Conclusion
This study showed the advantage of grinding and sieving
green tea leaves to increase content of polyphenols. Our re-
sults revealed that antioxidant activity was dependent on par-
ticle size. However, it is important to control grinding speed
and particle size to avoid catechin degradation by heat and
oxidation. The highest antioxidant activity and catechin con-
tent were obtained with the particle size of 100–180 μmat
6000 rpm, which then determine the best conditions for the
grinding of green tea leaves. This procedure maybe extended
to other food applications, for example to improve nutritive
values.