Although the vast majority of Demon's eat the "Fruit" from the Orchard as their main form of sustenance, demons that want to be extremely frugal with their favors will eat "Edible things". These also come from the Orchard, but they are not the perfectly formed "Fruits". These are growths that form on the trees and must be scraped off. For a long time they were discarded, but when it was found that the worker demons would snack on them, with no ill effect, they were then made available for general demon consumption. Ironically these have slightly higher energy density than the Fruit, but they don't taste nearly as good, and are considered an extremely "low class" food.
Of course none of the Masters would eat anything from the Orchard, importing all their food directly from the Surface. Demon Knights are also discouraged from eating from the Orchard, as they must maintain high energy reserves at all times.
-log of current events by Demon Master Dzu