Osmotic dehydration is a pre-drying treatment in which fruit is immersed in a concentrated sugar or salt solution so that water migrates out of the tissue by osmosis, reducing moisture content and improving texture and flavour retention in the finished product.
In trade practice
Processors use osmotic dehydration before air or belt drying to reduce the load on the dryer and improve the texture of the final product. Buyers of semi-dried or candied fruit should check Brix of the soaking solution and confirm residual sugar uptake, as this affects labelling and nutritional declarations. A common oversight is failing to account for the added sugar when declaring ingredients or calculating carbohydrate content. Specifications should state whether osmotic pre-treatment has been applied.
In a specification
Where osmotic dehydration is used, a specification or process sheet should state the solute type, concentration and immersion duration, and confirm whether the treatment affects the declared sugar content of the finished product.