A simplified model for predicting shrinkage during low temperature air drying of porous food materials

Food materials shrink when they are air-dried. However, owing largely to the complexity of modelling, most drying models so far have neglected this shrinkage, leading to inaccurate predictions. The empirical nature, inability to yield data on location-specific deformations and computational cost of detailed poro-mechanistic analyses and complex deformation modelling approaches make them unattractive for models that could be used in real-time process control algorithms. In this work, we develop a simplified transport model to predict spatial and temporal shrinkage during low temperature air drying process, and validate the model with experiments. In such drying, volumetric change is dominated by moisture loss; therefore the role of gas induced porosity is neglected. This model predicts shrinkage, temperature and moisture content at each spatial location at time intervals during the drying process. The model agrees well with experiments conducted by us (reported in this paper) as well as with those conducted by others (taken from the literature) on food samples. We expect that this generalized model will find wide applications in the food processing industry.