A convective multi-flash drying process for producing dehydrated crispy fruits

The aim of this work was to evaluate the application of a convective multi-flash drying process (CMFD) to producing dehydrated and crisp fruits. To accomplish this process, samples of banana (Musa sapientum L) or mango (Mangifera indica L) were heated to 60 degrees C by hot air, and a vacuum pulse was applied, which resulted in dehydration by a combination of convective drying and flash evaporation. Banana processed by CMFD had a moisture content of 0.293 g/g (dry basis) and a(w) = 0.272 after 3 h of processing. Mango had a moisture content of 0.09 g/g and a(w) = 0.359 after 4 h of processing. Puncture tests on fruits dehydrated by CMFD and on commercial freeze-dried fruits showed strain-force curves with many peaks (jagged curves). For CMFD much smaller global shrinkage was observed. These results indicate that the CMFD process can be applied for producing crispy fruits and is an alternative to the freeze-drying process. (C) 2011 Elsevier Ltd. All rights reserved.