definition:

It is a compound of polyhydroxy phenolic compounds in tea. It is composed of more than 30 phenolic substances. Its main component is catechins and their derivatives. It is the main chemical component with health care functions in tea.

Composition:

Tea polyphenols are the main components that determine the color, aroma, taste and efficacy of tea, accounting for 20% to 30% of the dry weight of tea. According to the main chemical components, tea polyphenols are divided into four categories: catechins, flavonoids, anthocyanins, and phenolic acids. Among them, catechins have the highest content, accounting for 60% to 80% of tea polyphenols. The catechins are mainly four substances: epicatechin (EC), epicatechin gallate (ECG), epigallocatechin (EGC) and epigallocatechin gallate (EGCG). Among them, the first two are called non-ester catechins, and the last two are called ester catechins. The highest content of catechins in tea is EGCG, followed by ECG, and again EGC

Physical and chemical properties:

Pure tea polyphenols are white amorphous crystalline substances. During the extraction process, due to the oxidation and polymerization of a small amount of tea polyphenols, it will appear light yellow to brown, with a slight tea aroma and astringent taste; it is easily soluble in ethanol, methanol, and ethyl acetate. , Acetone, etc., slightly soluble in fats, insoluble in organic solvents such as benzene and chloroform; good heat resistance, hygroscopicity, stable at pH 2-7, easy to oxidize and polymerize under light or pH>8. Can produce green and black compounds with iron ions

Application areas:

Application in the food industry

1. Used as an antioxidant

Tea polyphenols are used as antioxidants. Since most of the tea polyphenols contain more than two ortho-hydroxy polyphenols and have strong hydrogen supply capacity, they are an ideal antioxidant. Among the four main catechins, the antioxidant capacity is EGCG>EGC>ECG>EC. As an antioxidant for oily foods, it has excellent antioxidant properties, and its effectiveness is far superior to synthetic antioxidants 2,6-di-tert-butyl-4-methylphenol (BHT) and butylated hydroxyfennel (BHA). The antioxidant effect of tea polyphenols can be applied to meat product processing, oil storage, baked food, dairy products, fried food, and various beverage preparations. When freezing fresh fish, adding tea polyphenol antioxidants can prevent the oxidation of fish body fat [3-4].

2. Used as a food preservative

Tea polyphenols have inhibitory activity on nearly 100 kinds of bacteria in the natural world, show broad-spectrum antibacterial properties, and are good food preservatives. As a fresh-keeping agent, tea polyphenols can slow down the biochemical activities of fruits and vegetables after picking, and postpone the subsequent ripening period. In addition, the antistaling agent formulated with tea polyphenols can also prevent discoloration and corruption during the deep processing of various pastries, lactic acid beverages and livestock products [3] [5].

3. Used as food color retention agent

The oxidation of the same pigment can change the color of food. Tea polyphenols have strong reducing properties and can prevent natural pigments (such as carotene, chlorophyll, safflower yellow, vitamin

And carmine, etc.) faded by photooxidation, which has a certain effect on the stability of the pigment [3].

4. Used as a food deodorant

Bad breath is mainly caused by volatile sulfur-containing compounds and nitrogen-containing compounds, among which sulfur compounds such as hydrogen sulfide and methyl mercaptan have the heaviest odor. The deodorizing power of chewing gum containing tea polyphenols is 10 times higher than that of general chewing gum. For physiological bad breath, chewing for 3 minutes is effective. In addition, adding 0.1% green tea extract to wines and beverages can be developed into wines and beverages with the function of removing bad breath. Such wines and beverages also have obvious deodorizing effects on bad breath caused by methyl mercaptan. [3] .

Application of tea polyphenols in daily necessities

As an excellent additive for cosmetics and daily necessities, tea polyphenols have the following significant effects: strong antibacterial effect (including skin and oral bacteria) and inhibition of oxidase (such as tyrosinase, glucose transfer of Streptococcus mutans) Enzymes, urinine decarboxylase, lipoxygenase, etc.), it can prevent and treat skin diseases, skin allergies, skin pigmentation and anti-wrinkle, anti-caries, dental plaque, periodontitis and bad breath. At the same time, it can prevent the sun's rays from damaging the skin. In addition, it can also eliminate bad breath. Therefore, tea polyphenols can be used in cosmetics and daily necessities as antioxidants, preservation agents, anti-wrinkle agents, skin whitening agents, radiation protection agents, sunscreens and special cosmetic additives, etc., as well as in daily cosmetics, such as baths. Soap, bath lotion, shampoo, detergent, toothpaste, tooth powder, mouthwash, anti-halitosis, etc., increase the function of these products [4].

Application of tea polyphenols in medicine

Tea polyphenols have obvious effects on the prevention and treatment of the following diseases: lowering blood pressure, anticoagulation, lowering blood fat and obesity, preventing and treating cardiovascular diseases such as arteriosclerosis and thrombosis, lowering blood sugar, preventing and treating diabetes, sterilizing and antiviral; preventing and treating gastrointestinal and respiratory tract , Influenza and other diseases; prevention and treatment of hepatitis, anti-aging and enhancement of immune function; treatment of teeth, prevention of periodontitis, prevention of dental caries, deodorization and detoxification. Tea polyphenols can be used as raw materials for auxiliary medicines and health medicines for patients with the above diseases [6].

1. Antioxidant

Tea polyphenols is an excellent natural antioxidant, and its antioxidant properties are closely related to the synergy between the components. The best combination is EGCG (epigallocatechin gallate): ECG (epicatechin) Gallate): EGC (Epigallocatechin): EC (Epicatechin) = 5:2:2:1. Moreover, tea polyphenols and other antioxidants also have a synergistic effect, such as VC, VE, carotenoids and glutathione. These synergistic effects enhance the antioxidant effect of tea polyphenols. A large number of experimental studies have shown that the various pharmacological activities of tea polyphenols, such as anti-tumor, anti-aging, and blood lipid regulation, are closely related to the antioxidant properties of tea polyphenols [6].

2. Regulate blood lipids

Tea polyphenols can more comprehensively adjust blood lipids, especially lower serum TG (triglycerides), TC (total cholesterol) and low-density lipoprotein cholesterol (LDL-C) content, and increase high-density lipoprotein. In addition, tea polyphenols are strong inhibitors of low-density lipoprotein oxidation, which can effectively inhibit the oxidative modification of LDL, and have a certain inhibitory effect on the influencing factors of atherosclerosis [6].

3. Antiviral and antibacterial effects

As a broad-spectrum, potent and low-toxic antibacterial drug, tea polyphenols have been recognized by scholars in many countries around the world. In numerous antibacterial tests, people have found that it is against many pathogenic bacteria such as Proteus vulgaris, Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus mutans, Clostridium botulinum, Lactobacillus, Vibrio cholerae and Streptococcus mutans, especially It has different degrees of inhibition and killing effect on intestinal pathogenic bacteria. At the same time, it can effectively prevent antibiotic-resistant Staphylococcus infections and has inhibitory activity on hemolysin. In addition, tea polyphenols also have a strong inhibitory effect on pathogenic fungi that can cause human skin diseases, such as white ringworm of the head, spotted blisters white ringworm, sweaty blisters white ringworm, and stubborn ringworm. Tea polyphenols can also protect the beneficial bacteria in the intestine [6].

4. Anti-tumor effect

Tea polyphenols exhibit anti-mutagenic effects in vitro, and can inhibit the tumors of the skin, lung, stomach, esophagus, pancreas, prostate, duodenum, colon and rectum caused by carcinogens in rodents. The main mechanisms of tea polyphenols in inhibiting tumors are as follows: ① Anti-oxidation and scavenging free radicals. ② Block the formation of carcinogens and inhibit the metabolic transformation in the body. Tea polyphenols can block the synthesis of nitroso compounds with strong carcinogenic effects in the body, and further inhibit the carcinogenic effects of nitrosamine compounds. ③Inhibit the activity of enzymes with cancer-promoting effects, such as inhibiting the activity of telomerase to realize its anti-cancer activity. ④ Improve the body's immunity. ⑤ Reversal of multidrug resistance of tumor cells. ⑥ Influence on the opening of PT pores (pores for changing mitochondrial permeability). It is speculated that tea polyphenols may directly act on the protein components of the PT pores, thereby regulating mitochondrial permeability, changing the opening of the pores, and protecting mitochondria from damage. ⑦Inhibit the biosynthesis of tumor cell DNA. Tea polyphenols can induce DNA double-band breakage in tumor cells, showing a positive correlation between the concentration of tea polyphenols and the degree of DNA double-band breakage. Therefore, it can inhibit tumor cell DNA synthesis and further inhibit tumor growth and proliferation [6].

5. Other functions

Tea polyphenols is a natural antioxidant with significant antioxidant effect, which can eliminate excessive free radicals produced in the human body, protect the structure of cell membranes, slow down human aging, and prolong human life. Tea polyphenols have unique protective and therapeutic effects on the skin. They can effectively prevent ultraviolet rays from damaging the skin, as well as anti-aging wrinkles, clearing brown spots, preventing acne, preventing edema and anti-allergic effects. In addition, tea polyphenols can also improve chronic renal failure and glomerulonephritis, as well as regulate immunity