Dried stevia leaves are subjected to purified water first. Then followed by a precipitation process with ferric chloride and calcium hydroxide to remove non-soluble plant materials & other impurities and follow filtration.
So they’re washed with soap and water? Must we use the scariest language possible here?
TOS' quality drops off in the third season, but those first two years are almost all bangers. TNG era shows have a similar ratio, it's just reversed: they struggle at the start, and pick up as they go.