Research And Development Of Analytical Methods Of Tea Polyphenols And The Establishment Of Its Quality Standard

Tea polyphenols belong to one class of strong antioxidantpolyphenolic compounds in tea, and its weight percentage composition isabout15%to25%in dried fresh tea. In recent years, lots of studiesindicated that tea polyphenols had antioxidant, anti-inflammatory,anti-tumor, anti-radiation, anti-virus and other pharmacological effects,and the content was very important for the quality of the tea.Tea polyphenols are the derivatives of2-phenyl benzopyran as themain parent structure, which mainly include six categories, flavanols(also known as catechins), flavones, flavonols, phenolic acids, depsideclass and anthocyanin. Wherein the catechins are the major component ofthe tea polyphenols, accounting for90%of the total content, and it is theunique ingredient in tea. There are lots of components in catechins,wherein (-)-Epigallocatechin-3-O-gallate (EGCG) content is about80%.However, the complex composition and difficulty of accuratelydetermination restricthindered the further study of tea polyphenols.Based on lots of existing methods in the literatures’ method, we used the people’s Republic of China Light Industry Standard QB2154-1995,national standard GB/T5009.3-2003, the current enterprise standard etc.and the standard monograph of powdered decaffeinated green tea Extractin the United States Pharmacopoeia USP34-NF29, drafted a qualitystandard draft of tea polyphenols according to the requirement of UnitedStates Pharmacopoeia and Food Chemicals Codex (USP-FCC), andrespectively use the current enterprise standard and the tea polyphenolsquality standard draft of the United States Pharmacopoeia and FoodChemicals Codex (USP-FCC) to analyses6code of tea polyphenols, tomake a comparative study of the two quality standard analysis method,confirm that the tea polyphenols quality standard draft according to theUnited States Pharmacopoeia and Food Chemicals Codex (USP-FCC)can be suitable. We mainly study the determination method of teapolyphenols in the QB21541995standards, GB/T5009.3-2003standardsand the enterprise standard of determination, such as spectrophotometricmethod, HPLC method and the loss on drying method, and we also studythe quality standard draft which had been drafted according to therequirement of the United States Pharmacopoeia and Food ChemicalsCodex (USP-FCC),such as identification using TLC method, HPLCmethod and IR method, determination of moisture content, ignitionresidue detection, heavy metal limit detection, limit of caffeine usingHPLC method, polyphenol determination of content and EGCG determination of content using HPLC method, limit of gallic acid usingHPLC method and so on.Through the comparative study, we found that there is advantagesand disadvantages between the two kinds of quality standards. For thesmall and medium-sized enterprises which is limited to the kind ofexperimental equipment, the current enterprise generally qualitystandards of tea polyphenols is easy to operate (example, using thespectrophotometric methods which had been described in the nationalstandard to determine the content of tea polyphenols). For the large andmedium-sized enterprises, the drafted quality standard which had beendafted according to the United States Pharmacopoeia and FoodChemicals Codex (USP-FCC) has good specificity and high precision,reliable detection method, repeatability of the test results is high, thisstandard can be more accurate and rapid identification and determine thetea polyphenols, and it may serve as a provide the data support and thetheoretical reference for the further research on the establishment of foodquality standard.