Tracking the thermal induced vapor transport across foam microstructure by means of micro-sensing technology

In thermally processed multiphase systems such as cereal based foam, the material characteristics as well as the thermo-physical processes are of major impact on the internal heat transfer rate. Improving and optimizing this production step would contribute to an enormous amount of energy saving, considering the high demand on bakery products in the world. Bread baking is a high complex process and the determination of the included processes and their relevance is not simple, since the main processes are occurring in the micro-scale. Heat transfer in cereal based foam is expected to depend mainly on the evaporation–condensation mechanism, therefore it is crucial to determine heat and mass transfer phenomena inside the bread. Due to the hazardous surrounding conditions, such as high temperature and humidity it becomes challenging to find applicable sensors working reliable under such conditions. This study shows the application of micro-sensors to examine temperature and humidity distribution inside the foam during heating and gives insight in the impact of water vapor on the heating rate due to evaporation–condensation.

► Humidity and temperature were measured in cereal foam during thermo-treatment.
► Results enlighten the impact of water vapor distribution on the heating rate.
► Considerations of evaporation–condensation on heat transfer were realized.