The Broad Application Prospect of Green Tea Extract

The Broad Application Prospect of Green Tea Extract

The main component of Green tea extract are tea polyphenols, caffeine, aromatic oil, water, minerals, pigment, carbohydrate, protein, amino acids and vitamins, etc., which have blood pressure falling, hematic fat falling, blood sugar falling, weight loss, prevention and treatment of atherosclerosis, skin allergic prevention, skin pigment removing as well as prevention of bad breath effects. Tea polyphenols in particular, as a natural antioxidant, has a strong antibacterial effect and anti-enzyme action, and has a broad application prospect in food, medicine, health care and many other aspects.

Green tea extract market in the future

The extraction of tea polyphenols with tea as raw material has the most Chinese characteristics and advantages, and is also the inevitable way out for crude old tea, a byproduct of tea production. This development of turning waste into treasure makes the health care function of tea better benefit human beings and has considerable economic benefits. As a natural antioxidant preservative for food, tea polyphenols generally sell for 1-1.5 million yuan/ton. As the raw material of health care products, its price can reach 160-2 million yuan/ton. In the next five years, when synthetic food antioxidants coexist with natural products, the annual demand of tea polyphenols will gradually transition from 500 tons to 5,000 tons, and the annual demand will rise to tens of thousands tons in the future. As the main ingredient of health care products with huge added value, tea polyphenols will gradually increase from the current demand of dozens of tons to several hundred tons.

The extraction process of green tea extract

Tea polyphenols, a general term for catechins, flavonoids, phenolic acids and anthocyanins in tea, account for about 15-25% of the dry weight of tea leaves. The most important component of tea polyphenols is various catechins of flavanols. The study of tea polyphenols developed in the 1980s and reached its climax in the 1990s.At present, the study on the purification and application of tea polyphenols has been concerned at home and abroad. Research on the preparation of tea polyphenols from tea leaves, mainly in some patents and literatures, can be divided into three categories according to different separation methods: solvent extraction method, ion precipitation method and column separation preparation method. The solvent extraction method is to extract the leachate from tea leaves with polar solvent, then extract the leachate into liquid-liquid extraction separation, and finally concentrate and obtain the product. At present, the industrialized production of tea polyphenols mainly adopts this method, the product yield is 5%-10%, and the product purity is about 80%-98%, theobromine 4%-7%.Organic solvents used such as acetone, ether, methanol, hexane and trichloromethane. However, this method uses a variety of organic solvents, which are costly to produce. Some toxic organic solvents make the products and operations unsafe and easy to cause environmental pollution. Ionic precipitation uses metals to precipitate tea polyphenols, which are separated from caffeine, such as copper salts, lead salts, or aluminum trichloride. Because the method useS heavy metals that are toxic to the human body as precipitators, its products are not accepted by the food and pharmaceutical industries. Gel column, adsorption column and ion exchange column have been reported. 

Recently, more attention has been paid to the study of improving the purity. Therefore, there are many studies on the separation of column by column. The key of this technology is column filling and leaching. The results showed that the yield of tea polyphenols was between 4% and 8%, and the purity could reach 98.1%.However, column packing materials such as adsorption resin and lipophilic gel are very expensive, and a variety of organic solvents should be used in the leaching, obviously not suitable for industrial production of tea polyphenols. At present, there are about 30 or 40 tea polyphenols plants built or under construction in China, but only three or four have real market competitiveness (product quality, scale, cost and efficiency).The main reason is that the existing factories all adopt traditional solvent extraction method and precipitation separation, without adopting high-tech means, the color, purity, solvent residue and caffeine content of products cannot meet the increasing requirements of domestic and foreign merchants. 

In particular, due to the use of a large number of flammable and explosive organic solvents in the process, some even use toxic chloroform and other solvents, resulting in poor safety, poor quality and high comprehensive cost. In the food additive industry, the price cannot compete with some synthetic antioxidants, and the purity in the health product industry cannot meet the due requirements. And these problems cannot be solved with existing traditional techniques. High purity tea polyphenols can be produced by using supercritical carbon dioxide extraction technology combined with traditional technology, which can not only produce high quality tea polyphenols but also solve some disadvantages of traditional technology. By combining the supercritical carbon dioxide extraction technology with the traditional extraction, concentration and extraction technology, a new process for the preparation of high purity tea polyphenols has been obtained. Its advantages are as follows: High yield; Residual solvent can be completely removed; 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. It is also reported that the combined production process of extracting tea polyphenols and theobromine by resin adsorption method can make the absorption rate of tea polyphenols and theobromine accounts for 8.6% and 1.6% of the dry tea weight respectively with green tea, crushed old tea slices, tea clothes, tea dust and other raw materials.