Techniques for Extraction of Green Tea Polyphenols: A Review

Tea is the second most consumed beverage all over the world after water. In recent times, tea has stretched the eyebrows of researchers and catching all the attention towards its health benefits. Tea has been proven beneficial by preventing the risk of some diseases like cancer and cardiovascular problems. Green tea is least processed and gives maximum benefits. The main components of the green tea are polyphenols which include the catechins, epicatechins, epigallocatechins, epicatechingallate, epigallocatechingallate, gallic acid, flavanoids, flavanols, and flavonols. Other than polyphenols, caffeine and theophylline are also present. Among which compounds of catechins family has been widely reported to have most beneficial effects on the health. Currently, the extraction of catechins is catching much higher attention and many techniques have been discovered and modified to extract these compounds. But very limited reviews have been reported discussing the impact of various techniques used for extraction of green tea polyphenols. This review focuses on various techniques employed for the extraction of polyphenols from green tea and other sources (pine bark, grape seed, and pomegranate) with their advantages and limitations. The current trends and future prospects are also highlighted.