acerbate vs ruffle some feathers

acerbate

verb
  • To exasperate; to irritate. 

  • To make bitter or sour. 

adj
  • Embittered; having a sour disposition or nature. 

ruffle some feathers

verb
  • To cause a disturbance; to arouse resentment, anger, or concern. 

How often have the words acerbate and ruffle some feathers occurred in a corpus of books? (source: Google Ngram Viewer )