Osmotic dehydration has received greater attention in recent years as an effective method for preservation of
fruits and vegetables. Being a simple process, it facilitates processing of tropical fruits and vegetables such as
banana, sapota, pineapple, mango, and leafy vegetables etc. with retention of initial fruit and vegetables
characteristics viz., colour, aroma and nutritional compounds (Pokharkar & Prasad, 1998). It is less energy
intensive than air or vacuum drying processes because it can be conducted at low or ambient temperature. It has
potential advantages for the processing industry to maintain the food quality and to preserve the wholesomeness
of the food. It involves dehydration of fruit slices in two stages, removal of water using as an osmotic agent
(osmotic concentration) and subsequent dehydration in a dryer where moisture content is further reduced to
make the product shelf stable (Ponting, 1973).
Osmotic concentration is the process of water removal from fruits and vegetables, because the cell membranes
are semi-permeable and allow water to pass through them more rapidly than sugar. During osmosis small
quantity of fruit acid is removed along with water. It is a dynamic process, in which water and acid are removed
at first and then move slowly, while sugar penetration is very slight at first but increases with the time. Therefore,
the characteristics of the product can be varied by controlling temperature, sugar syrup concentration,
concentration of osmosis solution, time of osmosis etc. to make osmotic concentration process faster.