leavening agent vs sodium bicarbonate

leavening agent

noun
  • Any organism or substance added to a food product (such as dough or batter) that makes it rise when cooked. 

sodium bicarbonate

noun
  • This salt used in cooking as a raising agent, as an antacid, a cleaner, etc. 

  • A salt of sodium hydroxide and carbonic acid, NaHCO₃. 

How often have the words leavening agent and sodium bicarbonate occurred in a corpus of books? (source: Google Ngram Viewer )