Green tea Extract the main component of tea polyphenols, caffeine, aromatic oil, water, minerals, pigment, carbohydrate, protein, amino acids and vitamins, etc., have fall blood pressure, blood, fall hematic fat, fall blood sugar, weight loss, prevention and treatment of atherosclerosis, prevention of skin effect, to skin pigment as well as the methods of teeth, dental plaque, periodontitis and bad breath. In particular, tea polyphenols, as natural antioxidants, have a strong antibacterial action and inhibitory effect, and have broad application prospects in food, medicine and health care.
Green Tea polyphenols with tea as raw materials have the most Chinese characteristics and advantages. As a natural antioxidant, green tea polyphenols are sold at a price of 100 to 1.5 million yuan per ton. As a raw material for health care products, its price can reach 160 -- 2 million yuan/ton. In the synthetic food antioxidants and natural products in the next five years, green tea polyphenols in demand will gradually transition from 500 tons to 500 tons, annual demand in the future more will rise to tens of thousands of tons; As the main ingredient of health products with huge added value,green tea polyphenols will be gradually increased from the current dozens of tons to several hundred tons.
Extraction process of Green Tea Extract
Green Tea polyphenols are catechins, flavonoids, phenolic acids and anthocyanin compounds in tea, which accounts for about 15% to 25% of the dry weight of tea leaves. The most important ingredient in tea polyphenols is the various catechins of flavanols.
The study of green tea polyphenols developed in the 1980s and culminated in the 1990s. At present, the research on the purification and application of tea polyphenols has attracted the attention at home and abroad and is still in the ascendant stage.
On the study of the method from the preparation of green tea polyphenols in tea, mainly in some patents and literature, according to different separation methods are divided into three categories: solvent extraction, ion precipitation and column separation preparation method.
The solvent extraction method is extracted from tea by polar solvent, then the extract is extracted and separated, and the product is concentrated and obtained. At present, the industrial production of tea polyphenols is mainly produced by this method. The product yield is 5% to 10%, and the purity of the product is about 80% to 98%, and the coffee base is 4% to 7%. The organic solvents used are acetone, ether, methanol, hexane and trichloromethane. However, this method USES a variety of organic solvents, the production cost is high, some toxic substances organic solvents make the product and the operation not safe, and easy to cause environmental pollution.
Ionic precipitation is the use of metal to precipitate tea polyphenols, which are separated from caffeine, such as copper salt, lead salt, or aluminium trichloride. Since the method USES toxic heavy metals as precipitants, its products are not accepted by the food and pharmaceutical industry.
The column separation and preparation method has been reported to have gel column, adsorption column and ion exchange column. Recently, more attention has been paid to the improvement of purity. For this reason, there are many researches on separation of column chromatography. The key of this technique is column filling and leaching. The results showed that the yield of polyphenol was between 4% and 8%, and the purity could reach 98.1%. If the gel column was used to isolate the high caffeine, the residual amount was only 0.1%. But column filling material such as adsorbent resin, hydrophilic gel and so on are very expensive, and should use a variety of, a lot of organic solvents when washing, obviously is not suitable for industrialized production of tea polyphenols.
Especially because of the technology used in a large number of flammable organic solvents, some even use poison solvents such as chloroform, due to poor safety, poor quality and the comprehensive cost is high, prices in the food additive industry cannot compete with some synthetic antioxidants, in the health food industry purity can't satisfy the requirement. These problems cannot be solved by existing traditional techniques.
Upercritical carbon dioxide extraction technology, combined with traditional technology to produce high purity tea polyphenols, can produce high quality tea polyphenols, which can also solve some disadvantages of traditional technology.
A supercritical carbon dioxide extraction technology with traditional extraction, enrichment, extraction technology, the combination of the new process for preparation of high purity tea polyphenols, its advantages are as follows:
1.The dosage of organic solvent to reduce, good safety and less pollution;
2. High yield;
3. Residual solvent can be removed completely;
4. Low comprehensive cost.
The process can not only improve the purity and yield of tea polyphenols, its content is more than 90%, caffeine content is less than 2%, solvent residue is zero, and conform to the industrialized production of raw materials, the use of solvents, the safety of the production line, production process and the color of the products, yield, purity aspects of requirements, to facilitate more effective application in food, pharmaceutical industry.
Otherwise according to the report, resin adsorption method to extract tea polyphenols and caffeine joint production technology, with green tea, break the old tea, tea, raw materials such as dust, can make the absorption rate of tea polyphenols and caffeine reached 8.6% of the dry tea weight and 8.6%, respectively.