I know that this gets a little complicated, and it is further clouded by the issue of whether the Miracle-Mineral-Supplement is strongly oxidizing any organics in the drink at all ...
But green grass/powder, and/or veggie juice or veggie smoothies, are not alkaline in the glass. If you take a ph meter or a ph stick and test such a drink, you will find that a grass powder (such as a mix of barley grass, wheat grass, etc...) will LOWER the ph down to a slightly acidic state.
When I make Alkaline Water with my Jupiter, or with alkalizing mineral drops, I find that the addition of a green powder usually lowers the ph down to slightly below 7 ... maybe 6.5
These drinks are VERY alkalizing within the body though. This does not mean that they become alkaline within the stomach, when they hit the HCL, but that as they are broken down and absorbed they give the body what it needs to move to an alkaline state.
So, this should not interfere with the acidic reaction needed to continue activating the ClO2.