Chinese traditional medicine extraction technology of extraction methods of tea polyphenols in tea
Tea polyphenol is the major physiological active substances in tea, accounts for about 18% ~ 36% of the dry weight of the leaf.
In traditional Chinese medicine extraction technology to extract tea polyphenols has a variety of methods.
Tea polyphenols is the floorboard of the phenolic hydroxyl derivatives, including catechins (
, flavone, flavonol, anthocyanins, grey element, the composition such as phenolic acids, which is given priority to with catechins, accounts for about 70% ~ 80% of the total polyphenols.
Catechin, and ester type catechins content is the most abundant, is the first ingredient of tea health care function.
tea polyphenols for this kind of new type nontoxic natural antioxidant, in 1990 is listed as food additives,
And widely used.
Modern scientific research shows that � � � tea polyphenols has many biological activities and pharmacological effects.
Tea polyphenols as a biological antioxidant, has been widely used in food processing, medicine, health care and daily chemical and other fields, has a broad application prospect, is a kind of the development value extremely the natural products.
Therefore, development of high efficiency, safety of tea polyphenols extraction method is of great significance.
tea polyphenols extraction preparation methods tea polyphenols extraction preparation methods, there are mainly industrialized production more mature organic solvent extraction and metal ion salt precipitation, and in recent years began to industrial application of resin adsorption method.
solvent extraction method of organic solvent extraction method is compared with the traditional methods, mainly based on catechin soluble in water, methanol, ethanol, propyl alcohol and ethyl acetate, insoluble in chloroform, benzene and other organic solvent properties, use of other ingredients in the tea polyphenols and tea in different solvents for separation of difference in the solubility.
the commonly used solvent extraction to extract technology of preparation of tea polyphenols are as follows: the tea extraction - filter - filtrate concentrated to impurities, the ethyl acetate extract - recovered solvents - drying -> tea polyphenols products.
Hot water as extraction solvent, is commonly used in traditional process, however, with the increase of temperature, easy oxidation of catechin adjacent quinone primary product formation, and then continue to form aggregation diphenol quinones, further oxidation generated tea pigment.
Research has shown that using ethanol, chloroform as extraction solvent, can delay the oxidation of tea polyphenols.
although optimized conditions are not exactly the same, but the concentration of the organic solvent, dosage, the pH of the solution, extracting time and temperature, etc. , is the effect of tea polyphenols extraction rate and purity of the most important factors.
For organic solvent extraction, reoccupy after using enzyme for tea processing first organic solvent extraction, and can make the tea polyphenols loss, less extraction yield increased significantly.
Some research has shown that such as pan because tea contains pectin can affect the distribution of tea polyphenols in the organic phase and water phase ratio, to adding pectin enzyme extraction system can obviously improve the extraction system of extraction rate and mass transfer coefficient, increase of tea polyphenols extraction rate.
To join in extraction system Na2SO4 solution, can increase the polarity of the organic phase and water phase difference, shorten the extraction of tea polyphenols.
Generally speaking, the tea extract also contains cellulose, tea pigment, caffeine and other impurities.
The method to remove impurities in chloroform to remove caffeine, petroleum ether depigmentation, cryogenic static except precipitation, etc.
With the organic acids such as citric acid washing tea extract, can make the content of tea polyphenols, caffeine fell to about 1%, but the tea polyphenols loss more.
Organic solvent extraction of tea polyphenols, prepared by the process has become mature, the industrialized production, however, production of high-quality goods must be approved by removing impurity refined repeatedly, need to use the amount of organic solvent.
Application in production of organic solvent and part of the collection difficulties, large energy consumption, high production cost, toxic and other issues, such as improper processing, product possible residue of organic solvent.
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