In food industry,absorption isoterm curve give valuable information about design and optimization dry,storage,packaging,mixing and predication food stability.complicate structure of food creats problems in predection and it is necessary to do experimental tests.this curve explain points that curve have an humidity equilibrim with surrounding enviroments.this curve have many application in food science and agriculture and it can used in process such as storage & dry & packaging in this paper we evaluate rule of this curve in food process one we explain applications of this curve in about product such as grape and pistachio,