Question

Wheat dough is left in the open after a few days start to emit a foul smell and become unfit for use

Answer 1

In the presence of moisture, many useful as well as harmful microorganisms live there in order to get nutrients for their survival. This makes the dough unfit to use

Answer 2

Carbohydrates in wheat dough encourage growth of yeast and other saprophytic fungi elwhich break down carbohydrates, and emit a foul smell.