MATHEMATICAL-MODELING OF TRANSIENT HEAT AND MASS-TRANSPORT IN A BAKING BISCUIT

Drying behavior of a single baking biscuit was modeled using unsteady state, anisotropic, two dimensional, simultaneous heat and mass balanc es. Solutions of these equations agreed well with the experimentally d etermined temperature and the moisture data. Modeling revealed that in the outer sections of the baking biscuit conduction and diffusion wer e the dominant heat and mass transfer mechanisms, respectively. In the central section of the biscuit the gas cells cracked with the increas ed vapor pressure and the upward volume expansion, then air/vapor encl aves were formed among the horizontal dough layers in the radial direc tion. The dominant heat and mass transfer mechanisms in the central se ction of the biscuit were convection. Presence of two different regime zones in a baking biscuit may have important consequences concerning the strength of the commercial products against crumbling during marke ting and consumption.