The term is used in a number of contexts. It refers to the removal of frost from a cooler to improve heat transfer, e.g. From a cooling coil. It is used to describe the heating of plates in a contact freezer to release frozen produce (hot gas defrost), ease reloading and improve heat transfer. Demerit points The essential element of a system for rating the overall quality of an item. The attributes of the product that contribute to its quality are defined. The degree of change in each attribute as quality decreases is rated on a numeric scale starting at a low value, usually 0, for excellent quality of that , attribute.