Preparation method of instant berry tea

Abstract

The present invention provides a method for preparing instant berry tea, which relates to the technical field of instant beverage preparation. The method for preparing the instant berry tea mainly comprises drying fresh tender stems and leaves of Ampelopsis glauca, soaking them in a saturated sodium chloride solution for a certain period of time, treating them with plasma, performing high-pressure cold extraction, and then performing ultrasonic extraction at a higher temperature. During subsequent drying, the product is first frozen with liquid nitrogen and then freeze-dried. The present invention overcomes the shortcomings of the prior art, improves the extraction efficiency of the effective ingredients of berry tea, and the prepared instant powder can be quickly dissolved in water at a relatively low temperature, thereby enabling convenient brewing of the instant berry tea in various environments.

Description

Technical Field

[0001] The invention relates to the technical field of instant beverage preparation, and in particular to a preparation method of instant berry tea. Background Art

[0002] Instant tea is an important deep-processed tea product. It refers to a new type of beverage that is easily soluble in water and has no tea residue. It is made from finished tea, semi-finished tea, tea by-products, or fresh leaves through extraction, filtration, concentration, and drying. It is a granular or powdered beverage that is easily soluble in water and does not contain tea residue. Berry tea is one of the most common tea substitutes on the market. However, unlike conventional black tea and green tea, berry tea is made by processing the tender stems and leaves of the Ampelopsis glauca. Compared to ordinary tea, berry tea is rich in flavonoids, with dihydromyricetin being the highest content. The quality of berry tea itself is not only determined by its flavor, but also related to the dihydromyricetin content.

[0003] Most instant teas on the market are made with common teas like green or black tea, while berry tea instant teas are relatively rare. Traditionally, tea is steeped or brewed with warm or hot water. However, as society evolves, young people's tastes have shifted, leading to a preference for iced beverages. Consequently, iced teas have become increasingly popular. Instant teas have also evolved from being brewed with hot water to being brewed with room temperature or even cold water. However, many instant teas currently suffer from poor solubility at lower temperatures, resulting in incomplete dissolution and a cloudy brewing liquid.

[0004] There are two main points to note when preparing berry tea instant tea: 1. Ensuring the content of active ingredients in the berry tea instant tea; 2. Ensuring the solubility of the berry tea instant tea. The conventional preparation method for berry tea instant tea is mostly to extract the berry tea with a solvent and then dry it to produce an instant powder. However, there are many choices of solvents. The extraction efficiency of the overall active ingredients using water is not high, especially the use of heated hot water to extract, which will destroy the active ingredients (such as dihydromyricetin) to a certain extent. While the extraction efficiency of the active ingredients using solvents such as ethanol is better, problems such as solvent contamination will affect the quality of the instant tea. In addition, higher temperature water is usually required for brewing to achieve a better dissolution effect. The solubility is poor in water at room temperature or even low temperature, and the overall tea soup is relatively turbid, lacking the clear texture of tea, affecting the overall sensory experience.

[0005] Based on the above problems, how to promote the subsequent low-temperature dissolution of berry tea extract on the basis of improving the extraction efficiency of berry tea active ingredients is an important technical innovation direction and difficulty in the preparation of instant berry tea at this stage. Summary of the Invention

[0006] In response to the shortcomings of the existing technology, the present invention provides a method for preparing instant berry tea, which effectively improves the extraction rate of effective ingredients in the tender stems and leaves of Agave serrata, and the prepared instant powder can be quickly dissolved in water at a lower temperature, thereby realizing convenient brewing of instant berry tea in various environments.

[0007] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0008] A method for preparing instant berry tea, comprising the following steps:

[0009] S1. Soaking treatment: Select fresh tender stems and leaves of Ampelopsis glauca from June to August, air-dry them until the moisture content is 10-12%, soak them in a saturated sodium chloride solution at a pressure of 0.5 MPa for 3-5 minutes, and then remove them and rinse them with purified water to obtain preliminarily treated leaves;

[0010] S2. Plasma treatment: Spread the preliminarily treated leaves flat and use a mixture of argon and nitrogen for plasma treatment for 2-3 minutes, then take out the pretreated leaves;

[0011] S3, high-pressure cold extraction: The pretreated leaves are mixed with ice cubes and crushed, then placed in an environment of 4-6°C and the pressure is adjusted in the range of 0.2-0.4 MPa, 2-4 MPa, and 8-10 MPa for extraction, and then squeezed and filtered to obtain a filtrate and a residue;

[0012] S4, secondary extraction: the above filter residue is mixed with purified water and then ultrasonically shaken at 60-80 ° C and centrifuged to separate the precipitate and combine the above filtrate to obtain a mixed extract for use;

[0013] S5. Drying treatment: The mixed extract is frozen with liquid nitrogen, the temperature is adjusted for freeze-drying, and then pulverized to obtain instant berry tea powder.

[0014] Preferably, the temperature of soaking in the saturated sodium chloride solution in step S1 is room temperature.

[0015] Preferably, in step S2, the volume ratio of argon to nitrogen is 1-3:1-3, the flow rate of the mixed gas is 100-150 mL / min, and the processing power is 300-420W.

[0016] Preferably, the mass ratio of the pre-treated leaves to the ice cubes in step S3 is 1:3-5.

[0017] Preferably, in step S3, the extraction is carried out under a pressure of 0.2-0.4 MPa for 1-2 hours, under a pressure of 2-4 MPa for 30-40 minutes, and under a pressure of 8-10 MPa for 10-20 minutes.

[0018] Preferably, in step S4, the mass ratio of the filter residue to the purified water is 1:3-5, and the pH value of the feed solution is adjusted to 5.5-6.

[0019] Preferably, the power of the ultrasonic oscillation in step S4 is 400-600W, and the time of the ultrasonic oscillation is 15-30 minutes.

[0020] Preferably, the centrifugal speed in step S4 is 4000-5000 r / min, and the centrifugal time is 10-15 min.

[0021] Preferably, the liquid nitrogen freezing time in step S5 is 1-2 hours, the freeze-drying temperature is -55°C±5°C, and the freeze-drying vacuum degree is 10-20 Pa.

[0022] The present invention provides a method for preparing instant berry tea, which has the following advantages over the prior art:

[0023] The present invention adopts high-pressure short-time immersion of saturated sodium chloride solution in the early stage to effectively destroy the cells of the tender stems and leaves of Ampelopsis grossedentata preliminarily. Combined with the subsequent plasma treatment, more effective ingredients can be extracted in the high-pressure cold extraction. In addition, by controlling the pressure of the high-pressure cold extraction, the subsequent ultrasonic secondary extraction and the freeze-drying after liquid nitrogen freezing, the rapid dissolution of the final dried product in low-temperature and room-temperature water is effectively improved, the clarity of the solution after dissolution is ensured, and the quality of the instant berry tea finally obtained is comprehensively improved. DETAILED DESCRIPTION

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention are clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0025] Example:

[0026] Follow the instructions below to prepare instant berry tea:

[0027] (1) Soaking treatment: fresh tender stems and leaves of Ampelopsis glauca are air-dried to a moisture content of 10-12% and used as raw dry leaves. The same batch of dry leaves are placed in a saturated sodium chloride solution at room temperature and pressure increased to 0.5 MPa for soaking. After that, they are taken out and washed with purified water to obtain preliminary treated leaves.

[0028] (2) The pre-treated leaves were spread out and then treated with a mixed gas of argon and nitrogen in equal volume ratio at a gas flow rate of 120 mL / min at a power of 350 W for 160 s. The pre-treated leaves were then taken out.

[0029] (3) The pretreated leaves were mixed with ice cubes 4 times their mass and crushed, and then the extraction temperature was controlled and different pressures were adjusted for extraction, and the extraction was performed under pressure and squeezed to obtain the filtrate and residue;

[0030] (4) The above filter residue was mixed with 4 times the volume of pure water and then treated with 500W ultrasonic vibration at 70°C for 12 minutes, and then centrifuged at 4500 r / min for 15 minutes. After separation of the precipitate, the above filtrate was combined to obtain a mixed extract for later use;

[0031] (5) The mixed extract was frozen in liquid nitrogen for 90 min, then taken out and the temperature was adjusted to -55°C ± 5°C, the vacuum degree was 15 Pa, and then freeze-dried and pulverized to obtain instant berry tea powder.

[0032] According to the above preparation method, experimental groups 1-10 were set up respectively with reference to Table 1 below, and different preparation parameters were used to obtain different instant berry tea powders:

[0033] Table 1

[0034]

[0035] The total mass of the instant berry tea powder extracted from each 1 kg of raw material dry leaves in each group was calculated. The mass of dihydromyricetin extracted from each 1 kg of raw material dry leaves in each group was detected and calculated, as well as the percentage of dihydromyricetin in the total mass of the extract. The specific results are shown in Table 2 below.

[0036] Table 2

[0037]

[0038] From the above tests, it can be seen that experimental group 1 did not use saturated sodium chloride immersion treatment and experimental group 2 used a short time (1 min) immersion treatment, and the resulting instant berry tea powder had a smaller mass, and the overall dihydromyricetin content was also lower. Experimental group 5 used saturated sodium chloride immersion treatment for 8 minutes, and the resulting instant berry tea powder had even less mass than that of experimental groups 3 and 4. This may be because the saturated sodium chloride solution was soaked for too long, resulting in a higher degree of damage to the berry tea cells, and some extractable components were dissolved in the saturated sodium chloride solution or lost with subsequent washing. Therefore, it is more reasonable to control the saturated sodium chloride solution soaking time at 3-5 minutes; the overall instant berry tea powder obtained in experimental group 6 and dihydromyricetin were both higher; experimental groups 7-9 used a single pressure for static extraction, and the overall dihydromyricetin extraction amount and extraction rate were both low.

[0039] In summary, the overall extraction efficiency of the instant berry tea powder prepared by experimental group 3, experimental group 4, experimental group 6, and experimental group 10 was high;

[0040] In addition, a CK group was set up. Based on the principle of single-factor experiment, the instant berry tea powders of experimental group 3, experimental group 6, experimental group 10 and CK group were mixed with room temperature water (22±3℃) and ice water (2±2℃) at a mass ratio of 1:25, and then stirred evenly. The dissolution of the instant berry tea powder in each group was observed. After standing for 2 minutes, the filter was filtered, and the filter residue was dried with hot air at 45℃. The dissolution rate of the instant berry tea powder in each group was calculated (dissolution rate = (total mass - dry filter residue mass) / total mass × 100%). The specific dissolution rates are shown in Table 3 below:

[0041] Table 3

[0042]

[0043] The preparation method of the instant berry tea powder of the CK group is as follows:

[0044] Fresh tender stems and leaves of Ampelopsis glauca are air-dried to a moisture content of 11% and used as raw dry leaves. The raw dry leaves are crushed and passed through a 40-mesh sieve. Purified water is then used for countercurrent extraction at 35°C with a flow rate controlled at 20m3 / h. After extraction for 3 hours, the extract is concentrated and spray-dried to obtain instant berry tea powder.

[0045] Experimental Group 3 dissolved quickly when brewed with room temperature water and ice water. After stirring and letting it stand for 2 minutes, the overall tea soup was clear and no particles remained. The tea soup with room temperature water was clearer, while the tea soup with ice water was slightly turbid, but the overall solubility was good and the color was uniform.

[0046] When experimental group 6 was brewed with room temperature water, it dissolved in time. After stirring and standing for 2 minutes, the overall tea soup had a uniform color with a small amount of particles remaining. When brewed with ice water, the overall tea soup was less uniform and more turbid.

[0047] The experimental group 10 can basically dissolve when brewed with water at room temperature, but there is obvious particle dispersion in the tea soup and the uniformity is poor. When brewed with ice water, the solubility is slightly worse than that at room temperature, and the granularity is more obvious.

[0048] The CK group had poor overall solubility regardless of whether it was brewed with room temperature water or ice water, and the overall granularity was obvious, especially when brewed with ice water, where undissolved particles were severely attached to the wall.

[0049] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the steps and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for preparing instant berry tea, characterized in that: The preparation method comprises the following steps: S1. Soaking treatment: Select fresh tender stems and leaves of Ampelopsis glauca from June to August, air-dry them until the moisture content is 10-12%, soak them in a saturated sodium chloride solution at a pressure of 0.5 MPa for 3-5 minutes, remove them and rinse them with purified water to obtain preliminarily treated leaves; S2. Plasma treatment: After the preliminarily treated leaves are spread out, plasma treatment is performed using a mixture of argon and nitrogen for 2-3 minutes, and the pretreated leaves are taken out; S3, high-pressure cold extraction: The pretreated leaves are mixed with ice and crushed, then placed in an environment of 4-6°C, and extracted at a pressure of 0.2-0.4 MPa for 1-2 hours, at a pressure of 2-4 MPa for 30-40 minutes, and at a pressure of 8-10 MPa for 10-20 minutes, and then squeezed and filtered to obtain a filtrate and a residue; S4, secondary extraction: the above filter residue is mixed with purified water and then ultrasonically shaken at 60-80 ° C and centrifuged to separate the precipitate and combine the above filtrate to obtain a mixed extract for use; S5. Drying treatment: Freeze the mixed extract with liquid nitrogen, adjust the temperature for freeze-drying, and then grind to obtain instant berry tea powder.

2. The preparation method according to claim 1, wherein: The temperature for soaking in the saturated sodium chloride solution in step S1 is room temperature.

3. The preparation method according to claim 1, wherein: In step S2, the volume ratio of argon gas to nitrogen gas is 1-3:1-3, the flow rate of the mixed gas is 100-150 mL / min, and the processing power is 300-420W.

4. The preparation method according to claim 1, wherein: In step S3, the mass ratio of the pre-treated leaves to the ice cubes is 1:3-5.

5. The preparation method according to claim 1, wherein: In step S4, the mass ratio of the filter residue to pure water is 1:3-5, and the pH value of the feed solution is adjusted to 5.5-6.

6. The preparation method according to claim 1, wherein: The power of the ultrasonic oscillation in step S4 is 400-600W, and the time of the ultrasonic oscillation is 15-30 minutes.

7. The preparation method according to claim 1, wherein: The centrifugal speed in step S4 is 4000-5000 r / min, and the centrifugal time is 10-15 min.

8. The preparation method according to claim 1, wherein: The liquid nitrogen freezing time in step S5 is 1-2 hours, the freeze-drying temperature is -55°C±5°C, and the freeze-drying vacuum degree is 10-20 Pa.

Images