Changes in mechanical properties throughout osmotic processes - Cryoprotectant effect

In osmotic dehydration of fruits, physical and chemical changes occurring t hroughout the process provoke changes in the product texture and appearance to a different degree depending on the process conditions and product char acteristics. Nevertheless, water content reduction and sugar gain have been observed to have some cryoprotectant effects on colour and texture in seve ral fruits. In this work, the specific influence of osmotic treatments with sucrose solutions at 30 degreesC on mechanical properties of mango, kiwi a nd strawberry are discussed. The combined effect of blanching and vacuum im pregnation is analysed in mango. The influence of osmotic solution concentr ation and vacuum impregnation on kiwi fruit is discussed and the effect of osmotic dehydration, as compared with air drying is analysed in strawberry. In all cases, changes in mechanical properties of fresh and pre-dehydrated fruits due to freezing-thawing are compared in order to quantify the cryop rotectant effect of the osmotic treatment. (C) 2001 Elsevier Science Ltd. A ll rights reserved.