Coupling between heat and mass transfer and stoechio-kinetic models to bring insight into Maillard reaction kinetics during baking of sponge-cake products

The objective of this work is to present the methodology used to bring insight into interactions between heat and mass transfer phenomena (within the heating product and between the product and its environment) and the extent of Maillard reaction (influenced by the variations of local values of product moisture content, temperature and reactants concentration) during baking of a sponge-cake type bakery product. Therefore, a heat and mass transfer model coupled with a stoechio-kinetic model has been developed. This model aimed at mechanistically inter-relate the level of operating conditions and the initial composition of the bakery products (in terms of reducing sugars and amino-acid contents) with the nature and extent of Maillard reactions occurring during baking. The developed heat and mass transfer model takes into account internal moisture evaporation and vapour migration within the open porosity of the product during heating as well as apparent liquid moisture migration described by Fick's law. Internal heat transfer phenomena were described using Fourier's law and apparent thermal heat conductivity. External heat and mass transfer phenomena taken into account were convective drying, convective and radiative heat transfer for both heating product and baking tray. Concerning the stoechio-kinetic model developed in the present work, attention was paid to the nature of simplifying assumptions made to deal with phenomena of concern. This point is particularly important considering the complex reaction scheme of Maillard reaction which was necessarily reduced to a simplified observable scheme taking into account bibliographical references about the subject and available experimental data about reactivity acquired during the study. The level of physical realism of heat and mass transfer model previously discussed has hence been adapted to the level of complexity of the stoechio-kinetic model.