Minimally processed papaya by vacuum osmotic dehydration (VOD) techniques

The application of vacuum osmotic impregnation at constant temperature (25 degrees C) to obtain high moisture minimally processed papaya was evaluated . The fruit effective porosity was determined employing vacuum impregnation in isotonic sucrose solutions, obtaining values of around 3.4%. The fruit was submitted to vacuum osmotic dehydration (VOD) processes (60 mbar) in 60 degrees Brix sucrose syrups to depress aw from 0.99 to 0.98 (or less), alw ays having a greater effectiveness than in the case of osmotic dehydration (OD) processes at atmospheric pressure. The use of a VOD initial process fo r different times, followed by the application of OD (called pulsed vacuum osmotic dehydration, PVOD, processes) had a greater effectiveness in depres sing the a(w) than when only OD was applied in processes up to 240 min. The pH reduction due to the addition of citric acid (2.5, 5.0 and 7.5%) to the sucrose syrup was more effective when applying VOD or PVOD processes. Mini mally processed papaya (a(w) 0.98, pH 3.5) could be obtained by applying VO D for only 10 min if the sucrose syrup had a citric acid concentration of 7 .5%, or PVOD processes (VOD < 15 min and then OD < 45 min), employing conce ntrations of 2.5 and 5.0% of acid in the syrup.