WINNOWING

verb

1. To subject (granular material, especially food grain) to a current of air separating heavier and lighter components, as grain from chaff.
2. To separate, sift, analyze, or test by separating items having different values.
3. To blow upon or toss about by blowing; to set in motion as with a fan or wings.

noun

1. The act of separating chaff from grain.