Osmotic Dehydration in Food Processing
“In osmotic dehydration, the principle of osmosis i.e. movement of water from a low concentrated solution to a high concentration solution via a semi-permeable membrane is used.”
What is osmotic dehydration?
Osmotic dehydration is the removal of water by immersing the food in a solution of salt or sugars with high osmotic pressure. Water is removed from the food to the solution by virtue of the difference in osmotic pressure.
Water and some of the natural solutes of the food pass to the osmotic solution, while at the same time a certain amount of the “osmotic solute” penetrates the food. The rate of removal of water can be enhanced by increasing the concentration of the osmotic solution or the temperature.
Application
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- Essentially, the process of partial removal of water by osmosis is an operation that has been known and practiced for centuries. Salting fish and candying fruit (such as pethas) are examples of long-established food processing techniques where removal of water takes place together with solute penetration.
- Apart from this, the process is being used in industry to dehydrate fruits, vegetables, and meat, but the industrial application is still limited.
- Osmotic infusion of fruits can also be used as a pretreatment step prior to processing operations such as convection drying or freezing thereby reducing the overall energy requirements in the dehydration process.
“Selection of the osmotic solution composition and the process conditions aims at maximizing the water removal and minimizing all other transports. The osmotic solution is recycled, after concentration by evaporation.”
Popular Osmotically dehydrated products in India:
- Pethas
- Murabbas of Indian gooseberry (amla), apple and other fruits
- Mango Pickle
- Semi-dried fruit ingredients included in various complex foods such as ice-creams, cereals, dairy, confectionary and bakery products.
Among various methods of preservation of fruits and vegetables, osmotic dehydration is simple and an effective method. By this process, the product retains its original color, flavor, taste, and nutritional qualities in comparison to other drying and preservation methods. Keeping in view the benefits and advantages of this process, in the nearby future, consumers will prefer products which are preserved by osmotic dehydration.
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