Explain the Winnowing and Primary processing of wheat

 Winnowing: In this process, the impurities are  separated on the principle that their density differs from that of the grain kernels. The operation depends on air movement to remove the lighter fractions. The simplest method is to drop a basket of kernels and impurities in a thin stream onto a clean surface through a slight natural breeze. This is a slow and laborious process but it is still widely practiced. Winnowing machines operate on the same principle but a fan creates air movement.
 
Primary processing of wheat: Wheat is consumed mostly in the form of flour obtained by milling the grain. Wheat can be broadly classified into three groups from the milling and baking point of view: (a) Hard wheat, (b) Durum wheat, and (c) Soft wheat. Flour made from hard wheat is used for bread-making, while flour from soft wheat is used for biscuits, cakes and breakfast foods. Semolina  is prepared from hard wheat and durum wheat.