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Year: 2016, Issue: June
Methods to increase the rate of mass transfer during osmotic dehydration of fruits and vegetables.
V. Ramya and N. K. Jain
High hydrostatic pressure, Osmotic dehydration, Pulsed electric field ultrasound and vacuum impregnation.
Osmotic dehydration is more and more often used during processing of fruits and vegetables. It is a simultaneous mass transfer process which mainly promotes the flow out of water molecules from the food to osmoactive solution and some migration of solutes from the solution into the food. Thus, allows maintaining good organoleptic and functional properties in the finished product. The rate of mass transfer during osmotic dehydration of plant foods is generally slow process; the cellular membrane exerts high resistance to transfer and slows down the osmotic dehydration rate Thus, there has always been a need to develop supplementary techniques to enhance the mass transfer without adversely affecting the quality. Therefore, the partial damage of cell membranes using different pre-treatment methods can be advantageous for acceleration of mass transfers process. This review paper is focused on methods of streamlining the process of osmotic dehydration which include the use of: blanching, ultrasound, high hydrostatic pressure, pulsed electric field, vacuum impregnation and ohmic heating. These new combination methods increase mass transfer and drying rate of fruits and vegetables by increasing the cell membrane permeability. The operation time in the combined methods is shorter than that in traditional osmotic dehydration, causing further energy saving.
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