acerbate vs harsh one's mellow

acerbate

verb
  • To make bitter or sour. 

  • To exasperate; to irritate. 

adj
  • Embittered; having a sour disposition or nature. 

harsh one's mellow

verb
  • To spoil one's good mood or to annoy one. 

How often have the words acerbate and harsh one's mellow occurred in a corpus of books? (source: Google Ngram Viewer )