国产成人青青热久免费精品_国产xxxxx在线观看免费_污污在线观看_亚洲永久精品免费www_91视频免费污_韩国毛片免费看

Catechin are phenolic compounds extracted from tea leaves and etc natual plants.It is white or yellow powders or irregular crystal.

Catechin are four main types:①Epicatechin -- EC;②Epigallocatechin -- EGC;③Epicatechin gallate -- ECG;④Epigallocatechin gallate -- EGCG。