Purpose:Winnowing is a crucial step in grain processing, ensuring that the edible grain is clean and free from unwanted materials before further processing or consumption. How it works:The process relies on the difference in density between the grain and the chaff. When tossed into the air, the wind or a fan blows away the lighter chaff, while the heavier grain falls back down. Historical context:Winnowing is one of the oldest agricultural techniques, dating back to ancient times. Modern applications:While traditionally done manually, winnowing can also be performed using mechanical winnowers in modern farming. Other uses:The term winnowing can also be used more broadly to describe the separation of any lighter material from a heavier substance using a current of air, such as removing fine material from sediment by wind or water.