Which preposition to use with acidity

of Occurrences 16%

A little pounded sugar added to this sauce is by many persons considered an improvement, as the saccharine matter takes off the extreme acidity of the unripe fruit.

in Occurrences 2%

For the relaxation consequent on an overloaded stomach, or acidity in the bowels, a little magnesia dissolved in milk should be employed two or three times a day. 2575.

to Occurrences 1%

He touched theory again in continuing the cause of acidity to bacterial actionand the possibility of infection in epidemic form.

Which preposition to use with  acidity