In the world of dreams the rules of reality do not necessarily apply. Each dream is unique and it's a direct link to the soul and spirit. Psychology provides its own theories on what dreams mean, but so did tradition and the study of dreams for thousands of years before any relevant science had developed.
Dream Meanings - Grapes
If you dream of ripe grapes then you will enjoy progress at work and happiness and serenity at home. To eat rotten and vinegary grapes means you will argue with a superior at work. If you tread grapes to produce wine must then you will argue with some people but your anger will soon pass.