阅读说明：本技术 利用秋、冬季茶叶提取茶多糖和咖啡因的方法 (Method for extracting tea polysaccharide and caffeine from autumn and winter tea leaves ) 是由 赵昕梅 远凌威 乔春莲 饶本强 张苏锋 袁正仿 于 2020-07-04 设计创作，主要内容包括：本发明属于茶叶原料深加工技术领域,具体涉及利用秋、冬季茶叶提取茶多糖和咖啡因的方法。发明包括如下步骤：A.前处理阶段：(1)将新鲜茶叶原料风干为粗粉；(2)热水循环超声处理；(3)进行粗滤和精滤；(4)减压浓缩得滤液；(5)利用乙醇沉淀杂蛋白；B.茶多糖的提取：(6)离心/过滤,得粗多糖；(7)热水溶解沉淀,除蛋白和脱色；(8)离心/过滤,乙醇醇沉；(9)离心/过滤的精多糖；(10)减压干燥,得干茶多糖。C.咖啡因的提取：(11)将步骤(6)所得滤液,脱色,离心/过滤；(12)浓缩滤液得结晶；(13)洗晶、干燥；(14)减压升华,得纯咖啡因。本发明可提高秋、冬茶树资源利的综合利用率和利用价值。(The invention belongs to the technical field of deep processing of tea raw materials, and particularly relates to a method for extracting tea polysaccharide and caffeine from autumn and winter tea. The invention comprises the following steps: A. a pretreatment stage: (1) air-drying fresh tea raw materials into coarse powder; (2) hot water circulation ultrasonic treatment; (3) coarse filtration and fine filtration are carried out; (4) concentrating under reduced pressure to obtain filtrate; (5) precipitating the impure protein by using ethanol; B. extracting tea polysaccharide: (6) centrifuging/filtering to obtain crude polysaccharide; (7) dissolving the precipitate in hot water, removing protein and decolorizing; (8) centrifuging/filtering, and precipitating with ethanol; (9) (ii) centrifuged/filtered fine polysaccharide; (10) drying under reduced pressure to obtain dried tea polysaccharide. C. Extracting caffeine: (11) decoloring the filtrate obtained in the step (6), and centrifuging/filtering; (12) concentrating the filtrate to obtain crystals; (13) washing and drying the crystal; (14) decompressing and sublimating to obtain pure caffeine. The invention can improve the comprehensive utilization rate and the utilization value of the autumn and winter tea tree resource.)

1. A method for extracting tea polysaccharide and caffeine from tea leaves in autumn and winter is characterized by comprising the following steps:

(1) pretreatment: air-drying fresh autumn and winter tea leaves collected from 10 middle ten days to 12 last ten days of the month, then crushing the tea leaves to 0.1-5mm, adding water with the temperature of 95-100 ℃ according to the liquid-solid ratio of 15-20:1, filtering out tea leaf residues to obtain filtrate 1, and extracting tea polysaccharide and caffeine in the tea coarse powder by using a circulating ultrasonic method, wherein the ultrasonic frequency in the circulating ultrasonic method is 45-70kHz, the output power is 60-90%, and the ultrasonic time is 20-70 min; performing solid-liquid separation by adopting plate and frame filter pressing, performing reduced pressure concentration on the obtained filtrate 1 at 40-50 ℃ under the condition of 0.09-0.1MPa, adding 95-100% of ethanol into the concentrated solution 1 to enable the final concentration of the ethanol to be 75-80%, performing solid-liquid separation on the liquid after ethanol precipitation by adopting a centrifugal or filtration mode, and obtaining precipitate or retentate, namely crude tea polysaccharide;

(2) preparing high-purity tea polysaccharide: dissolving the crude tea polysaccharide obtained in step (1) with hot water at 95-100 deg.C, adding 20% trichloroacetic acid to 6% to precipitate protein impurities, decolorizing with 4-6 mesh granular activated carbon, filtering, and adding anhydrous ethanol into filtrate 4 until the volume concentration of ethanol is 75-80%; precipitating tea polysaccharide again, filtering, and drying under reduced pressure to obtain high-purity tea polysaccharide with content of more than or equal to 90%;

(3) extracting caffeine: carrying out solid-liquid separation on the liquid subjected to alcohol precipitation in the step (1) by adopting a centrifugal or filtering mode to obtain a filtrate 2, carrying out reduced pressure distillation to recover ethanol, adding 20% trichloroacetic acid into the obtained residual liquid until the concentration of trichloroacetic acid is 6% to precipitate protein impurities, decoloring by using granular activated carbon, filtering by using a grading membrane to obtain a filtrate 3, carrying out nanofiltration concentration to obtain a concentrated solution 2, and filtering the waste liquid to obtain high-purity water by using a reverse osmosis device; cooling the concentrated solution 2 to crystallize to obtain coarse caffeine crystal, and sublimating at 100-105 deg.C under reduced pressure to obtain pure caffeine product with purity not lower than 99%.

2. The method for extracting tea polysaccharides and caffeine from autumn winter tea leaves as claimed in claim 1, wherein: and recovering ethanol in the filtrate 2 by adopting a reduced pressure distillation mode, or concentrating the filtrate 3 by adopting nanofiltration to obtain a concentrated solution 2, and simultaneously filtering waste liquid to obtain high-purity RO water by using a reverse osmosis device.

Technical Field

The invention belongs to the technical field of tea deep processing, and particularly relates to a method for extracting tea polysaccharide and caffeine from autumn and winter tea (raw materials).

Background

Xinyang Maojian tea is a famous and excellent tea product in Xinyang areas of Henan province, raw materials of the Xinyang Maojian tea mainly utilize fresh bud tips of locally produced tea trees, but in the whole growth process of the tea trees, the yield of the bud tips is low, the picking period is short, and the supply of the raw materials is short. Meanwhile, a large amount of fresh tea leaves, particularly tea leaves trimmed in autumn and winter, can be left in a tea garden, so that resource waste is caused, and the sustainable utilization of tea tree resources is seriously restricted.

The tea mainly contains tea polysaccharide as a bioactive component, and the tea polysaccharide plays a unique role in reducing blood sugar, resisting fatigue, resisting oxidation, resisting tumor cells and the like and can be used for developing functional foods. The caffeine extracted from the tea leaves has the effects of removing fatigue and exciting nerves when being drunk in a proper amount, is clinically used for treating neurasthenia and coma resuscitation, and can be used for developing raw material medicines. The content types and contents of the tea leaves in the period from autumn to snowy are obviously different from other seasons, for example, the content of polysaccharide in the tea leaves in the season accounts for about 16-21% of the dry weight of the tea leaves, the content of caffeine accounts for about 2-3% of the dry weight of the tea leaves, and the contents of tea polyphenol, amino acid, theophylline, theobromine and the like are reduced, so that the tea leaves are not beneficial to making high-grade drinking tea, but are beneficial to extracting tea polysaccharide and caffeine. The tea leaves in autumn and winter have no insect damage, no pesticide is used, and the residue is low. Can realize mechanical pruning and leaf harvesting, is favorable for the germination of spring tea in the next year, has consistent germination and is also favorable for the picking of spring tea.

Disclosure of Invention

The invention aims to provide a method for extracting tea polysaccharide and caffeine from autumn and winter tea leaves, which aims to solve the technical problems in the prior art.

In order to solve the technical problems, the technical scheme adopted by the invention is as follows: the method takes unprocessed tea leaves in autumn and winter in Xinyang areas as raw materials, improves the dissolution rate of the dissolved substances and shortens the extraction time by a cyclic ultrasonic-assisted hot water extraction method in a pretreatment stage. In the tea polysaccharide extraction process, the organic solvent only relates to ethanol, and the recycling of ethanol and water is increased in the extraction process. In the caffeine extraction process, the invention adopts a nanofiltration concentration series reverse osmosis technology to replace the traditional decompression concentration process, thereby realizing energy saving and high efficiency, and the obtained RO water can provide high-purity water for the whole production process.

Specifically, the technical scheme of the invention is as follows:

a process for extracting tea polysaccharides and caffeine from autumn and winter season tea leaves (for convenience of description the invention is referred to collectively as tea leaves, which are essentially raw tea leaves, i.e., tea leaf material, the following) comprising the steps of:

(1) pretreatment: air-drying fresh autumn and winter tea leaves collected from 10 middle ten days to 12 last ten days, pulverizing into raw materials with the size of 0.1-5mm, adding water with the temperature of 90-100 ℃ according to the liquid-solid ratio of 15-20:1, filtering out tea leaf residues to obtain filtrate 1, and extracting tea polysaccharide and caffeine from the tea coarse powder by using a cyclic ultrasonic method, wherein the ultrasonic frequency in the cyclic ultrasonic method is 45-70kHz, the output power is 60-90%, and the ultrasonic treatment time is 20-70 min; performing solid-liquid separation by plate-and-frame filter pressing, concentrating the obtained filtrate 1 at 40-50 deg.C under 0.09-0.1MPa, adding 95-100% ethanol into the concentrated solution 1 to make ethanol concentration reach 75-80%; and (3) carrying out solid-liquid separation on the liquid after alcohol precipitation by adopting a centrifugal or filtration mode, wherein the obtained precipitate or retentate is the crude tea polysaccharide.

(2) Preparing high-purity tea polysaccharide: dissolving the crude tea polysaccharide obtained in step (1) with hot water at 95-100 deg.C, adding 20% trichloroacetic acid to 6% precipitate impurity protein, decolorizing with 4-6 mesh granular activated carbon, filtering to obtain filtrate 4, and adding anhydrous ethanol into filtrate 4 until ethanol concentration is 75-80%; precipitating tea polysaccharide again, filtering, and drying under reduced pressure to obtain high-purity tea polysaccharide with content of not less than 90%.

(3) Extracting caffeine: carrying out solid-liquid separation on the liquid subjected to alcohol precipitation in the step (1) by adopting a centrifugation or filtration mode to obtain a filtrate 2; distilling under reduced pressure to recover ethanol, adding 20% trichloroacetic acid into the obtained residual liquid until the concentration is 6% to precipitate protein impurities, decolorizing with granular activated carbon, filtering with a grading membrane to obtain filtrate 3, concentrating by nanofiltration to obtain concentrated solution 2, and passing the filtered clear liquid through a reverse osmosis device (conventional, commercially available equipment) to obtain high-purity RO water; cooling the concentrated solution 2 to crystallize to obtain coarse caffeine crystal; then carrying out decompression sublimation at the temperature of 100-105 ℃ to obtain the caffeine pure product with the purity of more than or equal to 99 percent.

The leftovers of the invention after extracting tea polysaccharide and caffeine, such as tea filter residue, can be used for producing animal feed or organic fertilizer by adopting a microorganism solid fermentation method.

The invention has the beneficial effects that:

(1) the utilization rate of tea products for making drinking tea from tea leaves in autumn and winter in China is low, and the main reason is that the tea leaves in this period have lower content of main components as drinking tea and are not suitable for making high-grade drinking tea. However, the tea polysaccharide and caffeine content in the raw material tea leaves of the tea plant in this period is significantly higher than in the other periods. In the practical production, the tea leaves in the period are mainly used as the green-clearing pruning and rotten tea garden. Xinyang is a key tea area in China, tea resources in autumn and winter are rich, and the process can be used for the perpetual utilization of the tea resources in autumn and winter, and especially lays a technical foundation for extracting tea polysaccharide and caffeine from the tea resources.

(2) The process of the invention adopts a membrane separation technology, and has the characteristics of energy conservation, environmental protection and high-efficiency production.

(3) The process of the invention establishes 2 recycling links, one is the recycling of ethanol, the other is the discharge liquid after nanofiltration concentration, and the high-purity RO water can be prepared after the discharge liquid passes through a reverse osmosis device.

Drawings

FIG. 1: technical route diagrams of the present invention.

Detailed Description