The mathematical modelling of the rehydration characteristics of fruits

Freeze-dried fruits (avocado, kiwi fruit, apple, banana and potato) were rehydrated by dipping them in water at room temperature and their rehydration characteristics examined. The samples were found to restore up to 90% of their original moisture content, depending on the type of fruit and various other factors like ripeness and the freezing condition. The water uptake happened rapidly during the first 30 s and then slowed down with time until it finally stopped altogether. A mathematical model based on one-dimensional, steady state, fully developed capillary flow of water with negligible inertia effects within the fruits was developed. The mathematical model was found to suitably describe the rehydration behavior and the model with the parameters generated can be used satisfactorily to predict the rehydration pattern of fruits.