You love the authentic tea fragrance and health benefits from tea powder, but don't want pay for tea powder whose quality is less than premium. How can you tell the difference between tea powder with filler versus pure tea powder?
They are fundamentally different product.
Instant tea powder: Tea leaves brewed with water to make tea juice ➜ Adjust tea juice ingredients according to planned product➜ Dry tea juice into powder.
Most of the nutritions ( let alone antioxidants) and tea fragrance will get loss during this multi-step producing process, so artificial flavor is necessary to make it acceptable to customers. That's why you can never find "pure" instant tea powder at supermarket.
Ground tea powder: Tea leaves are put into mills, and ground in to fine powder directly. Traditionally tea makers use stone mills, but more and more modernized factories choose to use supperalloy grinding machine, or combine stone and superalloy grinding, to offer tea powder with better quality. There is no further processing or adjustment involved.
That's why ground tea powder preserve almost all the natural, strong tea flavor, and antioxidants.