Examination of rehydration characteristics of dried bell pepper and eggplant

Drying is an important preservation method for the food industry. Dried products are also named as ready-made foods and they have more advantages like transportation, storage, preparation and usage rather than fresh foods. Some dried products need rehydration process before consumption. Herewith, dried products' water absorption capacity can be examined and also the quality of drying method can be commentated. The quality properties of rehydrated product are effected by the drying and rehydration process. Physicochemical changes, including textural structural modifications, migration of solutes and loss of volatiles are happened as an irreversible manner and play an important role on the quality during the drying process. Drying and rehydration conditions need to be optimizing to obtain the most suitable rehydration properties. The rehydration ratio is an important quality parameter so foods are processed in optimum conditions for preventing the food injuries and providing the shortest time of rehydration. The most important point of rehydration technology is mathematical modeling of rehydration process. The purpose of modeling is helping design engineers to choose the most suitable operation conditions for the process. In this study, rehydration modeling of dried bell pepper and eggplant was examined. The effect of pre-treatment (with 1% sugar and 1% salt) was determined and according to the results of all the experiments at 25, 45, 65 and 85°C, the highest rehydration ratio was calculated in untreated process. Besides, rehydration graphics were drew for both untreated and pre-treated experiments to saw the effects of temperature on rehydration process. For all the experiments, the results showed that rehydration at 85°C has the highest rehydration ratio at the end of the experiments. The increasing of rehydration temperature has a positive effect on rehydration ratio. To evaluate the rehydration kinetics of bell pepper and eggplant, the obtained experimental data were applied to Peleg, Weibull, First-order and Exponential models and the best model fit was determined. According to the results, Peleg model is superior to the other models for explaining rehydration behavior of bell pepper and eggplant.