Rehydration Characteristics and Structural Changes of Sweet Potato Cubes after Dehydration

摘要

Moisture removal from solids is an integral part of food processing with convective drying representing one of the most important techniques for preservation of biological products. However, removal of moisture during drying has detrimental effects on the physio chemical properties of the material. For evaluating of the rehydration capability the sweet potato cubes of 1.2x1.2x1.2 cm were dried to final moisture content of 6-7% (d.b.) under air temperature of 50, 60, 70, 80 and 90°C and air velocity of 3.5 m sec^-1 in a laboratory scale hot air dryer. Deterioration of the physical attributes of the system was evaluated on the basis of rehydration characteristics, namely the coefficient of rehydration and rehydration ratio at different soaking time period of 10, 15, 20, 25 and 30 min. Structural changes in Sweet potato cubes after drying were studied by light microscopy. The rate and degree of dehydration was dependent on the drying conditions, with extent of cellular and structure disruption dictating the rehydrational capacity. The drying temperature had an effect on the shrinkage of cell structures of sweet potato. It was observed that the degree of shrinkage of sweet potato during low temperature drying is greater than at high-temperature during drying.