When I first read this headline, I thought it had to do with purity of a certain Swiss-made variety that left its mark on San Francisco (and surprisingly, Palo Alto---e.g. Jerry Garcia and Ken Kesey). My mistake
I should have known better, especially in the context of this website. Due to a recent conversation with a friend about ph balance and the acidity of various foods, I thought it was a discussion of the chemical properties of various substances. Extraneous context affecting my initial impression.