Green tea production and processing technology

Abstract

The present invention discloses a green tea production and processing technology, and belongs to the technical field of instant green tea production, and the green tea production and processing technology comprises the following steps: green tea and cyclocarya paliurus are mixed and crushed, treated by a twin-screw extrusion bulking machine, and dried to obtain tea leaf powder; soaking the tea leaf powder in a composite extracting agent, adding fermentation liquor, and performing fermentation extraction to obtain a green tea extract and tea residues; concentrating and freeze-drying the green tea extract to obtain green tea powder; the preparation method comprises the following steps: preparing tea residue protein from tea residues, treating the tea residue protein by a twin-screw extruder, crushing and sieving to obtain porous tea residue protein; mixing the green tea powder and the porous tea residue protein, and performing negative pressure treatment to obtain the instant green tea. The tea leaf powder is soaked in the composite extracting agent, the nano-emulsion permeates into pore channels of the porous tea leaf powder, wall breaking is completed, and effective components of the tea leaves are released; and the content of cellulase and pectinase is increased, so that the degradation of the tea cheese is facilitated.

Description

Technical Field

[0001] The invention relates to the technical field of green tea instant tea production, in particular to a green tea production and processing technology. Background Art

[0002] Instant tea is a solid beverage tea that dissolves quickly in water. It uses finished tea, semi-finished tea, tea by-products or fresh leaves as raw materials. It is processed into a new type of beverage in the form of soluble powder, granules or discs that is easily soluble in water and has no tea residue residue through extraction, filtration, concentration, drying and other processes. Among them, green tea instant tea, as a natural product, is regarded as a good health drink in daily consumption. It can delay aging. The active ingredients it contains have strong antioxidant activity, can scavenge free radicals in the human body, help curb cardiovascular disease, and prevent blood from clotting.

[0003] The polyphenols contained in green tea and Cyclocarya paliurus, especially tea polyphenols, catechins, theaflavins and other aroma substances, provide many health benefits. However, during the storage of green tea instant tea, a large number of tea polyphenols, flavonoids and other aroma substances are easily oxidized, volatilized and lost, resulting in a decrease in the effective ingredients of the instant tea, affecting the quality of the instant tea. During the preparation of green tea instant tea, the cell walls of green tea and Cyclocarya paliurus are not completely decomposed, resulting in low extraction efficiency of green tea and Cyclocarya paliurus. Enzyme treatment of green tea can destroy the cell walls of green tea, improve the extraction efficiency of green tea and improve the quality of instant tea, but the enzyme is easily inactivated, resulting in a general wall breaking effect, and the inactivation of the enzyme and insufficient content make it difficult to degrade the tea cheese, resulting in a cheese-like turbidity. Summary of the invention

[0004] The object of the present invention is to provide a green tea production and processing process: green tea and Cyclocarya paliurus are mixed and crushed, and after being processed by a twin-screw extruder, the surface of the green tea and Cyclocarya paliurus powder has a porous structure, which is conducive to the release of phenolic substances in plant cells, and the porous structure increases the contact area with the composite nanoemulsion and fermentation liquid, thereby improving the extraction efficiency; natural vitamin E is mixed with a composite enzyme, and the natural vitamin E, as a carrier of the composite enzyme, can assist the composite enzyme to enter the pores of the porous tea powder, which is conducive to the diffusion and penetration of the composite enzyme inside the porous tea powder, thereby improving the extraction efficiency; the nanoemulsion formed by the mixture of modified natural vitamin E and proline can penetrate into the porous tea powder, and the nanoemulsion formed by the mixture of modified natural vitamin E and proline can penetrate into the porous tea powder. The pores of the leaf powder are broken, and the small size structure of the nanoemulsion allows the nanoemulsion to remain in the gaps formed by the loss of water in the green tea intercellular matrix, so as to destroy the cell structure and increase the content of the aroma components of the green tea. In the extraction process, fermentation liquid is added, and the Aspergillus niger in the fermentation liquid can promote the tea powder to produce cellulase and pectinase, which are helpful for the precipitation of the tea content, and increase the content of cellulase and pectinase, which is beneficial for the degradation of tea cheese and avoids the appearance of cheese-like turbidity. The green tea powder and the porous tea residue protein are mixed, and after negative pressure treatment, the stability of the green tea powder is improved, and the oxidation of the green tea powder and the poor storage performance lead to the decline of the quality of the green tea instant tea.

[0005] The technical problems to be solved by the present invention are as follows: during the storage of green tea instant tea, its tea polyphenols, flavonoids and other aroma substances are easily oxidized, volatilized and lost, resulting in a decrease in the effective ingredients of the instant tea, affecting the quality of the instant tea; the cell walls of green tea and Cyclocarya paliurus are not completely decomposed, resulting in low extraction efficiency of green tea and Cyclocarya paliurus; enzyme treatment of green tea can destroy the cell walls of green tea, improve the extraction efficiency of green tea and the quality of modified instant tea, but the enzyme is easily inactivated, resulting in a general cell wall breaking effect, and the inactivation and insufficient content of the enzyme make it difficult to degrade tea cheese, resulting in cheese-like turbidity.

[0006] To achieve the above object, the present invention provides the following technical solutions: A green tea production and processing process comprises the following steps: S1. Green tea and Cyclocarya paliurus are mixed and crushed, processed by a twin-screw extruder, and dried to obtain tea powder.

[0007] Among them, due to the high temperature, high pressure and high shear force in the extrusion chamber, especially when the pressure is released, the air in the green tea and Cyclocarya paliurus materials is discharged, destroying the plant cell wall and cell membrane structure, making the surface of the green tea and Cyclocarya paliurus powder have a porous structure, which is more conducive to the release of phenolic substances in plant cells. The porous structure increases the contact area with the composite nanoemulsion fermentation liquid and improves the extraction efficiency.

[0008] Furthermore, the mass ratio of green tea to Cyclocarya paliurus is (8-10):(0.5-1.5).

[0009] S2. After soaking the tea powder in a composite extractant, adding a fermentation liquid, and performing fermentation extraction to obtain a green tea extract and tea residues.

[0010] Furthermore, the dosage ratio of tea powder, composite extractant and fermentation liquid is (13-17) g: (80-120) mL: (8-12) mL.

[0011] S3. The green tea extract is filtered, concentrated, and freeze-dried to obtain green tea powder.

[0012] S4. Tea residue protein is prepared by using tea residue. The tea residue protein is placed in a twin-screw extruder, crushed, and sieved to obtain porous tea residue protein.

[0013] S5. Mix the green tea powder and the porous tea residue protein, and treat them under negative pressure to obtain instant green tea.

[0014] Furthermore, in step S1, the barrel temperature of the twin-screw extruder is 90-100°C, the screw speed is 200-220r / min, the feed rate is 10-12kg / h, and the amount of deionized water added is 45-55%.

[0015] Furthermore, the pore size of the tea powder is 2-5 μm.

[0016] Furthermore, the fermentation extraction temperature is 35-40°C, and the fermentation extraction time is 1-2h.

[0017] Furthermore, the quality ratio of green tea powder to porous tea residue protein is (2-5):(10-15).

[0018] Furthermore, the negative pressure is -(0.06-0.08)MPa.

[0019] Furthermore, the filtration is performed using an ultrafiltration membrane, and the pore size of the ultrafiltration membrane is 20-30 nm.

[0020] Furthermore, the concentration pressure is 1.5-2.5 MPa, the concentration temperature is controlled at 20-45°C, and the concentration is carried out to 1 / 4-1 / 2 of the original volume.

[0021] Furthermore, the freeze-drying temperature is -(20-30)°C, and the freeze-drying time is 12-15h.

[0022] Furthermore, the porous tea residue protein is prepared by the following steps: The tea residue protein is placed in a twin-screw extruder, extruded and expanded, taken out, and crushed through a 80-90 mesh sieve to obtain a porous protein matrix.

[0023] Among them, the tea residue protein is puffed by twin-screw extrusion. As the heating temperature rises, the screw speed increases and the water inlet speed slows down, which increases the hydrothermal degree and forms bubbles in the tea residue protein, thereby producing a porous structure on the surface of the tea residue protein. The porous tea residue protein has good stability, and its porous structure can adsorb green tea powder to the surface and pores of the porous tea residue protein, thereby improving the stability of the green tea powder.

[0024] Furthermore, the temperature of the twin-screw extruder is 120-130° C., the screw speed is 140-150 r / min, the deionized water flow rate is 500-520 g / h, and the feed rate is 600-620 g / h.

[0025] Furthermore, tea residue protein is prepared by the following steps: The tea residue was added into a 0.5-1.5 mol / L sodium hydroxide aqueous solution, stirred at 95°C for 4 h, centrifuged at 15000 r / min for 10 min, the supernatant was collected, and a 0.5-1.5 mol / L hydrochloric acid aqueous solution was added to the supernatant to adjust the pH to 3.5, and the solution was centrifuged at 15000 r / min to obtain tea residue protein.

[0026] Furthermore, the usage ratio of tea residue, sodium hydroxide aqueous solution and hydrochloric acid aqueous solution is (8-12) g:(180-220) mL:(1-3) mL.

[0027] Furthermore, the composite extractant is prepared by mixing modified natural vitamin E and proline, adding glycerol and an emulsifier, and stirring the mixture for reaction.

[0028] Furthermore, the emulsifier is selected from any one of monoglyceride, sucrose ester, sorbitan monolaurate, and polyoxyethylene sorbitan monostearate.

[0029] Further, the composite leaching agent is specifically prepared by the following steps: Add modified natural vitamin E and proline to deionized water, stir evenly to form a dispersed phase, add an emulsifier to glycerol, stir at 50°C for 10 minutes to fully dissolve the emulsifier, add the dispersed phase, heat to 70°C, shear at 5000rpm for 20 minutes, place in a homogenizer, homogenize twice at a homogenizing pressure of 250bar, store at room temperature to obtain a composite nanoemulsion, place the composite nanoemulsion in deionized water, stir, and obtain a composite extractant.

[0030] Among them, a modified natural vitamin E and proline mixture is used as a dispersed phase, and glycerol is used as a continuous phase to form a nanoemulsion. The nanoemulsion particle size is 1-3 μm and has a large surface area, so that the nanoemulsion can penetrate into the pores of the porous tea powder, complete the wall breaking, and realize the release of effective ingredients of tea such as tea polyphenols, catechins, flavonoids, amino acids and other effective ingredients. The small size of the nanoemulsion can remain in the gap formed by the dehydration of the green tea intercellular matrix to destroy the cell structure and increase the release of green tea aroma components.

[0031] Furthermore, the dosage ratio of modified natural vitamin E, proline, deionized water, emulsifier, and glycerol is (1-2) g: (0.2-0.4) g: (15-25) mL: (0.16-0.2) g: (50-70) mL.

[0032] Furthermore, the usage ratio of the composite nanoemulsion and deionized water is (45-55) mL:(90-110) mL.

[0033] Furthermore, the modified natural vitamin E is prepared by mixing natural vitamin E with a complex enzyme.

[0034] Furthermore, the composite enzyme is prepared by mixing protease, cellulase and pectinase in a mass ratio of (1-2):(0.5-1):(0.6-1).

[0035] Furthermore, the tocopherol content in natural vitamin E is 90.7-92.5%.

[0036] Further, the modified natural vitamin E is specifically prepared by the following steps: Add natural vitamin E and complex enzyme to ethanol, stir evenly, heat to 30°C, stir to react for 10 minutes, let stand overnight until ethanol evaporates, collect solids, and dry the solids in an oven at 30°C for 5 minutes to obtain modified natural vitamin E.

[0037] Among them, in the organic solvent ethanol, the hydroxyl group in natural vitamin E can combine with the carboxyl group and amino group in the complex enzyme through hydrogen bonds to form a stable structure. Natural vitamin E, as a carrier of the complex enzyme, can assist the complex enzyme to enter the pores of the porous tea powder, which is beneficial to the diffusion and penetration of the complex enzyme inside the porous tea powder, thereby improving the extraction efficiency.

[0038] Furthermore, the dosage ratio of natural vitamin E, complex enzyme and ethanol is (5.1-5.3) g: (3-3.2) g: (10-20) mL.

[0039] Further, the fermentation broth is specifically prepared by the following steps: Green tea and Cyclocarya paliurus are mixed and crushed, placed in deionized water, extracted at 60°C for 1 hour, and then the filtrate is collected by filtration. The filtrate is added to the culture medium and activated and cultured at 28°C for 7 days. Aspergillus niger is added to the culture medium for an inoculation test for 7 days. In an ultra-clean workbench, an inoculation loop is used to scrape the Aspergillus niger mycelium on a plate, placed in sterile water with small glass beads, and after sufficient shaking, filtered through absorbent cotton to obtain a fermentation liquid.

[0040] Furthermore, the ratio of green tea, Cyclocarya paliurus, and deionized water is (8-10) g: (0.5-1.5) g: (80-120) mL. Further, the Aspergillus niger is selected from Aspergillus niger 41125 or Aspergillus niger 40493.

[0041] Further, the culture medium is specifically prepared by the following steps: Peel and cut potatoes into pieces, add the peeled and cut potatoes into deionized water, boil at 100°C for 30 minutes, filter with gauze, collect the filtrate, add agar and glucose to the filtrate and stir evenly, add sufficient deionized water to 100 mL, sterilize under high pressure at 121°C for 20 minutes, and cool to obtain a culture medium.

[0042] Furthermore, compared with the prior art, the present invention has the following beneficial effects: (1) In the technical scheme of the present invention, green tea is rich in tea polyphenols, amino, and theaflavins, and Cyclocarya paliurus is rich in flavonoids, triterpenes, polyphenols, polysaccharides, and other essential trace elements for the human body. The instant green tea is prepared by using green tea and Cyclocarya paliurus as raw materials, so that the instant green tea has the effects of lasting aroma, mellow and smooth taste, and health preservation. The green tea and Cyclocarya paliurus materials are discharged under the action of high temperature, high pressure, and high shear force in the extrusion cavity, especially when the pressure is released, so that the air in the green tea and Cyclocarya paliurus materials is destroyed, and the plant cell wall and cell membrane structure are destroyed, so that the surface of the green tea and Cyclocarya paliurus powder has a porous structure, which is more conducive to the release of phenolic substances in plant cells. The porous structure increases the contact area with the composite extractant and the fermentation liquid, so that the composite nanoemulsion and the fermentation liquid enter the porous tea powder channel, thereby improving the extraction efficiency.

[0043] (2) In the technical solution of the present invention, the complex enzyme can break the glycosidic bonds on cellulose, thereby releasing tea polyphenols and increasing the content of tea polyphenols. The complex enzyme hydrolyzes the cell walls of green tea and Cyclocarya paliurus, which is beneficial to the dissolution of tea polyphenols, flavonoids and other components in green tea and Cyclocarya paliurus, thereby improving the extraction efficiency of green tea and Cyclocarya paliurus. Natural vitamin E is combined with the complex enzyme. Natural vitamin E, as a carrier of the complex enzyme, can assist the complex enzyme to enter the pores of the porous tea powder, which is beneficial to the diffusion and penetration of the complex enzyme inside the porous tea powder, thereby improving the extraction efficiency. In addition, natural vitamin E has a good antioxidant effect, which prevents the oxidation of green tea components during the extraction process.

[0044] (3) In the technical scheme of the present invention, modified natural vitamin E and proline are mixed. Proline is hydrophilic and can combine with the hydrophilic components polyphenols and amino acids in tea powder, so that the modified natural vitamin E is adsorbed on the surface of the tea powder, thereby improving the extraction efficiency. The modified natural vitamin E and proline mixture is used as the dispersed phase, and glycerol is used as the continuous phase to form a nanoemulsion. The nanoemulsion particle size is 1-3 μm and has a large surface area, so that the nanoemulsion can penetrate into the pores of the porous tea powder, complete the wall breaking, and realize the release of the effective ingredients of the tea, such as tea polyphenols, catechins, flavonoids, and amino acids. In addition, the small size of the nanoemulsion can be retained in the gap formed by the dehydration of the intercellular matrix of green tea, so as to destroy the cell structure and increase the content of the aroma components of green tea.

[0045] (4) In the technical scheme of the present invention, fermentation liquid is added during the extraction process. Aspergillus niger in the fermentation liquid can promote the tea powder to produce cellulase and pectinase. Cellulase and pectinase help to precipitate the tea contents, thereby promoting the fermentation of tea leaves. The content of cellulase and pectinase is also increased, and the efficiency of the composite enzyme breaking the wall is enhanced. The increased content of cellulase and pectinase is conducive to the degradation of tea cheese, avoiding the failure of the composite enzyme after breaking the wall, resulting in insufficient cellulase and pectinase to degrade the tea cheese, resulting in the appearance of cheese-like turbidity. In addition, the increased content of cellulase and pectinase is conducive to the synthesis of theaflavins, thereby improving the quality of green tea instant tea.

[0046] (5) In the technical scheme of the present invention, green tea powder and porous tea residue protein are mixed. After negative pressure treatment, the porous tea residue protein has good stability. Its porous structure can adsorb green tea powder onto the surface and pores of the porous tea residue protein, thereby improving the stability of the green tea powder and avoiding the quality degradation of instant green tea due to oxidation of the green tea powder and poor storage performance. The porous tea residue protein is prepared using tea residue, which is beneficial to resource utilization. The formed porous tea residue protein has good water solubility and does not affect the water solubility of instant tea. DETAILED DESCRIPTION

[0047] The technical solutions in the embodiments of the present invention are described clearly and completely. 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 creative work are within the scope of protection of the present invention.

[0048] The raw materials used in the embodiments of the present invention are as follows: natural vitamin E (Hubei Xinghengye Technology Co., Ltd., tocopherol content of 90.7-92.5%); protease (Shanghai Yuanye Biotechnology Co., Ltd., purity of 30u / mg); cellulase (Wuhan Huaxiang Kejie Biotechnology Co., Ltd., analytical grade); pectinase (Shanghai Huzheng Biotechnology Co., Ltd., purity 99%); monoglyceride (DuPont China Co., Ltd.); green tea (provided by Shaanxi Menglangchun Tea Factory); Cyclocarya paliurus (Baihuayuanlin Co., Ltd., identified by the Institute of Horticultural Plants; purity 98%); Aspergillus niger 41125, Aspergillus niger 40493 (Beijing Yuwei Technology Co., Ltd.).

[0049] Embodiment 1 is specifically prepared by the following steps: A1. Add 5.2 g of natural vitamin E and 3.1 g of complex enzyme to 15 mL of ethanol, stir evenly, heat to 30°C, stir to react for 10 min, let stand overnight until the ethanol evaporates, collect the solid, and dry the solid in an oven at 30°C for 5 min to obtain modified natural vitamin E, wherein the complex enzyme is a mixture of protease, cellulase and pectinase in a mass ratio of 1.5:0.7:0.8.

[0050] A2. Add 1.5 g of modified natural vitamin E and 0.3 g of proline to 20 mL of deionized water, stir evenly to form a dispersed phase, add 0.18 g of monoglyceride to 60 mL of glycerol, stir at 50 ° C for 10 min to fully dissolve the emulsifier, add the dispersed phase, heat to 70 ° C, shear at 5000 rpm for 20 min, place in a homogenizer, homogenize twice at a homogenizing pressure of 250 bar, store at room temperature to obtain a composite nanoemulsion, place 50 mL of the composite nanoemulsion in 100 mL of deionized water, stir, and obtain a composite extractant.

[0051] Comparative Example 1 The difference between this comparative example and Example 1 is that the modified natural vitamin E is replaced by natural vitamin E, and the remaining steps and raw materials are the same as Example 1.

[0052] 1.5 g of natural vitamin E and 0.3 g of proline were added to 20 mL of deionized water and stirred evenly to form a dispersed phase. 0.18 g of emulsifier monoglyceride was added to 60 mL of glycerol and stirred at 50° C. for 10 min to fully dissolve the emulsifier. The dispersed phase was added and the temperature was raised to 70° C. and sheared at 5000 rpm for 20 min. The mixture was placed in a homogenizer and homogenized twice at a homogenizing pressure of 250 bar. The mixture was stored at room temperature to obtain a composite nanoemulsion. 50 mL of the composite nanoemulsion was placed in 100 mL of deionized water and stirred to obtain a composite extractant.

[0053] Comparative Example 2 The difference between this comparative example and Example 1 is that the composite nanoemulsion is replaced by modified natural vitamin E, and the remaining steps and raw materials are the same as Example 1.

[0054] Add 5.2 g of natural vitamin E and 3.1 g of complex enzyme to 15 mL of ethanol, stir evenly, heat to 30°C, stir and react for 10 min, let stand overnight until ethanol evaporates, collect solids, and dry the solids in an oven at 30°C for 5 min to obtain modified natural vitamin E. Place 50 mL of modified natural vitamin E in 100 mL of deionized water and stir to obtain a composite extractant.

[0055] Example 2 The fermentation broth is prepared by the following steps: B1. Peel and cut potatoes into pieces. Add 20 g of peeled and cut potatoes into 50 mL of deionized water. Boil at 100°C for 30 min, filter with gauze, collect the filtrate, add 2 g of agar and 2 g of glucose to the filtrate and stir evenly. Add enough distilled water to 100 mL. Sterilize under high pressure at 121°C for 20 min, and cool to obtain a culture medium.

[0056] B2. 9g green tea and 1g Cyclocarya paliurus were mixed and crushed, placed in 100mL deionized water, and extracted at 60℃ for 1h. The filtrate was collected by filtration and added to the culture medium. The culture medium was activated at 28℃ for 7d. 1×10 7 CFU Aspergillus niger 41125, 1.2×10 7 The inoculation test of CFU Aspergillus niger 40493 was carried out for 7 days. The Aspergillus niger mycelium was scraped from the plate with an inoculation loop in an ultra-clean workbench, placed in sterile water with small glass beads, shaken thoroughly, and filtered through absorbent cotton to obtain the fermentation liquid.

[0057] Example 3 A green tea production and processing process comprises the following steps: S1. 8 g of green tea and 0.5 g of Cyclocarya paliurus were mixed and crushed in a grinder, and then processed by a twin-screw extruder and dried at 40° C. for 10 min to obtain tea powder, wherein the barrel temperature of the twin-screw extruder was 95° C., the screw speed was 210 r / min, the feed rate was 11 kg / h, and the amount of deionized water added was 50%.

[0058] S2. Soak 13 g of tea powder in 80 mL of a composite extractant for 15 min, add 8 mL of a fermentation solution, and perform fermentation extraction to obtain a green tea extract and tea residues, wherein the fermentation extraction temperature is 38° C. and the fermentation extraction time is 1.5 h.

[0059] S3. The green tea extract is filtered through an ultrafiltration membrane with a pore size of 25 nm, concentrated to 1 / 3 of the original volume at a concentration pressure of 2 MPa and a concentration temperature of 33°C, placed in a freeze dryer, and freeze-dried at -25°C for 13 hours to obtain green tea powder.

[0060] S4. Preparation of tea residue protein using tea residue: add 8 g of tea residue into 180 mL of 1 mol / L sodium hydroxide aqueous solution, stir at 95°C for 4 h, centrifuge at 15000 r / min for 10 min, collect the supernatant, add 1 mL of 1 mol / L hydrochloric acid aqueous solution to the supernatant to adjust the pH to 3.5, centrifuge at 15000 r / min to obtain tea residue protein.

[0061] S5. Place the tea residue protein in a twin-screw extruder for extrusion and puffing, take it out after puffing, and crush it through an 80-mesh sieve to obtain a porous protein matrix, wherein the temperature of the twin-screw extruder is 125°C, the screw speed is 145r / min, the deionized water flow rate is 510g / h, and the feed rate is 610g / h.

[0062] S6. 2g of green tea powder and 15g of porous tea residue protein were mixed, placed in a negative pressure machine, and evacuated to negative pressure to obtain green tea instant tea, wherein the negative pressure was -0.07MPa.

[0063] Example 4 A green tea production and processing process comprises the following steps: S1. 9 g of green tea and 1 g of Cyclocarya paliurus were mixed and crushed in a grinder, and then processed by a twin-screw extruder and dried at 40° C. for 10 min to obtain tea powder, wherein the barrel temperature of the twin-screw extruder was 95° C., the screw speed was 210 r / min, the feed rate was 11 kg / h, and the amount of deionized water added was 50%.

[0064] S2. Soak 15 g of tea powder in 100 mL of a composite extractant for 15 min, add 10 mL of a fermentation solution, and perform fermentation extraction to obtain a green tea extract and tea residues, wherein the fermentation extraction temperature is 38° C. and the fermentation extraction time is 1.5 h.

[0065] S3. The green tea extract is filtered through an ultrafiltration membrane with a pore size of 25 nm, concentrated to 1 / 3 of the original volume at a concentration pressure of 2 MPa and a concentration temperature of 33°C, placed in a freeze dryer, and freeze-dried at -25°C for 13 hours to obtain green tea powder.

[0066] S4. Preparation of tea residue protein using tea residue: add 10 g of tea residue into 200 mL of 1 mol / L sodium hydroxide aqueous solution, stir at 95°C for 4 h, centrifuge at 15,000 r / min for 10 min, collect the supernatant, add 2 mL of 1 mol / L hydrochloric acid aqueous solution to the supernatant and adjust the pH to 3.5, centrifuge at 15,000 r / min to obtain tea residue protein.

[0067] S5. Place the tea residue protein in a twin-screw extruder for extrusion and puffing, take it out after puffing, and crush it through an 80-mesh sieve to obtain a porous protein matrix, wherein the temperature of the twin-screw extruder is 125°C, the screw speed is 145r / min, the deionized water flow rate is 510g / h, and the feed rate is 610g / h.

[0068] S6. 3g of green tea powder and 13g of porous tea residue protein were mixed, placed in a negative pressure machine, and evacuated to negative pressure to obtain green tea instant tea, wherein the negative pressure was -0.07MPa.

[0069] Example 5 A green tea production and processing process comprises the following steps: S1. 10 g of green tea and 1.5 g of Cyclocarya paliurus were mixed and crushed in a grinder, and then processed by a twin-screw extruder and dried at 40° C. for 10 min to obtain tea powder, wherein the barrel temperature of the twin-screw extruder was 95° C., the screw speed was 210 r / min, the feed rate was 11 kg / h, and the amount of deionized water added was 50%.

[0070] S2. Soak 17 g of tea powder in 120 mL of a composite extractant for 15 min, add 12 mL of a fermentation solution, and perform fermentation extraction to obtain a green tea extract and tea residues, wherein the fermentation extraction temperature is 38° C. and the fermentation extraction time is 1.5 h.

[0071] S3. The green tea extract is filtered through an ultrafiltration membrane with a pore size of 25 nm, concentrated to 1 / 3 of the original volume at a concentration pressure of 2 MPa and a concentration temperature of 33°C, placed in a freeze dryer, and freeze-dried at -25°C for 13 hours to obtain green tea powder.

[0072] S4. Preparation of tea residue protein using tea residue: Add 12 g of tea residue into 220 mL of 1 mol / L sodium hydroxide aqueous solution, stir at 95°C for 4 h, centrifuge at 15,000 r / min for 10 min, collect the supernatant, add 3 mL of 1 mol / L hydrochloric acid aqueous solution to the supernatant to adjust the pH to 3.5, and centrifuge at 15,000 r / min to obtain tea residue protein.

[0073] S5. Place the tea residue protein in a twin-screw extruder for extrusion and puffing, take it out after puffing, and crush it through an 80-mesh sieve to obtain a porous protein matrix, wherein the temperature of the twin-screw extruder is 125°C, the screw speed is 145r / min, the deionized water flow rate is 510g / h, and the feed rate is 610g / h.

[0074] S6. 5g of green tea powder and 15g of porous tea residue protein were mixed, placed in a negative pressure machine, and evacuated to negative pressure to obtain green tea instant tea, wherein the negative pressure was -0.07MPa.

[0075] Comparative Example 5 The difference between this comparative example and Example 4 is that the composite nanoemulsion is replaced by the substance prepared in Comparative Example 1, and the remaining steps and raw materials are the same as those in Example 4.

[0076] Comparative Example 6 The difference between this comparative example and Example 4 is that the composite nanoemulsion is replaced by the substance prepared in Comparative Example 2, and the remaining steps and raw materials are the same as those in Example 4.

[0077] Comparative Example 7 The difference between this comparative example and Example 4 is that no fermentation liquid is added, and the remaining steps and raw materials are synchronized with Example 4. The remaining steps and raw materials are synchronized with Example 4.

[0078] Comparative Example 8 The difference between this comparative example and Example 4 is that no porous tea residue protein is added, and the remaining steps and raw materials are the same as Example 4.

[0079] The performance of the instant green tea prepared in Examples 3-5 and Comparative Examples 5-8 was tested. Instant tea yield (%) = instant tea dry basis mass (g) / tea powder dry basis mass (g) × 100.

[0080] The tea polyphenols content (%) was determined according to the spectrophotometer method in GB / T8313-2018; the catechin content (%) was determined according to the detection method in GB / T8313-2008.

[0081] According to the standard curve of mass concentration C (mg / mL) of green tea instant tea and absorbance (A): A=0.9803C+0.0011(R2=0.9994), the linearity is good. Accurately pipette 0.5mL of the solution to be tested, and measure the absorbance at 510nm according to the above test method. Substitute it into the standard curve and calculate the flavonoid yield (%) according to the formula: Flavonoid (%) = mass concentration of green tea instant tea·volume of the solution to be tested / 1000·amount of tea powder added.

[0082] The tea aroma, flavor and tea soup color are mainly evaluated, with a full score of 100, including 40% for flavor, 40% for aroma and 20% for tea soup color. The evaluation is conducted by 5 tea reviewers. Instant tea evaluation method: The evaluation is conducted according to the method specified in GB31740.1-2015. The results are shown in Tables 1 and 2 below.

[0083]

[0084]

[0085] It can be seen from the data in Tables 1 and 2 that in Comparative Example 5, the composite extractant prepared by replacing modified natural vitamin E with natural vitamin E is used to extract tea powder, and the yield and quality of instant green tea are reduced. This may be because the composite enzyme can break the glycosidic bonds on cellulose, thereby releasing tea polyphenols, and the composite enzyme hydrolyzes the cell walls of green tea and Cyclocarya paliurus, which is beneficial to the dissolution of tea polyphenols, flavonoids and other components in green tea and Cyclocarya paliurus, thereby improving the extraction efficiency of green tea and Cyclocarya paliurus; in Comparative Example 6, the composite nanoemulsion is replaced with modified natural vitamin E, and the composite extractant prepared is used to extract tea powder, and the yield and quality of instant green tea are reduced. This may be because the nanoemulsion with a particle size of 1-3 μm penetrates into the pores of the porous tea powder to complete the wall breaking, which has a significant impact on the release of effective ingredients in tea such as tea polyphenols, catechins, flavonoids and other effective ingredients. The small size of the nanoemulsion can be retained in the gap formed by the loss of water in the intercellular matrix of green tea to destroy the cell structure and improve the aroma components of green tea; in comparative example 7, no fermentation liquid was added and used to extract tea powder, and the yield and quality of instant green tea decreased. This may be because Aspergillus niger in the fermentation liquid can produce cellulase and pectinase, which are conducive to the precipitation of tea contents and the synthesis of theaflavins, and the increased content of cellulase and pectinase is conducive to the degradation of tea cheese, avoiding the breakage of the composite enzyme resulting in insufficient cellulase and pectinase content to degrade tea cheese, resulting in the appearance of cheese-like turbidity; in comparative example 8, no porous tea residue protein was added, and the quality of the prepared green tea instant tea decreased. This may be because the pore structure can adsorb green tea powder to the surface and pores of the porous tea residue protein, avoiding oxidation of green tea powder and poor storage performance leading to a decrease in the quality of green tea instant tea.

[0086] The data in Table 1 and Table 2 show that the green tea instant tea prepared in Examples 3-5 has good quality and extraction efficiency and meets the test performance requirements, while the green tea instant tea prepared in Comparative Examples 5-8 does not meet the performance requirements, indicating that the green tea instant tea prepared in the present invention has good quality and extraction efficiency.

[0087] In the description of the specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0088] The above contents are merely examples and explanations of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the invention or exceed the scope defined by the claims, they shall all fall within the protection scope of the present invention.

Claims

1. A green tea production and processing technology, It is characterized in that The following steps are involved: S1. The green tea and Cyclocarya paliurus were mixed and crushed, and then processed by a twin-screw extruder and dried to obtain tea powder; S2. After the tea powder is soaked in a composite extractant, a fermentation liquid is added, and fermentation extraction is performed to obtain a green tea extract and tea residues; The composite extractant is prepared by mixing modified natural vitamin E and proline, adding glycerol and an emulsifier, and stirring for reaction; The modified natural vitamin E is prepared by mixing natural vitamin E with a complex enzyme; S3. The green tea extract is concentrated and freeze-dried to obtain green tea powder; S4. Tea residue protein was prepared using tea residue, and the tea residue protein was processed by a twin-screw extruder, crushed, and sieved to obtain a porous tea residue protein; S5. Mix the green tea powder and the porous tea residue protein, and treat them under negative pressure to obtain instant green tea.

2. A green tea production and processing process according to claim 1, It is characterized in that In the step S1, the barrel temperature of the twin-screw extruder is 90-100° C., the screw speed is 200-220 r / min, the feed rate is 10-12 kg / h, and the amount of deionized water added is 45-55%.

3. A green tea production and processing process according to claim 1, It is characterized in that The pore size of the tea powder is 2-5 μm.

4. A green tea production and processing process according to claim 1, It is characterized in that The emulsifier is selected from any one of monoglyceride, sucrose ester, sorbitan monolaurate, and polyoxyethylene sorbitan monostearate; and the tocopherol content in the natural vitamin E is 90.7-92.5%.

5. A green tea production and processing process according to claim 1, It is characterized in that The complex enzyme is prepared by mixing protease, cellulase and pectinase in a mass ratio of (1-2):(0.5-1):(0.6-1).

6. A green tea production and processing process according to claim 1, It is characterized in that The fermentation and extraction temperature is 35-40° C., and the fermentation and extraction time is 1-2 hours.

7. A green tea production and processing process according to claim 1, It is characterized in that The dosage ratio of the tea powder, the composite extractant and the fermentation liquid is (13-17) g: (80-120) mL: (8-12) mL.

8. A green tea production and processing process according to claim 1, It is characterized in that The tea residue extraction and preparation of tea residue protein is specifically prepared by the following steps: The tea residue is added to a 0.5-1.5 mol / L sodium hydroxide aqueous solution, stirred, and centrifuged to collect the supernatant. A 0.5-1.5 mol / L hydrochloric acid aqueous solution is added to the supernatant to adjust the pH to 3.5, and centrifuged to obtain tea residue protein.

9. A green tea production and processing process according to claim 1, It is characterized in that The tea residue, sodium hydroxide aqueous solution and hydrochloric acid aqueous solution are used in a ratio of (8-12) g: (180-220) mL: (1-3) mL.

10. A green tea production and processing process according to claim 1, It is characterized in that The mass ratio of the green tea powder to the porous tea residue protein is (2-5):(10-15); and the negative pressure is -(0.06-0.08)MPa.

Images