What effect does the doctor's speech in support of jim have?

The Doctor says that Jim is a good man and that the people of that town shouldn't treat him badly just because he is black. The townspeople then change their behavior towards Jim a bit, because the Doctor is a respectable man and what he says must be true. Thus, Jim starts living in better conditions, although he is still chained and fed only bread and water.

Think it's rice because in many countries rice is the main food so it can be traditionally served all at once.