Heat transfer to a model dough product during mixed regime thermal processing

A number of food processes involve mixed regime (combination of conductive, convective, and radiant) heating. The behaviour of foods under these conditions is complex and requires on-line measurements. A laboratory-scale study has been undertaken to relate the heat transfer characteristics of a domestic oven to a dough product and the changes in food properties. Experiments were designed to isolate each of the heat transfer modes from the mixed regime process using metal discs with different surfaces. The convective heat transfer coefficient was determined at various oven settings, and this result used to prove the method by comparing the heat capacity of a known system to a published value. A dough product was heated in a process similar to an industrial heating process and the contributions of conduction, convection, and radiation were established. The heat capacity profile (C-pf) of the dough product was measured in the rig and compared to results obtained from a differential scanning calorimeter (DSC). The results suggest that the relative contribution of the various heat transfer mechanisms in an industrial processing environment could be manipulated to achieve a desired quality in the final product.