LU500845B1

LU500845B1 - High-aroma cold-soluble instant tea and preparation method thereof

Info

Publication number: LU500845B1
Application number: LU500845A
Authority: LU
Inventors: Kang Wei; Lanlan Peng; Yuanfeng Wang; Lizeng Cheng; Xinlin Wei
Original assignee: Univ Shanghai; Univ Shanghai Jiaotong
Priority date: 2021-09-15
Filing date: 2021-11-10
Publication date: 2023-03-16
Also published as: CN113892534A; CN113892534B

Abstract

The present disclosure relates to high-aroma cold-soluble instant tea and a preparation method thereof, and belongs to the field of deep processing of tea leaves. The method for preparing the instant tea sequentially comprises the following steps of 1 performing ultrasonic-assisted extraction and aroma fraction synchronous extraction on the tea leaves; 2 performing centrifugation and membrane separation; 3 performing vacuum concentration, low-temperature standing and centrifuging; 4 performing vacuum freeze drying; and ? performing essence refining and re-adding. Compared with the prior art, the preparation method disclosed by the present disclosure has the following advantages: 1) a device designed as shown in FIG.1 is adopted to perform ultrasonic-assisted extraction on tea leaf contents, and the tea leaf aroma fractions can be synchronously and continuously extracted; 2) centrifugation, membrane separation and vacuum freeze drying technologies are adopted, so that insoluble impurities in the instant tea are removed, the structure of the instant tea is kept loose and porous, and the instant cold-soluble characteristics of the instant tea are guaranteed; and 3) freezing deicing and nitrogen blowing to remove diethyl ether are adopted, so that the increase of water content and solvent residues are avoided when re-adding of tea essence, and the high-aroma quality of the instant tea is guaranteed. According to the high-aroma cold-soluble instant tea and the preparation method thereof disclosed by the present disclosure, the problems that the instant tea is light in aroma, poor in cold solubility and the like can be solved, and diversified and high-value utilization of the tea leaves is realized.

Description

BL-5318

LU500845

HIGH-AROMA COLD-SOLUBLE INSTANT TEA AND PREPARATION

METHOD THEREOF

TECHNICAL FIELD

[01] The present disclosure relates to the technical field of deep processing of tea leaves, and more particularly to high-aroma cold-soluble instant tea and a preparation method thereof.

BACKGROUND ART

[02] Instant tea is an instant tea product which is prepared by taking finished tea, semi-finished tea, tea byproducts or fresh tea leaves as raw materials and extracting water-soluble components and refining. The instant tea contains nutritional components and flavor substances which can enter tea soup in traditional tea leaves, and has all effects of tea on human body. The instant tea caters to the consumption fashion of modern beverages due to the characteristics of convenience and health, and is a beverage with a good development prospect.

[03] At present, the biggest problem of the quality of instant tea product is that the aroma is very light or the instant tea product does not have the aroma of freshly brewed tea. On one hand, volatile aroma substances in tea leaves exist in vacuoles of leaf cells, and are mostly volatilized along with water vapor in extraction process, and aroma flavor substances of the tea leaves are difficult to be effectively retained or captured by a conventional extraction technology. On the other hand, the boiling points of the aroma substances of the tea leaves are extremely low, and in the instant tea processing process, particularly the high-temperature effect of spray drying and the vacuumizing effect of vacuum concentration and vacuum freeze drying, may cause the loss of a large amount of volatile aroma substances contained in the tea leaves. As a result, the original aroma of the tea leaves is lost, and the flavor quality of the instant tea is seriously influenced.

Scientific researches and production practices have proved that after the tea leaves are subjected to the processes of vacuum concentration, spray drying, etc, the aroma intensity of the produced instant tea powder is only 10-20% of that of the freshly brewed tea. In the prior art, for example, in a method for preparing strong-aroma type instant tea and a product thereof disclosed by Chinese patent CN 112616966 A and a production process of high-aroma high-theanine Biluochun instant tea disclosed by

Chinese patent CN 108713614 A, after being extracted, the tea leaves are subjected to the processes of centrifugation, membrane concentration, vacuum freeze drying, etc. to prepare the instant tea. A large amount of aroma components of the instant tea prepared by these technologies are lost in the processes of extraction and vacuum freeze drying, so that the strong-aroma type instant tea cannot be obtained. For example, in a processing technology of high-aroma cold-soluble instant tea and plant instant beverage disclosed by Chinese patent CN 107348055 A, aroma fractions and taste water solution are extracted from in the tea leaves respectively, then the taste water solution is subjected to centrifugation, concentration and spray drying, and the aroma fractions are added into taste dry powder for freeze drying. According to the technology, the aroma

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LU500845 fractions and the taste components of the tea leaves are separately extracted, so that the process is tedious, and moreover, in the vacuum freeze drying process, the aroma fractions added into the instant tea are extremely easily volatilized in the vacuum state, and the problem that the aroma of the instant tea 1s relatively low 1s not solved. 104] The poor solubility is another important problem of the quality of instant tea.

Instant tea prepared in the prior art has solid insoluble substances after being brewed, and is poor in solubility. For example, in high-aroma instant tea and a preparation method thereof disclosed by Chinese patent CN 105145964 A, low-polarity aroma components and medium-high-polarity components of tea leaves are extracted by adopting petroleum ether and ethanol, respectively, and then the two components are blended to prepare high-aroma instant tea. According to the technology, the aroma components of tea leaves are blended to improve the aroma of the instant tea, but the instant tea extracted by an organic solvent is poor in water solubility and has relatively serious petroleum ether residues.

SUMMARY

[05] In order to solve the problems of relatively light aroma and poor cold solubility of instant tea produced by an existing process, the present disclosure provides high-aroma cold-soluble instant tea and a preparation method thereof.

[06] The object of the present disclosure can be achieved through the following technical solutions:

[07] A method for preparing high-aroma cold-soluble instant tea, comprising the following steps:

[08] 1) performing ultrasonic-assisted extraction and aroma fraction synchronous extraction on tea leaves: crushing tea leaves, extracting tea powder by an ultrasonic-assisted extraction and aroma fraction synchronous extraction device to obtain an extracting solution, synchronously condensing and collecting aroma fractions, and extracting by diethyl ether to obtain a tea essence extracting solution;

[09] 2) centrifuging the extracting solution, and performing membrane separation: centrifuging the extracting solution, taking supernatant, and filtering by a micro-filtration membrane to obtain permeate liquid;

[10] 3) performing vacuum concentration, low-temperature standing and centrifuging: performing vacuum concentration on the permeate liquid, and performing low-temperature standing and centrifugal separation in sequence to obtain concentrated supernatant;

[11] 4) performing vacuum freeze drying: performing low-temperature freezing and vacuum freeze drying on the concentrated supernatant in sequence to obtain instant tea freeze-dried powder; and

[12] 5) refining and re-adding tea essence: performing low-temperature freezing on the extracting solution, removing ice to remove water, and blowing off diethyl ether by nitrogen to obtain tea essence; and then re-adding the tea essence into the instant tea freeze-dried powder, and sealing and storing to obtain the high-aroma cold-soluble instant tea.

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[13] Further, the device in the step 1) comprises:

[14] an extraction mechanism which comprises an extraction tank, a motor arranged at the bottom of the extraction tank, a spiral shaft arranged in the extraction tank and in transmission connection with the motor, an auger arranged on the spiral shaft, an ultrasonic generator and a temperature sensor which are arranged on the side wall of the extraction tank, a liquid inlet and a liquid outlet which are formed in the extraction tank up and down respectively, and a material conveying pump which is in communication with the bottom of the extraction tank;

[15] a condensation and collection mechanism which comprises a condensation chamber which is arranged on the top of the extraction tank and in communication with the extraction tank, a spiral condensation pipe arranged in the condensation chamber, a water inlet and a water outlet which are formed in the side wall of the condensation chamber and in communication with the spiral condensation pipe, and a collection ring groove which is formed in the bottom side in the condensation chamber and used for collecting tea aroma steam fractions; and

[16] an extraction mechanism which comprises an extracting solution storage ball of which the top end is in communication with the collection ring groove, a U-shaped pipe of which one end is in communication with the bottom of the extracting solution storage ball and the other end is open, and an extracting solution inlet and an extracting solution outlet which are formed in the two ends of the extracting solution storage ball up and down respectively, wherein the open end of the U-shaped pipe is positioned between the bottom end and the top end of the extracting solution storage ball; diethyl ether is accommodated in the extracting solution storage ball; water is accommodated in the U-shaped pipe; and

[17] Further, the adding height of the diethyl ether is more than 10 cm, and the diethyl ether is added not more than the lowest end of the U-shaped pipe.

[18] Further, the mass ratio of tea powder to water is (1: 10) - (1: 40), the extraction temperature is 60-90°C, the ultrasonic frequency is 20-100 KHz, and the extraction time is 10-60 min.

[19] Further, in the step 2), the centrifuging speed is 3000-12000 r/min, and the centrifuging time is 5-60 min;

[20] The pore diameter of the micro-filtration membrane is 10-100 um.

[21] Further, in the step 3), the permeate liquid is concentrated to 1/4-1/8 of the original volume;

[22] The low-temperature standing temperature is 2-8°C, and the standing time is 6-24 h.

[23] Further, in the step 4), the freezing temperature of the concentrated supernatant is not higher than -20°C, the freezing time is 4-12 h, and the vacuum freeze-drying time is 12-36 h.

[24] Further, in the step 5), the freezing temperature of the tea essence extracting solution is not higher than -20°C, and the freezing time is 4-12 h;

[25] The re-adding amount of the tea essence relative to instant tea freeze-dried powder is 0.001-0.1wt%.

[26] The key points of the present disclosure are as follows: (a) extracting of tea

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LU500845 leaf contents and tea essence: extremely dissolving out the tea leaf contents at relatively low temperature and within relatively short extraction time, and synchronously extracting tea leaf aroma fractions; (b) separating and drying of instant tea: completely removing solid insoluble matters and water-soluble macromolecules in an extracting solution, and keeping instant tea powder loose and porous, so that the instant tea has extremely good solubility; and (c) re-adding of the tea essence: completely removing water in the tea essence, so as to avoid the condition that the quality guarantee period of the instant tea is influenced by the fact that the water content is increased when the tea essence is re-added.

[27] Compared with the prior art, the present disclosure has the following characteristics:

[28] 1) an ultrasonic-assisted extraction and aroma fraction synchronous extraction device: the device not only utilizes the cavitation effect and stirring effect generated by high-frequency vibration waves to accelerate dissolution of tea contents, but also utilizes the U-shaped tube communicating vessel principle to synchronously extract tea aroma fractions by diethyl ether; and in the U-shaped tube, tea aroma fractions are extracted by an extractant (diethyl ether) in a left tube, the tea essence is enriched in the diethyl ether extraction layer of the left tube, water sinks into a right tube and is discharged, and the tea aroma fractions are continuously extracted;

[29] 2) combination of centrifugation, membrane separation and vacuum freeze-drying processes: the centrifugation and membrane technology are adopted to separate the extracting solution, so that small-molecule solid insoluble substances can be removed, and water-soluble macromolecules can be intercepted; further, the concentrated solution is sequentially subjected to low-temperature standing and centrifuging to remove low-temperature insoluble substances in the instant tea; and further, the concentrated solution is subjected to vacuum freeze-drying to ensure that the instant tea is loose and porous, thereby ensuring the instant cold-soluble characteristic of the instant tea; and

[30] 3) refining and re-adding of tea essence: by utilizing the characteristic that water precipitates and crystallizes from diethyl ether at low temperature, a freeze deicing method is adopted to remove water in the tea essence extracting solution, thereby avoiding the increase of water content in the instant tea in the tea essence re-adding process and influencing the shelf life; and the refined tea essence is re-added into the instant tea freeze-dried powder to ensure the high-aroma quality of the instant tea.

BRIEF DESCRIPTION OF THE DRAWINGS

[31] FIG.1 is a structural schematic diagram of an ultrasonic-assisted extraction and aroma fraction synchronous extraction device used in the present disclosure;

[32] FIG.2 is refined tea essence: A, instant green tea essence; B, instant oolong tea essence; C, instant black tea essence; D, instant dark tea essence;

[33] FIG.3 is instant tea freeze-dried powder: A, instant green tea freeze-dried powder; B, instant oolong tea freeze-dried powder; C, instant black tea freeze-dried powder; D, instant dark tea freeze-dried powder; and

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[34] FIG .4 is freshly brewed tea (above), brewed instant tea and tea dregs thereof (below): A, freshly brewed green tea and instant green tea; B, freshly brewed oolong tea and instant oolong tea; C, freshly brewed black tea and Instant black tea; D, freshly brewed dark tea and instant dark tea. 5 [35] Description of marks in the drawings:

[36] 1. material conveying pump; 2, auger; 3, spiral shaft; 4, temperature sensor; 5, ultrasonic generator; 6, liquid inlet; 7, water inlet; 8, water outlet; 9, motor; 10, liquid outlet; 11, extracting solution outlet; 12, extracting solution inlet; 13, extraction layer; 14, water layer.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[37] In the step of performing ultrasonic-assisted extraction and aroma fraction synchronous extraction on tea leaves in the following examples, the device used is shown in FIG. 1, comprising:

DS] an extraction mechanism which comprises an extraction tank, a motor (9) arranged at the bottom of the extraction tank, a spiral shaft (3) arranged in the extraction tank and in transmission connection with the motor (9), an auger (2) arranged on the spiral shaft (3), an ultrasonic generator (5) and a temperature sensor (4) which are arranged on the side wall of the extraction tank, a liquid inlet (6) and a liquid outlet (10) which are formed in the extraction tank up and down respectively, and a material conveying pump (1) which is in communication with the bottom of the extraction tank;

[39] a condensation and collection mechanism which comprises a condensation chamber which is arranged on the top of the extraction tank and in communication with the extraction tank, a spiral condensation pipe arranged in the condensation chamber, a water inlet (7) and a water outlet (8) which are formed in the side wall of the condensation chamber and in communication with the spiral condensation pipe, and a collection ring groove which is formed in the bottom side in the condensation chamber and used for collecting tea aroma steam fractions; and

[40] an extraction mechanism which comprises an extracting solution storage ball of which the top end is in communication with the collection ring groove, a U-shaped pipe of which one end is in communication with the bottom of the extracting solution storage ball and the other end is open, and an extracting solution inlet (12) and an extracting solution outlet (11) which are formed in the two ends of the extracting solution storage ball up and down respectively, wherein the open end of the U-shaped pipe is positioned between the bottom end and the top end of the extracting solution storage ball, an extraction layer (13) is accommodated in the extracting solution storage ball, using diethyl ether as an extracting agent, and water is accommodated in the

U-shaped pipe and a water layer (14) for extraction is formed.

[41] Example 1:

[42] This example provides high-aroma cold-soluble instant tea prepared from green tea. À specific preparation method comprises the following steps:

[43] 1) performing ultrasonic-assisted extraction and aroma fraction synchronous extraction on tea leaves: crushing the green tea and carrying out the ultrasonic-assisted extraction on green tea powder by adopting an ultrasonic-assisted extraction and aroma

BL-5318

LU500845 fraction synchronous extraction device shown as FIG.1, wherein the mass ratio of the tea powder to water is 1: 30, the extraction temperature is 70°C, the ultrasonic frequency is 60 KHz and the extraction time is 15 min; and meanwhile, extracting aroma fractions by utilizing diethyl ether;

[44] 2) centrifuging an extracting solution and performing membrane separation: centrifuging the extracting solution at a speed of 5000 r/min for 10 min; and separating supernatant by utilizing a 50 um micro-filtration membrane to obtain permeate liquid,

[45] 3) performing vacuum concentration, low-temperature standing and centrifuging: concentrating the permeate liquid in vacuum to 1/4 volume; standing the obtained concentrated solution at 8°C for 12 h; and then centrifuging and taking supernatant;

[46] 4) performing vacuum freeze drying: freezing the supernatant in the step 3) at -20°C for 12 h and performing vacuum freeze drying for 36 h to obtain freeze-dried powder; and 147] 5) refining and re-adding tea essence: freezing the tea essence extracting solution obtained in the step 1) at -20°C or below for 12 h and removing ice to remove water; then blowing off the diethyl ether by nitrogen to obtain the tea essence; spraying the obtained tea essence into the freeze-dried powder, wherein the adding amount is 0.005wt%; and sealing and storing to obtain the high-aroma cold-soluble instant green tea.

[48] The obtained tea essence is shown as FIG.2A, and the refined tea essence does not contain water and has a rich tea aroma. The obtained freeze-dried powder is porous and loose and is shown as FIG3A. Sensory evaluation experiments (GB/T 31740.1-2015 and GB/T 23776-2018) show that the instant tea is brewed with cold water (25°C) and is completely dissolved within 3 min, and tea residues are not remained at the tea dregs (shown as FIG4A (below)); and the tea soup has the rich aroma and the aroma is close to that of freshly brewed green tea (shown as FIG.4A (above)).

[49] Example 2:

[50] This example provides high-aroma cold-soluble instant tea prepared from oolong tea. À specific preparation method comprises the following steps:

[51] 1) performing ultrasonic-assisted extraction and aroma fraction synchronous extraction on tea leaves: crushing the oolong tea and carrying out the ultrasonic-assisted extraction on oolong tea powder by adopting an ultrasonic-assisted extraction and aroma fraction synchronous extraction device shown as FIG.1, wherein the mass ratio of the tea powder to water is 1: 20, the extraction temperature is 60°C, the ultrasonic frequency is 30 KHz and the extraction time is 20 min; and meanwhile, extracting aroma fractions by utilizing diethyl ether;

[52] 2) centrifuging an extracting solution and performing membrane separation: centrifuging the extracting solution at a speed of 5000 r/min for 15 min; and separating supernatant by utilizing a 60 um micro-filtration membrane to obtain permeate liquid,

[53] 3) performing vacuum concentration, low-temperature standing and centrifuging: concentrating the permeate liquid in vacuum to 1/6 volume; standing the obtained concentrated solution at 4°C for 6 h; and then centrifuging;

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[54] 4) performing vacuum freeze drying: freezing the supernatant in the step 3) at -20°C for 8 h and performing vacuum freeze drying for 24 h to obtain freeze-dried powder; and

[55] 5) refining and re-adding tea essence: freezing the tea essence extracting solution obtained in the step 1) at -20°C for 6 h and removing ice to remove water; then blowing off the diethyl ether by nitrogen to obtain the tea essence; spraying the obtained tea essence into the freeze-dried powder, wherein the adding amount is 0.01wt%; and sealing and storing to obtain the high-aroma cold-soluble instant oolong tea.

[56] The obtained tea essence is shown as FIG.2B, and the refined tea essence does not contain water and has a rich tea aroma. The obtained freeze-dried powder is porous and loose and is shown as FIG.3B. Sensory evaluation experiments show that the instant tea is brewed with cold water (25°C) and is completely dissolved within 3 min, and tea residues are not remained at the tea dregs (shown as FIG.4B (below)); and the tea soup has the rich aroma and the aroma is close to that of freshly brewed oolong tea (shown as

FIG.4B (above)).

[57] Example 3:

[58] This example provides high-aroma cold-soluble instant tea prepared from black tea. A specific preparation method comprises the following steps:

[59] 1) performing ultrasonic-assisted extraction and aroma fraction synchronous extraction on tea leaves: crushing the black tea and carrying out the ultrasonic-assisted extraction on black tea powder by adopting an ultrasonic-assisted extraction and aroma fraction synchronous extraction device shown as FIG.1, wherein the mass ratio of the tea powder to water is 1: 30, the extraction temperature is 80°C, the ultrasonic frequency is 80 KHz and the extraction time is 40 min; and meanwhile, extracting aroma fractions by utilizing diethyl ether;

[60] 2) centrifuging an extracting solution and performing membrane separation: centrifuging the extracting solution at a speed of 6000 r/min for 12 min; and separating supernatant by utilizing a 20 um micro-filtration membrane to obtain permeate liquid,

[61] 3) performing vacuum concentration, low-temperature standing and centrifuging: concentrating the permeate liquid in vacuum to 1/8 volume; standing the obtained concentrated solution at 8°C for 6 h; and then centrifuging;

[62] 4) performing vacuum freeze drying: freezing the supernatant in the step 3) at -40°C for 4 h and performing vacuum freeze drying for 12 h to obtain freeze-dried powder; and

[63] 5) refining and re-adding tea essence: freezing the tea essence extracting solution obtained in the step 1) at -40°C for 4 h and removing ice to remove water; then blowing off the diethyl ether by nitrogen to obtain the tea essence; spraying the obtained tea essence into the freeze-dried powder, wherein the adding amount is 0.02 wt%; and sealing and storing to obtain the high-aroma cold-soluble instant black tea.

[64] The obtained tea essence is shown as FIG.2C, and the refined tea essence does not contain water and has a rich tea aroma. The obtained freeze-dried powder is porous and loose and is shown as FIG.3C. Sensory evaluation experiments show that the instant tea is brewed with cold water (25°C) and is completely dissolved within 3 min, and tea residues are not remained at the tea dregs (shown as FIG.4C (below)); and the tea soup

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LU500845 has the rich aroma and the aroma is close to that of freshly brewed black tea (shown as

FIG.4C (above)).

[65] Example 4:

[66] This example provides high-aroma cold-soluble instant tea prepared from dark tea. À specific preparation method comprises the following steps:

[67] 1) performing ultrasonic-assisted extraction and aroma fraction synchronous extraction on tea leaves: crushing the dark tea and carrying out the ultrasonic-assisted extraction on dark tea powder by adopting an ultrasonic-assisted extraction and aroma fraction synchronous extraction device shown as FIG.1, wherein the mass ratio of the tea powder to water is 1:40, the extraction temperature is 60-90°C, the ultrasonic frequency is 80 KHz and the extraction time is 60 min; and meanwhile, extracting aroma fractions by utilizing diethyl ether;

[68] 2) centrifuging an extracting solution and performing membrane separation: centrifuging the extracting solution at a speed of 12000 r/min for 60 min; and separating supernatant by utilizing a 10 um micro-filtration membrane to obtain permeate liquid;

[69] 3) performing vacuum concentration, low-temperature standing and centrifuging: concentrating the permeate liquid in vacuum to 1/5 volume; standing the obtained concentrated solution at 8°C for 24 h; and then centrifuging and taking supernatant;

[70] 4) performing vacuum freeze drying: freezing the supernatant in the step 3) at -20°C for 8 h and performing vacuum freeze drying for 36 h to obtain freeze-dried powder; and

[71] 5) refining and re-adding tea essence: freezing the tea essence extracting solution obtained in the step 1) at -20°C for 12 h and removing ice to remove water; then blowing off the diethyl ether by nitrogen to obtain the tea essence; spraying the obtained tea essence into the freeze-dried powder, wherein the adding amount is 0.03wt%; and sealing and storing to obtain the high-aroma cold-soluble instant dark tea.

[72] The obtained tea essence is shown as FIG.2D, and the refined tea essence does not contain water and has a rich tea aroma. The obtained freeze-dried powder is porous and loose and is shown as FIG.3D. Sensory evaluation experiments show that the instant tea is brewed with cold water (25°C) and is completely dissolved within 3 min, and tea residues are not remained at the tea dregs (shown as FIG.4D (below)); and the tea soup has the rich aroma and the aroma is close to that of freshly brewed dark tea (shown as FIG.4D (above)).

Claims

BL-5318 LU500845 CLAIMS

1. A method for preparing high-aroma cold-soluble instant tea, comprising the following steps: 1) performing ultrasonic-assisted extraction and aroma fraction synchronous extraction on tea leaves: crushing tea leaves, extracting tea powder by an ultrasonic-assisted extraction and aroma fraction synchronous extraction device to obtain an extracting solution, synchronously condensing and collecting aroma fractions, and extracting by diethyl ether to obtain a tea essence extracting solution; 2) centrifuging the extracting solution, and performing membrane separation: centrifuging the extracting solution, taking supernatant, and filtering by a micro-filtration membrane to obtain permeate liquid; 3) performing vacuum concentration, low-temperature standing and centrifuging: performing vacuum concentration on the permeate liquid, and performing low-temperature standing and centrifugal separation in sequence to obtain concentrated supernatant; 4) performing vacuum freeze drying: performing low-temperature freezing and vacuum freeze drying on the concentrated supernatant in sequence to obtain instant tea freeze-dried powder; and 5) refining and re-adding tea essence: performing low-temperature freezing on the tea essence extracting solution, removing ice to remove water, and blowing off diethyl ether by nitrogen to obtain the tea essence; and then re-adding the tea essence into the instant tea freeze-dried powder, and sealing and storing to obtain the high-aroma cold-soluble instant tea.

2. The method for preparing the high-aroma cold-soluble instant tea according to claim 1, wherein in the step 1), the device comprises: an extraction mechanism which comprises an extraction tank, a motor (9) arranged at the bottom of the extraction tank, a spiral shaft (3) arranged in the extraction tank and in transmission connection with the motor (9), an auger (2) arranged on the spiral shaft (3), an ultrasonic generator (5) and a temperature sensor (4) which are arranged on the side wall of the extraction tank, a liquid inlet (6) and a liquid outlet (10) which are formed in the extraction tank up and down respectively, and a material conveying pump (1) which is in communication with the bottom of the extraction tank; a condensation and collection mechanism which comprises a condensation chamber which is arranged on the top of the extraction tank and in communication with the extraction tank, a spiral condensation pipe arranged in the condensation chamber, a water inlet (7) and a water outlet (8) which are formed in the side wall of the condensation chamber and in communication with the spiral condensation pipe, and a collection ring groove which is formed in the bottom side in the condensation chamber and used for collecting tea aroma steam fractions; and an extraction mechanism which comprises an extracting solution storage ball of which the top end is in communication with the collection ring groove, a U-shaped pipe of which one end is in communication with the bottom of the extracting solution storage

BL-5318 LU500845 ball and the other end is open, and an extracting solution inlet (12) and an extracting solution outlet (11) which are formed in the two ends of the extracting solution storage ball up and down respectively, wherein the open end of the U-shaped pipe is positioned between the bottom end and the top end of the extracting solution storage ball; diethyl ether is accommodated in the extracting solution storage ball; water is accommodated in the U-shaped pipe; and the adding height of the diethyl ether is more than 10 cm, and the diethyl ether is added not more than the lowest end of the U-shaped pipe.

3. The method for preparing the high-aroma cold-soluble instant tea according to claim 1, wherein in the step 1), the mass ratio of tea powder to water is (1: 10) - (1: 40), the extraction temperature is 60-90°C, the ultrasonic frequency is 20-100 KHz, and the extraction time is 10-60 min.

4. The method for preparing the high-aroma cold-soluble instant tea according to claim 1, wherein in the step 2), the centrifuging speed is 3000-12000 r/min, and the centrifuging time is 5-60 min; the pore diameter of the micro-filtration membrane is 10-100 um.

5. The method for preparing the high-aroma cold-soluble instant tea according to claim 1, wherein in the step 3), the permeate liquid is concentrated to 1/4-1/8 of the original volume; and the low-temperature standing temperature is 2-8°C, and the standing time is 6-24 h.

6. The method for preparing the high-aroma cold-soluble instant tea according to claim 1, wherein in the step 4), the freezing temperature of the concentrated supernatant is not higher than -20°C, the freezing time is 4-12 h, and the vacuum freeze-drying time is 12-36 h.

7. The method for preparing the high-aroma cold-soluble instant tea according to claim 1, wherein in the step 5), the freezing temperature of the tea essence extracting solution is not higher than -20°C, the freezing time is 4-12 h; and the re-adding amount of the tea essence relative to instant tea freeze-dried powder is 0.001-0. 1wt%.

8. High-aroma cold-soluble instant tea, wherein the high-aroma cold-soluble instant tea is prepared by the method according to any one of claims 1 to 7.