Extraction method and extraction equipment of high-purity tea polyphenol

Abstract

The invention discloses a high-purity tea polyphenol extraction method, which comprises: S1, mixing a tea leaf raw material with deionized water, and carrying out shearing dispersion to obtain a solid-liquid homogeneous mixture; s2, performing water extraction on the solid-liquid homogenized mixture to obtain a water extract, and filtering the water extract to obtain filter residues and filtrate; s3, the filtrate is subjected to activated carbon adsorption, precision filtration and concentration, and tea polyphenol concentrated extract liquor is obtained; s4, mixing the tea polyphenol concentrated extract with an organic solvent for extraction to obtain an organic solvent phase and a water phase in which the tea polyphenol is located; and S5, adsorbing the water phase through a resin adsorption column, and drying to obtain the tea polyphenol. The invention further provides extraction equipment for the extraction method of the high-purity tea polyphenol. The tea polyphenols extracted by the extraction method and the extraction equipment of the high-purity tea polyphenols have the advantages of being continuous, efficient, small in organic solvent dosage, low in harmful trace substance content, low in production cost and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of plant extract extraction, and in particular relates to a method and device for extracting tea extract. Background Art

[0002] In recent years, with economic development and improved living standards, health products derived from natural plant extracts have become increasingly popular. Tea polyphenols, extracted from tea leaves, are a health supplement that can be used as both medicine and food. They possess potent free radical scavenging and antioxidant properties, effectively enhancing capillary activity and preventing arteriosclerosis. They also have lipid-lowering and blood sugar-lowering properties, as well as anti-cancer and anti-inflammatory benefits. In particular, authoritative research institutions have demonstrated that tea polyphenols offer a protective effect against the harmful effects of radioactive radiation, a crucial consideration for those who frequently use electronic devices such as mobile phones, computers, and microwave ovens. Consequently, health supplements derived from tea polyphenols are poised to experience significant market demand.

[0003] However, most tea polyphenols currently on the market often exceed standards for pesticide residues, dioxins, aflatoxins, plasticizers, benzopyrene, lead, mercury, arsenic, chromium, and other heavy metals when tested for quality indicators. Analysis has shown that these harmful trace substances are caused by polluted air and soil, pesticide residues, improper storage, transportation, and processing during the tea growth process. These substandard indicators significantly limit the entry of tea polyphenols into the high-end market. Existing extraction processes do not adequately address the removal of these harmful trace substances.

[0004] In addition, traditional production processes all adopt intermittent kettle processing methods, such as kettle negative pressure direct extraction, kettle extraction, kettle decompression desolventizing, etc. These traditional process methods require a large amount of organic solvents, cannot achieve continuous production, cannot recover heat, and have the disadvantages of high energy consumption, low production efficiency, large organic solvent consumption, and excessive pesticide residues. For example, patent application CN105693780A discloses a method for extracting tea polyphenols. Its core technology includes two steps: crude extraction and fine extraction: the core technology of the crude extraction process is to crush tea leaves and form a negative pressure to make tea polyphenols quickly seep out from the crushed tea leaves cells, filter to obtain a tea polyphenols crude extract, and then extract the tea polyphenols crude extract in ethanol, methanol, propanol or ethyl acetate to obtain the tea polyphenols finished product. Through industrial production, it was found that this process dissolves and extracts the active ingredients in the organic solvent liquid phase, the amount of organic solvent used is large, and after the ethanol, methanol, propanol or ethyl acetate is concentrated, the impurities in these organic solvents themselves remain in the tea polyphenols. Therefore, this process has very high requirements for the quality of the organic solvent, which increases production costs.

[0005] From the above problems, it can be seen that proposing a process method that is continuous, uses less organic solvents, is energy-saving and can produce high-purity tea polyphenols is a technical bottleneck that the industry urgently needs to overcome. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to overcome the deficiencies and defects mentioned in the above background technology and provide a continuous, energy-saving, low-organic solvent consumption, low-content of harmful trace substances, high-purity tea polyphenols extraction method and extraction equipment.

[0007] In order to solve the above technical problems, the technical solution proposed by the present invention is: A method for extracting high-purity tea polyphenols comprises the following steps: S1: Mixing tea raw materials with deionized water, and performing shear dispersion to obtain a homogeneous solid-liquid mixture; S2: extracting the homogeneous solid-liquid mixture with water to obtain a water extract, and filtering the water extract to obtain a filter residue and a filtrate; S3: subjecting the filtrate to activated carbon adsorption, precision filtration, and concentration to obtain a concentrated tea polyphenol extract; S4: mixing the concentrated tea polyphenol extract with an organic solvent for extraction to obtain an organic solvent phase and an aqueous phase, wherein the tea polyphenols are located in the aqueous phase; S5: The aqueous phase is adsorbed by a resin adsorption column and then dried to obtain tea polyphenols.

[0008] In the above extraction method, preferably, in step S1, during shear dispersion, the temperature of the deionized water is controlled to be 10-15° C., the stirring speed is controlled to be 1200-1250 rpm, and the tea raw material is stirred and dispersed to 0.3-3 mm.

[0009] In the above extraction method, preferably, in step S2, downstream water extraction is adopted, the water extraction temperature is controlled to be 80-95° C., and the water extraction time is 0.5-0.6 h.

[0010] In the above extraction method, preferably, in step S3, the activated carbon is 100-mesh food-grade activated carbon, and the addition amount is 0.1-0.3% of the mass of the filtrate; the precision filtration is 200-mesh microporous filtration; the concentration is molecular distillation concentration, and during molecular distillation concentration, the evaporation temperature is controlled to be 60-70°C and the vacuum degree is 2-3Pa.

[0011] In the above extraction method, preferably, in step S4, the extraction times are 1-3 times, and the organic solvent is C5H 12 、C6H 14 and C7H 16The volume ratio of the organic solvent to the concentrated tea polyphenol extract is (0.1-0.5):1, and the extraction temperature is 15-25°C; after the extraction is completed, deionized water is added to the organic solvent phase for stirring and dispersion, and the aqueous phase is returned to step S2 for water extraction.

[0012] In the above extraction method, preferably, in step S5, when the aqueous phase is adsorbed by a resin adsorption column, acrylic acid Neo Cry I B-725 resin and macroporous A-500P styrene resin are respectively used in series for adsorption, and the column temperature of the resin adsorption column is controlled to be 40-55°C, the flow rate in the column is 1m / h, the column height is 5 meters, and the pH of the aqueous phase is 6.5-7.

[0013] In the above extraction method, preferably, in step S5, the drying is first performed by molecular distillation concentration, and then by vacuum atomization drying.

[0014] The extraction method of the present invention, more specifically, comprises the following steps: S1. Add 1:1 deionized pure water to the pretreated tea raw material and stir at a high speed to obtain a flowable solid-liquid homogeneous mixture; this step mainly achieves two purposes: 1. Use deionized water as a carrier solvent, add the pretreated tea raw material, and disperse and shear the tea into small homogeneous fragments under the action of a high-speed dispersing stirring device, which is conducive to the rapid exudation of tea polyphenols from the broken tea leaves and uniform dispersion in the deionized pure water extract, so that the effective ingredient tea polyphenols in the tea can be efficiently extracted during subsequent water extraction; 2. Deionized water is used as a solvent, which is conducive to the later removal of trace harmful elements by the polar adsorption method.

[0015] S2. The obtained solid-liquid homogeneous mixture is injected into the spiral downstream plant extraction device at a certain flow rate, and the spiral screw is started to slowly lift the solid-liquid homogeneous mixture while heating. At this time, the heated pure deionized water is added from the spiral downstream plant extraction device for downstream water extraction.

[0016] S3. After the downstream extraction is completed, the water extract enters the spiral countercurrent heat exchange device to recover heat energy. At the same time, the material is cooled as quickly as possible to prevent overheating and oxidation of the raw materials. The hot deionized water obtained by recovering heat energy can be used in step S2.

[0017] S4. After the heat energy is recovered, the water extract is filtered to obtain a filter residue and a filtrate. The filtrate after removing the filter residue is adsorbed on food-grade activated carbon and finely filtered. The filtrate is then concentrated by molecular distillation and the heavy component is obtained to obtain a concentrated tea polyphenol extract.

[0018] S5. The concentrated extract of tea polyphenols is subjected to one or two liquid-liquid extractions with an extractant (organic solvent), and the organic solvent phase and the aqueous phase (active ingredient phase) are obtained after separation. The greatest advantage of this method is that the solvent phase is the raffinate phase, and the solvent phase only adsorbs organic harmful trace elements in the concentrated tea polyphenols, such as dioxins, aflatoxins, plasticizers, and benzopyrene. Since the content of organic harmful trace elements is generally below 100 ppm, the amount of organic solvent used is very small, and deionized pure water is then used to extract the tea polyphenols remaining in the solvent phase to increase the extraction yield of the tea polyphenols. The deionized pure water used for extracting the active ingredient phase is deionized pure water. Although the amount of deionized pure water used is large, the price is low, which can save a lot of production costs.

[0019] S6. Use acrylic acid Neo Cry I B-725 resin and macroporous A-500P styrene resin to adsorb harmful components in the effective ingredient phase, mainly to adsorb harmful heavy metal ions such as lead, mercury, arsenic, chromium, etc. remaining in the tea polyphenol solution.

[0020] S7. Finally, the active ingredient phase adsorbed by the resin adsorption column is concentrated by molecular distillation and vacuum atomization drying to obtain high-purity tea polyphenols.

[0021] The design concept of the present invention is that the inventors learned through analysis of the long-term production situation of traditional processes that the main problems with the current tea polyphenol extraction methods are: 1. The intermittent production method results in excessively high production costs. 2. Energy cannot be recovered and energy consumption is too high. 3. The large amount of organic solvent used results in excessively high costs. 4. It is difficult to pass the detection of pesticide residues and harmful component indicators, among which the indicators mainly include the content of heavy metals such as dioxins, aflatoxins, plasticizers, benzopyrene, acephate, imidacloprid, flucythrin, isocarbophos, chlorpyrifos, lead, mercury, arsenic, and chromium.

[0022] The present invention solves the problems in the above four aspects by: 1. Using a spiral downstream extraction device, a spiral countercurrent heat exchange device, and a two-stage continuous molecular distillation concentration device, the batch kettle processing method is transformed into a continuous production method, which greatly improves production efficiency. 2. Based on the physical properties of the raw materials, an innovative process spiral countercurrent heat exchange device is adopted to timely recover the heat energy of water extraction and reduce energy loss. 3. Water extraction is used to extract the active ingredients in tea leaves, and a solvent phase is used to extract pesticide residues and trace harmful components in the tea polyphenol aqueous solution. Through analysis, it is found that if the tea polyphenols in the tea leaves are extracted by solvent phase, the amount of solvent used is large, and the low-grade organic solvent also contains impurities that affect the quality of the tea polyphenols. If a high-quality food-grade organic solvent is used, the production cost will be further increased. In fact, the content of harmful trace elements in tea polyphenols is only below 100ppm. Therefore, if the process is designed to use pure water as the active ingredient phase, the amount of solvent used can be greatly reduced, achieving the purpose of cost saving. 4. Analysis of trace harmful components mainly includes pesticide residues, dioxins, aflatoxins, plasticizers, benzopyrene, acephate, imidacloprid, flucythrin, isocarbophos, permethrin, lead, mercury, arsenic, chromium, etc. These harmful components are produced in different situations and have different physical and chemical properties. It is impossible to remove them using one or two methods. The present invention mainly adopts four methods: (1) pre-treating the raw materials with low-temperature water washing; (2) adding activated carbon adsorption and precision filtration to remove all kinds of impurities; (3) using organic solvents to extract dioxins, aflatoxins, plasticizers, benzopyrene, acephate, imidacloprid, flucythrin, isocarbophos, permethrin, etc.; (4) using acrylic acid NeoCry I B-725 resin and macroporous A-500P styrene resin to perform a second adsorption of harmful heavy metals such as lead, mercury, arsenic, and chromium.

[0023] In step S1, the tea leaves are pretreated by washing them with low-temperature purified water. The water temperature is controlled at 10-15°C, and the washing is completed within 10 minutes before dehydration. This process is simple and easy to implement and will not be discussed here. The pretreated and dehydrated tea leaves are added to the dispersion kettle, along with purified water (deionized water) at a ratio of 1:1. This purified water must be deionized to facilitate the subsequent removal of trace harmful elements. The high-speed dispersive stirring speed is 1200-1250 rpm, and the raw materials are preferably dispersed to a size of 0.3-3 mm.

[0024] In step S2, the deionized water is extracted at a temperature of 80-95°C for 0.5-0.6 hours. The extraction time should not be too long, as prolonged exposure to high temperatures can cause overheating and oxidation of tea polyphenols, affecting product quality.

[0025] In step S3, heat recovery from the tea polyphenol extract occurs by utilizing the spiral countercurrent heat exchanger after downstream extraction. Room-temperature deionized water is introduced from the upper end of the spiral countercurrent heat exchanger into the outer shell (i.e., the second shell) at a flow rate of Q / 24. Q represents the daily weight of the processed raw material. Heat recovery in the spiral countercurrent heat exchanger maximizes extraction heat recovery while also preventing overheating and pipe blockage.

[0026] In step S4, the tea polyphenol extract is filtered through a plate filter press to separate the extract from the residue. After separation, the extract is mixed with 0.1% food-grade 100-mesh activated carbon and then filtered through a 200-mesh microfiltration filter until clear. The filtered residue can be used as fuel in a biomass boiler. The food-grade activated carbon primarily adsorbs heavy metals and solid impurities.

[0027] After the tea polyphenol extract is finely filtered, it is molecularly distilled to extract the heavy component, resulting in a concentrated tea polyphenol extract. Molecular distillation is used to concentrate the extract quickly and at low temperatures to prevent overheating and oxidation of the tea polyphenols, which could affect their quality. When molecular distilling the active ingredient tea polyphenol phase, the evaporation temperature is 60-70°C and the vacuum is 2-3 Pa. The heavy phase is the concentrated extract, and the light phase is distilled water, both of which can be reused. By adjusting the flow rate and extraction ratio, the heavy phase extraction volume is appropriately controlled at one-fifth of the total volume, increasing the tea polyphenol content by five times.

[0028] In the above step S5, the tea polyphenols extracted with water are concentrated, and then the extract is subjected to one to three liquid-liquid extractions. The above concentrated extract is added to C5H 12 、C6H 14 and C7H 16 The mixed liquid is subjected to the first liquid-liquid extraction, and the temperature at this time is controlled at 15-25°C. The extraction is allowed to stand for stratification; the heavy phase solution obtained by liquid-liquid extraction is tested for organic harmful trace elements, such as dioxins, aflatoxin, plasticizers, and benzopyrene. If the test indicators are unqualified, a second extraction is performed until they are qualified. The lower layer of the extract is allowed to stand for stratification, and the upper layer is the organic solvent residual phase. The organic solvent residual phase is added with one-third of deionized pure water and stirred at a high speed. The extraction is allowed to stand for stratification. The lower layer of the extract contains a small amount of tea polyphenols and can be used for the next batch of tea polyphenols water extraction, while the upper layer is the residual phase C5H 12 、C6H 14 and C7H 16The upper raffinate phase can be reused or sent to a recovery tower for recovery (when the content of organic harmful trace elements in the upper raffinate phase reaches 100ppm, it can be sent to a recovery tower for recovery and reuse). The greatest advantage of this method is that the solvent phase is the raffinate phase, while the extraction phase for the effective ingredient is deionized pure water. The organic solvent is used to adsorb the organic harmful trace elements in the concentrated tea polyphenols, and then deionized pure water is used to extract the tea polyphenols remaining in the solvent phase. Therefore, it has the characteristics of high tea polyphenol extraction yield, small solvent usage, high efficiency and good quality.

[0029] In the above step S5, the qualified effective ingredient tea polyphenol liquid is extracted and then enters the adsorption column made of acrylic acid B-725 resin and macroporous A500P styrene resin to adsorb harmful components. A two-stage polar resin fixed bed is used here, the column temperature is between 40-55°C, the flow rate in the column is 1 meter per hour, the column height is 5 meters, and the pH of the liquid is suitable to be 6.5-7. This step is mainly to adsorb harmful heavy metal ions such as lead, mercury, arsenic, chromium, etc. remaining in the tea polyphenol solution.

[0030] As a general technical concept, the present invention also provides an extraction device for the above-mentioned high-purity tea polyphenols extraction method, including a shear dispersion kettle, a water extraction device, a filter press, an activated carbon treatment tank, a fine filtration device, a primary concentration device, an extraction tank, a resin adsorption device, a secondary concentration device and a drying device connected in sequence.

[0031] In the above-mentioned extraction equipment, preferably, the water extraction device includes a spiral downstream extraction device and a spiral countercurrent heat exchange device, the spiral downstream extraction device includes a first inner cavity, a first shell layer is provided outside the first inner cavity, and a first spiral rotation device is provided in the first inner cavity, the spiral countercurrent heat exchange device includes a second inner cavity, a second shell layer is provided outside the second inner cavity, and a second spiral rotation device is provided in the second inner cavity, the liquid outlet of the shear dispersion kettle is connected to the top inlet of the first inner cavity, the bottom outlet of the first inner cavity is connected to the bottom inlet of the second inner cavity, the top outlet of the second inner cavity is connected to the filter press device, cold deionized water is introduced into the top inlet of the second shell layer, and the hot deionized water discharged from the bottom outlet of the second shell layer enters from the top inlet of the first inner cavity for use as water extract, and steam is introduced into the first shell layer.

[0032] In the above extraction equipment, preferably, the outlet of the extraction tank is provided with a heavy phase storage tank for temporarily storing the aqueous phase and a light phase storage tank for temporarily storing the organic solvent phase, and the heavy phase storage tank is connected to the resin adsorption device.

[0033] In the above-mentioned extraction equipment, the flow direction of the material in each device is as follows: first, the cleaned raw material is put into the feed port on the shear dispersion kettle, the lower end of the shear dispersion kettle is connected to the inlet of the No. 1 material pump through a pipeline, and a control valve is installed in the middle of the pipeline. The outlet of the No. 1 material pump is connected to the upper feed port of the spiral downstream extraction device through a pipeline, the lower part of the spiral downstream extraction device is connected to the lower inlet of the spiral countercurrent heat exchange device, the upper part of the spiral countercurrent heat exchange device is connected to the feed port of the air buffer tank and the plate and frame filter press respectively, the discharge port of the plate and frame filter press is connected to the upper part of the activated carbon treatment tank, the upper part of the activated carbon treatment tank is equipped with an activated carbon delivery port, the lower part of the activated carbon treatment tank is connected to the inlet of the No. 2 material pump, and a controllable valve is installed in the middle. The outlet of the No. 2 material pump is connected to the activated carbon treatment tank and the fine filtration device, and two controllable valves are used in the middle. To control the flow direction of the material, the lower outlet of the fine filtration device is connected to the upper inlet of the first-level molecular distillation column. There are two outlets at the bottom of the first-level molecular distillation column, one is the light phase outlet, the other is the heavy phase outlet, the heavy phase outlet is connected to the concentrated temporary storage kettle, the outlet of the concentrated temporary storage kettle is connected to the No. 3 material pump, the outlet of the No. 3 material pump is connected to the extraction tank for liquid-liquid extraction and dispersion, the lower part of the extraction tank is connected to two storage tanks, one is the light phase storage tank, the other is the heavy phase storage tank, the bottom of the heavy phase storage tank is connected to the No. 1 resin solidification bed and the No. 2 resin solidification bed through a pipeline, the upper part of the No. 1 resin solidification bed is equipped with a regulating valve for flow regulation, the lower part of the No. 2 resin solidification bed is connected to the No. 4 material pump inlet, the No. 4 material pump outlet is connected to the secondary molecular distillation concentration column inlet, the middle valve is used to control the flow direction of the liquid, and the lower part of the secondary molecular distillation concentration column enters the vacuum atomization dryer.

[0034] In the above extraction equipment, each device is connected by a closed pipeline, and is equipped with corresponding valves, flow meters, temperature meters, etc., all of which are supplemented by commonly used auxiliary spare parts.

[0035] Compared with the prior art, the advantages of the present invention are: 1. The tea polyphenols extracted by the extraction method and extraction equipment of the high-purity tea polyphenols of the present invention mainly utilize processes such as water extraction and organic solvent stripping of impurities, with high production efficiency, good extraction effect, high impurity separation accuracy, and the advantages of continuous high efficiency, low organic solvent usage, low content of harmful trace substances, and low production cost. It can solve the technical problems of high production cost, excessive organic solvent usage, and difficulty in passing the detection of harmful component indicators caused by the intermittent production mode of the current extraction process and equipment. It can be widely used in the refining and automated continuous production operations of various tea polyphenols, has no limitation on the selection of raw materials, and is suitable for large-scale industrial production.

[0036] 2. The high-purity tea polyphenols extraction equipment of the present invention has a simple structure and low manufacturing cost. The internal parts of the equipment are connected by fully enclosed pipelines, which is environmentally friendly and has a high degree of automation, reducing the complexity of production operations and labor costs. It is suitable for various automated continuous production operations for extracting high-purity tea polyphenols. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0038] Figure 1 Schematic diagram of the structure of the high-purity tea polyphenols extraction equipment in the embodiment.

[0039] Figure 2 Schematic diagram of the connection structure of the spiral downstream plant extraction device and the spiral countercurrent heat exchange device in the embodiment.

[0040] Legend: 1. Shearing dispersion kettle; 2. Material pump No. 1; 3. Spiral downstream extraction device; 31. First inner cavity; 32. First shell layer; 33. First spiral rotating device; 4. Spiral countercurrent heat exchange device; 41. Second inner cavity; 42. Second shell layer; 43. Second spiral rotating device; 5. Air buffer tank; 6. Activated carbon inlet; 7. Activated carbon treatment tank; 8. Filter press device; 9. Material pump No. 2; 10. Fine filtration device; 11. First-stage molecular distillation light phase outlet; 12. First-stage concentration device; 13. Concentration temporary storage kettle; 14. Material pump No. 3; 15. Extraction tank; 16. Light phase storage tank; 17. Heavy phase storage tank; 18. Resin curing bed No. 1; 19. Resin curing bed No. 2; 20. Material pump No. 4; 21. Second-stage concentration device; 22. Drying device; 23. Dryer solid phase finished product outlet. DETAILED DESCRIPTION

[0041] To facilitate understanding of the present invention, the present invention will be described in more comprehensive and detailed form below in conjunction with the accompanying drawings and preferred embodiments. However, the protection scope of the present invention is not limited to the following specific embodiments.

[0042] It should be noted that when an element is described as being "fixed, fixed, connected or communicated with" another element, it can be directly fixed, fixed, connected or communicated with the other element, or it can be indirectly fixed, fixed, connected or communicated with the other element through other intermediate connectors.

[0043] Unless otherwise defined, all technical terms used hereinafter have the same meanings as those generally understood by those skilled in the art. The technical terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0044] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0045] Example: like Figure 1 As shown, the extraction equipment of the high-purity tea polyphenols extraction method of this embodiment includes a shearing and dispersion kettle 1, a water extraction device, a filter press 8 (plate and frame filter press), an activated carbon treatment tank 7, a fine filtration device 10 (precision filter), a primary concentration device 12 (primary molecular distillation column), an extraction tank 15, a resin adsorption device (No. 1 resin solidification bed 18 and No. 2 resin solidification bed 19), a secondary concentration device 21 (secondary molecular distillation concentration column) and a drying device 22 (vacuum atomization dryer) connected in sequence.

[0046] Specifically, such as Figure 2 As shown, in this embodiment, the water extraction device includes a spiral downstream extraction device 3 and a spiral countercurrent heat exchange device 4. The spiral downstream extraction device 3 includes a first inner cavity 31, a first shell 32 is provided outside the first inner cavity 31, and a first spiral rotating device 33 is provided in the first inner cavity 31. The spiral countercurrent heat exchange device 4 includes a second inner cavity 41, a second shell 42 is provided outside the second inner cavity 41, and a second spiral rotating device 43 is provided in the second inner cavity 41. The liquid outlet of the shearing dispersion kettle 1 is connected to the top inlet of the first inner cavity 31, the bottom outlet of the first inner cavity 31 is connected to the bottom inlet of the second inner cavity 41, the top outlet of the second inner cavity 41 is connected to the filter press 8, cold deionized water is introduced into the top inlet of the second shell 42, and the hot deionized water discharged from the bottom outlet of the second shell 42 enters from the top inlet of the first inner cavity 31 for use as water extract, and steam is introduced into the first shell 32.

[0047] In this embodiment, a heavy phase storage tank 17 for temporarily storing the aqueous phase and a light phase storage tank 16 for temporarily storing the organic solvent phase are provided at the outlet of the extraction tank 15 , and the heavy phase storage tank 17 is connected to the resin adsorption device.

[0048] In this embodiment, according to the flow direction of the logistics, the connection components of each device are as follows: First, the cleaned raw materials are put into the feed port on the shearing and dispersing kettle 1. The lower end of the shearing and dispersing kettle 1 is connected to the inlet of the No. 1 material pump 2 through a pipeline. A control valve is installed in the middle of the pipeline. The outlet of the No. 1 material pump 2 is connected to the upper feed port of the spiral downstream plant extraction device 3 through a pipeline. The lower part of the spiral downstream plant extraction device 3 is connected to the lower inlet of the spiral countercurrent heat exchange device 4. The upper part of the spiral countercurrent heat exchange device 4 is respectively connected to the feed port of the air buffer tank 5 and the plate and frame filter press. The discharge port of the plate and frame filter press is connected to the upper part of the activated carbon treatment tank 7. The upper part of the activated carbon treatment tank 7 is equipped with an activated carbon input port 6. The lower part of the activated carbon treatment tank 7 is connected to the inlet of the No. 2 material pump 9. A controllable valve is installed in the middle. The outlet of the No. 2 material pump 9 is connected to the activated carbon treatment tank 7 and the fine filtration device 10. Two controllable valves are used in the middle to control the flow direction of the material. The lower outlet of the fine filtration device 10 is connected to the upper outlet of the first-level molecular distillation column. The first molecular distillation column is connected to the inlet, and there are two outlets at the bottom of the first molecular distillation column, one is the light phase outlet (the first molecular distillation light phase outlet 11), and the other is the heavy phase outlet. The heavy phase outlet is connected to a temporary concentrated storage kettle 13, and the outlet of the temporary concentrated storage kettle 13 is connected to a No. 3 material pump 14. The outlet of the No. 3 material pump 14 is connected to an extraction tank 15 for liquid-liquid extraction dispersion. The lower part of the extraction tank 15 is connected to two storage tanks, a light phase storage tank 16, and a heavy phase storage tank 17. The bottom of the heavy phase storage tank 17 is connected to the No. 1 resin solidification bed 18 and the No. 2 resin solidification bed 19 through a pipeline. The upper part of the No. 1 resin solidification bed 18 is equipped with a regulating valve for flow regulation. The lower part of the No. 2 resin solidification bed 19 is connected to the inlet of the No. 4 material pump 20. The outlet of the No. 4 material pump 20 is connected to the inlet of the secondary molecular distillation concentration column. The flow direction of the liquid is controlled by a valve in the middle. The lower part of the secondary molecular distillation concentration column enters the vacuum atomization dryer and is discharged through the solid phase finished product outlet 23 of the dryer.

[0049] The method for extracting high-purity tea polyphenols using the extraction equipment of the above-mentioned method for extracting high-purity tea polyphenols comprises the following steps: S1: Mixing tea raw materials with deionized water, and performing shear dispersion to obtain a homogeneous solid-liquid mixture; S2: extracting the homogeneous solid-liquid mixture with water to obtain a water extract, and filtering the water extract to obtain a filter residue and a filtrate; S3: The filtrate is subjected to activated carbon adsorption, precision filtration, and concentration to obtain a concentrated tea polyphenol extract; S4: mixing the concentrated tea polyphenol extract with an organic solvent for extraction to obtain an organic solvent phase and an aqueous phase, wherein the tea polyphenols are located in the aqueous phase; S5: The aqueous phase is adsorbed by a resin adsorption column and then dried to obtain tea polyphenols.

[0050] To illustrate the advantages of the above extraction equipment and extraction method, this embodiment provides a more specific method for extracting high-purity tea polyphenols, comprising the following steps: S1. Take 1000kg of tea leaves as raw material for pretreatment. The pretreatment of tea leaves is to wash with low-temperature purified water. The water temperature is controlled at 10°C, 3000kg of purified water is used, and the washing and stirring are carried out for 10 minutes, and then dehydrated. 1000kg of deionized purified water is added to the tea leaves after pretreatment and dehydration, and high-speed dispersive stirring is performed to obtain a solid-liquid homogeneous mixture. The speed of high-speed dispersive stirring is adjusted to 1200 rpm. Samples are taken for testing. The tea leaves are stirred and dispersed into a size of 1mm, which is qualified.

[0051] S2. The obtained solid-liquid homogeneous mixture is injected into the spiral downstream extraction device 3 at a flow rate of 5 kg / min, the spiral screw is started, and the solid-liquid homogeneous mixture is slowly lifted while heating. At this time, the heated pure deionized water is added to the spiral downstream extraction device 3 to extract the effective ingredients in the tea leaves in the downstream water. The water extraction temperature is controlled at 90° C. and the water extraction time is 0.5 h. A small sample of the extracted effective ingredient liquid is concentrated and dried and then tested to detect pesticide residues and trace harmful elements in the crude tea polyphenols. The test report is shown in Table 1 below.

[0052] Table 1: Test report of the extracted active ingredient liquid

[0053] S3. After the countercurrent extraction is completed, the heat enters the spiral countercurrent heat exchange device 4 to recover heat energy. According to measurement, the heat entering the spiral countercurrent heat exchange device 4 is 88°C at the hot phase inlet and 22°C at the hot phase outlet; 18°C ​​at the cold phase inlet and 83°C at the cold phase outlet; the flow rate is 5kg / min; and the heat recovery rate reaches 95%.

[0054] S4. After the countercurrent extraction is completed, 1128 kg of filter residue and 870 kg of filtrate are obtained by filtration. The filtrate is then added to 8.7 kg of food-grade 100-mesh activated carbon and stirred for 1 hour before being filtered through a 200-mesh microporous filter until it is clear. After precise filtration, the heavy component is extracted by molecular distillation to obtain a concentrated tea polyphenol extract. The purpose of molecular distillation to concentrate the extract is to quickly distill and concentrate the extract at low temperature to prevent the tea polyphenols from overheating and oxidation, which affects the quality. When molecular distilling the active ingredient tea polyphenol phase, the evaporation temperature is 60-70 ° C and the vacuum degree is 2-3 Pa; the heavy phase is the concentrated extract active ingredient liquid, with a heavy phase recovery of 176 kg, and the light phase is 690 kg of distilled water.

[0055] S5, liquid-liquid extraction was performed on 176 kg of concentrated liquid extracted from the heavy phase, and C5H 12 、C6H 14 and C7H 1680 kg of mixed liquid was separated to obtain 175 kg of solvent phase and active ingredient phase. The temperature was controlled at 20°C during extraction and the extraction was allowed to stand for 30 minutes for stratification. The mixture was separated in a conical tank and the heavy phase was concentrated. The organic chemical pesticide residues, dioxins, aflatoxins, plasticizers, benzopyrene and other indicators were tested and found to be qualified. 60 kg of deionized pure water was then added to the light phase solvent to strip out the active ingredient tea polyphenols remaining in the organic solvent and added to the next batch for reuse.

[0056] S6. 175 kg of the qualified tea polyphenols concentrate was passed through fixed beds made of acrylic acid Neo Cry I B-725 resin and macroporous A-500P styrene resin, respectively, to adsorb harmful components. The column temperature was 50°C, the pH of the liquid was 7, and the adsorption time was 4 hours. The test report of the tea polyphenols concentrate after passing through the adsorption column is shown in Table 2 below.

[0057] S7. The tea polyphenols concentrate after passing through the adsorption column is subjected to secondary molecular distillation and then vacuum dried to obtain tea polyphenols.

[0058] Table 2: Test report of tea polyphenols concentrate after adsorption column

[0059] From the comparison between the above test reports 1 and 2, it can be seen that the quality of tea polyphenols is greatly improved by adopting the extraction process of the present invention, and the content of harmful substances obviously meets the requirements.

Claims

1. A method for extracting high-purity tea polyphenols, characterized in that: The following steps are involved: S1: Mixing tea raw materials with deionized water, and performing shear dispersion to obtain a homogeneous solid-liquid mixture; S2: extracting the homogeneous solid-liquid mixture with water to obtain a water extract, and filtering the water extract to obtain a filter residue and a filtrate; S3: subjecting the filtrate to activated carbon adsorption, precision filtration, and concentration to obtain a concentrated tea polyphenol extract; S4: mixing the concentrated tea polyphenol extract with an organic solvent for extraction to obtain an organic solvent phase and an aqueous phase, wherein the tea polyphenols are located in the aqueous phase; S5: The aqueous phase is adsorbed by a resin adsorption column and then dried to obtain tea polyphenols.

2. The extraction method according to claim 1, wherein In step S1, during shear dispersion, the temperature of the deionized water is controlled to be 10-15° C., the stirring speed is controlled to be 1200-1250 rpm, and the tea material is stirred and dispersed to 0.3-3 mm.

3. The extraction method according to claim 1, wherein In the step S2, downstream water extraction is adopted, the water extraction temperature is controlled to be 80-95° C., and the water extraction time is 0.5-0.6 h.

4. The extraction method according to claim 1, wherein In step S3, the activated carbon is 100-mesh food-grade activated carbon, and the added amount is 0.1-0.3% of the mass of the filtrate; the precision filtration is 200-mesh microporous filtration; the concentration is carried out by molecular distillation concentration, and during the molecular distillation concentration, the evaporation temperature is controlled to be 60-70°C and the vacuum degree is 2-3Pa.

5. The extraction method according to claim 1, wherein In step S4, the extraction times are 1-3 times, and the organic solvent is C5H 12 、C6H 14 and C7H 16 The volume ratio of the organic solvent to the concentrated tea polyphenol extract is (0.1-0.5):1, and the extraction temperature is 15-25°C; after the extraction is completed, deionized water is added to the organic solvent phase for stirring and dispersion, and the aqueous phase is returned to step S2 for water extraction.

6. The extraction method according to claim 1, characterized in that In step S5, when the aqueous phase is adsorbed by a resin adsorption column, acrylic acid Neo Cry I B-725 resin and macroporous A-500P styrene resin are respectively used for adsorption in series, and the column temperature of the resin adsorption column is controlled to be 40-55° C., the flow rate in the column is 1 m / h, the column height is 5 meters, and the pH of the aqueous phase is 6.5-7.

7. The extraction method according to claim 1, characterized in that In step S5, the drying is performed by first molecular distillation concentration and then vacuum atomization drying.

8. An extraction device for the method for extracting high-purity tea polyphenols according to any one of claims 1 to 7, characterized in that: The invention comprises a shearing and dispersing kettle (1), a water extraction device, a filter press device (8), an activated carbon treatment tank (7), a fine filtration device (10), a primary concentration device (12), an extraction tank (15), a resin adsorption device, a secondary concentration device (21) and a drying device (22) which are connected in sequence.

9. The extraction device according to claim 8, characterized in that The water extraction device comprises a spiral downstream plant extraction device (3) and a spiral countercurrent heat exchange device (4), wherein the spiral downstream plant extraction device (3) comprises a first inner cavity (31), a first shell layer (32) is provided outside the first inner cavity (31), and a first spiral rotating device (33) is provided inside the first inner cavity (31); the spiral countercurrent heat exchange device (4) comprises a second inner cavity (41), a second shell layer (42) is provided outside the second inner cavity (41), and a second spiral rotating device (43) is provided inside the second inner cavity (41); the shear separation The liquid outlet of the bulk kettle (1) is connected to the top inlet of the first inner cavity (31), the bottom outlet of the first inner cavity (31) is connected to the bottom inlet of the second inner cavity (41), the top outlet of the second inner cavity (41) is connected to the filter press device (8), cold deionized water is introduced into the top inlet of the second shell layer (42), hot deionized water discharged from the bottom outlet of the second shell layer (42) enters from the top inlet of the first inner cavity (31) for use as a water extract, and steam is introduced into the first shell layer (32).

10. The extraction device according to claim 8 or 9, characterized in that The outlet of the extraction tank (15) is provided with a heavy phase storage tank (17) for temporarily storing the aqueous phase and a light phase storage tank (16) for temporarily storing the organic solvent phase. The heavy phase storage tank (17) is connected to the resin adsorption device.

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