Abstract:
The objective of this research is to suggest appropriate methodto predict temperature profile in food substances considering the effect ofshape, structure and composition. The project considered 2-layer compositecylindrical shape food substances having various compositions and differentthermal properties . Generally, the heat transfer phenomena during foodprocessing is unsteady state process. The essential property of a materialthat indicates thermal penetration potential of the material is the thermaldiffusivity which depends on the compositions of food. This researchstudied three different mathematical models to predict temperature profile infood materials. The three models assumed that the materials can be modelas single infinite cylinder ( Model l), composite 2-layer infinite cylinder( Model 2 ) or single finite cylinder ( Model 3).For the effect of shape on cylindrical shaped food substances, itwas found that selecting a proper model depends on the ratio of diameterand length (O/L) and the position distance from center (x/x,) of thecylinder. On the effect of non-homogeniety of materials in the case of2-layer composite materials which contain different compositions, it wasfound that the effect of homogeniety of material on the heat transferdepends on the ratio of inner and outer diameters of the cylinder (r&J.On the effect of compositions, it was recommended that model whichconsider only water content such as Martenss model be used for foodsubstances with water content greater than 40 percents. For low watercontent, the effect of compositions are important and model such as thatof Chois should be use. For cooked tuna with water content greater than40 percents, Martens s model was used with Model 1 and found to be asuitable model for tuna.