Effect of Pulsed Vacuum Treatment on Mass Transfer and Mechanical Properties during Osmotic Dehydration of Pineapple Slices

The influence of operating pressure during osmotic dehydration on mass transfer and mechanical properties in pineapple fruits was analyzed. Dehydration trials were performed at atmospheric pressure (OD) and by applying a vacuum pulse (VPOD), in sucrose solution at 60°Brix and 40°C for 300 min. Seven operation conditions were implemented with a vacuum pulse of 100 mbar or 250 mbar for 0, 5, 15 or 25 min at the beginning of the process. The decrease of pressure favored the solute uptake, but the water loss has not been significantly affected. No significant effect of vacuum time was observed. However, solute uptake in trials with vacuum pulse of 100 mbar was significantly higher than in OD process. In general, mechanical properties and shrinkage were not affected by operation conditions. Osmotic dehydration process (both OD and VPOD) originates a more resistant tissue structure than the one in fresh pineapple fruit.