Method for simultaneously preparing two kinds of instant tea powder with high yield

Abstract

The invention provides a method for simultaneously preparing two instant tea powder with high yield. The method specifically comprises the following steps: S1, screening tea leaf raw materials; S2, carrying out pot-type extraction on the tea leaf raw materials under a high-temperature condition to obtain an extract liquid and tea residues; S3, carrying out countercurrent extraction on the tea residues under an alkali-adding high-temperature condition to obtain an extract liquid and tea residues; S4, centrifuging the obtained different extract liquids to obtain a purified liquid; s7, adjusting the pH value of the conversion solution to obtain a blended solution; S8, carrying out high-temperature instantaneous sterilization on the concentrated solution and the blended solution; and S9, drying by using a pressure type spray drying tower. The selected raw materials can be blended raw materials, various instant tea powder can be obtained at the same time, residual contained components in tea residues are dissolved out to the maximum extent in a mode of combining alkaline water and dynamic countercurrent extraction, the total extraction yield of tea leaves is remarkably increased, and the production cost is reduced. The invention provides a processing method for improving the extraction rate of tea leaves and simultaneously obtaining various instant tea powder.

Description

Technical Field

[0001] The invention belongs to the technical field of deep processing of tea leaves, and particularly relates to a method for preparing two instant tea powders with high yield at the same time. Background Art

[0002] Tea can extraction is to add tea leaves (material) and water (solvent) of a certain temperature and volume into the extraction tank. After a certain period of time, the ingredients in the tea leaves gradually diffuse into the solvent to form a tea soup solution of a certain concentration. The mixed liquid is extracted and utilized at the bottom of the extraction tank, and the tea residue is retained. However, a large amount of solution is still adsorbed in the tea residue and cannot be completely extracted. Moreover, a high proportion of the substances contained in the tea residue are still not dissolved (diffused) into the solution, resulting in a low extraction rate. Countercurrent extraction means that during the extraction process, the material and the solvent move continuously at the same time, but in opposite directions. Countercurrent extraction is a continuous quantitative feeding through mechanical transmission. The material and the solvent are fully in contact, and the solvent in the equipment is constantly renewed. This method is combined with the slag squeezing treatment in the slag separation process. Although its extraction rate is higher than that of tank extraction, about 30% of the contained components cannot be extracted. If the material-liquid ratio is further increased, the energy consumption will increase. If the slag squeezing force is increased, the wind quality will drop rapidly. The comprehensive result is that this method cannot further improve the extraction rate. During the extraction process, auxiliary extraction methods such as ultrasound, microwaves, and enzymatic hydrolysis are also used. Although the extraction rate has been improved to a certain extent, it still cannot solve the fundamental problem (the maximum extraction rate of the existing comprehensive technology does not exceed 75%), and it has a certain impact on the flavor quality of the product. First, the price of tea extract raw materials used to prepare instant tea is relatively low, and it is sufficient to extract only useful ingredients or meet product quality requirements. Excessive pursuit of extraction rate may reduce quality; secondly, there are many varieties of tea used for extraction, and the flavors vary greatly. The extraction rate after conventional extraction is low, and the flavor is poor, which cannot meet the requirements for continued use; finally, the tea residue after extraction can be used as fertilizer after fermentation and other treatments; in summary, there is little research on further improving the extraction rate in peers and the industry. The raw materials required for its production are generally more expensive, the extraction rate is lower, and the tea residue is not reused. After cost accounting, the price is higher. With the trend of consumption downgrade, the cost pressure of new tea drinks is increasing, and it is more meaningful to use the comprehensive utilization of tea residue to reduce costs. Summary of the invention

[0003] Technical problems to be solved: In view of the above technical problems, the purpose of the present invention is to provide a method for preparing two kinds of instant tea powders at the same time with high yield, wherein the tea raw materials are screened, extracted in a tank under high temperature conditions to obtain an extract and tea residues, the tea residues are countercurrently extracted under high temperature conditions with alkali to obtain an extract and tea residues, the obtained different extracts are centrifuged to obtain a purified liquid, the purified liquid is concentrated, the pH of the concentrated liquid is adjusted, pure oxygen is introduced to obtain a conversion liquid, the pH of the conversion liquid is adjusted to obtain a formulation liquid, the concentrated liquid and the formulation liquid are instantaneously sterilized at high temperature, and a pressure spray drying tower is used to dry to obtain a variety of instant tea powders. The present invention uses a method combining alkali extraction and dynamic countercurrent extraction to improve the extraction rate of tea leaves, and the tea raw materials are not limited to a single tea leaf, and can be blending raw materials, raw materials containing tea stems or high-end raw materials, with a wider applicability, and instant tea powders for different purposes are obtained at the same time, maximizing the value of the product.

[0004] Technical solution: A method for preparing two instant tea powders at a high yield, by parts by weight, comprising the following steps: S1. Raw material screening: screening green tea raw materials and crushing; S2. Tank extraction: 1 part of green tea raw material is put into 10-15 parts of pure water and extracted at 85-90°C for 30-60 minutes, filtered to obtain extract A and tea residue B; S3. Alkali countercurrent extraction: take 1 part of tea residue B and put it into 5-9 parts of alkaline solution at 90-95 ° C for 30-40 min, filter and obtain extract C and tea residue D; S4. Separation and purification: The extracts A and C are centrifuged using a horizontal centrifuge and a disc centrifuge to obtain purified solutions E and F, respectively; S5. Concentration: Using a triple-effect vacuum concentrator, the purified liquids E and F were concentrated to a solid content of 20 to 25% Brix to obtain concentrated liquids G and H; S6 conversion: the concentrated solution H was adjusted to pH 10 by adding alkali, pure oxygen was introduced to control the reaction pressure to 1.5Mpa, and the conversion was 30 to 60min to obtain a conversion solution I; S7. Preparation: Using citric acid to adjust the pH value of the conversion solution I to 6.5 to obtain a preparation solution J; S8. Sterilization: Put the concentrated solution G and the prepared solution J into a UHT high temperature instantaneous sterilizer at 115℃~127℃ for 10~15s, and cool to 45~60℃; S9. Drying: Use pressure spray drying tower for drying respectively, control the homogenization pressure at 20Mpa, the air inlet temperature at 180-210°C, the temperature inside the tower at 85-95°C, and the exhaust temperature at 80-90°C, to obtain two kinds of instant tea powders. Furthermore, the green tea raw material in step S1 includes a single raw material, a blended raw material, a raw material containing tea stems or a high-end green tea raw material, and the polyphenol content of the green tea is 18-22%, and the water extract is 35-40%. Furthermore, in step S2, the resistivity of pure water is less than 10 MΩ·cm, and the water content of tea residue B is 70-75%. Furthermore, the alkali content of the alkali solution in step S3 is 5% of the mass of the green tea raw material in S1. Furthermore, in step S4, the feed rate of the horizontal centrifuge is 6000-7000 kg / h, the main engine speed is 2600-2700 r / min, and the auxiliary engine speed is 1200-1300 r / min; the feed rate of the disc centrifuge is 2300-2500 kg / h. Furthermore, the triple-effect vacuum concentration equipment in step S5 has a vacuum degree of -65 to -95 MPa and a temperature of 45 to 75°C. Furthermore, the alkaline solution in step S6 is a sodium hydroxide solution, a potassium hydroxide solution or a mixture of the two. Beneficial effects: 1. The raw materials used in the present invention can be selected from single raw materials, or can be blended raw materials, raw materials containing tea stems or high-end raw materials, which have wider applicability, and the tea residues finally obtained are more conducive to processing, such as preparing organic fertilizer, biomass energy, animal feed, etc. 2. The present invention firstly uses static tank extraction to extract tea soup with good flavor, and can also be used for the preparation of high-end tea extract to ensure the stability of the flavor and excellent quality of the main tea powder product. Secondly, a certain concentration of alkaline water is combined with dynamic countercurrent extraction to maximize the reaction and dissolution of the residual components in the tea residue, thereby significantly improving the total extraction rate of tea leaves. 3. After the residue material of the present invention is processed and then converted for different time periods, two instant tea powders for different purposes can be obtained at the same time. The tea powder can gradually deepen its soup color as the conversion time increases, and has a high amino acid content. It can be used not only for coloring conventional tea powder, but also for other special needs. The tea extraction rate is maximized, and the total product production energy consumption is lower than that of the traditional process, thereby maximizing the product value. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION The present invention proposes a method for preparing two instant tea powders at the same time with high yield. In order to make the purpose, technical scheme and effect of the present invention clearer and more specific, the present invention will be further described in detail with reference to the embodiments below. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. Example 1 A method for preparing two instant tea powders at a high yield and at the same time, in parts by weight, comprises the following steps: S1. Raw material screening: select green tea raw materials with 22% tea polyphenols, 37% water extract, and 15% powder content of the crushed material with a crushing degree of less than 40 mesh; S2. Tank extraction: 1 part of green tea raw material was put into 13 parts of pure water and extracted at 85°C for 30 minutes, filtered, and the extract A and tea residue B were obtained; S3. Alkali countercurrent extraction: 5% sodium hydroxide by weight of tea leaves was added to the solvent, 1 part of tea residue B was placed in 5 parts of a solution containing 5% sodium hydroxide, and extracted at a temperature of 95 ° C for 30 min, filtered, and the extract C and tea residue D were obtained; S4. Separation and purification: The extracts A and C are centrifuged using a horizontal centrifuge and a disc centrifuge to obtain purified solutions E and F, respectively. S5. Concentration: Using a triple-effect vacuum concentrator, the purified liquids E and F were concentrated to a solid content of 22% Brix to obtain concentrated liquids G and H. S6. Conversion: The concentrated solution H was added with sodium hydroxide to adjust the pH value to 10, pure oxygen was introduced to control the reaction pressure to 1.5 MPa, and the conversion was carried out for 30 minutes to obtain conversion solution I. S7. Preparation: Use citric acid to adjust the pH value of conversion solution I to 6.5 to prepare solution J; S8. Sterilization: Place the concentrated liquid G and the prepared liquid J into a UHT high-temperature instantaneous sterilizer and sterilize at 127°C for 15 seconds, then cool to 50°C; S9. Drying: Use a pressure spray drying tower for drying, control the homogenization pressure at 20Mpa, the air inlet temperature at 190°C, the tower temperature at 90°C, and the exhaust temperature at 85°C, to obtain instant green tea powder and instant black tea powder. Example 2 A method for preparing two instant tea powders at a high yield and at the same time, in parts by weight, comprises the following steps: S1. Raw material screening: select green tea raw materials with 22% tea polyphenols, 37% water extract, and 15% powder content of the crushed material with a crushing degree of less than 40 mesh; S2. Tank extraction: 1 part of green tea raw material is put into 12 parts of pure water and extracted at 85°C for 30 minutes, filtered, and the extract A and tea residue B are obtained; S3. Alkali countercurrent extraction: 5% sodium hydroxide by weight of tea leaves was added to the solvent, 1 part of tea residue B was placed in 5 parts of a solution containing 5% sodium hydroxide, and extracted at a temperature of 95 ° C for 30 min, filtered, and the extract C and tea residue D were obtained; S4. Separation and purification: The extracts A and C are centrifuged using a horizontal centrifuge and a disc centrifuge to obtain purified solutions E and F, respectively. S5. Concentration: Using a triple-effect vacuum concentrator, the purified liquids E and F were concentrated to a solid content of 22% Brix to obtain concentrated liquids G and H. S6. Conversion: The concentrated solution H was added with sodium hydroxide to adjust the pH value to 10, pure oxygen was introduced to control the reaction pressure to 1.5 MPa, and the conversion was carried out for 30 minutes to obtain conversion solution I. S7. Preparation: Use citric acid to adjust the pH value of conversion solution I to 6.5 to prepare solution J; S8. Sterilization: Place the concentrated liquid G and the prepared liquid J into a UHT high-temperature instantaneous sterilizer and sterilize at 127°C for 15 seconds, then cool to 50°C; S9. Drying: Use a pressure spray drying tower for drying, control the homogenization pressure at 20Mpa, the air inlet temperature at 190°C, the tower temperature at 90°C, and the exhaust temperature at 85°C, to obtain instant green tea powder and instant black tea powder. Example 3 A method for preparing two instant tea powders at a high yield and at the same time, in parts by weight, comprises the following steps: S1. Raw material screening: select green tea raw materials with 22% tea polyphenols, 37% water extract, and 15% powder content of the crushed material with a crushing degree of less than 40 mesh; S2. Tank extraction: 1 part of green tea raw material was put into 11 parts of pure water and extracted at 85°C for 30 minutes, filtered, and the extract A and tea residue B were obtained; S3. Alkali countercurrent extraction: 5% sodium hydroxide by weight of tea leaves was added to the solvent, 1 part of tea residue B was placed in 5 parts of a solution containing 5% sodium hydroxide, and extracted at a temperature of 95 ° C for 30 min, filtered, and the extract C and tea residue D were obtained; S4. Separation and purification: The extracts A and C are centrifuged using a horizontal centrifuge and a disc centrifuge to obtain purified solutions E and F, respectively. S5. Concentration: Using a triple-effect vacuum concentrator, the purified liquids E and F were concentrated to a solid content of 22% Brix to obtain concentrated liquids G and H. S6. Conversion: The concentrated solution H was added with sodium hydroxide to adjust the pH value to 10, pure oxygen was introduced to control the reaction pressure to 1.5 MPa, and the conversion was carried out for 30 minutes to obtain conversion solution I. S7. Preparation: Use citric acid to adjust the pH value of conversion solution I to 6.5 to prepare solution J; S8. Sterilization: Place the concentrated liquid G and the prepared liquid J into a UHT high-temperature instantaneous sterilizer and sterilize at 127°C for 15 seconds, then cool to 50°C; S9. Drying: Use a pressure spray drying tower for drying, control the homogenization pressure at 20Mpa, the air inlet temperature at 190°C, the tower temperature at 90°C, and the exhaust temperature at 85°C, to obtain instant green tea powder and instant black tea powder. Example 4 A method for preparing two instant tea powders at a high yield and at the same time, in parts by weight, comprises the following steps: S1. Raw material screening: select green tea raw materials with 22% tea polyphenols, 37% water extract, and 15% powder content of the crushed material with a crushing degree of less than 40 mesh; S2. Tank extraction: 1 part of green tea raw material was put into 11 parts of pure water and extracted at 85°C for 30 minutes, filtered, and the extract A and tea residue B were obtained; S3. Alkali countercurrent extraction: 5% sodium hydroxide by weight of tea leaves was added to the solvent, 1 part of tea residue B was placed in 6 parts of a solution containing 5% sodium hydroxide, and extracted at a temperature of 95 ° C for 30 min, filtered, and the extract C and tea residue D were obtained; S4. Separation and purification: The extracts A and C are centrifuged using a horizontal centrifuge and a disc centrifuge to obtain purified solutions E and F, respectively. S5. Concentration: Using a triple-effect vacuum concentrator, the purified liquids E and F were concentrated to a solid content of 22% Brix to obtain concentrated liquids G and H. S6. Conversion: The concentrated solution H was added with sodium hydroxide to adjust the pH value to 10, pure oxygen was introduced to control the reaction pressure to 1.5 MPa, and the conversion was carried out for 30 minutes to obtain conversion solution I. S7. Preparation: Use citric acid to adjust the pH value of conversion solution I to 6.5 to prepare solution J; S8. Sterilization: Place the concentrated liquid G and the prepared liquid J into a UHT high-temperature instantaneous sterilizer and sterilize at 127°C for 15 seconds, then cool to 50°C; S9. Drying: Use a pressure spray drying tower for drying, control the homogenization pressure at 20Mpa, the air inlet temperature at 190°C, the tower temperature at 90°C, and the exhaust temperature at 85°C, to obtain instant green tea powder and instant black tea powder. Example 5 A method for preparing two instant tea powders at a high yield and at the same time, in parts by weight, comprises the following steps: S1. Raw material screening: select green tea raw materials with 22% tea polyphenols, 37% water extract, and 15% powder content of the crushed material with a crushing degree of less than 40 mesh; S2. Tank extraction: 1 part of green tea raw material was put into 11 parts of pure water and extracted at 85°C for 30 minutes, filtered, and the extract A and tea residue B were obtained; S3. Alkali countercurrent extraction: 5% sodium hydroxide by weight of tea leaves was added to the solvent, 1 part of tea residue B was placed in 7 parts of a solution containing 5% sodium hydroxide and extracted at a temperature of 95 ° C for 30 min, filtered, and the extract C and tea residue D were obtained; S4. Separation and purification: The extracts A and C are centrifuged using a horizontal centrifuge and a disc centrifuge to obtain purified solutions E and F, respectively. S5. Concentration: Using a triple-effect vacuum concentrator, the purified liquids E and F were concentrated to a solid content of 22% Brix to obtain concentrated liquids G and H. S6. Conversion: The concentrated solution H was added with sodium hydroxide to adjust the pH value to 10, pure oxygen was introduced to control the reaction pressure to 1.5 MPa, and the conversion was carried out for 30 minutes to obtain conversion solution I. S7. Preparation: Use citric acid to adjust the pH value of conversion solution I to 6.5 to prepare solution J; S8. Sterilization: Place the concentrated liquid G and the prepared liquid J into a UHT high-temperature instantaneous sterilizer and sterilize at 127°C for 15 seconds, then cool to 50°C; S9. Drying: Use a pressure spray drying tower for drying, control the homogenization pressure at 20Mpa, the air inlet temperature at 190°C, the tower temperature at 90°C, and the exhaust temperature at 85°C, to obtain instant green tea powder and instant black tea powder. Example 6 A method for preparing two instant tea powders at a high yield and at the same time, in parts by weight, comprises the following steps: S1. Raw material screening: select green tea raw materials with 22% tea polyphenols, 37% water extract, and 15% powder content of the crushed material with a crushing degree of less than 40 mesh; S2. Tank extraction: 1 part of green tea raw material is put into 12 parts of pure water and extracted at 85°C for 30 minutes, filtered, and the extract A and tea residue B are obtained; S3. Alkali countercurrent extraction: 5% sodium hydroxide by weight of tea leaves was added to the solvent, 1 part of tea residue B was placed in 5 parts of a solution containing 5% sodium hydroxide, and extracted at a temperature of 95 ° C for 30 min, filtered, and the extract C and tea residue D were obtained; S4. Separation and purification: The extracts A and C are centrifuged using a horizontal centrifuge and a disc centrifuge to obtain purified solutions E and F, respectively. S5. Concentration: Using a triple-effect vacuum concentrator, the purified liquids E and F were concentrated to a solid content of 22% Brix to obtain concentrated liquids G and H. S6. Conversion: The concentrated solution H was added with sodium hydroxide to adjust the pH value to 10, pure oxygen was introduced to control the reaction pressure to 1.5 MPa, and the conversion was performed for 60 min to obtain conversion solution I. S7. Preparation: Use citric acid to adjust the pH value of conversion solution I to 6.5 to prepare solution J; S8. Sterilization: Place the concentrated liquid G and the prepared liquid J into a UHT high-temperature instantaneous sterilizer and sterilize at 127°C for 15 seconds, then cool to 50°C; S9. Drying: Use a pressure spray drying tower for drying, control the homogenization pressure at 20Mpa, the air inlet temperature at 190°C, the tower temperature at 90°C, and the exhaust temperature at 85°C, to obtain instant green tea powder and instant black tea powder. Example 7 A method for preparing two instant tea powders at a high yield and at the same time, in parts by weight, comprises the following steps: S1. Raw material screening: select green tea raw materials with 22% tea polyphenols, 37% water extract, and 15% powder content of the crushed material with a crushing degree of less than 40 mesh; S2. Tank extraction: 1 part of green tea raw material is put into 12 parts of pure water and extracted at 85°C for 30 minutes, filtered, and the extract A and tea residue B are obtained; S3. Alkali countercurrent extraction: 5% sodium hydroxide by weight of tea leaves was added to the solvent, 1 part of tea residue B was placed in 6 parts of a solution containing 5% sodium hydroxide, and extracted at a temperature of 95 ° C for 30 min, filtered, and the extract C and tea residue D were obtained; S4. Separation and purification: The extracts A and C are centrifuged using a horizontal centrifuge and a disc centrifuge to obtain purified solutions E and F, respectively. S5. Concentration: Using a triple-effect vacuum concentrator, the purified liquids E and F were concentrated to a solid content of 22% Brix to obtain concentrated liquids G and H. S6. Conversion: The concentrated solution H was added with sodium hydroxide to adjust the pH value to 10, pure oxygen was introduced to control the reaction pressure to 1.5 MPa, and the conversion was performed for 60 min to obtain conversion solution I. S7. Preparation: Use citric acid to adjust the pH value of conversion solution I to 6.5 to prepare solution J; S8. Sterilization: Place the concentrated liquid G and the prepared liquid J into a UHT high-temperature instantaneous sterilizer and sterilize at 127°C for 15 seconds, then cool to 50°C; S9. Drying: Use a pressure spray drying tower for drying, control the homogenization pressure at 20Mpa, the air inlet temperature at 190°C, the tower temperature at 90°C, and the exhaust temperature at 85°C, to obtain instant green tea powder and instant black tea powder. Example 8 A method for preparing two instant tea powders at a high yield and at the same time, in parts by weight, comprises the following steps: S1. Raw material screening: select green tea raw materials with 22% tea polyphenols, 37% water extract, and 15% powder content of the crushed material with a crushing degree of less than 40 mesh; S2. Tank extraction: 1 part of green tea raw material is put into 12 parts of pure water and extracted at 85°C for 30 minutes, filtered, and the extract A and tea residue B are obtained; S3. Alkali countercurrent extraction: 5% sodium hydroxide by weight of tea leaves was added to the solvent, 1 part of tea residue B was placed in 7 parts of a solution containing 5% sodium hydroxide and extracted at a temperature of 95 ° C for 30 min, filtered, and the extract C and tea residue D were obtained; S4. Separation and purification: The extracts A and C are centrifuged using a horizontal centrifuge and a disc centrifuge to obtain purified solutions E and F, respectively. S5. Concentration: Using a triple-effect vacuum concentrator, the purified liquids E and F were concentrated to a solid content of 22% Brix to obtain concentrated liquids G and H. S6. Conversion: The concentrated solution H was added with sodium hydroxide to adjust the pH value to 10, pure oxygen was introduced to control the reaction pressure to 1.5 MPa, and the conversion was performed for 60 min to obtain conversion solution I. S7. Preparation: Use citric acid to adjust the pH value of conversion solution I to 6.5 to prepare solution J; S8. Sterilization: Place the concentrated liquid G and the prepared liquid J into a UHT high-temperature instantaneous sterilizer and sterilize at 127°C for 15 seconds, then cool to 50°C; S9. Drying: Use a pressure spray drying tower for drying, control the homogenization pressure at 20Mpa, the air inlet temperature at 190°C, the tower temperature at 90°C, and the exhaust temperature at 85°C, to obtain instant green tea powder and instant black tea powder. Example 9 A method for preparing two instant tea powders at a high yield and at the same time, in parts by weight, comprises the following steps: S1. Raw material screening: select green tea raw materials with 22% tea polyphenols, 37% water extract, and 15% powder content of the crushed material with a crushing degree of less than 40 mesh; S2. Tank extraction: 1 part of green tea raw material was put into 11 parts of pure water and extracted at 85°C for 30 minutes, filtered, and the extract A and tea residue B were obtained; S3. Alkali countercurrent extraction: 5% sodium hydroxide by weight of tea leaves was added to the solvent, 1 part of tea residue B was placed in 7 parts of a solution containing 5% sodium hydroxide and extracted at a temperature of 95 ° C for 30 min, filtered, and the extract C and tea residue D were obtained; S4. Separation and purification: The extracts A and C are centrifuged using a horizontal centrifuge and a disc centrifuge to obtain purified solutions E and F, respectively. S5. Concentration: Using a triple-effect vacuum concentrator, the purified liquids E and F were concentrated to a solid content of 22% Brix to obtain concentrated liquids G and H. S6. Conversion: The concentrated solution H was added with sodium hydroxide to adjust the pH value to 10, pure oxygen was introduced to control the reaction pressure to 1.5 MPa, and the conversion was performed for 60 min to obtain conversion solution I. S7. Preparation: Use citric acid to adjust the pH value of conversion solution I to 6.5 to prepare solution J; S8. Sterilization: Place the concentrated liquid G and the prepared liquid J into a UHT high-temperature instantaneous sterilizer and sterilize at 127°C for 15 seconds, then cool to 50°C; S9. Drying: Use a pressure spray drying tower for drying, control the homogenization pressure at 20Mpa, the air inlet temperature at 190°C, the tower temperature at 90°C, and the exhaust temperature at 85°C, to obtain instant green tea powder and instant black tea powder. Example 10 A method for preparing two instant tea powders at a high yield and at the same time, in parts by weight, comprises the following steps: S1. Raw material screening: select green tea raw materials with 22% tea polyphenols, 37% water extract, and 15% powder content of the crushed material with a crushing degree of less than 40 mesh; S2. Tank extraction: 1 part of green tea raw material was put into 13 parts of pure water and extracted at 85°C for 30 minutes, filtered, and the extract A and tea residue B were obtained; S3. Alkali countercurrent extraction: 5% sodium hydroxide by weight of tea leaves was added to the solvent, 1 part of tea residue B was placed in 7 parts of a solution containing 5% sodium hydroxide and extracted at a temperature of 95 ° C for 30 min, filtered, and the extract C and tea residue D were obtained; S4. Separation and purification: The extracts A and C are centrifuged using a horizontal centrifuge and a disc centrifuge to obtain purified solutions E and F, respectively. S5. Concentration: Using a triple-effect vacuum concentrator, the purified liquids E and F were concentrated to a solid content of 22% Brix to obtain concentrated liquids G and H. S6. Conversion: The concentrated solution H was added with sodium hydroxide to adjust the pH value to 10, pure oxygen was introduced to control the reaction pressure to 1.5 MPa, and the conversion was performed for 60 min to obtain conversion solution I. S7. Preparation: Use citric acid to adjust the pH value of conversion solution I to 6.5 to prepare solution J; S8. Sterilization: Place the concentrated liquid G and the prepared liquid J into a UHT high-temperature instantaneous sterilizer and sterilize at 127°C for 15 seconds, then cool to 50°C; S9. Drying: Use a pressure spray drying tower for drying, control the homogenization pressure at 20Mpa, the air inlet temperature at 190°C, the tower temperature at 90°C, and the exhaust temperature at 85°C, to obtain instant green tea powder and instant black tea powder. Comparative Example 1 The difference between this comparative example and Example 1 is that no alkali is added for countercurrent extraction. A method for preparing instant green tea powder, in parts by weight, comprises the following steps: S1. Raw material screening: select green tea raw materials with 22% tea polyphenols, 37% water extract, and 15% powder content of the crushed material with a crushing degree of less than 40 mesh; S2. Tank extraction: 1 part of green tea raw material was put into 13 parts of pure water and extracted at 85°C for 30 minutes, filtered, and the extract A and tea residue B were obtained; S3. Separation and purification: The extract A is centrifuged to obtain purified liquid E. S4. Concentration: Use a triple-effect vacuum concentration device to concentrate the purified liquid E to a solid content of 22% Brix to obtain a concentrated liquid G. S5. Sterilization: Place the concentrated liquid G in a UHT high-temperature instantaneous sterilizer and sterilize at 127°C for 15s, then cool to 50°C; S6. Drying: Use a pressure spray drying tower for drying, control the homogenization pressure to 20Mpa, the air inlet temperature to 190°C, the tower temperature to 90°C, and the exhaust temperature to 85°C to obtain instant green tea powder. Performance Testing The calculation formula of instant tea powder yield is as follows: Table 1 Tea yield of Examples 1 to 11 and Comparative Example 1 It can be seen from Table 1 that the total yields of instant tea powder in all embodiments are higher than that in Comparative Example 1, indicating that the present invention can significantly improve the total yield of instant tea powder; by comparing Examples 1 to 3, it can be seen that the total yields of instant green tea powder and instant black tea powder show an upward trend with the increase of the tea-water ratio, and the total yields of instant green tea powder and instant black tea powder obtained in Example 3 are the highest; by comparing Examples 3 to 5, it can be seen that the total yields of instant green tea powder and instant black tea powder show an upward trend with the increase of the tea residue and alkali countercurrent extraction tea-water ratio, and the total yields of instant green tea powder and instant black tea powder obtained in Example 5 are the highest ; It can also be seen from Examples 6 to 8 that the total yield of instant green tea powder and instant black tea powder shows an upward trend with the increase of the ratio of tea residue to tea water in alkali countercurrent extraction, and the instant green tea powder and instant black tea powder obtained in Example 8 have the highest total yield; It can be seen from Examples 8 to 10 that the total yield of instant green tea powder and instant black tea powder is jointly determined by the tank extraction yield and the countercurrent yield, the lower the tank extraction yield, the higher the countercurrent yield, and the instant green tea powder and instant black tea powder obtained in Example 9 have the highest total yield, which also reflects the key influence of the second stage alkali countercurrent extraction on the total yield of the present invention. The above is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any technician familiar with the art can make many possible changes and modifications to the technical solution of the present invention by using the above disclosed methods and technical contents without departing from the spirit and technical solution of the present invention, or modify it into an equivalent embodiment of equivalent changes. Therefore, any simple modification, equivalent replacement, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the scope of protection of the technical solution of the present invention.

Claims

1. A method for preparing two instant tea powders at a high yield, characterized in that: By weight, the method comprises the following steps: S1. Raw material screening: screening green tea raw materials and crushing; S2. Tank extraction: 1 part of green tea raw material is put into 10-15 parts of pure water and extracted at 85-90°C for 30-60 minutes, filtered to obtain extract A and tea residue B; S3. Alkali countercurrent extraction: take 1 part of tea residue B and put it into 5-9 parts of alkaline solution at 90-95 ° C for 30-40 min, filter and obtain extract C and tea residue D; S4. Separation and purification: The extracts A and C are centrifuged using a horizontal centrifuge and a disc centrifuge to obtain purified solutions E and F, respectively; S5. Concentration: Using a triple-effect vacuum concentrator, the purified liquids E and F were concentrated to a solid content of 20 to 25% Brix to obtain concentrated liquids G and H; S6 conversion: the concentrated solution H was adjusted to pH 10 by adding alkali, pure oxygen was introduced to control the reaction pressure to 1.5Mpa, and the conversion was 30 to 60min to obtain a conversion solution I; S7. Preparation: Using citric acid to adjust the pH value of the conversion solution I to 6.5 to obtain a preparation solution J; S8. Sterilization: Put the concentrated solution G and the prepared solution J into a UHT high temperature instantaneous sterilizer at 115℃~127℃ for 10~15s, and cool to 45~60℃; S9. Drying: Use pressure spray drying tower for drying respectively, control the homogenization pressure at 20Mpa, the air inlet temperature at 180-210°C, the temperature inside the tower at 85-95°C, and the exhaust temperature at 80-90°C, to obtain two kinds of instant tea powders.

2. A method for preparing two instant tea powders with high yield at the same time according to claim 1, characterized in that: The green tea raw material in step S1 includes a single raw material, a blended raw material, a raw material containing tea stems or a high-end green tea raw material, and the polyphenol content of the green tea is 18-22%, and the water extract is 35-40%.

3. The method for preparing two instant tea powders with high yield at the same time according to claim 1, characterized in that: In step S2, the resistivity of the pure water is less than 10 MΩ·cm, and the water content of the tea residue B is 70-75%.

4. The method for preparing two instant tea powders with high yield at the same time according to claim 1, characterized in that: The alkali content of the alkali solution in step S3 is 5% of the mass of the green tea raw material in S1.

5. The method for preparing two instant tea powders with high yield at the same time according to claim 1, characterized in that: In step S4, the feed rate of the horizontal centrifuge is 6000-7000 kg / h, the main engine speed is 2600-2700 r / min, and the auxiliary engine speed is 1200-1300 r / min; the feed rate of the disc centrifuge is 2300-2500 kg / h.

6. The method for preparing two instant tea powders with high yield at the same time according to claim 1, characterized in that: The triple-effect vacuum concentration equipment in step S5 has a vacuum degree of -65 to -95 MPa and a temperature of 45 to 75°C.

7. The method for preparing two instant tea powders with high yield at the same time according to claim 1, characterized in that: The alkaline solution in step S6 is a sodium hydroxide solution, a potassium hydroxide solution or a mixture of the two.

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