A new method is presented to compute the sensitivity of the temperature course inside conduction heated foods with respect to the surface heat transfer coefficient. The method is based on the finite element formulation of the heat conduction equation. As an illustrative example, a sensitivity analysis of the reheating process of ready-made lasagna is carried out. Sensitivity charts are constructed which relate the dimensionless centre temperature with the Blot and Fourier number for slab, cylinder and sphere shapes. It is shown that in the case of processes with low surface heat transfer coefficient, such as food chilling using air at moderate speeds or convection heating of prepared meals, small deviations in the surface heat transfer coefficient may result in large deviations in the core temperature of the food.