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.