Cold extraction tea and preparation method thereof

Abstract

The invention belongs to the technical field of tea making, and particularly relates to cold extraction tea and a making method thereof. The making method of the cold-extracted tea comprises the following steps: S1, mixing tea leaves with RO water at 0-4 DEG C to obtain a tea water mixture; s2, grinding the obtained tea water mixture to obtain tea soup; and S3, carrying out high-pressure jet treatment on the obtained tea soup, standing for a certain time, and filtering to obtain a tea extract. According to the tea making process, on the basis of ensuring the extraction rate of small molecular substances such as theanine in the tea leaves, the release rate of caffeine can be inhibited to a certain extent, premature oxidation of tea soup is prevented, the turbidity of the tea soup is reduced, the problem of secondary precipitation of products is prevented, and the taste of the tea soup is kept.

Description

Technical Field

[0001] The invention belongs to the technical field of tea making, and in particular relates to cold-brewed tea and a making method thereof. Background Art

[0002] The existing industrial tea extraction method uses the traditional hot water extraction method of tea leaves, and finally filters and sterilizes the tea leaves. Although hot water extraction can quickly release most of the beneficial ingredients in tea leaves, it can also easily cause some bitter substances such as caffeine to dissolve, affecting the flavor of the product. In addition, hot extraction of tea leaves will also cause a large loss of nutrients, rapid oxidation of the tea soup, and secondary precipitation after cooling. Summary of the invention

[0003] The purpose of the present invention is to provide a cold brew tea and a preparation method thereof, so as to ensure the extraction rate of small molecular substances such as theanine in tea leaves and inhibit the release rate of caffeine, thereby improving the quality of cold brew tea products.

[0004] To this end, the present invention provides the following technical solutions.

[0005] One aspect of the present invention provides a method for preparing cold brew tea, the method comprising the following steps:

[0006] S1: Mixing tea leaves with 0-4°C RO water to obtain a tea mixture;

[0007] S2: Grinding the obtained tea mixture to obtain tea soup;

[0008] S3: The obtained tea soup is treated with high-pressure jet flow, and then allowed to stand for a certain period of time, and then filtered to obtain a tea extract.

[0009] As a preferred embodiment of the present invention, in step S1, the tea leaves are selected from one or more of jasmine tea, green orange Pu'er tea, and golden osmanthus oolong tea.

[0010] As a preferred embodiment of the present invention, in step S1, the tea leaves are mixed with RO water in a mass-to-volume ratio of 1:30-40.

[0011] As a preferred embodiment of the present invention, in step S2, the grinding process includes primary grinding and secondary grinding.

[0012] The processing conditions of the first-stage grinding are: power: 15-20 Hz, efficiency setting: 15-20%;

[0013] The processing conditions of the secondary grinding are: power: 35-40 Hz, efficiency setting: 15-20%.

[0014] As a preferred embodiment of the present invention, in step S3, the high-pressure jet treatment conditions are: pressure 60-80 MPa; the standing time is 25-35 min.

[0015] As a preferred embodiment of the present invention, in step S3, the filtration includes ceramic membrane filtration, and the filtration diameter of the ceramic membrane is 0.2 μm.

[0016] As a preferred embodiment of the present invention, it also includes:

[0017] S4: filtering the obtained tea extract through a series filter to obtain a filtrate, and finally sterilizing the obtained filtrate before bottling.

[0018] As a preferred embodiment of the present invention, the filter diameter of the series filter is 1 μm-1 μm.

[0019] As a preferred embodiment of the present invention, the sterilization conditions are: UTH sterilization, temperature 133±1°C, time 30s.

[0020] Another aspect of the present invention further provides a cold brew tea, which is produced according to the production method as described above.

[0021] By means of the above technical solution, the present invention has at least the following advantages:

[0022] The present invention aims at the problems of large loss of nutrients, fast oxidation speed of tea soup and secondary precipitation after cooling in the existing hot extraction of tea leaves. The present invention obtains tea soup by mixing tea leaves with low temperature (0-4°C) RO water and grinding them by a colloid mill in the first and second stages. The tea soup has good processing characteristics while maintaining the original various nutrients and flavor characteristics of the tea leaves. Then the tea soup is treated by a high-pressure device to better increase the contact area between tea leaves and water. On the basis of ensuring the extraction rate of small molecules such as theanine in tea leaves, the release rate of caffeine can be inhibited to a certain extent. At the same time, the rapid oxidation and browning of flavor substances in the tea soup at high temperature can be avoided, and the deterioration of the color and aroma of tea leaves can be avoided, so as to maintain the nutritional value and flavor quality of tea beverages. Finally, the tea soup is filtered by a 0.2μm ceramic membrane to improve the clarity of the finished product and reduce the turbidity. At the same time, the secondary precipitation problem of tea beverages after being placed for a period of time can be effectively solved, and the taste of the tea soup can be continuously maintained.

[0023] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the preferred embodiments of the present invention are described in detail as follows. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1This is a process flow chart of the cold brew tea of ​​Examples 1 to 2 of the present invention;

[0025] Figure 2 A comparison chart of theanine and caffeine concentrations in tea extracts obtained at different extraction temperatures and times;

[0026] Figure 3 The turbidity comparison chart of tea extract obtained under different membrane filtration conditions;

[0027] Figure 4 This is a comparison chart of the average particle size of tea leaves in the tea soup obtained after and without high-pressure jet treatment. DETAILED DESCRIPTION

[0028] In order to make the technical means, creative features, objectives and effects of the present invention easy to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] Unless otherwise specified, the experimental methods used in the following examples are all conventional methods.

[0030] Unless otherwise specified, the materials and reagents used in the following examples can be obtained from commercial sources.

[0031] Unless otherwise specified, the jasmine tea used in the following examples is Wuyin special jasmine tea from Hengxian County, Guangxi.

[0032] Unless otherwise specified, the instrument models and sources used in the following examples are:

[0033] 1. High-pressure jet equipment, model: FJ3076S-1t / h, purchased from: Beijing Collaborative Innovation Center;

[0034] 2. The equipment used for primary and secondary grinding is a soybean-specific wet mill, model: FML-CFX-7, purchased from: Beijing Collaborative Innovation Center;

[0035] 3. Ceramic membrane, model: HY-TC / MZx3, purchased from Liaoning Hengyuan Filtration Technology Co., Ltd.;

[0036] 4. Series filter, model: 1 μm bag filter, purchased from: Hangzhou Dali Filtration Equipment Co., Ltd.;

[0037] 5. Turbidimeter, model: LPG4390100002, purchased from: HACH;

[0038] 6. Laser particle size analyzer, model: MASTERSIZER3000, purchased from: Malven.

[0039] Unless otherwise specified, the high-pressure jet described in the present invention is a process that uses high-pressure jet equipment to convert liquid pressure energy into jet kinetic energy. Its working principle is: water or other liquids are pressurized to an extremely high pressure through a booster pump, and then ejected through a specially designed nozzle to form a high-speed jet. The specific high-pressure jet treatment process for tea soup in the present invention is: ① Pour the tea soup into the feed tank of the high-pressure jet equipment; ② Turn on the equipment to extract the material, and check that the equipment pressure rises to the set value. After the extraction is completed, the tea soup is ejected through the equipment nozzle; ③ Feed the above-treated liquid into a static barrel and proceed to the next step. The high-pressure jet treatment of tea soup in the present invention utilizes this principle. After the material in the tea leaves is treated with a high-pressure jet, the cell wall of the material is broken, so that the internal substance can be better dissolved.

[0040] Embodiment 1:

[0041] Weigh 25 kg of jasmine tea, and mix the jasmine tea with 0° C. RO water in a mass-to-volume ratio of 1:35 to obtain a tea mixture.

[0042] The obtained tea mixture is subjected to primary grinding and secondary grinding in sequence to obtain tea soup. The primary grinding conditions are: power: 15 Hz, efficiency setting: 15%; the secondary grinding conditions are: power: 38 Hz, efficiency setting: 19%; the total time of the two grindings is: 15 minutes.

[0043] The obtained tea soup was subjected to 60Mpa high-pressure jet treatment and then left to stand for extraction for 30 minutes to obtain an extract. The obtained extract was filtered, and the specific operation was as follows: first, it was filtered using a 100-mesh stainless steel filter, and then filtered through a 75μm and 1μm bag filter in sequence to obtain a filtrate. The obtained filtrate was then centrifuged to obtain a supernatant. Finally, the obtained supernatant was filtered through a 0.2μm ceramic membrane to obtain a tea extract.

[0044] The obtained tea extract is filtered through a 1 μm-1 μm series filter to obtain a filtrate. Finally, the obtained filtrate is sterilized by UTH (133.5° C., time 30 s) and then bottled.

[0045] Embodiment 2:

[0046] Weigh 25 kg of jasmine tea, and mix the jasmine tea with 4° C. RO water in a mass-to-volume ratio of 1:35 to obtain a tea mixture.

[0047] The obtained tea mixture is subjected to primary grinding and secondary grinding in sequence to obtain tea soup. The primary grinding conditions are: power: 15 Hz, efficiency setting: 15%; the secondary grinding conditions are: power: 38 Hz, efficiency setting: 19%; the total time of the two grindings is: 15 minutes.

[0048] The obtained tea soup was subjected to 60Mpa high-pressure jet treatment and then left to stand for extraction for 30 minutes to obtain an extract. The obtained extract was filtered, and the specific operation was as follows: first, it was filtered using a 100-mesh stainless steel filter, and then filtered through a 75μm and 1μm bag filter in sequence to obtain a filtrate. The obtained filtrate was then centrifuged to obtain a supernatant. Finally, the obtained supernatant was filtered through a 0.2μm ceramic membrane to obtain a tea extract.

[0049] The obtained tea extract is filtered through a 1 μm-1 μm series filter to obtain a filtrate. Finally, the obtained filtrate is sterilized by UTH (133.5° C., time 30 s) and then bottled.

[0050] Embodiment 3:

[0051] Weigh 25 kg of jasmine tea, and mix the jasmine tea with 70° C. RO water in a mass-to-volume ratio of 1:35 to obtain a tea mixture.

[0052] The obtained tea mixture is subjected to primary grinding and secondary grinding in sequence to obtain tea soup. The primary grinding conditions are: power: 15 Hz, efficiency setting: 15%; the secondary grinding conditions are: power: 38 Hz, efficiency setting: 19%; the total time of the two grindings is: 15 minutes.

[0053] The obtained tea soup was subjected to 60Mpa high-pressure jet treatment and then left to stand for extraction for 30 minutes to obtain an extract. The obtained extract was filtered, and the specific operation was as follows: first, it was filtered using a 100-mesh stainless steel filter, and then filtered through a 75μm and 1μm bag filter in sequence to obtain a filtrate. The obtained filtrate was then centrifuged to obtain a supernatant. Finally, the obtained supernatant was filtered through a 0.2μm ceramic membrane to obtain a tea extract.

[0054] The obtained tea extract is filtered through a 1 μm-1 μm series filter to obtain a filtrate. Finally, the obtained filtrate is sterilized by UTH (133.5° C., time 30 s) and then bottled.

[0055] Comparative Example 1:

[0056] The difference from Example 1 is that the ceramic membrane is replaced by a fiber membrane, and the rest is the same as Example 1.

[0057] Comparative Example 2:

[0058] The difference from Example 2 is that the ceramic membrane is replaced by a fiber membrane, and the rest is the same as Example 2.

[0059] Comparative Example 3:

[0060] The difference from Example 3 is that the ceramic membrane is replaced by a fiber membrane, and the rest is the same as Example 3.

[0061] Comparative Example 4:

[0062] The difference from Example 1 is that the tea soup is directly filtered without being treated by a 60 MPa high-pressure jet, and the rest is the same as Example 1.

[0063] Comparative Example 5:

[0064] The difference from Example 2 is that the tea soup is directly filtered without being treated with a 60 MPa high-pressure jet, and the rest is the same as Example 2.

[0065] Comparative Example 6:

[0066] The difference from Example 3 is that the tea soup is directly filtered without being treated by a 60 MPa high-pressure jet, and the rest is the same as Example 3.

[0067] Experiment 1: Comparison of theanine, caffeine and catechin concentrations in tea extracts using different processes

[0068] Theanine accounts for about 50% to 60% of the total amino acids in tea. Its aqueous solution is slightly acidic, with a caramel aroma and a fresh taste similar to that of MSG. It is easily soluble in water and has a sweet and fresh taste. It is the main ingredient of the fresh taste of tea. The caffeine contained in tea has a refreshing effect. In addition, a moderate amount of caffeine can also enhance the taste of tea juice. However, excessive caffeine will increase the alkaline bitterness of tea juice and reduce the taste of tea juice. In addition, excessive intake of caffeine can also lead to some adverse reactions, such as insomnia, palpitations, anxiety, etc. Catechins are the main functional ingredients in tea, accounting for 12% to 24% of the dry mass of tea. The catechin compounds in tea mainly include 8 monomers: catechin (C), epicatechin (EC), gallocatechin (GC), epigallocatechin (EGC), catechin gallate (CG), epicatechin gallate (ECG), gallocatechin gallate (GCG) and epigallocatechin gallate (EGCG). Catechins have anti-inflammatory, antibacterial, antiviral and antioxidant effects.

[0069] In order to explore the differences in the concentrations of theanine, caffeine, and catechins in tea extracts obtained under different production processes, this experiment tested the concentrations of theanine, caffeine, and catechins in the tea extracts obtained in Example 1, Example 2, and Example 3. The results are shown in Table 1. Figure 2 and Table 1.

[0070] Table 1 Statistics of catechin content in tea extract

[0071]

[0072] like Figure 2 As shown, under the same production process except for the extraction temperature and time: the tea extract obtained under the conditions of 4°C and static extraction for 30 minutes (corresponding to Example 2) has the highest theanine content (5.14μg / ml); the tea extract obtained under the conditions of 70°C and static extraction for 30 minutes (corresponding to Example 3) has the second highest theanine content (4.58μg / ml); the tea extract obtained under the conditions of 0°C and static extraction for 30 minutes (corresponding to Example 1) has the lowest theanine content (3.9μg / ml). Obviously, the tea extract obtained under the processing conditions of Example 2 has the highest theanine content, which is more conducive to improving the flavor of the tea soup.

[0073] Although the caffeine concentration (300 ppm) in the tea extract obtained under the treatment conditions of Example 2 is higher than the caffeine concentration (92 ppm) in the tea extract obtained under the treatment conditions of 0°C and 30 min (corresponding to Example 1), theanine can alleviate the bitterness of caffeine alkali and the bitterness of tea polyphenols, and an appropriate amount of caffeine can also enhance the taste of tea juice.

[0074] In addition, according to the results in Table 1, the dissolution rate of catechins in the tea extract of Example 2 is significantly higher than that of Example 1. Since catechins are more conducive to improving the flavor of the tea extract, overall, the tea extract obtained in Example 2 has the best flavor.

[0075] Experiment 2: Effects of different filtration membrane treatments on the turbidity of tea extract

[0076] The turbidity of the tea extract will directly affect whether the product will have the problem of secondary precipitation. The higher the turbidity, the more likely it is to have the above problem. In order to explore the difference in turbidity of tea extracts obtained under different production processes, this experiment used a turbidity meter to test the turbidity of the tea extracts obtained in Examples 1 to 3 and Comparative Examples 1 to 3. The results are shown in Table 1. Figure 3 .

[0077] like Figure 3As shown, the turbidity of the tea extract obtained by filtering the tea soup using the ceramic membrane (Examples 1 to 3) is significantly lower than that using the fiber membrane (corresponding to Comparative Examples 1 to 3). This result shows that compared with the fiber membrane, the ceramic membrane has a better filtering effect, the obtained tea extract has a higher clarity, and the product can better avoid the problem of secondary precipitation.

[0078] Experiment 3: Effect of high-pressure jet treatment on the average particle size of tea leaves in tea soup

[0079] The particle size of the tea soup will affect the subsequent extraction effect. In order to explore the effect of high-pressure jet treatment on the particle size of the tea soup, the tea soup obtained in Examples 1 to 3 and Comparative Examples 4 to 6 was tested for the particle size of the tea particles using a MASTERSIZER3000 laser particle size analyzer. The results are as follows: Figure 4 shown.

[0080] like Figure 4 As shown, compared with comparative examples 4 to 6, the tea soup obtained in examples 1 to 3 has a significantly reduced particle size of tea particles after high-pressure jet treatment, which indicates that high-pressure jet treatment has a crushing effect on tea particles in the tea soup. In addition, compared with examples 1 and 3, the particle size of the tea soup in example 2 is significantly lower, which indicates that an extraction temperature of 4°C can obtain tea soup with the smallest particle size.

[0081] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with this profession can make some changes or modifications to equivalent embodiments of equivalent changes by using the methods and technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A method for preparing cold brew tea, characterized in that: The production method comprises the following steps: S1: Mixing tea leaves with 0-4°C RO water to obtain a tea mixture; S2: Grinding the obtained tea mixture to obtain tea soup; S3: The obtained tea soup is treated with high-pressure jet flow, and then allowed to stand for a certain period of time, and then filtered to obtain a tea extract.

2. The method according to claim 1, characterized in that: In step S1, the tea leaves are selected from one or more of jasmine tea, green citrus Pu'er tea, and golden osmanthus oolong tea.

3. The method according to claim 1, characterized in that: In step S1, the tea leaves are mixed with RO water in a mass-to-volume ratio of 1:30-40.

4. The method according to claim 1, characterized in that: In step S2, the grinding process includes primary grinding and secondary grinding. The processing conditions of the first-stage grinding are: power: 15-20 Hz, efficiency setting: 15-20%; The processing conditions of the secondary grinding are: power: 35-40 Hz, efficiency setting: 15-20%.

5. The method according to claim 1, characterized in that: In step S3, the high-pressure jet treatment conditions are: pressure 60-80 MPa; the standing time is 25-35 min.

6. The method according to claim 1, characterized in that: In step S3, the filtration includes ceramic membrane filtration, and the filtration diameter of the ceramic membrane is 0.2 μm.

7. The manufacturing method according to claim 1, characterized in that: Also includes: S4: filtering the obtained tea extract through a series filter to obtain a filtrate, and finally sterilizing the obtained filtrate before bottling.

8. The method according to claim 7, characterized in that: The filter diameter of the series filter is 1 μm-1 μm.

9. The manufacturing method according to claim 7, characterized in that: The sterilization conditions are: UTH sterilization, temperature 133±1°C, time 30s.

10. A cold brew tea, characterized in that: The cold brew tea is produced by the production method according to any one of claims 1 to 9.

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