Osmotic dehydration

Osmotic dehydration is a process based on the immersion of a food, either whole or in pieces, in hypertonic solutions, promoting a simultaneous water loss and solutes penetration into the food. In osmotic dehydration, equilibrium conditions are maintained on both sides of the membrane by evacuating water from a lower solute concentration to a higher concentration.

Osmotic dehydration is one of the best and suitable method to increase the shelf life of fruits and vegetables. In osmotic dehydration, the fruit or vegetable pieces are immersed in concentrated aqueous solution of high osmotic pressure (hypertonic media) for a specified time and temperature.

This is multicomponent diffusion process. In this process water flow from fruits or vegetables to solution and along with water some components of fruits and vegetables such as minerals, vitamins, fruit acids etc. also move towards solution. The sugar and salt migrate towards the fruits and vegetables.

The driving force for water removal is the concentration gradient between the solution and the intracellular fluid.

Osmotic dehydration is a low-cost treatment and preferred over other methods due to their color, aroma, taste retention property, nutritional quality of food, and flavor compound retention value.

Factors such as the fruit: solution ratio, temperature, solution concentration, agitation level and processing time and temperature can influence the mass transfer of water and solutes in the osmotic dehydration process.
Osmotic dehydration