milldust vs semolina

milldust

noun
  • The fine, flour-like dust produced when corn or wheat is milled 

semolina

noun
  • Coarse grains produced at an intermediate stage of wheat flour milling. 

  • Such grains, usually from durum wheat, used in the preparation of pasta, couscous and various sweet dishes. 

How often have the words milldust and semolina occurred in a corpus of books? (source: Google Ngram Viewer )