Method for preparing sterile low-dissolved-oxygen concentrated tea extract, tea extract, method for preparing instant tea beverage and tea beverage

Abstract

The invention relates to a method for preparing a sterile low-dissolved-oxygen concentrated tea extracting solution. The method comprises the following steps: a) extracting tea leaves with water for 1 minute to 2 hours; b) separating the tea leaves from the tea soup, and cooling the tea soup to room temperature or keeping the temperature of the tea soup at 5-25 DEG C to obtain an initial tea extracting solution; c) removing dissolved oxygen until the dissolved oxygen concentration of the initial tea extracting solution is below 5.0 mg / L; d) sterilizing to obtain a final sterile low-dissolved-oxygen concentrated tea extracting solution; wherein the Brix degree Brix of the sterile low dissolved oxygen concentrated tea extracting solution is 0.3 to 3.3. The invention also relates to a product obtained by the method, a tea beverage based on the product and a preparation method of the tea beverage. According to the method, oxidation of tea polyphenol can be reduced, the flavor of the tea beverage is close to that of the freshly-brewed tea, quality degradation is delayed, and the production cost is low.

Description

Technical Field

[0001] The present invention relates to a method for preparing a tea extract, a tea extract obtained by the method, a method for preparing a tea beverage, and a tea beverage obtained by the method. Specifically, the present invention relates to a method for preparing a sterile low-dissolved oxygen concentrated tea extract, a sterile low-dissolved oxygen concentrated tea extract obtained by the method, a method for preparing a ready-to-drink tea beverage, and a ready-to-drink tea beverage obtained by the method. Background Art

[0002] Tea leaves, which are the raw materials of tea beverages, are rich in antioxidant tea polyphenols. Tea polyphenol molecules have phenolic hydroxyl groups, which can dissociate H(+), thus showing acidity. Tea polyphenols are easily oxidized, especially in aqueous solution or in the presence of polyphenol oxidase, where phenolic hydroxyl groups are dissociated to generate oxygen anions, which further lose electrons to generate o-quinones, which can capture hydrogen from other substances and be reduced to phenols, and can also polymerize to produce reddish-brown polymers. Therefore, in the process of preparing tea beverages, the prior art tries every possible means to reduce the damage of oxygen to tea polyphenols in tea and the adverse effects on the quality of tea beverages, for example:

[0003] CN 102754711B discloses a tea beverage and a production method thereof, which includes measures of "all temporary storage tanks are sealed tanks during the filtering or clarifying process", "≥99% pure nitrogen is introduced into the mixing tank in advance to replace the air in the tank body", etc., for "full-process nitrogen filling protection", regardless of cost.

[0004] JP4411250B2 discloses a method for preparing a tea beverage, which includes the steps of extracting tea leaves and adjusting the pH of the obtained tea extract to 5.0 to 6.0 to obtain a blended liquid; mixing nitrogen with the blended liquid and applying a negative pressure of more than 0.01 MPa; after the step of applying the negative pressure, maintaining the blended liquid under atmospheric pressure and pressurizing it for 30 seconds to 20 minutes for stabilization. The blended liquid of JP4411250B2 needs to be replaced and stabilized with nitrogen under negative pressure conditions, and the long processing time affects production efficiency, and the negative pressure processing will cause aroma loss.

[0005] In summary, there is an urgent need for a method for preparing tea beverages that can overcome the above defects, especially a method for preparing tea beverages that can simultaneously reduce the oxidation of tea polyphenols, make the flavor of the tea beverage close to freshly brewed tea, and have a low dissolved oxygen content in the final product, thereby delaying quality deterioration and reducing production costs. Summary of the invention

[0006] The technical problem to be solved by the present invention is to overcome the following disadvantages of the current tea beverage preparation methods: adding a large amount of antioxidants, which affects the taste of the final product; or sparing no effort to create a low dissolved oxygen environment, resulting in unnecessary odor loss and too high production costs; to provide a method for preparing a tea beverage with good protection effect of tea polyphenols, reasonable dosage of antioxidants, the flavor of the final product being close to that of freshly brewed tea, delaying the quality deterioration and having low cost.

[0007] The inventors of the present invention unexpectedly found that by preparing a sterile low dissolved oxygen concentrated tea extract, thereby strictly controlling the amount of dissolved oxygen, and with the adjustment of the preparation steps, without the need to overly maintain or create an absolute low dissolved oxygen condition, it is possible to simultaneously achieve the technical effects of not affecting the taste of the final product, delaying the quality deterioration, and reducing the production cost.

[0008] The present invention provides a method for preparing a sterile low dissolved oxygen concentrated tea extract, which comprises:

[0009] a) Extracting tea leaves with water for 1 minute to 2 hours;

[0010] b) Separating the tea leaves from the tea soup,

[0011] Cooling the tea soup to room temperature or maintaining the tea soup at a temperature of 5°C to 25°C to obtain an initial tea extract;

[0012] c) Removing dissolved oxygen until the dissolved oxygen concentration of the initial tea extract is below 5.0 mg / L;

[0013] d) Obtaining a final sterile low dissolved oxygen concentrated tea extract by sterilization;

[0014] Wherein the Brix of the sterile low dissolved oxygen concentrated tea extract is 0.3 to 3.3.

[0015] The present invention also provides a sterile low dissolved oxygen concentrated tea extract prepared by the method of the present invention.

[0016] The present invention also provides a method for preparing an instant tea beverage, which comprises:

[0017] i) Mixing the sterile low dissolved oxygen concentrated tea extract obtained by the method of the present invention or the sterile low dissolved oxygen concentrated tea extract of the present invention and sterile deoxygenated water to obtain a tea beverage, ii) Sterile filling the tea beverage prepared in step i); and

[0018] Wherein the dissolved oxygen concentration of the sterile deoxygenated water in step i) is below 1.0 mg / L, more preferably below 0.8 mg / L, and below 0.5 mg / L.

[0019] The present invention also provides an instant tea beverage prepared by the method of the present invention.

[0020] The beneficial effects of the present invention compared with the prior art are as follows: By controlling the amount of dissolved oxygen in the concentrated tea extract, without adding a large amount of antioxidants and without using a large amount of nitrogen gas replacement protection, it is possible to simultaneously achieve the technical effects of not affecting the taste of the final product, making the flavor of the final product close to that of freshly brewed tea, delaying quality deterioration, and reducing production costs.

[0021] From the following detailed description, other objects, features and advantages of the present invention will become apparent. However, it should be understood that the detailed description and specific embodiments, although indicating preferred embodiments of the present invention, are given by way of example only, since various changes and improvements within the spirit and scope of the present invention will become apparent to those skilled in the art from this detailed description. Detailed Embodiments

[0022] The method for preparing a sterile low-dissolved oxygen concentrated tea extract provided by the present invention includes:

[0023] a) Extracting tea leaves with water for 1 minute to 2 hours, preferably 5 minutes to 1 hour, more preferably 10 minutes to 40 minutes;

[0024] b) Separating the tea leaves from the tea soup,

[0025] Cooling the tea soup to room temperature or maintaining the tea soup at a temperature of 5°C to 25°C, preferably 10°C to 20°C, more preferably 13°C to 17°C to obtain an initial tea extract;

[0026] c) Removing dissolved oxygen until the dissolved oxygen concentration of the initial tea extract is 5.0 mg / L or less, preferably 3.0 mg / L or less, more preferably 1.0 mg / L or less;

[0027] d) Obtaining a final sterile low-dissolved oxygen concentrated tea extract through sterilization;

[0028] Wherein the Brix of the sterile low-dissolved oxygen concentrated tea extract is 0.3 to 3.3.

[0029] As used herein, "dissolved oxygen (DO)" refers to the oxygen concentration in an aqueous solution. The inventors of the present invention have found that by controlling the dissolved oxygen concentration of the initial tea extract and coordinating with the sterilization conditions for the dissolved oxygen concentration of the initial tea extract, it is possible to simultaneously achieve the technical effects of not affecting the taste of the final product, making the flavor of the final product close to that of freshly brewed tea, delaying quality deterioration, and reducing production costs.

[0030] The tea leaves described herein in the present invention can be common tea varieties in the art, preferably selected from the group consisting of green tea, oolong tea, yellow tea, black tea, white tea, dark tea, scented tea, and any combination thereof.

[0031] Preferably, in addition to tea leaves, the step a) further contains other plant raw materials, such as the plant materials with both medicinal and edible properties; red dates, wolfberries, hawthorns, longans, sesame seeds, nuts (peanuts, walnut kernels, etc.), dried fruits (raisins, dried apples, tangerine peels, dried pears, lemon slices, etc.), flowers (roses, chrysanthemums, gardenias, sophora flowers, osmanthus flowers, honeysuckle, etc.), yam, platycodon, liquorice, pteridophytum, ginseng, etc. The other plant raw materials can add interesting properties to the final product, such as increasing the fragrance, taste, efficacy, etc. of the final product.

[0032] Preferably, the weight-to-volume ratio of tea leaves to water in step a) is 10-200 g / l, more preferably 20-150 g / l, and more preferably 30-70 g / l. The time and temperature for extracting tea leaves here depend on the type of tea leaves. Hot extraction can be performed under conditions close to those of freshly brewed tea, or cold extraction can be performed in accordance with the principle of minimizing the destruction of the main components of the tea raw materials (such as tea polyphenols, etc.). The shape of the tea leaves in step a) can be the original shape of dry tea leaves; or crushed (broken) broken tea leaves, the particle size of the broken tea leaves is in the range of 4-50 mesh (0.3 mm to 4 mm), more preferably in the range of 10-30 mesh (0.5 mm-2 mm). In step a), water is used for extraction at 5°C to 35°C for 15-120 minutes, preferably at 5°C to 35°C for 15-70 minutes, or at 35°C to 100°C for 3-30 minutes. It is further preferred to extract at 20°C to 30°C for 15-50 minutes, under which the flavor is more refreshing and the production efficiency is high; preferably 40°C-98°C, and further preferably 60°C to 95°C, under which the tea soup obtained has a richer flavor.

[0033] The present invention can remove dissolved oxygen by a method commonly used in the art. Preferably, the removal of dissolved oxygen in step c) is to add 0.1-1.0 wt% of antioxidants based on the total weight of the initial tea extract to the initial tea extract and / or to vacuum treat the initial tea extract at a temperature below 0.8 bar; more preferably, the removal of dissolved oxygen in step c) is to add 0.1-1.0 wt% of antioxidants based on the total weight of the initial tea extract to the initial tea extract alone; further preferably, the removal of dissolved oxygen in step c) is to add 0.1-0.8 wt% of antioxidants based on the total weight of the initial tea extract to the initial tea extract alone and to vacuum treat the initial tea extract at a temperature below 0.5 bar. The added antioxidant may bring other flavors to the tea soup, and the vacuum negative pressure treatment is prone to lose the aroma. The combination of the two can reduce the amount of antioxidants used and the aroma lost by the vacuum negative pressure.

[0034] The "content of soluble solids" or "Brix" in the present invention refers to the content of all compounds dissolved in water in a liquid, including sugars, acids, vitamins, minerals, etc. The Brix of the aseptic low-dissolved-oxygen concentrated tea extract obtained by the method of the present invention is 0.3 to 3.3. Further preferably, the Brix of the aseptic low-dissolved-oxygen concentrated tea extract is 0.5 to 2.4, and further preferably 0.6 to 1.8.

[0035] In addition to controlling the dissolved oxygen in step c), more preferably, the dissolved oxygen concentration of the water used in step a) is less than 1.2 mg / L, preferably less than 1.0 mg / L, more preferably less than 0.8 mg / L, and most preferably the water used in step a) is deoxygenated water. More preferably, it is "deoxygenated RO water", that is, RO water treated by a deoxygenation method to obtain RO water with a lower dissolved oxygen concentration. The "RO water (reverse osmosis water)" is deionized water produced by a reverse osmosis-ion exchange device; its preparation process may include: raw water → multi-media filter → activated carbon filter → precision filter → reverse osmosis device.

[0036] The extraction step in step a) can be carried out under stirring, wherein the stirring is carried out at a rate of 10 - 60 RPM, preferably 15 - 40 RPM, or preferably 10 - 20 RPM, and lasts for 10 seconds to 30 minutes, preferably 30 seconds to 20 minutes, more preferably 1 minute to 10 minutes. The stirring can be continuous stirring or intermittent stirring.

[0037] The antioxidant in step c) is selected from ascorbic acid, sodium ascorbate, sodium erythorbate, potassium ascorbate, and potassium erythorbate, and combinations thereof. The addition amount of the antioxidant in step c) is 0.2 - 0.6% by weight, preferably 0.25 - 0.35% by weight, based on the total weight of the initial tea extract.

[0038] Preferably, the dissolved oxygen concentration of the initial tea extract before treatment in step c) is 5 mg / L to the saturated dissolved oxygen.

[0039] The present invention obtains a sterile low dissolved oxygen concentrated tea extract obtained by the method of the present invention. The sterile low dissolved oxygen concentrated tea extract of the present invention is a "tea concentrate", that is, a tea soup with a high content of soluble solids (Brix), which can be diluted with an appropriate amount of water to obtain a drinkable tea beverage. The "N-fold concentrate" mentioned in the present invention, such as "4-fold concentrate", refers to one portion of such a concentrate, and the concentrate is diluted with four volumes of water to obtain an RTD beverage. Similarly, "1-fold concentrate", "2-fold concentrate", "3-fold concentrate", "5-fold concentrate", etc. here refer to one portion of the concentrate diluted with 1 portion, 2 portions, 3 portions, 5 portions, etc. of water by volume to obtain an RTD beverage. The present invention preferably uses a 2-5 fold concentrate, more preferably a 3-4 fold concentrate.

[0040] The "ready-to-drink beverage" or "RTD beverage" described in the present invention refers to a liquid beverage that can be directly consumed without further adding liquid. The present invention provides a method for preparing an instant tea beverage, which includes:

[0041] i) Mixing the sterile low dissolved oxygen concentrated tea extract obtained by the method of the present invention or the sterile low dissolved oxygen concentrated tea extract of the present invention and sterile deoxygenated water to obtain a tea beverage, and ii) aseptically filling the tea beverage prepared in step i); and

[0042] wherein the dissolved oxygen concentration of the sterile deoxygenated water in step i) is 1.0 mg / L or less, more preferably 0.8 mg / L or less, and 0.5 mg / L or less.

[0043] The sterile low dissolved oxygen concentrated tea extract and the sterile deoxygenated water are filled into the final container simultaneously / batchwise to achieve mixing. The volume ratio of the sterile low dissolved oxygen concentrated tea extract to the sterile deoxygenated water is 1:1 to 1:10, preferably 1:1 to 1:6, more preferably 1:2 to 1:4.

[0044] Preferably, the sterile low dissolved oxygen concentrated tea extract of the present invention can be filled into the final container first, and then the sterile deoxygenated water can be filled into the final container.

[0045] The sterile deoxygenated water in step (i) is degassed by a method selected from vacuum negative pressure degassing, high-temperature degassing, antioxidant-added degassing, membrane separation deoxygenation, and nitrogen replacement deoxygenation. Preferably, the sterile deoxygenated water in step (i) is degassed by vacuum negative pressure at a corresponding temperature (for example, degassed at a temperature of 65°C - 80°C within a vacuum degree range of -0.6 bar to -0.8 bar, preferably degassed at a vacuum degree of -0.7 bar and a temperature of 70°C); high-temperature degassing is preferably carried out at a temperature of 104°C - 108°C, more preferably at 104°C; antioxidant-added degassing preferably adds 0.004% - 0.02% of an antioxidant, more preferably adds an antioxidant-to-dissolved oxygen ratio of 5.5 (calculated as vitamin C):1 (calculated as oxygen); membrane separation deoxygenation preferably uses a polypropylene membrane or a polytetrafluoroethylene membrane for degassing. More preferably, RO water treated by a deoxygenation method is used to obtain RO water with a lower dissolved oxygen concentration. The "RO water (reverse osmosis water)" is deionized water produced by a reverse osmosis-ion exchange device; its preparation process may include: raw water → multi-media filter → activated carbon filter → precision filter → reverse osmosis device.

[0046] When producing tea beverages by the method of the present invention, the sterile low-dissolved-oxygen concentrated tea extract and the sterile deoxygenated water described in the present invention are prepared under different conditions respectively. Thus, since the sterile low-dissolved-oxygen concentrated tea extract of the present invention belongs to concentrated tea soup, and the solvent in the concentrated tea soup is limited and can dissolve less oxygen itself, using less antioxidant can further maintain the dissolved oxygen in the concentrated tea soup at a very low level. Although the content of the antioxidant in the final product is reduced, it can still ensure the reduction of the oxidation of tea polyphenols. And the sterile low-dissolved-oxygen concentrated tea extract described in the present invention can be used as a separate semi-finished product for storage and transportation when needed. For example, during the peak season of tea raw material production, a large amount of the sterile low-dissolved-oxygen concentrated tea extract described in the present invention can be preferentially prepared and stored separately, and then normal production with continuous output can be carried out in the off-season. In addition, in the sterilization process, compared with sterilizing a large-volume final product under mild conditions, sterilizing a smaller-volume concentrated tea soup under mild conditions can save more energy, improve production efficiency, and reduce production costs. The preferred sterilization method for the sterile low-dissolved-oxygen concentrated tea extract described in the present invention can use the ultra-high temperature instantaneous sterilization method (UHT), with a sterilization temperature of 98 degrees Celsius to 145 degrees Celsius and a sterilization time of 4 seconds to 60 seconds.

[0047] In addition, for the separately treated sterile deoxygenated water, since it does not contain sensitive active ingredients and there is no need to worry about the destruction of the active ingredients, very harsh conditions can be selected for more rapid and thorough sterilization. The mixing of the sterile low-dissolved-oxygen concentrated tea extract and the sterile deoxygenated water described in the present invention can be achieved in a sterile filling environment.

[0048] The present invention also provides a tea beverage obtained by the method of the present invention. The final product of the tea beverage of the present invention has a flavor close to that of freshly brewed tea, delays the deterioration of quality, and has a low production cost.

[0049] The following further elaborates on the objectives, structural features, and advantages of the present invention by listing specific embodiments. The following embodiments are only listed for better illustrating the present invention and do not serve to limit the scope of protection.

[0050] The testing method used in the embodiments of the present invention:

[0051] 1) Determination of the content of soluble solids / Brix: Use a Rudolph refractometer J157 from the United States. Place the sample to be measured into the sample cell, start the measurement, and read the value after the display stabilizes.

[0052] 2) Determination of dissolved oxygen / DO concentration: Use an HQ40d dissolved oxygen meter. Insert the dissolved oxygen electrode into the liquid to be measured and read the value after the display stabilizes.

[0053] 3) Method for determining aroma components:

[0054] Apply solid-phase microextraction (SPME), combined with gas chromatography and mass spectrometry (GC-MS) coupling technology to analyze the aroma components of the tea beverage:

[0055] SPME: Weigh 5 g of the tea beverage sample and add it to a 20 mL headspace vial. Select Fiber as DVB / CAR / PDMS. The instrument is equipped with a Gerstel automatic injection arm (MPS). The temperature of the incubator is 50 °C, the equilibration time is 5 min, and the shaking frequency is 250 rpm at the same time; then the Fiber adsorbs the sample for 30 min. Desorb it at the injection port equipped with an SPME liner.

[0056] GC-MS conditions: The GCMS model is Agilent 7890A-5975C. Select an HP-INNOWAX chromatographic column; the carrier gas is He (purity ≥ 99.999%); splitless injection; the GC is set for programmed temperature rise, with an initial temperature of 45 °C, finally rising to 240 °C and holding for 5 min. The ion source is an EI source, the electron energy is 70 eV, and the data acquisition mode is full scan (Scan). The qualitative data of volatile substances are identified by retrieving the NIST 14.L standard spectral library, and the analysis software is Agilent's Chemstation software. The odor activity value OAV is obtained by dividing the peak area integrated by the Chemstation software by the corresponding threshold.

[0057] 4) Determination of tea polyphenols: Adopt the ferrous tartrate colorimetric method, referring to GB / T 21733-2008.

[0058] 5) Determination of catechins: Detection was carried out using a Waters high-performance liquid chromatograph with reference to GB / T 8313-2018.

[0059] 6) Determination of ascorbic acid: High-performance liquid chromatography was adopted with reference to GB5009.86—2016.

[0060] 7) Sensory evaluation: The tea beverage samples were randomly numbered with three digits, and 10 professional tasters evaluated the tea beverage samples with reference to the sensory evaluation criteria for tea (refer to the literature Sensory Evaluation Techniques, 2nd Edition, Meilgaard Civille Carr. Scaling introduction).

[0061] Example 1

[0062] This example is used to illustrate the preparation method of the sterile low-dissolved oxygen concentrated tea extract and the preparation method of the tea beverage of the present invention.

[0063] 3.0 kg of Longjing green tea leaves were stirred and extracted in 108 L of RO water at 30 °C at a speed of 20 revolutions per minute (RPM) for 30 minutes. After removing the tea leaves, the tea soup was cooled to 15 °C and passed through centrifugation (centrifuge LAPX404 SGP-31C flow rate: 200 L / hr) and filtration (200-mesh sieve) to obtain 107 L of primary tea soup extract with a Brix of 0.64 (measured by the above-mentioned J157 refractometer).

[0064] The primary tea soup extract was diluted with RO water to a secondary tea soup concentrate with a Brix of 0.60, and its dissolved oxygen was measured (dissolved oxygen concentration was 7.3 mg / L). After heating to 65 °C through a plate heat exchanger, its dissolved oxygen was measured (dissolved oxygen concentration was 2.7 mg / L); then it was sterilized by a high-temperature and high-pressure autoclave (model: GR85DA, 121 °C, 5 min), and cooled to room temperature in a closed environment to obtain the sterile low-dissolved oxygen concentrated tea extract (4-fold tea soup concentrate) of the present invention.

[0065] The sterile low-dissolved oxygen concentrated tea extract of the present invention was mixed with 4 times the volume of sterile deoxygenated water (the dissolved oxygen concentration of the sterile deoxygenated water was close to 0 mg / L) in a sterile filling environment to obtain the tea beverage of the present invention (dissolved oxygen concentration was 0.54 mg / L). That is, the sterile low-dissolved oxygen concentrated tea extract of the present invention was diluted with sterile deoxygenated water to form a ready-to-drink (RTD) tea beverage, and the sterile deoxygenated water did not introduce dissolved oxygen.

[0066] Comparative Example 1

[0067] 3.0 kg of Longjing green tea leaves were stirred and extracted in 108 L of RO water at 30 °C at a speed of 20 revolutions per minute (RPM) for 30 minutes. After removing the tea leaves, the tea soup was cooled to 15 °C and centrifuged (centrifuge flow rate: 200 L / hr) and filtered (200-mesh sieve) to obtain 107 L of a primary tea soup extract with a Brix of 0.64 (measured by the above-mentioned J157 refractometer).

[0068] The primary tea soup extract was diluted with RO water to a tea soup with a Brix of 0.15, and its dissolved oxygen was measured (dissolved oxygen concentration: 8.5 mg / L); it was heated to 65 °C through a plate heat exchanger, then degassed under a vacuum negative pressure of -0.7 Bar, and its dissolved oxygen was measured again. After sterilization treatment in a high-temperature and high-pressure autoclave (model: GR85DA, 121 °C, 5 min) and cooled to room temperature in a closed environment, an RTD tea beverage of the prior art was obtained (dissolved oxygen concentration: 1.8 mg / L).

[0069] Table 1 below shows the difference in the dissolved oxygen concentration (mg / L) between the sterile low-dissolved oxygen concentrated tea extract obtained in Example 1 and the RTD tea beverage and the RTD tea beverage obtained in Comparative Example 1:

[0070] Table 1: Test results of dissolved oxygen concentration

[0071]

[0072] As can be seen from Table 1, the sterile low-dissolved oxygen concentrated tea extract of Example 1 (4-fold tea soup concentrate) does not require vacuum degassing treatment. The dissolved oxygen after being heated to 65 °C through a plate heat exchanger only before sterilization is 2.7 mg / L. After preparing the RTD tea beverage of the present invention, the dissolved oxygen of the final product RTD tea beverage is only 0.54 mg / L, which is significantly lower than the dissolved oxygen (1.8 mg / L) of the RTD tea beverage of Comparative Example 1 of the prior art that has undergone vacuum negative pressure degassing treatment. In the final product RTD tea beverage of the present invention, due to the low dissolved oxygen content, it is beneficial to the longer-term preservation of the product with stable quality, and the production cost is also reduced due to the reduction of the vacuum degassing treatment.

[0073] In addition, the odor of the sterile low-dissolved oxygen concentrated tea extract obtained in Example 1 and the RTD tea beverage obtained in Comparative Example 1 was also tested, and the test results are shown in Table 2 below:

[0074] Table 2: Test results of main aroma components

[0075]

[0076] It can be seen from Table 2 that the aseptic low dissolved oxygen concentrated tea extract (4 times tea soup concentrate) of Example 1 does not need to be subjected to vacuum degassing treatment. Compared with the RTD tea beverage of the prior art comparative example 1 which has undergone vacuum negative pressure degassing treatment, the aseptic low dissolved oxygen concentrated tea extract of Example 1 of the present invention has a significantly lower content of unpleasant gases (such as sulfide smell, green smell, dust smell and grease smell), and the pleasant floral and fruity flavors are retained in the aseptic low dissolved oxygen concentrated tea extract of Example 1 of the present invention.

[0077] Example 2

[0078] This example is used to illustrate the differences in the retention rate of VC (indirectly reflecting the content of dissolved oxygen), the retention rate of tea active ingredients (reflecting the quality of tea soup), and the content of dimethyl trisulfide (dimethyl trisulfide), an unpleasant component of rotten cabbage taste, and sensory aspects after the aseptic low dissolved oxygen concentrated tea extract of the present invention with different concentrations and the same antioxidant (vitamin C) addition amount is treated with UHT sterilization.

[0079] 1.2 kg of steamed green tea leaves were extracted in 30 L of RO water at 55° C. at 20 revolutions per minute (RPM) for 20 minutes. After the tea leaves were removed, the tea soup was cooled to 15° C., centrifuged (centrifuge flow rate: 200 L / hr), and filtered (200 mesh screen) to obtain 22 L of primary tea soup extract with a Brix of 1.39 (measured by the above-mentioned J157 refractometer).

[0080] The primary tea extract was diluted with RO water to obtain secondary tea concentrates of Brix 0.55, 0.91 and 1.28, and 0.30% vitamin C was added by weight; then sterilized in a high-temperature autoclave (model: GR85DA, 121°C, 5 min), and cooled to room temperature in a closed environment to obtain the sterile low dissolved oxygen concentrated tea extracts of the present invention (Examples 2-1, 2-2 and 2-3). The retention rates of VC and tea active ingredients (epigallocatechin gallate (EGCG), catechins and tea polyphenols) after sterilization were tested.

[0081] The sterile low dissolved oxygen concentrated tea extracts of the present invention described in Examples 2-1, 2-2 and 2-3 are mixed with 2, 4 and 6 volumes of sterile deoxygenated water (the dissolved oxygen concentration of the sterile deoxygenated water is close to 0 mg / L) under a sterile filling environment to obtain the RTD tea beverage final products of Examples 2-1, 2-2 and 2-3 of the present invention.

[0082] Comparative Example 2

[0083] The primary tea soup extract of Example 2 was diluted in one step with RO water to obtain the final product of an RTD tea beverage with a Brix of 0.18. Vitamin C at a weight percentage of 0.06% was added, and then it was sterilized by a high-temperature and high-pressure autoclave (model: GR85DA, 121 °C, 5 min), and cooled to room temperature in a closed environment to obtain the final product of the RTD tea beverage of Comparative Example 2. The retention rate of VC and the retention rates of tea active ingredients (epigallocatechin gallate (EGCG), catechin, and tea polyphenols) after sterilization were detected.

[0084] The contents and sensory differences of the unpleasant component dimethyl trisulfide in the final products of the RTD tea beverages of Examples 2-1, 2-2, and 2-3 and Comparative Example 2 were detected.

[0085] Table 3 shows the differences in many aspects between the aseptic low-dissolved-oxygen concentrated tea extracts and the final products of tea beverages of Examples 2-1, 2-2, and 2-3 and the final products of the RTD tea beverages of Comparative Example 2.

[0086] Table 3

[0087]

[0088] It can be seen from Table 3 that for concentrated tea soups of different multiples, with the addition of the same amount of VC, after UHT sterilization, there are differences in the retention rates of VC and catechin. Based on the above experimental results, on the premise of comprehensively considering the flavor of the final product, when the 4-fold concentrated tea soup of Example 2-2 is added with 0.30% of VC, the flavor retention of the final product after sterilization and the retention rates of VC and catechin after sterilization are the best. It can also be seen that the quality of the tea beverages of the present invention prepared by separately sterilizing the concentrated tea soup and the dilution water in Examples 2-1, 2-2, and 2-3 is significantly better than the quality of the tea beverages prepared by one-step dilution in place and then sterilization in Comparative Example 2.

[0089] Example 3

[0090] This example is used to illustrate the differences in the retention rate of VC (indirectly reflecting the content of dissolved oxygen), the retention rates of tea active ingredients (reflecting the quality of the tea soup), and the content and sensory aspects of the unpleasant component dimethyl trisulfide in the aseptic low-dissolved-oxygen concentrated tea extracts of the present invention with the same concentration and different combinations of antioxidant (vitamin C) addition amounts after UHT sterilization treatment.

[0091] 1.2 kg of steamed green tea leaves were stirred and extracted in 30 L of RO water at 55 °C at a speed of 20 revolutions per minute (RPM) for 20 minutes. After removing the tea leaves, the tea soup was cooled to 15 °C and centrifuged (centrifuge flow rate: 200 L / hr) and filtered (200-mesh sieve) to obtain 22 L of a primary tea soup extract with a Brix of 1.39 (measured by the above-mentioned J157 refractometer).

[0092] The primary tea soup extract was diluted with RO water to a secondary tea soup concentrate with a Brix of 0.91, and vitamin C was added at 0.30%, 0.45%, and 0.15% by weight, respectively. Then, it was sterilized by a high-temperature and high-pressure autoclave (model: GR85DA, 121 °C, 5 min) and cooled to room temperature in a closed environment to obtain the sterile low-dissolved-oxygen concentrated tea extract of the present invention (Examples 3-1, 3-2, and 3-3). The retention rates of VC and the retention rates of tea active ingredients (epigallocatechin gallate (EGCG), catechin, and tea polyphenols) were tested after sterilization, respectively.

[0093] The sterile low-dissolved-oxygen concentrated tea extracts of the present invention in Examples 3-1, 3-2, and 3-3 were respectively mixed with 4 times the volume of sterile deoxygenated water (the dissolved oxygen concentration of the sterile deoxygenated water is close to 0 mg / L) in a sterile filling environment to obtain the final RTD tea beverage products of Examples 3-1, 3-2, and 3-3 of the present invention.

[0094] The content and sensory differences of the unpleasant component dimethyl trisulfide in the final RTD tea beverage products of Examples 3-1, 3-2, and 3-3 and Comparative Example 2 were detected.

[0095] Table 4 shows the differences in many aspects between the sterile low-dissolved-oxygen concentrated tea extracts and the final tea beverage products of Examples 3-1, 3-2, and 3-3 and the final RTD tea beverage products of Comparative Example 2.

[0096] Table 4

[0097]

[0098] It can be seen from Table 4 that in 4-fold concentrated tea soup, different amounts of VC were added. After UHT sterilization, there were differences in the retention rates of VC and catechin. According to the above experimental results, on the premise of comprehensively considering the flavor of the final product, when 0.30% of VC was added to the 4-fold concentrated tea soup of Example 3-1, the flavor retention of the final product after sterilization and the retention rates of VC and catechin after sterilization were the best. It can also be seen that the quality of the tea beverages of the present invention prepared by separately sterilizing the concentrated tea soup and the dilution water in Examples 3-1, 3-2, and 3-3 was significantly better than that of the tea beverages prepared by one-step dilution and then sterilization in Comparative Example 2.

[0099] Table 5 shows the effects of the treatments at different heating temperatures before UHT sterilization on the dissolved oxygen content in the concentrated tea soup of the aseptic low-dissolved-oxygen concentrated tea extract and the final tea beverage product in Example 3-1 and the final RTD tea beverage product in Comparative Example 2.

[0100] Table 5

[0101]

[0102] As can be seen from Table 5, compared with Comparative Example 3 that prepares the RTD final product by one-step dilution in the prior art, in the present invention, during the process of preparing the final tea beverage product, a technical route of first preparing an aseptic low-dissolved-oxygen concentrated tea extract and then mixing it with aseptic deoxygenated water (the dissolved oxygen concentration of the aseptic deoxygenated water is close to 0 mg / L) in an aseptic filling environment is adopted. Therefore, during the heating treatment process of the preparation, the amount of oxygen redissolved into the semi-finished product is small, and the dissolved oxygen content of the final tea beverage product of the present invention is also significantly reduced. In addition, as the heating treatment temperature before UHT sterilization increases, the dissolved oxygen amount decreases.

[0103] Example 4

[0104] This example is used to illustrate the effects of different concentrated tea soup concentrations, the same antioxidant (vitamin C) addition amount, and different heating temperatures on the dissolved oxygen content of the aseptic low-dissolved-oxygen concentrated tea extract of the present invention.

[0105] 1.2 kg of steamed green tea leaves were stirred and extracted in 22 L of deoxygenated RO water at 25 °C (dissolved oxygen concentration: 1.83 mg / L) at a speed of 20 revolutions per minute (RPM) for 20 minutes. After removing the tea leaves, the tea soup was cooled to 15 °C and then centrifuged (centrifuge flow rate: 200 L / hr) and filtered (200-mesh sieve) to obtain 16 L of primary tea soup extract with a Brix of 1.43 (measured by the above-mentioned J157 refractometer).

[0106] The primary tea soup extract was respectively diluted with deoxygenated RO water (dissolved oxygen concentration: 1.83 mg / L) to secondary tea soup concentrates with Brix 0.78 (3-fold concentrated tea soup), 0.98 (4-fold concentrated tea soup), and 1.17 (5-fold concentrated tea soup), and vitamin C with a weight percentage of 0.30% was respectively added; after standing at room temperature for 30 minutes, the dissolved oxygen content was measured for the first time, and then after heating to 65 °C through a plate heat exchanger, the dissolved oxygen content was measured for the second time. Then, after being sterilized by a high-temperature and high-pressure autoclave (model: GR85DA, 121 °C, 5 min) and cooled to room temperature in a closed environment, the aseptic low-dissolved-oxygen concentrated tea extract of the present invention (Examples 4-1, 4-2, and 4-3) was obtained.

[0107] The aseptic low-dissolved-oxygen concentrated tea extracts described in Examples 4-1, 4-2, and 4-3 of the present invention were respectively mixed with 3 times, 4 times, and 5 times the volume of aseptic deoxygenated water (the dissolved oxygen concentration of the aseptic deoxygenated water is close to 0 mg / L) in an aseptic filling environment to obtain the final RTD tea beverage products of Examples 4-1, 4-2, and 4-3 of the present invention.

[0108] Comparative Example 3

[0109] The primary tea soup extract of Example 4 was diluted in one step with RO water to obtain the final RTD tea beverage product with a Brix of 0.20. Vitamin C was added at a weight percentage of 0.06%. It was left standing at room temperature for 30 minutes, and its dissolved oxygen content was measured for the first time. Then, it was heated to 65 °C through a plate heat exchanger, and its dissolved oxygen content was measured for the second time. After being sterilized by a high-temperature and high-pressure autoclave (model: GR85DA, 121 °C, 5 min), it was cooled to room temperature in a closed environment to obtain the final RTD tea beverage product of Comparative Example 3.

[0110] Table 6 shows the differences in dissolved oxygen content between the aseptic low-dissolved-oxygen concentrated tea extracts and the final tea beverage products of Examples 4-1, 4-2, and 4-3 and the final RTD tea beverage product of Comparative Example 3.

[0111] Table 6

[0112]

[0113] As can be seen from Table 6, compared with Comparative Example 3 that prepares the final RTD product by one-step dilution in the prior art, in the present invention, since in the process of preparing the final tea beverage product, a technical route of first preparing an aseptic low-dissolved-oxygen concentrated tea extract and then mixing it with aseptic deoxygenated water (the dissolved oxygen concentration of the aseptic deoxygenated water is close to 0 mg / L) in an aseptic filling environment is adopted, the amount of oxygen redissolved into the semi-finished product during the heating treatment process of preparation is small, and the dissolved oxygen content of the final tea beverage product of the present invention is also significantly reduced.

[0114] Example 5

[0115] This example is used to illustrate the influence of the same concentrated-concentration tea soup and different addition amounts of antioxidant (vitamin C) on the dissolved oxygen content of the aseptic low-dissolved-oxygen concentrated tea extract of the present invention.

[0116] 1.2 kg of steamed green tea leaves were stirred and extracted in 22 L of deoxygenated RO water at 25 °C (dissolved oxygen concentration: 1.83 mg / L) at a speed of 20 revolutions per minute (RPM) for 20 minutes. After removing the tea leaves, the tea soup was cooled to 15 °C and centrifuged (centrifuge flow rate: 200 L / hr) and filtered (200-mesh sieve) to obtain 16 L of primary tea soup extract with a Brix of 1.43 (measured by the above J157 refractometer).

[0117] The primary tea soup extract was diluted with deoxygenated RO water (dissolved oxygen concentration: 1.83 mg / L) to a secondary tea soup concentrate with a Brix of 0.98 (4-fold concentrated tea soup), and vitamin C was added at 0.24%, 0.30%, and 0.36% by weight respectively; it was left standing at room temperature for 30 minutes, and the dissolved oxygen content was measured for the first time. Then, after heating to 65 °C through a plate heat exchanger, the dissolved oxygen content was measured for the second time. After sterilization treatment in a high-temperature and high-pressure autoclave (model: GR85DA, 121 °C, 5 min), it was cooled to room temperature in a closed environment to obtain the sterile low-dissolved oxygen concentrated tea extract of the present invention (Examples 5-1, 5-2, and 5-3).

[0118] The sterile low-dissolved oxygen concentrated tea extracts of the present invention in Examples 5-1, 5-2, and 5-3 were respectively mixed with 4 times the volume of sterile deoxygenated water (the dissolved oxygen concentration of the sterile deoxygenated water is close to 0 mg / L) in a sterile filling environment to obtain the final RTD tea beverage products of Examples 5-1, 5-2, and 5-3 of the present invention.

[0119] Table 7 shows the differences in the dissolved oxygen content between the sterile low-dissolved oxygen concentrated tea extracts and the final RTD tea beverage products of Examples 5-1, 5-2, and 5-3 of the present invention and the final RTD tea beverage product of Comparative Example 3.

[0120] Table 7

[0121]

[0122] As can be seen from Table 7, under the condition of the same concentrated tea soup concentration, the dissolved oxygen content is negatively correlated with the VC addition amount; in addition, it can still be seen that compared with Comparative Example 3 that prepares the final RTD product by one-step dilution in the prior art, in the present invention, since in the process of preparing the final RTD tea beverage product, a technical route of first preparing a sterile low-dissolved oxygen concentrated tea extract and then mixing it with sterile deoxygenated water (the dissolved oxygen concentration of the sterile deoxygenated water is close to 0 mg / L) in a sterile filling environment is adopted, the amount of oxygen redissolved into the semi-finished product during the heating treatment process of the preparation is small, and the dissolved oxygen content of the final RTD tea beverage product of the present invention is also significantly reduced.

[0123] Example 6

[0124] This example is used to illustrate the method for preparing the sterile low-dissolved oxygen concentrated tea extract and the tea beverage of the present invention using jasmine tea as the raw material, as well as the influence of different concentrated tea soup concentrations, the same antioxidant (vitamin C) addition amount, and different heating temperatures on the dissolved oxygen content of the sterile low-dissolved oxygen concentrated tea extract of the present invention.

[0125] 1.0 kg of jasmine tea leaves were stirred and extracted in 20 L of RO water at 25 °C at a speed of 20 revolutions per minute (RPM) for 18 minutes. After removing the tea leaves, the tea soup was cooled to 15 °C and centrifuged (centrifuge flow rate: 200 L / hr) and filtered (200-mesh sieve) to obtain 15 L of a primary tea soup extract with a Brix of 1.72 (measured by the above-mentioned J157 refractometer).

[0126] The primary tea soup extract was diluted with RO water to secondary tea soup concentrates with Brix 0.69 (3-fold concentrated tea soup), 0.86 (4-fold concentrated tea soup), and 1.03 (5-fold concentrated tea soup) respectively, and 0.30% by weight of vitamin C was added; it was left standing at room temperature for 30 minutes, and its dissolved oxygen content was measured for the first time. After heating to 65 °C through a plate heat exchanger, its dissolved oxygen content was measured for the second time. Then it was sterilized by a high-temperature and high-pressure autoclave (model: GR85DA, 121 °C, 5 min), and cooled to room temperature in a closed environment to obtain the sterile low-dissolved-oxygen concentrated tea extract of the present invention (Examples 6-1, 6-2, and 6-3).

[0127] The sterile low-dissolved-oxygen concentrated tea extracts of the present invention in Examples 6-1, 6-2, and 6-3 were respectively mixed with 3-fold, 4-fold, and 5-fold volumes of sterile deoxygenated water (the dissolved oxygen concentration of the sterile deoxygenated water is close to 0 mg / L) in a sterile filling environment to obtain the final RTD tea beverage products of Examples 6-1, 6-2, and 6-3 of the present invention.

[0128] Comparative Example 4

[0129] The primary tea soup extract of Example 6 was diluted in one step with RO water to a final RTD tea beverage product with a Brix of 0.20, 0.06% by weight of vitamin C was added, it was left standing at room temperature for 30 minutes, and its dissolved oxygen content was measured for the first time. After heating to 65 °C, its dissolved oxygen content was measured for the second time. Then it was sterilized by a high-temperature and high-pressure autoclave (model: GR85DA, 121 °C, 5 min), and cooled to room temperature in a closed environment to obtain the final RTD tea beverage product of Comparative Example 4.

[0130] Table 8 shows the differences in dissolved oxygen content between the sterile low-dissolved-oxygen concentrated tea extracts and the final RTD tea beverage products of Examples 6-1, 6-2, and 6-3 and the final RTD tea beverage product of Comparative Example 4.

[0131] Table 8

[0132]

[0133] As can be seen from Table 8, when jasmine tea is used as the raw material, compared with Comparative Example 4 of the prior art for directly diluting to prepare the RTD end product in one step, in the process of preparing the tea beverage end product of the present invention, a technical route is adopted in which a sterile low-dissolved-oxygen concentrated tea extract is first prepared, and then mixed with sterile deoxygenated water (the dissolved oxygen concentration of the sterile deoxygenated water is close to 0 mg / L) in a sterile filling environment. Therefore, during the heating treatment process of the preparation, the amount of oxygen redissolved into the semi-finished product is small, and the dissolved oxygen content of the tea beverage end product of the present invention is significantly reduced.

[0134] Example 7

[0135] This example is used to illustrate the method for preparing the sterile low-dissolved-oxygen concentrated tea extract and tea beverage of the present invention using jasmine tea as the raw material. This example is also used to illustrate the influence of the same concentrated-concentration tea soup and different addition amounts of antioxidant (vitamin C) on the dissolved oxygen content of the sterile low-dissolved-oxygen concentrated tea extract of the present invention.

[0136] 1.0 kg of jasmine tea leaves were stirred and extracted in 20 L of RO water at 25 °C at a speed of 20 revolutions per minute (RPM) for 18 minutes. After the tea soup was cooled to 15 °C after removing the tea leaves, a primary tea soup extract with a Brix of 1.72 (measured by the above-mentioned J157 refractometer) was obtained through centrifugation (centrifuge flow rate: 200 L / hr) and filtration (200-mesh sieve).

[0137] The primary tea soup extract was diluted with RO water to a secondary tea soup concentrate of 0.86 (4-fold concentrated tea soup), and vitamin C was added at 0.24%, 0.30%, and 0.36% by weight respectively; it was left standing at room temperature for 30 minutes, and its dissolved oxygen content was measured for the first time. After heating to 65 °C through a plate heat exchanger, its dissolved oxygen content was measured for the second time. Then, it was sterilized by a high-temperature and high-pressure autoclave (model: GR85DA, 121 °C, 5 min), and cooled to room temperature in a closed environment to obtain the sterile low-dissolved-oxygen concentrated tea extract of the present invention (Examples 7-1, 7-2, and 7-3).

[0138] The sterile low-dissolved-oxygen concentrated tea extracts of the present invention in Examples 7-1, 7-2, and 7-3 were respectively mixed with 3-fold, 4-fold, and 5-fold volumes of sterile deoxygenated water (the dissolved oxygen concentration of the sterile deoxygenated water is close to 0 mg / L) in a sterile filling environment to obtain the RTD tea beverage end products of Examples 7-1, 7-2, and 7-3 of the present invention.

[0139] Table 9 shows the differences in dissolved oxygen content between the sterile low-dissolved-oxygen concentrated tea extracts and tea beverage end products of Examples 7-1, 7-2, and 7-3 and the RTD tea beverage end product of Comparative Example 4.

[0140] Table 9

[0141]

[0142] As can be seen from Table 9, when jasmine tea is used as the raw material and the concentration of the concentrated tea soup is the same, the dissolved oxygen content is negatively correlated with the addition amount of VC. In addition, it can still be seen that compared with Comparative Example 4 for preparing the RTD final product by one-step dilution of the prior art, in the process of preparing the tea beverage final product of the present invention, a technical route of first preparing a sterile low-dissolved-oxygen concentrated tea extract and then mixing it with sterile deoxygenated water (the dissolved oxygen concentration of the sterile deoxygenated water is close to 0 mg / L) in a sterile filling environment is adopted. Therefore, during the heating treatment process of the preparation, the amount of oxygen redissolved into the semi-finished product is small, and the dissolved oxygen content of the tea beverage final product of the present invention is also significantly reduced.

[0143] Example 8

[0144] This example is used to illustrate the method for preparing the sterile low-dissolved-oxygen concentrated tea extract and tea beverage of the present invention using oolong tea (Da Hong Pao) as the raw material, and to illustrate the influence of the same concentrated-concentration tea soup and different addition amounts of antioxidant (vitamin C) on the dissolved oxygen content of the sterile low-dissolved-oxygen concentrated tea extract of the present invention.

[0145] 2.0 kg of Da Hong Pao tea leaves were statically extracted in 30 L of RO water at 80 °C for 10 minutes. After the tea soup was cooled to 15 °C after removing the tea leaves, a primary tea soup extract with a Brix of 1.19 (measured by the above-mentioned J157 refractometer) was obtained through centrifugation (centrifuge flow rate: 200 L / hr) and filtration (200-mesh sieve).

[0146] The primary tea soup extract was diluted with RO water to a secondary tea soup concentrate of 0.75 (4-fold concentrated tea soup), and vitamin C was added at 0.24%, 0.30% and 0.36% by weight respectively; it was left standing at room temperature for 30 minutes, and its dissolved oxygen content was measured for the first time. Then it was heated to 65 °C through a plate heat exchanger, and its dissolved oxygen content was measured for the second time. After being sterilized by a high-temperature and high-pressure autoclave (model: GR85DA, 121 °C, 5 min), it was cooled to room temperature in a closed environment to obtain the sterile low-dissolved-oxygen concentrated tea extract of the present invention (Examples 8-1, 8-2 and 8-3).

[0147] The sterile low-dissolved-oxygen concentrated tea extracts of the present invention in Examples 8-1, 8-2 and 8-3 were respectively mixed with 4 times the volume of sterile deoxygenated water (the dissolved oxygen concentration of the sterile deoxygenated water is close to 0 mg / L) in a sterile filling environment to obtain the RTD tea beverage final products of Examples 8-1, 8-2 and 8-3 of the present invention.

[0148] Comparative Example 5

[0149] The primary tea soup extract of Example 8 was diluted in one step with RO water to the final RTD tea beverage product with a Brix of 0.15, vitamin C with a weight percentage of 0.06% was added, and it was left standing at room temperature for 30 minutes. Its dissolved oxygen content was measured for the first time, and then after heating to 65 °C through a plate heat exchanger, its dissolved oxygen content was measured for the second time. It was then sterilized by a high-temperature and high-pressure autoclave (model: GR85DA, 121 °C, 5 min), and cooled to room temperature under a closed environment to obtain the final RTD tea beverage product of Comparative Example 5.

[0150] Table 10 shows the differences in dissolved oxygen content between the sterile low-dissolved-oxygen concentrated tea extracts and the final tea beverage products of Examples 8-1, 8-2, and 8-3 and the final RTD tea beverage product of Comparative Example 5.

[0151] Table 10

[0152]

[0153] It can be seen from Table 10 that when oolong tea is used as the raw material and the concentration of the concentrated tea soup is the same, the dissolved oxygen content is negatively correlated with the VC addition amount; in addition, it can still be seen that compared with Comparative Example 5 that prepares the final RTD product by one-step dilution in the prior art, in the present invention, in the process of preparing the final tea beverage product, a technical route of first preparing a sterile low-dissolved-oxygen concentrated tea extract and then mixing it with sterile deoxygenated water (the dissolved oxygen concentration of the sterile deoxygenated water is close to 0 mg / L) in a sterile filling environment is adopted. Therefore, the amount of oxygen redissolved into the semi-finished product during the heating treatment process of the preparation is small, and the dissolved oxygen content of the final tea beverage product of the present invention is also significantly reduced.

[0154] Example 9

[0155] This example is used to illustrate the method for preparing the sterile low-dissolved-oxygen concentrated tea extract and tea beverage of the present invention using black tea as the raw material, and the influence of different concentrated tea soup concentrations, the same antioxidant (vitamin C) addition amount, and different heating temperatures on the dissolved oxygen content of the sterile low-dissolved-oxygen concentrated tea extract of the present invention.

[0156] 2.0 kg of Dahongpao tea leaves were left standing and extracted in 30 L of RO water at 70 °C for 5 minutes. After the tea soup was removed from the tea leaves, it was cooled to 15 °C, and a primary tea soup extract with a Brix of 1.72 (measured by the above-mentioned J157 refractometer) was obtained through centrifugation (centrifuge flow rate: 200 L / hr) and filtration (200-mesh sieve).

[0157] The primary tea soup extract was diluted with RO water to secondary tea soup concentrates of Brix 0.69 (3-fold concentrated tea soup), 0.86 (4-fold concentrated tea soup), and 1.03 (5-fold concentrated tea soup) respectively, and vitamin C at 0.30% by weight was added to each; it was left standing at room temperature for 30 minutes, and its dissolved oxygen content was measured for the first time. Then, after heating to 65 °C through a plate heat exchanger, its dissolved oxygen content was measured for the second time. After that, it was sterilized by a high-temperature and high-pressure autoclave (model: GR85DA, 121 °C, 5 min), and cooled to room temperature in a closed environment to obtain the sterile low-dissolved-oxygen concentrated tea extract of the present invention (Examples 9-1, 9-2, and 9-3).

[0158] The sterile low-dissolved-oxygen concentrated tea extracts of the present invention in Examples 9-1, 9-2, and 9-3 were respectively mixed with 3-fold, 4-fold, and 5-fold volumes of sterile deoxygenated water (the dissolved oxygen concentration of the sterile deoxygenated water is close to 0 mg / L) in a sterile filling environment to obtain the final RTD tea beverage products of Examples 9-1, 9-2, and 9-3 of the present invention.

[0159] Comparative Example 6

[0160] The primary tea soup extract of Example 9 was directly diluted with RO water to the final RTD tea beverage product of Brix 0.17, and vitamin C at 0.06% by weight was added. It was left standing at room temperature for 30 minutes, and its dissolved oxygen content was measured for the first time. Then, after heating to 65 °C through a plate heat exchanger, its dissolved oxygen content was measured for the second time. After that, it was sterilized by a high-temperature and high-pressure autoclave (model: GR85DA, 121 °C, 5 min), and cooled to room temperature in a closed environment to obtain the final RTD tea beverage product of Comparative Example 6.

[0161] Table 11 shows the differences in dissolved oxygen content between the sterile low-dissolved-oxygen concentrated tea extracts and the final tea beverage products of Examples 9-1, 9-2, and 9-3 of the present invention and the final RTD tea beverage product of Comparative Example 6.

[0162] Table 11

[0163]

[0164] As can be seen from Table 11, when using black tea as the raw material, compared with Comparative Example 6 of the prior art that directly dilutes to prepare the final RTD product in one step, in the present invention, during the process of preparing the final tea beverage product, a technical route of first preparing a sterile low-dissolved-oxygen concentrated tea extract and then mixing it with sterile deoxygenated water (the dissolved oxygen concentration of the sterile deoxygenated water is close to 0 mg / L) in a sterile filling environment is adopted. Therefore, during the heating treatment process of the preparation, the amount of oxygen redissolved into the semi-finished product is small, and the dissolved oxygen content of the final tea beverage product of the present invention is significantly reduced.

[0165] The invention disclosed schematically herein may suitably be practiced in the absence of any element not specifically disclosed herein. However, it will be apparent to those skilled in the art that many modifications, variations, improvements, other uses and applications of the method are possible and modifications, variations, improvements, other uses and applications which do not depart from the spirit and scope of the invention are also considered to be covered by the invention, which is limited only by the appended claims.

Claims

1. A method for preparing a sterile low dissolved oxygen concentrated tea extract, which comprises: a) extracting tea leaves with water for 1 minute to 2 hours; b) separating the tea leaves from the tea soup, cooling the tea soup to room temperature or maintaining the tea soup at a temperature of 5°C to 25°C to obtain an initial tea extract; c) removing dissolved oxygen until the dissolved oxygen concentration of the initial tea extract is 5.0 mg / L or less; d) obtaining a final sterile low dissolved oxygen concentrated tea extract by sterilization; wherein the Brix of the sterile low dissolved oxygen concentrated tea extract is 0.3 to 3.

3.

2. The method according to claim 1, wherein The step a) further contains additional plant raw materials that are both medicine and food.

3. The method according to claim 1 or 2, wherein, In the step a), the weight-to-volume ratio of tea leaves to water is 10 - 200 g / l.

4. The method according to any one of claims 1-3, wherein, In the step a), the shape of the tea leaves is the original shape of dry tea leaves or broken tea, and the particle size range of the broken tea is 4 - 50 mesh.

5. The method according to any one of claims 1-4, wherein, In the step a), water is used for extraction at 5°C to 35°C for 15 - 120 minutes, or at 35°C to 100°C for 3 - 30 minutes.

6. According to the method described in any one of claims 1 - 5, in the step c), the removal of dissolved oxygen is to add 0.1 - 1.0% by weight of an antioxidant based on the total weight of the initial tea extract to the initial tea extract and / or subject the initial tea extract to vacuum treatment at 0.8 bar or less.

7. According to the method described in any one of claims 1 - 6, wherein the Brix of the sterile low dissolved oxygen concentrated tea extract is 0.5 to 2.

4.

8. According to the method described in any one of claims 1 - 7, wherein the dissolved oxygen concentration of the water used in the step a) is less than 1.2 mg / L.

9. According to the method described in any one of claims 1 - 8, wherein the extraction step in the step a) is carried out under stirring, and the stirring is carried out at a rate of 10 - 60 RPM and lasts for 10 seconds to 30 minutes.

10. According to the method described in any one of claims 1 - 9, wherein the antioxidant in the step c) is selected from ascorbic acid, sodium ascorbate, sodium isoascorbate, potassium ascorbate, and potassium isoascorbate, and combinations thereof.

11. According to the method described in any one of claims 1 - 10, wherein the addition amount of the antioxidant in the step c) is 0.2 - 0.6% by weight based on the total weight of the initial tea extract.

12. According to the method described in any one of claims 1 - 11, wherein the dissolved oxygen concentration of the initial tea extract before treatment in the step c) is 5 mg / L to saturated dissolved oxygen.

13. According to the method described in any one of claims 1 - 12, wherein the tea leaves are selected from the group consisting of green tea, oolong tea, yellow tea, black tea, white tea, dark tea, scented tea, and any combination thereof.

14. An aseptic low dissolved oxygen concentrated tea extract, wherein, The Brix of the sterile low dissolved oxygen concentrated tea extract is 0.3 to 3.

3.

15. A sterile low dissolved oxygen concentrated tea extract obtained by the method described in any one of claims 1 - 13.

16. A method for preparing an instant tea beverage, which comprises: i) Mix the aseptic low-dissolved-oxygen concentrated tea extract obtained by the method according to any one of claims 1-13 or the aseptic low-dissolved-oxygen concentrated tea extract according to claim 14 with aseptic deoxygenated water to obtain a tea beverage; ii) aseptically fill the tea beverage prepared in step i); and wherein the dissolved oxygen concentration of the aseptic deoxygenated water in step i) is 1.0 mg / L or less.

17. The method according to claim 16, wherein, The aseptic low-dissolved-oxygen concentrated tea extract and the aseptic deoxygenated water are filled into the final container simultaneously / batchwise to achieve mixing.

18. The method according to claim 17, wherein the aseptic low-dissolved-oxygen concentrated tea extract is first filled into the final container, and then the aseptic deoxygenated water is filled into the final container.

19. The method according to any one of claims 16-18, wherein the volume ratio of the aseptic low-dissolved-oxygen concentrated tea extract to the aseptic deoxygenated water is 1:1 to 1:

10.

20. The method according to any one of claims 16-19, wherein the aseptic deoxygenated water in step i) is degassed by a method selected from vacuum negative pressure degassing, high temperature degassing, degassing by adding an antioxidant, membrane separation deoxidation, and nitrogen replacement deoxidation.

21. A tea beverage obtained by the method according to any one of claims 16-20.

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