Question

Why is hand picking is necessary after winnowing?

Answer 1

Hi I have an answer for you

In the fields there are a lot of substances that can be mixed due to winnowing like small stones or grains. In the process of winnowing they are blown into the product and it is difficult to separate it.

In the process of hand picking the weightless contamination i.e. stones and grains and grain cover can be separated easily that is why hand picking is preferred in most areas

Answer 2

Hand Picking is necessary after winnowing because through winnowing, the wind blows away the lighter chaff while the heavier and slightly larger sized impurities fall back down and mix with the grain. The method of hand picking can be used for separating slightly larger sized impurities like the pieces of stone, dirt, and the husk from wheat, rice or pulses. 

The quantity of these impurities is usually not very large. In such situations, the hand picking is a convenient method of separating above mentioned impurities.