28℃, the relative humidity at 65%-70%, and the withering time at 8-10 hours until the moisture content of the withered leaves reaches 55%.

[0023] S2, Kneading process Place the withered leaves in a rolling machine and roll them for 45 minutes. Adjust the rolling pressure gradually according to the principle of light-heavy-light to break the tea cell tissue appropriately.

[0024] S3, Fermentation Treatment After kneading, spread the kneaded leaves in a 15cm thick layer for fermentation. The fermentation environment temperature is controlled at 22℃, the relative humidity is above 90%, and the fermentation time is 2.5 hours, until the fermented leaves turn a bright reddish-brown and emit a pure floral and fruity fragrance.

[0025] S4, First Immersion After fermentation, place the fermented leaves in 98℃ hot water at a mass ratio of 1:2.5 and soak for 22 minutes.

[0026] S5, First Filtration The soaked fermented leaves were placed in a 250-mesh non-woven bag and filtered for the first time using a plate and frame filter press. The filtrate was then collected.

[0027] S6, Second Immersion After the first filtration, the fermented leaves were placed in 98℃ hot water at a mass ratio of 1:2.5 and soaked for 18 minutes.

[0028] S7, Second Filtration After the second soaking, the fermented leaves were placed in a 250-mesh non-woven bag for a second pressure filtration, and the filtrate was collected.

[0029] S8, Centrifugal Filtration The tea juice obtained from the first filtration is mixed with the tea juice obtained from the second filtration and placed in a tubular centrifuge. It is centrifuged at 10,000 r / min to remove fine suspended matter and obtain clear tea juice for later use.

[0030] S9, marinating Take 5 kg of jasmine flowers, wash and dry them, then place them in 98℃ hot water at a mass ratio of 1:20 and soak for 35 minutes.

[0031] S10, Seasoning Filtering After soaking, the jasmine flowers were placed in a 250-mesh non-woven bag for pressure filtration, and the flavoring filtrate was collected.

[0032] S11, Centrifugal filtration of flavoring liquid The flavoring filtrate was placed in a tubular centrifuge and centrifuged at 10,000 r / min to obtain a clear jasmine flavoring liquid.

[0033] S12, compounding and pre-freezing The clarified tea juice obtained in step S8 and the clarified jasmine flavoring liquid obtained in step S11 are mixed evenly at a mass ratio of 17:3 (i.e., the mass ratio of clarified flavoring liquid to clarified tea juice is 3:17) to obtain flavored tea juice. The flavored tea juice is divided into freeze-drying trays with a mass of 3.5 kg per tray and pre-frozen at -30℃ for 8 hours.

[0034] S13, Vacuum freeze drying The pre-frozen flavored tea juice was placed in a vacuum freeze dryer and freeze-dried at a vacuum degree of 15 Pa for 40 hours to obtain jasmine flavored fresh tea juice freeze-dried powder (e.g., Figure 4 (As shown).

[0035] Reference Figure 1 Example 2: Freeze-dried powder of rose-flavored fresh tea juice S1, withering treatment Take 100 kg of fresh tea leaves of small and medium-sized leaves and place them in a withering trough for withering treatment. Control the ambient temperature at 26-30℃, the relative humidity at 65%-70%, and the withering time at 9-11 hours until the moisture content of the withered leaves reaches 58%.

[0036] S2, Kneading process Place the withered leaves in a rolling machine and roll them for 50 minutes. Adjust the rolling pressure gradually according to the principle of light-heavy-light.

[0037] S3, Fermentation Treatment After kneading, spread the kneaded leaves in a 12cm thickness for fermentation. The fermentation environment temperature should be controlled at 24℃, the relative humidity above 90%, and the fermentation time should be 2 hours, until the fermented leaves turn a bright reddish-brown.

[0038] S4, First Immersion After fermentation, place the fermented leaves in 95℃ hot water at a mass ratio of 1:3 and soak for 25 minutes.

[0039] S5, First Filtration The soaked fermented leaves were placed in a 300-mesh non-woven bag and filtered for the first time using a plate and frame filter press. The filtrate was then collected.

[0040] S6, Second Immersion After the first filtration, the fermented leaves were placed in 95℃ hot water at a mass ratio of 1:3 and soaked for 20 minutes.

[0041] S7, Second Filtration After the second soaking, the fermented leaves were placed in a 300-mesh non-woven bag for a second pressure filtration, and the filtrate was collected.

[0042] S8, Centrifugal Filtration The tea juice obtained from the first filtration is mixed with the tea juice obtained from the second filtration and placed in a tubular centrifuge. The mixture is centrifuged and filtered at a speed of 12000 r / min to obtain clear tea juice for later use.

[0043] S9, marinating Take 5 kg of rose petals (double-petaled red roses), wash and dry them, then place them in 95℃ hot water at a mass ratio of 1:18 and soak for 40 minutes.

[0044] S10, Seasoning Filtering The soaked rose petals were placed in a 300-mesh non-woven bag for pressure filtration, and the flavoring filtrate was collected.

[0045] S11, Centrifugal filtration of flavoring liquid The flavoring filtrate was placed in a tubular centrifuge and centrifuged at 12,000 r / min to obtain a clear rose flavoring liquid.

[0046] S12, compounding and pre-freezing The clarified tea juice obtained in step S8 and the clarified rose flavoring liquid obtained in step S11 are mixed evenly at a mass ratio of 2:3 (i.e., the mass ratio of clarified flavoring liquid to clarified tea juice is 2:3) to obtain flavored tea juice. The flavored tea juice is divided into freeze-drying trays with a mass of 3.8 kg per tray and pre-frozen at -40℃ for 7 hours.

[0047] S13, Vacuum freeze drying The pre-frozen flavored tea juice was placed in a vacuum freeze dryer and freeze-dried at a vacuum degree of 12 Pa for 45 hours to obtain freeze-dried powder of rose flavored fresh tea juice (e.g. Figure 5 (As shown).

[0048] Reference Figure 1 Example 3: Osmanthus-flavored fresh tea juice freeze-dried powder S1, withering treatment Take 100 kg of fresh leaves of large-leaf tea and place them in a withering trough for withering treatment. Control the ambient temperature at 24-28℃, the relative humidity at 60%-65%, and the withering time at 10-12 hours until the moisture content of the withered leaves reaches 52%.

[0049] S2, Kneading process Place the withered leaves in a rolling machine and roll them for 35 minutes.

[0050] S3, Fermentation Treatment After kneading, spread the kneaded leaves in a thickness of 18cm for fermentation. The fermentation environment temperature is controlled at 21℃, the relative humidity is above 90%, and the fermentation time is 3 hours.

[0051] S4, First Immersion After fermentation, place the fermented leaves in 100℃ hot water at a mass ratio of 1:2 and soak for 20 minutes.

[0052] S5, First Filtration The soaked fermented leaves were placed in a 200-mesh non-woven bag for the first pressure filtration, and the filtrate was collected.

[0053] S6, Second Immersion After the first filtration, the fermented leaves were placed in 100℃ hot water at a mass ratio of 1:2 and soaked for 15 minutes.

[0054] S7, Second Filtration After the second soaking, the fermented leaves were placed in a 200-mesh non-woven bag for a second pressure filtration, and the filtrate was collected.

[0055] S8, Centrifugal Filtration The tea juice obtained from the first filtration is mixed with the tea juice obtained from the second filtration, and then centrifuged at 8000 r / min to obtain clear tea juice for later use.

[0056] S9, marinating Take 3 kg of osmanthus flowers, wash and dry them, then place them in 100℃ hot water at a mass ratio of 1:25 and soak for 30 minutes.

[0057] S10, Seasoning Filtering After soaking, the osmanthus flowers were placed in a 200-mesh non-woven bag for pressure filtration, and the flavoring filtrate was collected.

[0058] S11, Centrifugal filtration of flavoring liquid The flavoring filtrate was centrifuged at 8000 r / min to obtain a clear osmanthus flavoring liquid.

[0059] S12, compounding and pre-freezing The clarified tea juice obtained in step S8 and the clarified osmanthus flavoring liquid obtained in step S11 are mixed evenly at a mass ratio of 17:3 (i.e., the mass ratio of clarified flavoring liquid to clarified tea juice is 3:17) to obtain flavored tea juice. The flavored tea juice is divided into freeze-drying trays with a mass of 3.3 kg per tray and pre-frozen at -20℃ for 10 hours.

[0060] S13, Vacuum freeze drying The pre-frozen flavored tea juice was placed in a vacuum freeze dryer and freeze-dried at a vacuum degree of 18 Pa for 35 hours to obtain freeze-dried osmanthus flavored fresh tea juice powder (e.g., Figure 6 (As shown).

[0061] Reference Figure 1 Example 4: Freeze-dried powder of peppermint-flavored fresh tea juice S1, withering treatment Take 100 kg of fresh tea leaves of small and medium-sized leaves and place them in a withering trough for withering treatment. Control the ambient temperature at 25-29℃, the relative humidity at 62%-68%, and the withering time at 8.5-10.5 hours until the moisture content of the withered leaves reaches 56%.

[0062] S2, Kneading process Place the withered leaves in a rolling machine and roll them for 40 minutes. Adjust the rolling pressure gradually according to the principle of light-heavy-light.

[0063] S3, Fermentation Treatment After kneading, spread the kneaded leaves in a 14cm thick layer for fermentation. The fermentation environment temperature is controlled at 23℃, the relative humidity is above 90%, and the fermentation time is 2.5 hours.

[0064] S4, First Immersion After fermentation, place the fermented leaves in 96℃ hot water at a mass ratio of 1:2.8 and soak for 23 minutes.

[0065] S5, First Filtration The soaked fermented leaves were placed in a 280-mesh non-woven bag and filtered for the first time using a plate and frame filter press. The filtrate was then collected.

[0066] S6, Second Immersion After the first filtration, the fermented leaves were placed in 96℃ hot water at a mass ratio of 1:2.8 and soaked for 17 minutes.

[0067] S7, Second Filtration After the second soaking, the fermented leaves were placed in a 280-mesh non-woven bag for a second pressure filtration, and the filtrate was collected.

[0068] S8, Centrifugal Filtration The tea juice obtained from the first filtration is mixed with the tea juice obtained from the second filtration and placed in a tubular centrifuge. The mixture is then centrifuged at 9000 r / min to obtain clear tea juice for later use.

[0069] S9, marinating Take 4 kg of mint, wash and dry it, then place it in 96℃ hot water at a mass ratio of 1:22 and soak for 38 minutes.

[0070] S10, Seasoning Filtering The soaked mint was placed in a 280-mesh non-woven bag for pressure filtration, and the flavoring filtrate was collected.

[0071] S11, Centrifugal filtration of flavoring liquid The flavoring filtrate was placed in a tubular centrifuge and centrifuged at 9000 r / min to obtain a clear mint flavoring liquid.

[0072] S12, compounding and pre-freezing The clarified tea juice obtained in step S8 and the clarified mint flavoring liquid obtained in step S11 are mixed evenly at a mass ratio of 17:3 (i.e., the mass ratio of clarified flavoring liquid to clarified tea juice is 3:17) to obtain flavored tea juice. The flavored tea juice is divided into freeze-drying trays with a mass of 3.6 kg per tray and pre-frozen at -35℃ for 9 hours.

[0073] S13, Vacuum freeze drying The pre-frozen flavored tea juice was placed in a vacuum freeze dryer and freeze-dried at a vacuum degree of 14 Pa for 42 hours to obtain the freeze-dried powder of mint-flavored fresh tea juice (e.g. Figure 7 (As shown).

[0074] Comparative Example 1: Freeze-dried powder prepared from dried tea leaves S1, Raw Material Processing Take 100 kg of dried tea leaves of the same variety as in Example 1.

[0075] S2, Hot water extraction Place the dried tea leaves in 95℃ hot water at a mass ratio of 1:15 and steep for 40 minutes.

[0076] S3, Coarse Filter After extraction, coarse filtration is performed using a 200-mesh filter cloth, and the filtrate is collected.

[0077] S4, Centrifugal Filtration The filtrate was centrifuged at 10,000 r / min to obtain clear tea juice.

[0078] S5. Pre-freezing and drying The clarified tea juice was divided into freeze-drying trays at a mass of 3.5 kg per tray, pre-frozen at -30℃ for 8 hours, and then freeze-dried at a vacuum of 15 Pa for 40 hours to obtain freeze-dried tea powder (tea powder 2#).

[0079] Experimental Example 1: Comparative Detection of Tea Polyphenol and Theanine Content 1. Experimental Objective The contents of tea polyphenols and theanine in the freeze-dried jasmine flavored fresh tea juice prepared in Example 1 (tea powder 1#) and the freeze-dried dry tea powder prepared in Comparative Example 1 (tea powder 2#) were determined to verify the significant advantages of the technical solution of the present invention in retaining the active ingredients of tea polyphenols and theanine.

[0080] 2. Experimental Materials Sample 1 (Tea Powder 1#): Freeze-dried jasmine-flavored fresh tea juice prepared in Example 1 Sample 2 (Tea Powder 2#): Dry tea freeze-dried powder prepared in Comparative Example 1 3. Detection Method The Yunnan Provincial Analysis and Testing Center was commissioned to conduct the testing.

[0081] Testing equipment: high performance liquid chromatograph, ultraviolet-visible spectrophotometer. Each sample was measured in triplicate, and the average value was taken.

[0082] 4. Test Results Test report numbers: KYHX202511058 (tea powder 1#), KYHX202511059 (tea powder 2#), test results are attached. Figure 2 , Figure 3 As shown.

[0083] From the appendix Figure 2 , Figure 3 It can be seen that the freeze-dried powder of flavored fresh tea juice prepared by the present invention (tea powder 1#) has a tea polyphenol content of 26.4% and a theanine content of 1.19%; while the freeze-dried powder prepared from dry tea in Comparative Example 1 (tea powder 2#) has a tea polyphenol content of only 16.1% and a theanine content of only 0.98%. The tea polyphenol content of tea powder 1# is 64.0% higher than that of the comparative example, and the theanine content is 21.4% higher.

[0084] The above results demonstrate that this invention, using fresh tea leaves as raw material and combining a two-stage hot water soaking and filtration extraction process with low-temperature vacuum freeze-drying, can significantly increase the content of tea polyphenols and theanine in the final product. This is because: fresh tea leaves are not subjected to high-temperature drying, thus preserving heat-sensitive components intact; the two-stage soaking and filtration process, compared to a single extraction, allows for more complete extraction of active components from tea cell cells; and low-temperature vacuum freeze-drying, compared to hot air drying or spray drying, minimizes the degradation and loss of heat-sensitive components. This experimental result proves that this invention effectively solves the technical problems of "limited antioxidant activity of single-origin tea powder" and "insufficient theanine content and bitter taste" in the prior art.

[0085] Experiment Example 2: Comparative Detection of Synergistic Antioxidant Activity of Jasmine Flower Flavoring 1. Experimental Objective The antioxidant activity (DPPH free radical scavenging rate) of the jasmine-flavored fresh tea juice freeze-dried powder prepared in Example 1 (sample A), pure tea freeze-dried powder without added flower extract (control A1), freeze-dried powder made only from jasmine extract (control A2), and dry tea freeze-dried powder prepared in Comparative Example 1 (tea powder 2#) was measured respectively to verify the synergistic effect of the combination of clarified tea juice and jasmine clarified flavoring liquid in this invention.

[0086] 2. Experimental Materials Sample A: Freeze-dried jasmine-flavored fresh tea juice prepared in Example 1 Comparison A1: Pure tea freeze-dried powder prepared according to the same method as in Example 1, but without the addition of jasmine flavoring liquid. Comparison A2: Freeze-dried powder of flower extract prepared solely from jasmine flowers using the same method as in Example 1 (excluding tea components). Tea Powder 2#: Freeze-dried tea powder prepared in Comparative Example 1 3. Detection Method The antioxidant activity of each sample was determined using the DPPH free radical scavenging method. Each lyophilized powder sample was reconstituted with deionized water to the same concentration (1.0 mg / mL). 100 μL of the sample solution was mixed with 100 μL of DPPH working solution (0.2 mmol / L), and the mixture was reacted in the dark for 30 min. The absorbance was measured at 517 nm. Ascorbic acid (Vc, 0.1 mg / mL) was used as a positive control. Each sample was measured in triplicate, and the average value was taken. The DPPH free radical scavenging rate was calculated using the following formula: Clearance rate (%) = [1 - (A sample - A background) / A blank] × 100% Meanwhile, to verify the synergistic effect, the theoretical additive clearance rate was calculated: theoretical value = clearance rate of pure tea freeze-dried powder × tea juice ratio in the compound ratio + clearance rate of flower freeze-dried powder × flavoring liquid ratio in the compound ratio (jasmine is 3:17, that is, tea juice accounts for 85% and flavoring liquid accounts for 15%).

[0087] 4. Test Results Table 1. Results of Detection of Synergistic Antioxidant Activity of Jasmine Flavoring 5. Results Analysis As shown in Table 1, the DPPH free radical scavenging rate of the jasmine-flavored fresh tea juice freeze-dried powder prepared in Example 1 reached 85.7%, significantly higher than that of pure tea freeze-dried powder (72.6%), jasmine freeze-dried powder (51.4%), and comparative tea powder 2# (58.2%). More importantly, the actual scavenging rate of Example 1 (85.7%) was significantly higher than the theoretical additive scavenging rate (69.4%), with a relative improvement rate of 23.5%. This fully demonstrates that there is a clear synergistic effect between the antioxidant components such as tea polyphenols in the tea juice and the antioxidant components in the jasmine extract, rather than a simple functional additive effect.

[0088] Experiment Example 3: Comparative Detection of Synergistic Antioxidant Activity of Rose Flavoring 1. Experimental Objective The antioxidant activity (DPPH free radical scavenging rate) of the freeze-dried powder of rose flavored fresh tea juice prepared in Example 2 (sample B), the freeze-dried powder of pure tea without added flower extract (control B1), the freeze-dried powder made only from rose extract (control B2), and the freeze-dried powder of dry tea prepared in Comparative Example 1 (tea powder 2#) were measured respectively to verify the synergistic effect of the combination of clarified tea juice and rose flavoring liquid in this invention.

[0089] 2. Experimental Materials Sample B: Freeze-dried powder of rose-flavored fresh tea juice prepared in Example 2 Control B1: Pure tea freeze-dried powder prepared according to the same method as in Example 2, but without the addition of rose flavoring liquid. Comparison B2: Freeze-dried powder of flower extract prepared solely from rose petals using the same method as in Example 2 (excluding tea components). Tea Powder 2#: Freeze-dried tea powder prepared in Comparative Example 1 3. Detection Method Similar to Experiment 2, the proportion of pure tea freeze-dried powder in the rose blend was 40% (2:3), and the proportion of rose freeze-dried powder was 60%.

[0090] 4. Test Results Table 2 Results of Detection of Synergistic Antioxidant Activity of Rose Flavoring 5. Results Analysis As shown in Table 2, the DPPH free radical scavenging rate of the rose-flavored fresh tea juice freeze-dried powder prepared in Example 2 reached 82.9%, significantly higher than that of pure tea freeze-dried powder (73.1%), rose freeze-dried powder (63.8%), and comparative tea powder 2# (58.2%). More importantly, the actual scavenging rate of Example 2 (82.9%) was significantly higher than the theoretical additive scavenging rate (67.5%), with a relative improvement rate of 22.8%, fully demonstrating that the combination of tea juice and rose extract has a clear synergistic antioxidant effect.

[0091] Experiment Example 4: Comparative Detection of Synergistic Antioxidant Activity of Osmanthus Flavoring 1. Experimental Objective The antioxidant activity (DPPH free radical scavenging rate) of the freeze-dried powder of osmanthus flavored fresh tea juice prepared in Example 3 (sample C), the freeze-dried powder of pure tea without added flower extract (control C1), the freeze-dried powder made only from osmanthus extract (control C2), and the freeze-dried powder of dry tea prepared in Comparative Example 1 (tea powder 2#) were measured respectively to verify the synergistic effect of the combination of clarified tea juice and osmanthus clarified flavoring liquid in this invention.

[0092] 2. Experimental Materials Sample C: Freeze-dried Osmanthus-flavored Fresh Tea Juice Powder prepared in Example 3 Control C1: Pure tea freeze-dried powder prepared according to the same method as in Example 3, but without the addition of osmanthus flavoring liquid. Comparison C2: Freeze-dried powder of flower extract prepared solely from osmanthus flowers using the same method as in Example 3 (excluding tea components). Tea Powder 2#: Freeze-dried tea powder prepared in Comparative Example 1 3. Detection Method Similar to Experiment 2, the ratio of osmanthus compounding was 3:17, which is the mass ratio of osmanthus clarified flavoring liquid to clarified tea juice, i.e., pure tea freeze-dried powder accounted for 85% and osmanthus freeze-dried powder accounted for 15%.

[0093] 4. Test Results Table 3 Results of Detection of Synergistic Antioxidant Activity of Osmanthus Flavoring 5. Results Analysis As shown in Table 3, the DPPH free radical scavenging rate of the osmanthus-flavored fresh tea juice freeze-dried powder prepared in Example 3 reached 84.3%, which was significantly higher than that of pure tea freeze-dried powder (72.6%), osmanthus freeze-dried powder (49.7%), and comparative tea powder 2# (58.2%). The actual scavenging rate of Example 3 (84.3%) was significantly higher than the theoretical additive scavenging rate (69.2%), with a relative improvement rate of 21.8%, proving that the combination of tea juice and osmanthus extract has a clear synergistic antioxidant effect.

[0094] Experiment Example 5: Comparative Detection of Synergistic Antioxidant Activity of Peppermint Flavoring 1. Experimental Objective The antioxidant activity (DPPH free radical scavenging rate) of the freeze-dried powder of peppermint flavored fresh tea juice prepared in Example 4 (sample D), the freeze-dried powder of pure tea without added flower extract (control D1), the freeze-dried powder made only from peppermint extract (control D2), and the freeze-dried powder of dry tea prepared in Comparative Example 1 (tea powder 2#) were measured respectively to verify the synergistic effect of the combination of clarified tea juice and peppermint clarified flavoring liquid in this invention.

[0095] 2. Experimental Materials Sample D: Freeze-dried powder of peppermint-flavored fresh tea juice prepared in Example 4 Control D1: Pure tea freeze-dried powder prepared according to the same method as in Example 4, but without the addition of peppermint flavoring liquid. Control D2: Freeze-dried powder of flower extract prepared solely from peppermint using the same method as in Example 4 (excluding tea components). Tea Powder 2#: Freeze-dried tea powder prepared in Comparative Example 1 3. Detection Method Similar to Experiment 2, the ratio of peppermint compound was 3:17, which is the mass ratio of peppermint clarified flavoring liquid to clarified tea juice, that is, pure tea freeze-dried powder accounted for 85% and peppermint freeze-dried powder accounted for 15%.

[0096] 4. Test Results Table 4 Results of Detection of Synergistic Antioxidant Activity of Peppermint Flavor 5. Results Analysis As shown in Table 4, the DPPH free radical scavenging rate of the peppermint-flavored fresh tea juice freeze-dried powder prepared in Example 4 reached 86.2%, which was significantly higher than that of pure tea freeze-dried powder (72.6%), peppermint freeze-dried powder (53.1%), and comparative tea powder 2# (58.2%). The actual scavenging rate of Example 4 (86.2%) was significantly higher than the theoretical additive scavenging rate (69.7%), with a relative improvement rate of 23.7%, demonstrating that the combination of tea juice and peppermint extract has a clear synergistic antioxidant effect.

[0097] A Comparison of Synergistic Effects of Four Seasonings Table 5 Summary of the synergistic antioxidant activity of four seasonings As summarized in Table 5, the four seasonings selected in this invention (jasmine, rose, osmanthus, and mint) all exhibited significant synergistic antioxidant effects when combined with clarified tea juice in a specific ratio, with relative increases exceeding 21%. Mint (23.7%) and jasmine (23.5%) showed the most significant increases. In contrast, Comparative Example 1, prepared using dried tea without the addition of flower extracts, had a DPPH scavenging rate of only 58.2%, far lower than that of the embodiments of this invention.

[0098] The above-mentioned experimental examples 2-5 fully demonstrate that, through the specific ratio of clarified tea juice and clarified flavoring liquid, the four different flower extracts can produce a synergistic effect with the antioxidant components such as tea polyphenols and theanine in tea, rather than a simple functional additive effect. This series of testing experiments proves that the present invention effectively solves the technical problem of "lack of multi-component synergistic effect" in the background art, achieving a unity of "flavor improvement and enhanced antioxidant function".

Claims

1. A method for preparing a freeze-dried powder of flavored fresh tea juice, characterized in that, Includes the following steps: S1. The fresh tea leaves are withered until the moisture content of the withered leaves reaches 50% to 60%. S2. After withering, the withered leaves are kneaded for 30 to 60 minutes. S3. After kneading, spread the kneaded leaves out thickly and let them ferment for 2-3 hours. S4. After fermentation, place the fermented leaves in hot water for 20-25 minutes. S5. Place the soaked fermented leaves in a 200-300 mesh non-woven bag for the first pressure filtration. S6. After the first filter press, the fermented leaves are placed back into hot water for a second soaking for 15-20 minutes. S7. After the second soaking, the fermented leaves are placed in a 200-300 mesh non-woven bag for a second pressure filtration. S8. Mix the tea juice obtained from the first pressing and the tea juice obtained from the second pressing and filter it by centrifugation to obtain clear tea juice. S9. Take one of the following: jasmine, rose, mint or osmanthus flowers, wash and dry them, and use them as seasonings. Soak the dried seasonings in hot water for 30 to 40 minutes. S10. Place the soaked seasoning in a 200-300 mesh non-woven bag for pressure filtration to obtain seasoning filtrate; S11. The flavoring filtrate is centrifuged and filtered to obtain a clear flavoring liquid; S12. Mix the clarified tea juice obtained in step S8 with the clarified flavoring liquid obtained in step S11 evenly to obtain flavored tea juice. The mass ratio of the clarified flavoring liquid made from jasmine, mint and osmanthus to the clarified tea juice is 3:17, and the mass ratio of the clarified flavoring liquid made from rose to the clarified tea juice is 2:

3. Pre-freeze the flavored tea juice in an environment of -45℃ to -10℃. S13. Place the pre-frozen flavored tea juice in a vacuum freeze dryer for drying to obtain freeze-dried flavored fresh tea juice powder.

2. The method for preparing the freeze-dried flavored fresh tea juice powder as described in claim 1, characterized in that, In step S1, the fresh tea leaves are either large-leaf or small-leaf varieties.

3. The method for preparing the freeze-dried flavored fresh tea juice powder as described in claim 1, characterized in that, In step S3, the thickness of the rolled leaves is 10-20 cm, and the fermentation temperature is 20-25℃.

4. The method for preparing flavored fresh tea juice and freeze-dried powder as described in claim 1, characterized in that, In steps S4 and S6, the hot water temperature is 95–100 °C, and the mass ratio of fermented leaves to hot water is 1:2–1:

3.

5. The method for preparing the freeze-dried flavored fresh tea juice powder as described in claim 1, characterized in that, The centrifuge speed is the same in steps S8 and S11, which is 7000-15000 r / min.

6. The method for preparing the freeze-dried flavored fresh tea juice powder as described in claim 1, characterized in that, In step S9, the hot water temperature is 95-100 ℃, and the mass ratio of seasoning to hot water is 1:15-1:

25.

7. The method for preparing the freeze-dried flavored fresh tea juice powder as described in claim 1, characterized in that, In step S12, during pre-freezing, the weight of each plate of flavored tea juice is 3.3-4 kg, and the pre-freezing time is 6-10 hours.

8. The method for preparing the freeze-dried powder of flavored fresh tea juice as described in claim 1, characterized in that, In step S13, the vacuum degree of the vacuum freeze dryer is 10-20 Pa, and the freeze drying time is 30-50 h.

9. A freeze-dried powder of flavored fresh tea juice, characterized in that, It is prepared by the method described in any one of claims 1-9 for preparing freeze-dried flavored fresh tea juice powder.

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