From the results, both black tea and oolong tea samples had the
highest content of quercetin types of FOG, and green tea samples
had the highest content of kaempferol types of FOG. Referring to
the classification of 6 tea classes in the world, both black tea and
oolong tea were mostly manufactured from the Large-leaved species
and with the process of fermentation, while green tea was
mostly manufactured from the Small-leaved species and without
the process of fermentation, tea cultivar and processing method
might be the uppermost factors for the FOG content in tea samples.
This should be further studied.