[NorthMountain]

This is NOT new ... I heard this in the 1980s.

“Alum” (aluminum sulfate) was used in pickles and as a component in baking powder, among other things. I don’t see it in commercial pickles any more, and not all brands of baking powder use it. Aluminum toxicity can cause dementia ...

[Calvin Locke]

“Alum” (aluminum sulfate) was used in pickles and as a component in baking powder,...

Alum was used in the early 1800s to "renew" old flour.

Something on the 5-6oz per a sack (280lbs?) of flour.

[Hillbillary]

"“Alum” (aluminum sulfate) was used in pickles and as a component in baking powder, among other things."

I didn't know that. I remember as a child, I had a canker sore in my mouth and my mother sprinkled powdered alum on it to deaden the pain.